IJSPT Volume 17, Number 3

IJSPT

INTERNATIONAL JOURNAL OF SPORTS PHYSICAL THERAPY

An Official Publication of

A North American Sports Medicine Institute Publication

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1. Dima R, Tieppo Francio V, Towery C, Davani S. Review of Literature on Low-level Laser Therapy Benefits for Nonpharmacological Pain Control in Chronic Pain and Osteoarthritis. Altern Ther Health Med. 2018 Sep;24(5):8-10. PMID: 28987080.

2. Larkin KA, Martin JS, Zeanah EH, True JM, Braith RW, Borsa PA. Limb blood flow after class 4 laser therapy. J Athl Train. 2012 Mar-Apr;47(2):178-83. doi: 10.4085/1062-6050-47.2.178. PMID: 22488283; PMCID: PMC3418129.

3. Chow RT, Johnson MI, Lopes-Martins RA, Bjordal JM. Efficacy of low-level laser therapy in the management of neck pain: a systematic review and meta-analysis of randomised placebo or active-treatment controlled trials. Lancet. 2009 Dec 5;374(9705):1897-908. doi: 10.1016/S0140-6736(09)61522-1. Epub 2009 Nov 13. Erratum in: Lancet. 2010 Mar 13;375(9718):894. PMID: 19913903.

4. Alayat MS, Atya AM, Ali MM, Shosha TM. Long-term effect of high-intensity laser therapy in the treatment of patients with chronic low back pain: a randomized blinded placebo-controlled trial. Lasers Med Sci. 2014 May;29(3):1065-73. doi: 10.1007/s10103-013-1472-5. Epub 2013 Nov 2.

5. Yousefi-Nooraie R, Schonstein E, Heidari K, Rashidian A, Pennick V, Akbari-Kamrani M, Irani S, Shakiba B, Mortaz Hejri SA, Mortaz Hejri SO, Jonaidi A. Low level laser therapy for nonspecific low-back pain. Cochrane Database Syst Rev. 2008 Apr 16;(2):CD005107. doi: 10.1002/14651858.CD005107.pub4. PMID: 18425909.

6. Holanda VM, Chavantes MC, Silva DF, de Holanda CV, de Oliveira JO Jr, Wu X, Anders JJ. Photobiomodulation of the dorsal root ganglion for the treatment of low back pain: A pilot study. Lasers Surg Med. 2016 Sep;48(7):653-9. doi: 10.1002/lsm.22522. Epub 2016 May 2. PMID: 27135465.

7. Jovicić M, Konstantinović L, Lazović M, Jovicić V. Clinical and functional evaluation of patients with acute low back pain and radiculopathy treated with different energy doses of low level laser therapy. Vojnosanit Pregl.

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8. Abbasgholizadeh ZS, Evren B, Ozkan Y. Evaluation of the efficacy of different treatment modalities for painful temporomandibular disorders. Int J Oral Maxillofac Surg. 2020 May;49(5):628-635. doi: 10.1016/j. ijom.2019.08.010. Epub 2019 Sep 21. PMID: 31547949.

9. Khairnar S, Bhate K, S N SK, Kshirsagar K, Jagtap B, Kakodkar P. Comparative evaluation of low-level laser therapy and ultrasound heat therapy in reducing temporomandibular joint disorder pain. J Dent Anesth Pain Med. 2019 Oct;19(5):289-294. doi: 10.17245/jdapm.2019.19.5.289. Epub 2019 Oct 30. PMID: 31723669; PMCID: PMC6834715.

10. Roberts DB, Kruse RJ, Stoll SF. The effectiveness of therapeutic class IV (10 W) laser treatment for epicondylitis. Lasers Surg Med. 2013 Jul;45(5):311-7. doi: 10.1002/lsm.22140. Epub 2013 Jun 3. PMID: 23733499.

Copyright © 2022 by DJO, LLC • MKT00-12297 Rev A Individual results may vary. Neither DJO, LLC nor any of its subsidiaries dispense medical advice. The contents of this document do not constitute medical, legal, or any other type of professional advice. Rather, please consult your healthcare professional for information on the courses of treatment, if any, which may be appropriate for you.

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Staff Executive Editor/Publisher Michael L. Voight, PT, DHSc, OCS, SCS, ATC, CSCS Director of Operations and Marketing Mary Wilkinson Editor in Chief Barbara Hoogenboom, PT, EdD, SCS, ATC Managing Editor Ashley Campbell, PT, DPT, SCS, CSCS Manuscript Coordinator Casey Lewis, PTA, ATC

NORTH AMERICAN SPORTS MEDICINE INSTITUTE Publisher Contact Information International Journal of Sports Physical Therapy 6011 Hillsboro Pike Nashville, TN 37215, US, http://www.ijspt.org IJSPT is a bimonthly publication, with release dates in February, April, June, August, October and December.

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IJSPT

INTERNATIONAL JOURNAL OF SPORTS PHYSICAL THERAPY

Executive Editor/Publisher Michael L. Voight, PT, DHSc, OCS, SCS, ATC, CSCS Belmont University Nashville, Tennessee – USA Editor in Chief Barbara Hoogenboom, PT, EdD, SCS, ATC Grand Valley State University Grand Rapids, Michigan - USA Managing Editor Ashley Campbell, PT, DPT, SCS, CSCS Nashville Sports Medicine and Orthopaedic Center Nashville, Tennessee – USA Manuscript Coordinator Casey Lewis, PTA, ATC Nashville Sports Medicine and Orthopaedic Center Nashville, Tennessee – USA Editors Robert Manske PT, DPT, Med, SCS, ATC, CSCS University of Wichita Wichita, KS, USA Terry Grindstaff, PT, PhD, ATC, SCS, CSCS Creighton University Omaha, NE, USA Phil Page PT, PhD, ATC, CSCS Franciscan University DPT Program Baton Rouge, LA, USA Kevin Wilk PT, DPT, FAPTA Clinical Viewpoint Editor Champion Sports Medicine Birmingham, AL, USA International Editors Kristian Thorborg PT, PhD, RISPT Copenhagen University, Amager-Hvidovre Hospital Hvidovre, Denmark Colin Paterson PT, MSc PGCert(Ed), MCSP, RISPT, SFHEA University of Brighton Brighton, England, UK Luciana De Michelis Mendonça, PT, PhD UFVJM Diamantina, Brazil Chris Napier, PT, PhD Clinical Assistant Professor University of British Coumbia, Vancouver, BC, Canada Associate Editors Eva Ageberg, PT, PhD Professor, Lund University Lund, Sweden Lindsay Becker, PT, DPT, SCS, USAW Buckeye Performance Golf Dublin, Ohio, USA

Keelan Enseki, PT, MS, OCS, SCS, ATC University of Pittsburgh Pittsburgh, PA, USA John Heick, PT, PhD, DPT, OCS, NCS, SCS Northern Arizona University Flagstaff, AZ, USA Julie Sandell Jacobsen, MHSc, PhD VIA University Aarhus, Denmark RobRoy L. Martin, PhD, PT, CSCS Duquesne University Pittsburgh, PA, USA Andrea Mosler, PhD, FACP, FASMF La Trobe Sport and Exercise Medicine Research Centre, School of Allied Health, Human Services and Sport, La Trobe University Melbourne, Victoria, Australia Brandon Schmitt, DPT, ATC PRO Sports Physical Therapy Scarsdale, NY, USA Barry Shafer, PT, DPT Elite Motion Physical Therapy Arcadia, CA, USA Laurie Stickler, PT, DHSc, OCS Grand Valley State University Grand Rapids, MI, USA Editorial Board James Andrews, MD Andrews Institute & Sports Medicine Center Gulf Breeze, AL, USA Amelia (Amy) Arundale, PT, PhD, DPT, SCS Red Bull/Ichan School of Medicine Salzburg, Austria/New York, NY, USA Gary Austin, PT PhD Belmont University Nashville, TN, USA Roald Bahr, MD Oslo Sports Trauma Research Center Oslo, Norway Lane Bailey, PT, PhD Memorial Hermann IRONMAN Sports Medicine Institute Houston, Texas, USA Gül Baltaci, PT,Ph.D. Professor, CKTI, FACSM Private Guven Hospital Ankara, Turkey Asheesh Bedi, MD University of Michigan Ann Arbor, MI, USA David Behm, PhD Memorial University of Newfoundland St. John's, Newfoundland, Canada

EDITORIAL BOARD Barton N. Bishop, PT, DPT, SCS, CSCS Kaizo Clinical Research Institute Rockville, Maryland, USA

Brian Cole, MD Midwest Orthopaedics at Rush Chicago, IL, USA

Mario Bizzini, PhD, PT Schulthess Clinic Human Performance Lab Zürich, Switzerland

Ann Cools, PT, PhD Ghent University Ghent, Belgium

Joe Black, PT, DPT, SCS, ATC Total Rehabilitation Maryville, Tennesse, USA

Andrew Contreras, DPT, SCS Washington, DC, USA

Turner A. "Tab" Blackburn, APTA Life Member, ATC-Ret, AOSSM-Ret NASMI Lanett, AL, USA Lori Bolgla, PT, PhD, MAcc, ATC Augusta University Augusta, Georgia, USA Matthew Briggs The Ohio State University Columbus, OH, USA Tony Brosky, PT, PhD Bellarmine University Louisville, KY, USA Brian Busconi, MD UMass Memorial Hospital Boston, MA, USA Robert J. Butler, PT, PhD St. Louis Cardinals St. Louis, MO, USA Duane Button, PhD Memorial University St. Johns, Newfoundland, Canada

George Davies, PT, DPT, MEd, SCS, ATC, LAT, CSCS, PES, FAPTA Georgia Southern University Savannah, Georgia, USA Pete Draovich, PT Jacksonville Jaguars Footbal Jacksonvile, FL, USA Jeffrey Dugas, MD Andrews Institute & Sports Medicine Center Birmingham, AL, USA Jiri Dvorak, MD Schulthess Clinic Zurich, Switzerland Todd Ellenbecker Rehab Plus Phoenix, AZ, USA Carolyn Emery, PT, PhD University of Calgary Calgary, Alberta, Canada Ernest Esteve Caupena, PT, PhD University of Girona Girona, Spain

J. W. Thomas Byrd, MD Nashville Sports Medicine and Orthopaedic Center Nashville, TN, USA

Sue Falsone, PT, MS, SCS, ATC, CSCS, COMT Structure and Function Education and A.T. Still University Phoenix, Arizona, USA

Lyle Cain, MD Andrews Institute & Sports Medicine Center Birmingham, AL, USA

J. Craig Garrison, PhD, PT, ATC, SCS Texas Health Sports Medicine Fort Worth, Texas, USA

Gary Calabrese, PT, DPT Cleveland Clinic Cleveland, Ohio, USA

Maggie Gebhardt, PT, DPT, OCS, FAAOMPT Fit Core Physical Therapy/Myopain Seminars Atlanta, GA and Bethesda, MD, USA

Meredith Chaput, PT, DPT, SCS Ohio University Athens, OH, USA

Lance Gill, ATC LG Performance-TPI Oceanside, CA, USA

Rita Chorba, PT, DPT, MAT, SCS, ATC, CSCS United States Army Special Operations Command Fort Campbell, KY, USA

Phil Glasgow, PhD, MTh, MRes, MCSP Sports Institute of Northern Ireland Belfast, Northern Ireland, UK

John Christoferreti, MD Texas Health Dallas, TX, USA

Robert S. Gray, MS, AT Cleveland Clinic Sports Health Cleveland, Ohio, USA

Richard Clark, PT, PhD Tennessee State University Nashville, TN, USA

Jay Greenstein, DC Kaizo Health Baltimore, MD, USA

Juan Colado, PT, PhD University of Valencia Valencia, Spain

Martin Hagglund, PT PhD Linkoping University Linkoping, Sweden

EDITORIAL BOARD Allen Hardin, PT, SCS, ATC, CSCS University of Texas Austin, TX, USA

Terry Malone, PT, EdD, ATC, FAPTA University of Kentucky Lexington, KY, USA

Richard Hawkins, MD Professor of surgery, University of South Carolina Adjunct Professor, Clemson University Principal, Steadman Hawkins, Greenville and Denver (CU)

Robert Mangine, PT University of Cincinnati Cincinnati, OH, USA

John D.Heick, PT, PhD, DPT, OCS, NCS, SCS Northern Arizona University Flagstaff, AZ, USA Tim Hewett, PhD Hewett Consulting Minneapolis, Minnesota, USA Per Hølmich, MD Copenhagen University Hospital Copenhagen, Denmark Kara Mae Hughes, PT, DPT, CSCS Wolfe PT Nashville, TN, USA Lasse Ishøi, PT, MSc Sports Orthopedic Research Center Copenhagen University Hospital Hvidovre, Denmark Jon Karlsson, MD Sahlgrenska University Goteborg, Sweden Brian Kelly, MD Hospital for Special Surgery New York, NY, USA Benjamin R. Kivlan, PhD, PT, OCS, SCS Duquesne University Pittsburgh, PA, USA Dave Kohlrieser, PT, DPT, SCS, OCS, CSCS Ortho One Columbus, OH, USA Andre Labbe PT, MOPT Tulane Institute of Sports Medicine New Orleans, LA USA Henning Langberg, PT, PhD University of Copenhagen Copenhagen, Denmark Robert LaPrade, MD Twin Cities Orthopedics Edina, MN, USA Lace Luedke, PT, DPT University of Wisconsin Oshkosh Oshkosh, WI, USA Lenny Macrina, PT, SCS, CSCS, C-PS Champion Physical Therapy and Performance Boston, MA, USA Phillip Malloy, PT, PhD Arcadia University/Rush University Medical Center Glenside, PA and Chicago, IL, USA

Eric McCarty, MD University of Colorado Boulder, CO, USA Ryan P. McGovern, PhD, LAT, ATC Texas Health Sports Medicine Specialists Dallas/Fort Worth, Texas, USA Mal McHugh, PhD NISMAT New York, NY, USA Joseph Miller, PT, DSc, OCS, SCS, CSCS Pikes Peak Community College Colorado Springs, CO, USA Havard Moksnes, PT PhD Oslo Sports Trauma Research Center Oslo, Norway Michael J. Mullaney, PT, SCS NISMAT Mullaney & Associates Physical Therapy New York, NY and Matawan, NJ, USA Andrew Murray, MD, PhD European PGA Tour Edinburgh, Scotland, UK Andrew Naylor, PT, DPT, SCS Bellin Health Green Bay, WI, USA Stephen Nicholas, MD NISMAT New York New York, NY, USA John O'Donnel, MD Royal Melbourne Hospital Melbourne, Australia Russ Paine, PT McGovern Medical School Houston, TX, USA Snehal Patel, PT, MSPT, SCD HSS Sports Rehabilitation Institute New York, NY, USA Marc Philippon, MD Steadman-Hawkins Clinic Vail, CO, USA Nicola Phillips, OBE, PT, PhD, FCSP Professor School of Healthcare Sciences Cardiff University, Cardiff, Wales, UK Kevin Plancher, MD, MPH, FAAOS Plancher Orthopedics and Sports Medicine New York, NY USA

EDITORIAL BOARD Marisa Pontillo, PT, PhD, DPT, SCS University of Pennsylvania Health System Philadelphia, PA, USA

Andreas Serner, PT PhD Aspetar Orthopedic and Sports Medicine Hospital Doha, Qatar

Matthew Provencher, MD Steadman Hawkins Clinic Vail, CO, USA

Ellen Shanley, PT, PhD ATI Spartanburg, SC, USA

Charles E. Rainey, PT, DSc, DPT, MS, OCS, SCS, CSCS, FAAOMPT United States Public Health Service Springfield, MO, USA

Karin Silbernagel, PT, PhD University of Delaware Newark, DE, USA

Alexandre Rambaud, PT PhD Saint-Etienne, France Carlo Ramponi, PT Physiotherapist, Kinè Rehabilitation and Orthopaedic Center Treviso, Italy Michael Reiman, PT, PhD Duke University Durham, NC, USA Mark F. Reinking, PT, PhD, SCS, ATC Regis University Denver, CO, USA Mike Reinold, PT, DPT, SCS, ATC, CSCS, C-PS Champion Physical Therapy and Performance Boston, MA, USA

Holly Silvers, PT, PhD Velocity Physical Therapy Los Angeles, CA, USA Lynn Snyder-Mackler, PT, ScD, FAPTA STAR University of Delaware Newark, DE, USA Alston Stubbs, MD Wake Forest University Winston-Salem, NC, USA Amir Takla, B.Phys, Mast.Physio (Manip), A/Prof Australian Sports Physiotherapy The University of Melbourne Melbourne, Australia Charles Thigpen, PhD, PT, ATC ATI Spartanburg, SC, USA

Mark Ryan, ATC Steadman-Hawkins Clinic Vail, CO, USA

Steven Tippett, PT, PhD, ATC, SCS Bradley University Peoria, IL, USA

David Sachse, PT, DPT, OCS, SCS USAF San Antonio, TX, USA

Tim Tyler, PT, ATC NISMAT New York, NY, USA

Marc Safran, MD Stanford University Palo Alto, CA, USA

Timothy Uhl, PT, PhD, ATC University of Kentucky Lexington, KY, USA

Alanna Salituro, PT, DPT, SCS, CSCS New York Mets Port Saint Lucie, FL, USA

Bakare Ummukulthoum, PT University of the Witswatersrand Johannesburg, Gauteng, South Africa

Mina Samukawa, PT, PhD, AT (JSPO) Hokkaido University Sapporo, Japan Barbara Sanders, PT, PhD, FAPTA, Board Certified Sports Physical Therapy Emeritus Professor and Chair, Department of Physical Therapy Texas State University Round Rock, TX, USA Felix “Buddy” Savoie, MD, FAAOS Tulane Institute of Sport Medicine New Orleans, LA, USA Teresa Schuemann, PT, DPT, ATC, CSCS, Board Certified Specialist in Sports Physical Therapy Evidence in Motion Fort Collins, CO, USA Timothy Sell, PhD, PT, FACSM Atrium Health Musculoskeletal Institute Charlotte, NC, USA

Yuling Leo Wang, PT, PhD Sun Yat-sen University Guangzhou, China Mark D. Weber, PT, PhD, SCS, ATC Texas Women’s University Dallas, TX, USA Richard B. Westrick, PT, DPT, DSc, OCS, SCS US Army Research Institute Boston, MA, USA Chris Wolfe, PT, DPT Belmont University Nashville, TN, USA Tobias Wörner, PT, MSc Lund University Stockholm, Sweden

TABLE OF CONTENTS VOLUME 17, NUMBER 3 PAGE

TITLE

EDITORIAL Top 10 “Intangibles” That Will Help You Become a Better Physical Therapist.

Manske R IN MEMORIAM INTERNATIONAL PERSPECTIVE 327 Injury Prevention in Women’s Gymnastics – A Need for New Routines.

Anker-Petersen C, Thorborg K INVITED CLINICAL COMMENTARY 330 The Management of Biceps Pain: Non-Operative & Surgical.

Moore Z, Cain EL, Wilk KE SYSTEMATIC REVIEW 334 Effect of Low-Load Blood Flow Restriction Training After Anterior Cruciate Ligament Reconstruction: A Systematic Review.

Koc BB, Truyens A, Heymans MJLF, Jansen EJP, Schotanus MGM. ORIGINAL RESEARCH 347 Side Effects and Patient Tolerance with the Use of Blood Flow Restriction Training after ACL Reconstruction in Adolescents: A Pilot Study.

Prue J, Roman DP, Giampetruzzi NG, et al.

355 Dual-Task Gait Performance Following Head Impact Exposure in Male and Female Collegiate Rugby Players.

Kieffer EE, Brolinson PG, Rowson S. 366 Normative Data for the NeuroCom Sensory Organization Test in United States Military Academy Boxers.

Henry NE, Weart AN, Miller EM, Feltner LD, Goss DL. 378 Feasibility and Reliability of a Novel Game-Based Test of Neurological Function in Youth: The Equilibrium Test Battery.

Shepherd HA, van Rassel CR, Black AM, et al.

390 Machine Learning Does Not Improve Humeral Torsion Prediction Compared to Regression in Baseball Pitchers.

Bullock GS, Thigpen CA, Collins GS, et al.

400 Band Pull-Apart Exercise: Effects of Movement Direction and Hand Position on Shoulder Muscle Activity.

Fukunaga T, Fedge C, Tyler T, et al.

409 Survey with Innovations to Increase Response Rate Reveals Low Compliance with Guidelines among Youth Baseball Coaches – Including a Survey of Differences between Cities.

Kaizu Y, Oyama Y, Ishihara Y, Honma Y. 420 Injury and Illness in Elite Athletics: A Prospective Cohort Study Over Three Seasons.

Kelly S, Pollock N, Polglass G, Clarsen B 434 Quadriceps Strength following Anterior Cruciate Ligament Reconstruction: Normative Values based on Sex, Graft Type and Meniscal Status at 3, 6 & 9 Months.

Schwery NA, Kiely MT, Larson CM, et al.

445 Are Elite Collegiate Female Athletes PRIME for a Safe Return to Sport after ACLR? An Investigation of Physical Readiness and Integrated Movement Efficiency (PRIME).

Chaaban CR, Hearn D, Goerger B, Padua DA. 456 Reliability of the Expanded Cutting Alignment Scoring Tool (E-CAST) to Assess Trunk and Limb Alignment During a 45-Degree Side-Step Cut. Butler LS, Martinez AR, Sugimoto D, et al.

466 Reliability and Differences Between Sexes in Landing Mechanics when Performing the Lateral Bound Test.

Waldhelm A, Allen S, Grand L, et al.

TABLE OF CONTENTS (continued) VOLUME 17, NUMBER 3 PAGE 474

483

493

TITLE Sex-related Anthropometrics in a Lower-Body Mobility Assessment Among Professional Soccer Athletes.

Hedt CA, Le JT, Heimdal T, et al.

Lower Extremity and Trunk Electromyographic Muscle Activity During Performance of the Y-Balance Test on Stable and Unstable Surfaces.

Kaur N, Bhanot K, Ferreira G. Intra-rater Reliability of a Qualitative Landing Scale for the Single-Hop Test: A Pilot Study.

Measson MV, Ithurburn MP, Rambaud AJM.

501

Training Habits and Injury Rate in Masters Female Runners.

Loudon J, Parkerson-Mitchell A. CLINICAL COMMENTARY 508 Classification Based Treatment of Greater Trochanteric Pain Syndrome (GTPS) with Integration of the Movement System.

Disantis AE, Martin RL. 519

Nonoperative Management of Traumatic Acromioclavicular Joint Injury: A Clinical Commentary with Clinical Practice Considerations.

Sciascia A, Bois AJ, Kibler WB. TECHNICAL REPORT 541 Can a Patient use an App at Home to Measure Knee Range of Motion? Utilizing a Mobile App, Curovate, to Improve Access and Adherence to Knee Range of Motion Measurements.

Shah N, Grunberg C, Hussain Z.

EDITORIAL

Top 10 “Intangibles” that will help you become a better physical therapist

By Robert Manske, PT, DPT, MEd, SCS, ATC, LATC, CSCS Associate Professor, Doctoral Physical Therapy Program at Wichita State University, Wichita, Kansas

I was recently asked to give a short 5-minute talk at a national meeting, and the topic was “What I will and what I won’t do in the training room/physical therapy clinic.” I sat on this for some time, thinking about what content I should include. What equipment do I include, what type of treatments will I or won’t I use in the clinic? After months of putting the formulation of this talk off, I decided to pull out my inner Tom Brady and call an audible at the line and completely change the play. I decided to slightly change my talk to be “What I will do in the clinic and what intangibles are needed to be a better sports physical therapist or athletic trainer?”

One of my former patients was an active NBA player. I was fortunate enough to take my family to see him play the Oklahoma City Thunder. On that night, instead of watching the game, I noticed myself watching him interact with his coaches, players, and their fans. What I saw was a brilliant display of someone giving everything for the betterment of the team. During warm-ups, while everyone else was jogging around taking it easy, he was sprinting from baseline to mid-court like he had a purpose. During layup drills, he attacked the basket and ran all the way back to half court every time, while everyone else jogged about half as far as he did. When the game started, he was the most enthusiastic player on the team – for HIS teammates. During a time out, guess who the first guy off the bench was? Of course, it was my guy! If a player came off the court and dropped their towel, guess who was there to pick it up and give them a pat on the back? You are right again, my guy! What I noticed that night was a player exhibiting all the “intangibles” of a great athlete. Although he did not

get much playing time that night, he was one of the most valuable players on the team. An intangible asset is an asset that is not physical in nature. You will not see intangibles in the stat sheet.

They will not be seen on a resume or even with a face-toface interview. They will not show up on your weekly productivity report to your managers.

However, these are characteristics that are more valuable than any skill we can learn during physical therapy school or during any post education continuing educational course.

The primary goal of this editorial is to describe a list of 10 intangibles that will help you become a better sports physical therapist, and, in all reality, become a better version of yourself. These intangibles are not listed in any order, nor is this an exhaustive list.

There are many more intangibles than the ten that I will list. But I believe these are a good start at some of the best. #1: Teamwork Teamwork is a collaborative effort of a group to achieve a common goal or to complete a task in the most efficient way possible. It is rare that any one individual makes up a team. Shaquille O’Neil was quoted that during a stretch of one season some of the team felt that Kobe Bryant was not passing the ball enough. Shaq told Kobe that “there’s no I in team.” Kobe replied, “There’s an M-E in that mother f—er.” Teamwork in our setting of healthcare includes many individuals that can be seen in Figure 1. To be a good team player we must trust each other and understand that we are all equals.

We should all work together for a common goal of getting the athlete back to their sport as soon as

they are able. There #3. Integrity are times that we may C.S. Lewis said that feel that our cog in the “Integrity is doing the wheel is more imporright thing. Even when no tant than those of the one is watching.” Integrity other cogs. Remember, is the quality of being the other cogs probably honest and having strong feel the same as you – moral principles. I would that they are more hope that we all want to important. We must have integrity. I can put that feeling of supeassure you that no one riority aside so that we will ever not value can keep open lines of integrity. There are many communication and ways in which you can work together. Every demonstrate integrity in member of the team is the rehabilitation setting. critical for success to Come to work ready to occur. We need to be put in a full day, without Figure 1: The healthcare team. respectful, caring, and complaints or frustration. compassionate for our Be a team player at work athlete and each member of our team. The great and give help when it is needed, not just when it is coach Phil Jackson once said, “The strength of the convenient. Don’t talk about co-workers behind their team is each individual member. The strength of back, especially about things that you know would be each member is the team.” hurtful to them. Try to see other peoples’ point of view if there is a disagreement. Be accountable for #2: Honesty your actions. If you have a patient that is struggling, Honesty is the quality of being honest with people. don’t constantly blame them. Practice enough selfIt simply implies a refusal to lie to someone. There reflection to see that maybe you are not giving them are times when honesty is difficult. Have you ever 100%. And if you have that ability to self-reflect, fix been asked the dreaded question by your signifiwhat is wrong. Try to stay cool under pressure and cant other, “Do I look fat in this outfit?” The honest make sound decisions, even when the stress level is person tells the truth, the smarter person tells a lie! high. Lead by example. You want to be the person All kidding aside as you can clearly see honesty is your co-workers look up to when they need motivanot always easy. Being totally honest can make tion. If you lead by a good example others will follow patients, people you work with, or your family and pick up on your integrity and want to follow angry or upset. I have learned the hard way that your example. sometimes it is better to soften the honesty instead of just laying it all out on the table. Instead of #4: Loyalty telling the co-worker they are lazy, maybe suggest Loyalty is the quality of being loyal. Loyalty is a ways that they could be more productive. If a strong feeling of support or allegiance. If you value patient asks if they are doing as well as most people patients, they will be loyal to you for life. One way to at this timeframe after surgery, it is best to be know if you are a good therapist or not is how loyal honest. But maybe be honest in a way that allows your patients are. We all have patients that return for them to build hope and trust in you as their healthevery injury and recommend everyone they know to care provider. Honesty is a key component of one’s come see you for any musculoskeletal issues. And by character and a very admiral trait to have. John the way, they will only see you and nobody else.

Lennon said it well when he was quoted, “Being That is true loyalty. The patient probably feels this honest may not get you a lot of friends, but it’ll way because you were able to help them when they always get you the right ones.” needed care the most. They obviously trust you and

more than likely you made them feel valued. But it is not only our patients who should be loyal. We as therapists should be loyal to our patients. If you do not have the expertise to help them, you should be confident enough to refer them to someone else who can. Be loyal in return. We need to be loyal to our co-workers and physicians we work for and with. People appreciate loyalty. Please remember though, loyalty is earned and not given easily.

Earning loyalty takes time, it does not happen overnight. #5: Positive Attitude Your attitude is the feeling or way of thinking that affects a person’s behavior. It is a state of mind as it relates to situations, people, or things. We know that we are not going to have a great attitude everyday as attitudes are situational. When under stress, attitudes are not always high. However, we need to bring a positive attitude to work 100% of the time.

We know that positive attitudes exhibit optimism and this is especially important for patients during rehabilitation. This positive attitude is especially important to your patients who do not always feel positive. You need to be their guiding light. Despite what you are feeling, you should always be positive toward your patients and co-workers. A positive attitude can help overcome adversity. If you are positive, you can look at the bright side of any situation and help others see light at the end of the tunnel.

Your positive attitude will attract people, not repel them. Confucius said: “If you are positive, you’ll see opportunities instead of obstacles.” #6: Energetic Being energetic is having a zest for life and what you do for your profession. It should be easy to be energetic when you feel like you have a calling toward physical therapy and rehabilitation. It is easy when you feel that you have purpose! When you have energy and confidence you can emit a sense of peace and calm and help to energize those whom you meet. Remember that being positive is a choice only you can make every single day. Don’t let others bring you down or try to steal your positive energy.

Positive energy is especially important for your patients who most likely are in some level of pain or have some form of functional limitation. Think of how you feel when you are hurt, or not able to do the things that you want to do. Just like us, patients are not always energetic, or positive when they are

hurting or under stress. Hopefully, the patients can feed off your positive energy to overcome their limitations. #7: Authentic Authenticity is the quality of being genuine. I would hope that this is how you would want people to see you. To be authentic you must be yourself. To be able to show people the real you, you first must know the real you. That in and of itself can be a huge hurdle for many who have been hurt emotionally. Anyone who follows social media knows that we are constantly bombarded with images of who we should be, and who we should want to be. Being authentic is a collection of choices you must make every day. Try not to be what society thinks you should be, as that only suppresses the real you. That can leave you disconnected from others. That is certainly not what you need if you are wanting to be the best PT version of yourself. #8: Patience If I were totally honest, I would probably say that patience is the one intangible that I struggle with the most and I am guessing a lot of you are the same. We want something now. We need immediate gratification. To have patience is the capacity to accept or tolerate delay, trouble, or suffering without getting angry or upset. It is the ability to stay calm in adversity. I do know that with time and experience we gain patience, especially in the clinical setting. Having patience allows you to stay calm in adversity and allows you time to make better judgments. I have been in the operating room watching surgeons when things do not go exactly as planned. You can quickly tell the surgeons with patience from those who are impatient. The impatient surgeons typically yell at staff and blame others for things that go wrong. The surgeons with patience think for a moment, don’t get upset, and come up with a resolution to fix the problem without even raising their voice. We should be like the latter while we are in the clinic.

Stay calm when things are not going exactly as planned. Take a deep breath and exhale before making a rash decision. Your patience will usually have a calming effect on your patients and other co workers around you.

#9: Dependable Being dependable means being trustworthy and reliable. That means you will not let others around you down. This is an extremely important virtue to have for not only work, but also for family and friends. To be dependable you must put yourself in a position where your actions matter. You show dependability by your actions not your words.

Being dependable means showing up to work on time. It means getting your paperwork turned in on time. If a co-worker needs help with a patient whose condition you are familiar with, help them out, share your knowledge with them about the subject. You prove you are dependable through action and results, not through words. However, if you do give your word to someone, stand by it.

Carry through with what you say you will do. I sometimes use the desire to be dependable to my advantage. I have had instances where I want to do something, but I was not certain I would be able or that I was good enough to accomplish the task. Or when someone asks me to do something I am not sure I can do the task but want to push myself. I either tell someone I am going to do it or agree to do the given task. Because I want to be known as being dependable – it forces me to do things I do not have 100% comfort in doing. So, if you find yourself needing a push and you are the type of person that is dependable – say yes or announce to people you are going to do something. Then keep your word, start putting together an action plan, get to work, and prove your dependability. Most often you will have pushed yourself just enough that whatever you agreed to do will be a hit. #10: Kindness I have left the most important tangible for the last.

Simply enough it is to be kind. Kindness is the quality of being friendly, generous, and considerate.

The Dalai Lama once said, “Be kind whenever possible. It is always possible.” For our patients and co-workers there are so many ways that we can show kindness and they are not that difficult for us to do. It can be as simple as being happy and smiling. How hard is it to smile at work? Other ways are to help around the clinic when it is busy. We have several great physical therapist assistants at our clinic who always come to help clean tables or pick up equipment when they have downtime.

They could just sit in the office and talk, but they show kindness and consideration for others. It is extremely helpful for those of us that have full case loads all day long.

Although we sometimes think our patients should be grateful for us, we should be grateful for them.

Because of them we get the opportunity to heal and make people feel better daily. What job is better than that? Share praise for a co-worker when they do a good job. Tell your co-workers that you appreciate them. You will never find a person who does not like to hear that they are appreciated. Admit that you are wrong and don’t be afraid to share your mistakes. It makes others feel much better when they realize they are not the only one that makes mistakes. And if all else fails – tell a joke. A very good friend and former student of mine works in our clinic and constantly tells goofy jokes. It never fails to bring laughter. As much as people like to say they hate the “dad jokes,” you know that they all love them!

If you follow and try to be compliant with even half of these intangibles, you will no doubt be a better clinician, a better friend, a family member, spouse, etc. I challenge you to try to adopt even one or two of these intangibles for 3-4 weeks and see how it changes your own mindset and even those around you. If you already have adopted some of these in your personal and work life, I would challenge you to add one or two more. Take an index card and write several of the intangibles on them and tape them to your mirror in the bathroom so you are reminded daily of the “intangibles” you want to possess. This will help keep them in your mind daily. It is much easier to remember them when you see them constantly.

If you can think of other intangibles that I have not mentioned feel free to contact me on social media at Twitter - @robptatcscs and Instagram – Robert_Manske.

I think these intangibles and others like them are important enough that I would love to keep the dialog going and spread the word. Go out, take it to the max, and be the best physical therapist version of yourself you can be!

CHAMP L. BAKER, Jr., MD: IN MEMORIAM

By Turner A. “TAB” Blackburn, Jr.

The sports medicine world suffered a great loss March 18, 2022 when Champ L. Baker, Jr., MD, passed away at 75 years of age in Columbus, GA. His passing will be mourned not only by his family and friends, former patients and surgeon colleagues, but by many sports physical therapists.

Dr. Baker was a native of Alexandria, LA. His mother, a nurse, was his inspiration to go into medicine. His undergraduate and medical school degrees were earned at LSU. He was recruited to play basketball at LSU and the 6’5” freshman showed a lot of promise, but in his second year, a 6’5” shooting guard named “Pistol” Pete Maravich joined the team. The NBA was out but sports medicine gained quite an addition.

Following medical school, Champ joined the U.S. Army, where he completed his orthopedic residency at Letterman Army Medical Center in San Francisco, CA, and Shriners Hospital for Crippled Children in St. Louis, MO. He later completed a sports medicine fellowship under Dr. Jack Hughston in Columbus, GA in 1979.

After retiring from the Army as a Lt. Colonel, he joined the Hughston Clinic in 1982.

He and his wife Sue Ann raised three children which gave him the joy of eight grandchildren.

He served as president of The Hughston Clinic from 1994 until 2000, and was an orthopedics professor at Tulane University School of Medicine and at the Medical College of Georgia.

He formerly served as Chair of the Board of Directors of The Hughston Foundation and as program director of the Hughston Sports Medicine Fellowship. He had an extremely active practice in Columbus. Champ served as team physician for numerous local and regional athletic teams, including the University of

Alabama and Columbus State University, where he was inducted into the CSU Sports Hall of Fame. He was a volunteer physician for the U.S. Olympic Committee. He started and funded scholarships for students in nursing and athletic training careers.

Nationally and internationally, Champ was active in many professional societies and served as an officer or committee member of the American Academy of Orthopaedic Surgeons; American Shoulder and Elbow Society; American Orthopaedic Society for Sports Medicine; American Orthopaedic Association; International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine; and Arthroscopy Association of North America.

He was president of the American Orthopaedic Society for Sports Medicine, Southern Orthopaedic Association, Georgia Orthopaedic Society, and Georgia Shoulder and Elbow Society.

He was inducted into the Halls of Fame of both the Chattahoochee Valley Sports Foundation and the American Orthopaedic Society of Sports Medicine; he was honored in 2010 by the latter with the George D. Rovere Award for his contribution to sports medicine education and the title of “Mr. Sports Medicine” for his significant contributions to the field. He was also a recipient of the Distinguished Southern Orthopaedist Award from the Southern Orthopaedic Association and the President’s Challenge Award from the National Athletic Trainers Association.

But none of this speaks to what he has done for the AASPT and for sports physical therapists over the years. At every instance, when the AASPT needed a speaker, a dissection leader, a panelist or a connection to the AOSSM or AAOS, he was there. Hard to believe that when he was president of AOSSM…during the yearly meeting, with

many meetings and presentations he was involved with, he showed up to present at the Academy’s AOSSM Pre-Conference course!

Here are comments from some of the Academy members: “We mourn the loss of Champ, his enthusiasm and dedication to Sports Medicine, and his love of family and friends. We send our deepest condolences and prayers to Champ’s wife, Sue Ann and their family.”

“He was a good man and giant in Ortho and supporter of our world.”

“I also had the chance to work with Champ’s daughter Sarah up at HSS so we talked about her Dad often. RIP. He was a good man and a huge LSU fan.”

“A true stalwart of sports medicine.”

“NEVER said no to us when we asked him to speak.”

“Impressive gentleman and great role model.

He will be missed.”

“Will greatly miss him. He was one of the greats that made You feel special when speaking with him. He always looked you in the eye and was listening intently to what you had to say.

Prayers to his family...”

“Another sad day in Sports Medicine to lose a class person and professional such as Champ, he will be missed.”

“Champ will be missed because he was always so supportive of PT and a great gentleman.”

I had the pleasure of working with Champ directly for many years. I can only echo what the Academy members have related above.

Champ believed in what sports physical therapists do and how we assisted patients. I traveled around the USA and the world with him teaching in many countries. His easy manner and humor disarmed the “stuffiest of folks.” His wit, wisdom, and leadership were legendary. But the bottom line was that he cared for his patients. I was never more honored than when he would refer a patient with only a diagnosis and “TAB FIX.” – Turner A. “TAB” Blackburn, Jr.

Anker-Petersen C, Thorborg K. Injury Prevention in Women’s Gymnastics – A Need for New Routines. IJSPT. 2022;17(3):327-329.

IFSPT International Perspective

Injury Prevention in Women’s Gymnastics – A Need for New Routines a

Charlotte Anker-Petersen, PT, MSc 1 , Kristian Thorborg, PT, PhD 1

b

1

Sports Orthopedic Research Center-Copenhagen, Department of Orthopedic Surgery, Amager-Hvidovre Hospital, Copenhagen University Hospital, Denmark Keywords: gymnastics, injury prevention https://doi.org/10.26603/001c.33751

International Journal of Sports Physical Therapy Vol. 17, Issue 3, 2022

For many years, fake smiles in female gymnasts have been the norm – and part of the “routine” during performance. However, lately, these “routines” have drawn negative public attention. Cases involving sexism, ruthless training culture and repression of female gymnasts have made headlines and given rise to considerations in gymnastic federations worldwide. Fortunately, the female gymnasts involved have risen against this oppression and sports culture. For example, the female German national team gymnasts at last year’s Olympic Games in artistic gymnastics chose to line up in suits with long legs to dissociate themselves from sexualization. In addition, gymnast star Simone Biles withdrew from the competition. She honestly and publicly shared that she was not mentally fit to compete and that she did not want to do something silly with the potential of getting injured, and the world’s athletes showed her their sympathy and solidarity.

In Denmark, there is a proud tradition within gymnastics. Every fourth year a giant sports festival takes place and gymnastics is the epicenter of the festival. Gymnastic teams with more than 200 gymnasts perform together, showing the diversity and solidarity in the unique Danish gymnastic culture – a culture that accommodates both the recreational and the elite gymnast. Moreover, it is a culture that to a great extent is based on volunteerism. Further, the distance from idea to action is short which is experienced both in the clubs and in the national Federation of Gymnastics, GymDanmark. Currently, GymDanmark has an ethical code where the objective is to create a value-based foundation that ensures mutual respect no matter where you are in the hierarchy. In addition, Danish Gymnastics & Sports Associations have allocated 9.4 million euro to encourage diversity in sport in Denmark. Gymnastics, however, is a sport where pain and injury of both traumatic and overuse nature is common. Currently, Danish gymnastic clubs experi-

a

Corresponding author: Charlotte Anker-Petersen Sports Orthopedic Research Center – Copenhagen (SORC-C), Copenhagen University hospital, Amager-Hvidovre Kettegaard Alle 30, 2650 Hvidovre, Denmark E-mail: anne.charlotte.anker-petersen@regionh.dk Twitter: @C_AnkerPetersen

b

Twitter: @KThorborg

ence challenges retaining adolescent gymnasts in the sport through the transition to adulthood, where up to 19% of the drop-out is caused by injuries.1 In this International Perspective we share some of our initial experiences from Denmark where we have been conducting one of the largest gymnastics injury surveillance studies, including more than 600 TeamGym gymnasts in both retrospective and prospective injury surveillance studies.

THE JUMPSMILE PROJECT Looking at the various gymnastic disciplines, Team Gymnastics within rhythm and jump (TeamGym), is the most popular discipline in Denmark (Figure 1). Despite the increasing popularity, TeamGym has not received much attention from sports medicine and physical therapy researchers. Results from a study by Harringe et al. (2007) found in a small cohort of 42 senior gymnasts, from two top-level TeamGym teams that the incidence rate was 2 injuries per 1000 gymnastic hours.2 This is supported by another study, reporting 50 injuries per 1000 gymnastic hours in TeamGym competition.3 The JumpSmile project, from our research institution, aims to investigate and describe the injury epidemiology and risk factors in TeamGym. Results from the retrospective survey showed that in TeamGym gymnasts between 10-30 years of age, 80% suffer from musculoskeletal pain related to gymnastics during season, with approximately 2 injuries per gymnast and an average duration of 8 weeks per injury, suggesting a potential large injury burden from gymnastics injury (unpublished data). The majority of injuries were overuse injuries, and the total gymnastic exposure was high, with more than 7 hours on average per week for these athletes. While foot/ankle, knee, back and wrist injuries

Injury Prevention in Women’s Gymnastics – A Need for New Routines

were the most commonly reported injury regions, these differed according to sex and body region, with especially the knee being a problem in the youngest gymnasts. Further, it is alarming that several gymnasts in the study and their parents have expressed that pain is an unavoidable part of the sport. Thus, the importance of focusing on training culture and beliefs, as well as developing effective injury prevention strategies within TeamGym gymnastic seems important. To address this challenge, the ongoing JumpSmile project in Denmark now prospectively follows more than 500 young gymnasts during a full season (10-11 months) to see if the data from the retrospective surveillance can be confirmed an further explained in a prospective injury surveillance set-up. This set-up includes: weekly SMS-track, telephone interviews and growth measures, in-depth knowledge about injury epidemiology, time-loss due to injuries and potential injury risk factors in the sport, such as exposure, growth spurt and joint hypermobility. Furthermore, a clinical examination will be offered by a physiotherapist to all gymnasts with an overuse injury that lasts more than 3 weeks, with a special focus on growth-related apophyseal injuries.

Hopefully, the JumpSmile project can contribute to the continued development of gymnastics, further education of coaches and new future injury prevention strategies, helping local gymnastic clubs in retaining their gymnasts.

Thereby, many more true smiles in the future will see the light of the day and many positive stories and effects of

gymnastics can be shared. Gymnastics is a sport that should include and exemplify joyful movement and physical activity – in a multicultural and diverse setting and culture where fake smiles should not be necessary.

FUNDING

The authors have not declared a specific grant for this from any funding agency in the public, commercial or nor-forprofit sectors.

COMPETING INTERESTS

None declared PATIENT CONSENT FOR PUBLICATION

Not required DATA AVAILABILITY STATEMENT

No data are available Submitted: February 21, 2022 CDT, Accepted: March 15, 2022 CDT

This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CCBY-NC-4.0). View this license’s legal deed at https://creativecommons.org/licenses/by-nc/4.0 and legal code at https://creativecommons.org/licenses/by-nc/4.0/legalcode for more information.

International Journal of Sports Physical Therapy

Injury Prevention in Women’s Gymnastics – A Need for New Routines

REFERENCES 1. Asserhøj TL. Pigers idrætsvaner. Idrættens Analyseinstitut; 2017:1-42.

2. Harringe ML, Renstrom P, Werner S. Injury incidence, mechanism and diagnosis in top-level teamgym: a prospective study conducted over one season. Scand J Med Sci Sports. 2007;17(2):115-119. d oi:10.1111/j.1600-0838.2006.00546.x

3. Lund SS, Myklebust G. High injury incidence in TeamGym competition: a prospective cohort study.

Scand J Med Sci Sports. 2011;21(6):e439-44. doi:10.11 11/j.1600-0838.2011.01362.x

International Journal of Sports Physical Therapy

Moore Z, Cain EL, Wilk KE. The Management of Biceps Pain: Non-Operative & Surgical.

IJSPT. 2022;17(3):330-333.

Clinical Viewpoint

The Management of Biceps Pain: Non-Operative & Surgical Zachary Moore, MD 1, Edward Lyle Cain, MD 1, Kevin E Wilk, PT, DPT, FAPTA 2 1

a

American Sports Medicine Institute, 2 Champion Sports Medicine

Keywords: shoulder, biceps pain, shoulder rehab https://doi.org/10.26603/001c.33646

International Journal of Sports Physical Therapy Vol. 17, Issue 3, 2022

Proximal biceps pain has become increasingly prominent in the discussion of shoulder pathology and especially when associated with rotator cuff injuries and superior labrum from anterior to posterior (SLAP) lesions. Pain in the long head of the biceps (LHB) is usually inflammatory in nature and can be caused by a variety of pathologies which was well described in Sethi et al.1 LHB pathology can fall into three main categories of inflammatory, instability, and traumatic.

Patients falling into any of these categories can present with debilitating anterior shoulder pain. Inflammation in the LHB can stimulate a robust sensory and sympathetic innervation in this area which contributes to the intensity of pain these patients experience. Taylor et al, have described 3 zones where the biceps can exhibit pathology and specific tests to identify these lesions called the “3 pack examination”.2 Patients that present with LHB pain fall into a bimodal distribution. Young overhead athletes and older patients with rotator cuff pathology make up the majority of the patients that present to our clinics. With an increasing number of young athletes playing year-round sports, biceps pathology is a common complaint in our clinics. In a different mechanism, our older patients suffer from subacromial impingement and rotator cuff tears that cause increased stress on the LHB. We believe the LHB becomes a significant humeral head depressor in the setting of a large rotator cuff tear which contributes to this presentation. Although controversy exists regarding the function of the long head of the biceps brachii.3 Treatment options for proximal biceps tendon pain should often start with non-operative treatment and the treatment modalities are dictated by the etiology of the biceps pathology. Wilk et al, have described six different proximal biceps lesions and specific treatment approaches for each.4 For an inflammatory process, (i.e., biceps paratendinitis) activity modification, anti-inflammatories and other modalities have all been used successfully. Laser therapy and iontophoresis can also be beneficial in this setting.

In addition, a rehabilitation program which emphasizes scapular muscle strengthening, postural correction and rotator cuff strengthening is critical. With biceps tendonosis, non-operative treatment focused on increasing circulation and promoting healing is focused. This includes, heat, soft

a

Corresponding author: kwilkpt@hotmail.com

tissue mobilization, piezo wave therapy, laser, eccentric exercise, and a scapular & rotator cuff strengthening program while avoiding NSAIDs and ice to create a healing environment.

When non operative treatments have failed to give the patient adequate relief and function, surgical intervention can be considered. If surgery is elected, the surgeon may perform a tenotomy, or a biceps tenodesis (either suprapectoralis or sub pectoralis location). At our institution, we perform all sub-pectoralis biceps tenodesis. We believe this gives the advantage restoring proper tendon tension and length and avoidance of the “Popeye” deformity that is seen with a tenotomy alone.5 Tenotomy can lead to painful muscle spasms as it retracts into the arm. The location of the tenodesis is at the level of the pallium pectoralis. This is a consistent fascial sleeve that extends from the superior boarder of the pectoralis major tendon to the humerus which lies in the metaphyseal-diaphyseal junction of the humerus. This location is ideal since it avoids the risk of fracture when placed in the diaphysis and is also inferior enough to avoid insertion into the humeral head. After cutting the biceps tendon intraarticularly in the joint just above its labral attachment, a longitudinal 3 cm incision is made just inferior to the palpable boarder of the pectoralis major tendon. We use the Birmingham Biceps Technique that uses a 5.5 SwiveLock PEEK screw (Arthrex) to secure the tendon using a Fiberloop suture. Of note, at our institution we do use smaller anchors in high level throwing athletes to avoid the risk of humerus fracture while throwing.

A measuring device is used to ensure that the most proximal extent of the tendon that is whipstitched is 4 cm from the musculotendinous junction of the LHB. The screw is inserted into the bicipital groove at the level of the pallium pectoralis which ensures adequate tension. This avoids a “Popeye deformity” as well as retains anatomic muscle/tendon length with the correct anatomic force vector on the tendon. We believe that this technique removes the biceps tendon from the bicipital groove which is a common source of pain. This location places the anchor out of the diaphyseal portion of the bone to reduce post operative fracture risk.

Clinical photographs detailing the subpectoralis LHB tenodesis is shown in Figures 1-5.6

The Management of Biceps Pain: Non-Operative & Surgical

The post operative rehabilitation includes that the patient is instructed not to lift any heavy objects overhead and avoid activation of the biceps in the immediate post operative period. No isolated biceps strengthening exercises for 6-8 weeks post operatively. The rehabilitation can be broken down into 3 phases. Phase 1, is the immediate motion phase weeks 0-2 which our goal is to re-establish non-painful range of motion, retard muscular atrophy, reestablish dynamic stabilization, and decrease pain and inflammation. During phase 1 the patients begin with pendulums and rope and pulley. They will progress to full elevation range of motion and initiate external and internal tubing at 30 degrees of abduction in the scapular plane by the end of phase 1. Exercises focused on rotator cuff and scapula posture are emphasized.

Phase 2 is completed from weeks 2 through 6. The goals of this phase are to regain and improve muscular strength, normalize arthrokinematics, improve neuromuscular control of the shoulder complex, and continuing to diminish pain. Before beginning phase 2 The patients must have full range of motion, minimal pain, and have progressed well with internal/external rotation at 0 degrees of abduction.

The goal by the end of phase 2 is the have the patient normalize their arthrokinematics with the use of L-bar range of motion and be able to achieve normal internal and external rotation at 90 degrees of abduction. During this phase, scapular strengthening exercises, postural correction drills and a shoulder strengthening program is utilized. Strengthening exercises focus on dynamic stabilization, and scapular synchronization with active movements.

Phase 3 is the dynamic strengthening phase and consists of weeks 6-12. The goals of this phase are to improve strength, improve neuromuscular control, and prepare patients to return to sport if applicable. To enter phase 3 of rehabilitation patients must have full non-painful range of motion, no pain, and strength at 70% of contralateral extremity. During this phase all exercises are progressed, biceps strengthening is initiated, but more functional exercises are utilized during this phase.

Phase 4 consists of more maintenance and the progression of strength and range of motion. The patient is instructed to continue their ROM exercises and any capsular stretches as needed to avoid any post operative capsular tightness. For athletes, plyometrics can be initiated beginning with 2 handed and progressing to 1 handed plyometrics. We will initiate a gradual return to sport at approximately 12 weeks. Rehabilitation concludes with gradual return to all unrestricted functional activities.4 The outcomes of LHB tenodesis are favorable across all age groups and activity levels. A study currently in review from American Sports Medicine Institute examined 76 softball players and compared results of SLAP repair versus biceps tenodesis. This study revealed no statistical difference between these groups in return to play rates as well as pain and function. This data would suggest a biceps tenodesis is a reasonable option with similar results and shorter follow up time than SLAP repairs for collegiate level throwing athletes.7 An additional study by Griffin et al., demonstrated a satisfaction rate of 40% for SLAP repairs versus 93% for biceps tenodesis in patients under 25 years of age with SLAP tears.8 In Ek et al., they showed favorable results in patients

Figure 1. Exposing the LHB tendon under the pectoralis major tendon.

Figure 2. The highlighted area is the pallium pectoralis which is the fascial sling that is a consistent anatomic landmark used to reproducibly achieve proper tension for a biceps tenodesis. The anchor is placed at this level in the bicipital groove.

Figure 3. The LHB tendon is then whip stitched and attached to an anchor for insertion.

older then 35 undergoing biceps tenodesis.9 LHB tenodesis has reliable results across age groups and activity levels.

LHB tenodesis by the technique listed above has given us a safe and reliable way to treat patients who have failed non-operative management. Our technique has given us excellent results in patients of all ages including younger overhead athletes. This technique also avoids the problem of cosmetic deformity as well as muscle spasm and pain

International Journal of Sports Physical Therapy

The Management of Biceps Pain: Non-Operative & Surgical

that some patients experience with a tenotomy alone as discussed in Hsu et al. Tenodesis also has the added benefit of increased flexion and supination strength compared with tenotomy alone.5 Our use of anatomic landmarks and placement of the anchor ensures that we have reduced risk of fracture with adequate tension maintained in the musculotendinous unit. Placing the anchor in the anatomic location of the more distal portion of the tendons normal position also maintains proper tendon vector that is consistent with native anatomy.

Submitted: February 01, 2022 CDT, Accepted: March 14, 2022 CDT

Figure 4. Anchor is secured at the level of the Pallium Pectoralis.

Figure 5. Anchor is advanced into the bone and the subpectoralis biceps tenodesis is complete.

This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CCBY-NC-4.0). View this license’s legal deed at https://creativecommons.org/licenses/by-nc/4.0 and legal code at https://creativecommons.org/licenses/by-nc/4.0/legalcode for more information.

International Journal of Sports Physical Therapy

The Management of Biceps Pain: Non-Operative & Surgical

REFERENCES 1. Sethi N, Wright R, Yamaguchi K. Disorders of the long head of the biceps tendon. J Shoulder Elbow Surg.

1999;8(6):644-654. doi:10.1016/s1058-2746(99)9010 5-2 2. Taylor SA, Newman AM, Dawson C, et al. The “3-Pack” Examination Is Critical for Comprehensive Evaluation of the Biceps-Labrum Complex and the Bicipital Tunnel: A Prospective Study. Arthroscopy.

2017;33(1):28-38. doi:10.1016/j.arthro.2016.05.015 3. Elser F, Braun S, Dewing CB, Giphart JE, Millett PJ. Anatomy, function, injuries, and treatment of the long head of the biceps brachii tendon. Arthroscopy.

2011;27(4):581-592. doi:10.1016/j.arthro.2010.10.014 4. Wilk KE, Hooks TR. The Painful Long Head of the Biceps Brachii. Clin Sports Med. 2016;35(1):75-92. do i:10.1016/j.csm.2015.08.012 5. Hsu AR, Ghodadra NS, Provencher CMT, Lewis PB, Bach BR. Biceps tenotomy versus tenodesis: a review of clinical outcomes and biomechanical results. J Shoulder Elbow Surg. 2011;20(2):326-332. doi:10.101 6/j.jse.2010.08.019

6. Cain EL, Rothermich M, Ryan M, et al. The Birmingham Biceps Technique For Open Subpectoral Tenodesis. Arthrex. Published April 8, 2019. https://w ww.arthrex.com/resources/video/xbal0WemPk-IMwFP d6yhpA/the-birmingham-biceps-technique-for-opensubpectoral-tenodesis?referringTeam=shoulder7 7. Rothermich M, Ryan M, Fleisig G, et al. Clinical Outcomes and Return to Play in Softball Players Following SLAP Repair or Biceps Tenodesis, currently in review at Am J Sports Med. 8. Griffin JW, Cvetanovich GL, Kim J, et al. Biceps tenodesis is a viable option for management of proximal biceps injuries in patients less than 25 years of age. Arthroscopy. 2019;35(4):1036-1041. doi:10.101 6/j.arthro.2018.10.151 9. Ek ETH, Shi LL, Tompson JD, Freehill MT, Warner JJP. Surgical treatment of isolated type II superior labrum anterior-posterior (SLAP) lesions: repair versus biceps tenodesis. J Shoulder Elbow Surg.

2014;23(7):1059-1065. doi:10.1016/j.jse.2013.09.030

International Journal of Sports Physical Therapy

Koc BB, Truyens A, Heymans MJLF, Jansen EJP, Schotanus MGM. Effect of Low-Load Blood Flow Restriction Training After Anterior Cruciate Ligament Reconstruction: A Systematic Review. IJSPT. 2022;17(3):334-346.

Systematic Review/Meta-Analysis

Effect of Low-Load Blood Flow Restriction Training After Anterior Cruciate Ligament Reconstruction: A Systematic Review a

Baris B. Koc 1 , Alexander Truyens 1, Marion J.L.F. Heymans 2, Edwin J.P. Jansen 1, Martijn G.M. Schotanus 3 1

Department of Orthopedics and Sports Surgery, Zuyderland Medical Center, 2 Zuyderland Academy, Zuyderland Medical Center, 3 Department of Orthopedics and Sports Surgery, Zuyderland Medical Centre; School of Care and Public Health Research Institute, Faculty of Health, Medicine & Life Sciences, Maastricht University Medical Centre Keywords: resistance training, quadriceps strength, quadriceps mass, postoperative rehabilitation, knee pain, graft laxity https://doi.org/10.26603/001c.33151

International Journal of Sports Physical Therapy Vol. 17, Issue 3, 2022

Background Quadriceps strength and mass deficits are common after anterior cruciate ligament (ACL) reconstruction. Postoperatively, heavy load resistance training can have detrimental effects on knee joint pain and ACL graft laxity. Therefore, low-load blood flow restriction (LL-BFR) training has been suggested as an alternative to traditional strength rehabilitation.

Purpose The present systematic review aimed to investigate the effect of LL-BFR training on quadriceps strength, quadriceps mass, knee joint pain, and ACL graft laxity after ACL reconstruction compared to non-BFR training.

Study design Systematic review

Methods A systematic literature search of PubMed, EMBASE.com, Cochrane Library/Wiley, CINAHL/Ebsco and Web of Science/Clarivate Analytics was performed on 19 February 2021. Studies were included if they compared LL-BFR and non-BFR training after ACL reconstruction with pre- and post-intervention quadriceps strength, quadriceps mass, knee joint pain or ACL graft laxity measurement. Systematic reviews, editorials, case reports and studies not published in a scientific peer reviewed journal were excluded. The risk of bias of randomized studies was assessed with the use of the Cochrane Risk of Bias Tool.

Results A total of six randomized controlled trials were included. Random sequence generation and allocation concealment was defined as high risk in two of the six studies. In all studies blinding of participants and personnel was unclear or could not be performed. The included studies used different LL-BFR and non-BFR protocols with heterogeneous outcome measurements. Therefore, a qualitative analysis was performed. Two of the six studies assessed quadriceps strength and demonstrated significant greater quadriceps strength after LL-BFR compared to non-BFR training. Quadriceps mass was evaluated in four studies. Two studies observed significant greater quadriceps mass after LL-BFR compared to non-BFR training, while two studies observed no significant difference in quadriceps mass. Knee joint pain was assessed in three studies with significantly less knee joint pain after LL-BFR compared to non-BFR training. Two studies evaluated ACL graft

a

Corresponding author: Baris B. Koc Zuyderland Medical Centre, Dr. H. vd Hoffplein 1, 6162 AG Sittard-Geleen, the Netherlands Phone: +32 484 19 12 24 Email: baris.koc1991@gmail.com

Effect of Low-Load Blood Flow Restriction Training After Anterior Cruciate Ligament Reconstruction: A Systematic Review

laxity and observed no significant difference in ACL graft laxity between LL-BFR and non-BFR training.

Conclusion The results of this systematic review indicate that LL-BFR training after ACL reconstruction may be beneficial on quadriceps strength, quadriceps mass, and knee joint pain compared to non-BFR training with non-detrimental effects on ACL graft laxity.

However, more randomized controlled trials with standardized intervention protocols and outcome measurements are needed to add evidence on the clinical value of LL-BFR training.

Level of evidence 2a Preferred Reporting Items for Systematic Reviews and Meta-analysis guidelines.29

INTRODUCTION Quadriceps strength and mass deficits are common after anterior cruciate ligament (ACL) reconstruction.1–6 Approximately 30% of patients have quadriceps strength deficits 12 months after ACL surgery.1,3 Quadriceps mass deficits can be as high as 30% and can persist for many years after ACL reconstruction.5 Furthermore, quadriceps mass deficits can negatively affect quadriceps strength.7–9 This is of importance as quadriceps strength after ACL reconstruction is associated with patient reported outcome measurements, functional performance, return to sport and ACL re-injury.1,10–16 Therefore, interventions to address quadriceps strength and mass deficits after ACL reconstruction are imperative.

Heavy load resistance (HLR) training using external loads >60% of one repetition maximum (1RM) is recommended to increase quadriceps strength and mass.17 However, after ACL reconstruction, training with external loads >60% 1RM can have detrimental effects on knee joint pain and ACL graft laxity.18–23 Therefore, low-load blood flow restriction (LL-BFR) training using external loads of 20-40% 1RM has been suggested as an alternative to traditional strength rehabilitation.24,25 During LL-BFR training, a pressurized cuff is applied to the proximal thigh that occludes venous outflow while maintaining arterial inflow.24,25 The combination of venous occlusion and resistance training is believed to induce muscle hypertrophy secondary to elevated systematic hormone production, cell swelling, production of reactive oxygen species, intramuscular anabolic signaling and fast-twitch fiber recruitment.25–27 A recent systematic review showed promising results of LL-BFR training on quadriceps mass after ACL reconstruction.28 As LL-BFR training is an increasingly popular method for the rehabilitation after an ACL reconstruction, it is important to evaluate the value of this treatment.24,25 Therefore, the present systematic review aimed to investigate the effect of LL-BFR training on quadriceps strength, quadriceps mass, knee joint pain and ACL graft laxity after ACL reconstruction compared to non-BFR training.

SEARCH STRATEGY AND STUDY SELECTION

A systematic literature search in PubMed, EMBASE.com, Cochrane Library/Wiley, CINAHL/Ebsco and Web of Science/Clarivate Analytics was performed on 19 February 2021 (BK, MH). The following search terms, including all synonyms, were used to search in all databases as index term and as free-text words: blood flow restriction and anterior cruciate ligament (See Appendix 1 for the detailed search strategy). The results of the literature search were collected in the reference management program RefWorks and were de-duplicated.30 Studies were included if they compared LL-BFR and non-BFR training after ACL reconstruction with pre- and post-intervention quadriceps strength or quadriceps mass or knee joint pain or ACL graft laxity measurement. Non-BFR training was defined as strength training without vascular restriction. The exclusion criteria were: systematic reviews, editorials, case reports and studies not published in a scientific, peer reviewed journal. Two reviewers (BK and AT) separately and independently screened all titles and abstracts. The full text was reviewed if title and abstract suggested a study of interest. In case of disagreement, consensus was achieved by a third researcher (MS). In addition, trial reference lists of included studies were screened for relevant articles.

DATA EXTRACTION

Data of included articles were extracted with the use of RevMan 5.4 (Review Manager 5.4, The Cochrane Centre Collaboration, Copenhagen, Denmark, 2020) including: year of publication, study design, number of patients, study arms, graft used for ACL reconstruction, patient characteristics, LL-BFR training protocol, non-BFR training protocol, and quadriceps strength, quadriceps mass, knee joint pain, and ACL graft laxity measurements.31 When raw data of outcome measurements were not available, the authors were contacted to provide raw data.

STUDY QUALITY AND REPORTING

MATERIALS AND METHODS The review protocol was registered on PROSPERO (CRD42020163467) and was performed according to the

The independent reviewers (BK and AT) assessed the risk of bias of the included studies with the use of the Cochrane Risk of Bias Tool. Non-randomized studies were assessed

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Effect of Low-Load Blood Flow Restriction Training After Anterior Cruciate Ligament Reconstruction: A Systematic Review

Table 1. Overview of study characteristics.

Author (Year)

Study design

Total number of patients

Study arms (No.)

Outcome

Hughes (2019a)

Randomized controlled trial

24

LL-BFR group (n=12) Non-BFR group (n=12)

Quadriceps strength Quadriceps mass Knee joint pain ACL graft laxity

Hughes (2019b)

Randomized controlled trial

24

LL-BFR group (n=12) Non-BFR group (n=12)

Knee joint pain

Hughes (2018)

Randomized controlled trial

20

LL-BFR group (n=10) Non-BFR group (n=10)

Knee joint pain

Iversen (2014)

Randomized controlled trial

24

LL-BFR group (n=12) Non-BFR group (n=12)

Quadriceps mass

Ohta (2003)

Randomized controlled trial

44

LL-BFR group (n=22) Non-BFR group (n=22)

Quadriceps strength Quadriceps mass ACL graft laxity

Takarada (2000)

Controlled trial

16

LL-BFR group (n=8) Non-BFR group (n=8)

Quadriceps mass

LL-BFR: Low-load blood flow restriction.

with the ROBINS-I checklist.32 The included studies were evaluated on: selection bias, performance bias, detection bias, attrition bias, reporting bias and other bias.

DATA SYNTHESIS

Outcome measurements were extracted with the use of RevMan 5.4.31 The difference in pre- and post-intervention mean and standard deviation (SD) was used to calculate the standardized mean difference (SMD). In case SD was not available, this was estimated in accordance with recommendations provided by Cochrane Handbook for Systematic Reviews.33 Data were pooled for a meta-analysis if the included studies were clinically, methodologically and statistically homogenous. In case of considerable heterogeneity (I2 >75%) of the study results, a qualitative analysis was performed.34 The level of statistical significance was set at p≤0.05.

RESULTS STUDY SELECTION AND CHARACTERISTICS

The database search yielded 1474 articles. After initial title and abstract screening, 11 articles were assessed for eligibility. The remaining 11 articles were fully read and six articles met the inclusion criteria. The two independent reviewers agreed on selection of eligible studies and achieved consensus on which studies to include. No additional studies were identified through reference list screening. Therefore, six articles were included in the systematic review (Figure 1). Table 1 shows an overview of the study characteristics.

Three studies were conducted in the United Kingdom, two in Japan and one in Norway.18,35–39 The studies conducted in the United Kingdom are three reports from the same study.18,35,36 However, the three reports from the

same study described different outcome measurements, thus, were included in this review. The included studies involved a total of 152 patients who had been randomized into LL-BFR (n=76) or non-BFR (n=76) group.18,35–39 Sample sizes ranged between 16 and 44 patients.18,35–39 Five studies used hamstring graft for ACL reconstruction, whereas one study did not report type of graft.18,35–39 Patient characteristics were not statistically significant different between the LL-BFR and non-BFR group. Table 2 shows an overview of the patient characteristics.

LL-BFR AND NON-BFR PROTOCOLS

The intervention protocols are shown in Table 3. The duration of the intervention varied from 11 days up to 14 weeks and training sessions varied from two sessions/week up to two sessions/day.18,35–39 LL-BFR training was used in combination with low-load leg press, leg extension or straight leg raise exercises.18,35–39 The external load varied from body weight up to 30% 1RM and was not specified in two studies.18,35–39 Automatic personalized tourniquet systems and pneumatic cuffs were used during LL-BFR training.18,35–39 The occlusion pressure ranged between 148 and 238 mmHg, while cuff width ranged from 9 to 14 cm.18,35–39 In three studies LL-BFR pressure was defined as 80% of the limb occlusion pressure (ranged from 140 to 160 mmHg), whereas the occlusion pressure was based on previous research in three studies (ranged from 180 to 240mmHg).18,35–39 LL-BFR was intermittently applied with reperfusion periods ranging from 30 to 180 seconds.18,35,36,38,39 In three studies, non-BFR training consisted of the same exercise protocol as LL-BFR training but without vascular restriction.37–39 Hughes et al. used different exercise protocols in the non-BFR and LL-BFR group.18,35,36 In the non-BFR group, the patients performed three sets of 10 repetitions using external loads of 70% 1RM. In the LL-BFR group, the patients performed four

International Journal of Sports Physical Therapy

Effect of Low-Load Blood Flow Restriction Training After Anterior Cruciate Ligament Reconstruction: A Systematic Review

Table 2. Overview of patient characteristics.

Author (Year)

Graft for ACL reconstruction

Male in LL-BFR & non-BFR group

Age (years) in LLBFR & non-BFR group

Weight (kg) in LLBFR & non-BFR group

BMI in LL-BFR & non-BFR group

Hughes (2019a)

Hamstring

7 (58%) & 10 (83%)

29 (7) & 29 (7)

76 (15) & 79 (15)

25.4 (3.9) & 26.4 (4.4)

Hughes (2019b)

Hamstring

7 (58%) & 10 (83%)

29 (7) & 29 (7)

76 (15) & 79 (15)

25.4 (3.9) & 26.4 (4.4)

Hughes (2018)

Hamstring

6 (60%) & 7 (70%)

29 (5) & 31 (7)

77 (16) & 81 (12)

25.7 (4.2) & 23.5 (3.4)

Iversen (2014)

Hamstring

7 (58%) & 7 (58%)

25 (7) & 30 (9)

77 (12) & 78 (10)

-

Ohta (2003)

Hamstring

13 (59%) & 12 (55%)

28 (10) & 30 (10)

65 (14) & 63 (9)

-

Takarada (2000)

-

4 (50%) & 4 (50%)

22 (1) & 23 (1)

59 (1) & 62 (2)

-

Results are presented as numbers (percentage) or mean (SD). ACL: anterior cruciate ligament; BMI: body mass index; LL-BFR: low-load blood flow restriction.

Figure 1. Flow chart of the literature search and selection procedure.

sets (30-15-15-15) using external loads of 30% 1RM.18,35,36

International Journal of Sports Physical Therapy

Effect of Low-Load Blood Flow Restriction Training After Anterior Cruciate Ligament Reconstruction: A Systematic Review

Table 3. Overview of intervention.

Author (Year)

BFR device

Cuff width

BFR pressure

LL-BFR training

Non-BFR training

Exercises

Duration

Total training sessions

Hughes (2019a)

Automatic personalized tourniquet system

11.5 cm

Mean 150 mmHg

4 sets (30-15-15-15 reps)

3 sets (10-10-10 reps)

Unilateral leg press

8 weeks

16

Interset rest periods: 30 seconds

Interset rest periods: 30 seconds

External load: 30% 1RM

External load: 70% 1RM

Session: 2x/ week

Session: 2x/ week

4 sets (30-15-15-15 reps)

3 sets (10-10-10 reps)

Interset rest periods: 30 seconds

Interset rest periods: 30 seconds

External load: 30% 1RM

External load: 70% 1RM

Session: 2x/ week

Session: 2x/ week

4 sets (30-15-15-15 reps)

3 sets (10-10-10 reps)

Interset rest periods: 30 seconds

Interset rest periods: 30 seconds

External load: 30% 1RM

External load: 70% 1RM

Session: 2x/ week

Session: 2x/ week

Hughes (2019b)

Hughes (2018)

Automatic personalized tourniquet system

Automatic personalized tourniquet system

Based on 80% of LOP

11.5 cm

Mean 150 mmHg Based on 80% of LOP

11.5 cm

Mean 148 mmHg Based on 80% of LOP

Start: 2 weeks postop End: 10 weeks postop

Unilateral leg press

8 weeks

16

Start: 2 weeks postop End: 10 weeks postop

Unilateral leg press

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8 weeks Start: 2 weeks postop End: 10 weeks postop

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Effect of Low-Load Blood Flow Restriction Training After Anterior Cruciate Ligament Reconstruction: A Systematic Review

Author (Year)

BFR device

Cuff width

BFR pressure

LL-BFR training

Non-BFR training

Exercises

Duration

Total training sessions

Iversen (2014)

Contoured pneumatic occlusion cuff

14 cm

Start:130 mmHg

5 sets of 20 reps

5 sets of 20 reps

Isometric quadriceps contraction progressing to leg extension over a knee-roll and straight leg raise

12 days

24

End: 180 mmHg

Interset rest periods: 3 minutes

Interset rest periods: 3 minutes

External load: low

External load: low

Session: 2x/ day

Session: 2x/ day

1-3 sets (20 reps)

1-3 sets (20 reps)

Interset rest periods: unknown

Interset rest periods: unknown

External load: 0-14 kg

External load: 0-14 kg

Session: 6x/ week

Session: 6x/ week

5 sets

5 sets

Interset rest periods: 3 minutes

Interset rest periods: 3 minutes

External load: low

External load: low

Session: 2x/ day

Session: 2x/ day

Based on previous research

Ohta (2003)

Hand-pumped air tourniquet

-

180 mmHg Based on previous research

Takarada (2000)

Pneumatic occlusion cuff

9 cm

Start: 180 mmHg End: 238 mmHg Based on previous research

Start: 2 days postop End: 14 days postop

Straight leg raise, hip joint abduction/ adduction, half squat, step up, elastic tube and knee-bending walking exercise

14 weeks

84

Start: 2 weeks postop End: 16 weeks postop

Hospital rehabilitation protocol with knee brace immobilization

LL-BFR: low-load blood flow restriction; LOP: limb occlusion pressure; 1RM: one repetition maximum; Postop: postoperatively; Reps: repetitions.

International Journal of Sports Physical Therapy

11 days Start: 3 days postop End: 14 days postop

22

Effect of Low-Load Blood Flow Restriction Training After Anterior Cruciate Ligament Reconstruction: A Systematic Review

RISK OF BIAS

An overview of the quality assessment of the included studies is reported in Figure 2. Random sequence generation and allocation concealment was defined as high risk for bias in two of the six studies. In all studies blinding of participants and personnel was unclear or could not be performed.

HETEROGENEITY

Comorbidities and concomitant injuries of study participants were not defined in the included studies. Furthermore, different LL-BFR and non-BFR protocols with heterogeneous outcome measurements were used. Therefore, only a qualitative analysis was performed.

OUTCOME MEASUREMENTS QUADRICEPS STRENGTH

Quadriceps strength was evaluated in two studies by measuring RM, isokinetic contraction at 60°/seconds, isokinetic contraction at 150°/seconds, isokinetic contraction at 180°/seconds, isokinetic contraction at 300°/seconds or isometric contraction at 60° knee flexion.35,37 Quadriceps strength was measured pre-operatively and at nine up to 16 weeks postoperatively.35,37 Ohta et al. showed significantly less strength deficits in isokinetic knee extension at 60°/seconds (p<0.001), isokinetic knee extension at 180°/seconds (p=0.004) and isometric contraction at 60° knee flexion (p<0.001) after LL-BFR compared to non-BFR training.37 Hughes et al. reported significantly less strength deficits in isokinetic knee extension at 150° and 300°/seconds after LL-BFR compared to non-BFR training (p=0.010).35 However, no significant differences in RM (p=0.220) and isokinetic knee extension at 60°/seconds (p=0.200) were observed between LL-BFR and non-BFR training.35 QUADRICEPS MASS

Three studies used MRI to measure changes in quadriceps cross-sectional area (CSA), while one study used ultrasound to measure changes in vastus lateralis muscle thickness.35,37–39 Quadriceps mass was measured pre-operatively and 14 days up to 16 weeks postoperatively.35,37–39 Takarada et al. showed significant less reduction in quadriceps CSA after LL-BFR compared to non-BFR training (p=0.046).38 Ohta et. al reported a significant increase in quadriceps CSA after 14 weeks LL-BFR compared to nonBFR training (p=0.040).37 Iversen et al. concluded that there was no significant difference in quadriceps CSA between LL-BFR and non-BFR training (p=0.626).39 Hughes et al. used ultrasound to assess changes in vastus lateralis muscle thickness and demonstrated no significant difference in quadriceps increase between LL-BFR and non-BFR training (p=0.230).35 KNEE JOINT PAIN

Knee joint pain was assessed using a numerical rating scale in two studies, while one study used the Knee Injury and

Figure 2. Review authors’ judgements about each risk of bias domain with the use of the Cochrane Risk of Bias Tool.

Osteoarthritis Outcome Score (KOOS) pain score.18,35,36 Knee joint pain was evaluated following each session, 24h post-exercise or 10 weeks postoperatively.18,35,36 Two studies observed significant lower knee joint pain scores in LLBFR compared to non-BFR training.18,36 Furthermore, one study showed significant greater increase in KOOS pain score after LL-BFR compared to non-BFR training.35 ACL GRAFT LAXITY

Two studies used a knee ligament arthrometer to measure changes in ACL graft laxity.35,37 ACL graft laxity was measured pre-operatively and at 10 up to 16 weeks postoperatively. No significant difference in ACL graft laxity was observed between LL-BFR and non-BFR.35,37

DISCUSSION The most important finding of the present systematic review was that low-load blood flow restriction (LL-BFR) training after anterior cruciate ligament (ACL) reconstruction may be beneficial on quadriceps strength and quadriceps mass compared to non-BFR training. Furthermore, LLBFR training may decrease knee joint pain compared to non-BFR training with similar effects on ACL graft laxity.

Thus, the present systematic review suggests that LL-BFR training may be an effective alternative to non-BFR training after an ACL reconstruction.

Regarding quadriceps strength, Ohta et al. showed less quadriceps strength deficits after LL-BFR compared to nonBFR training.37 In addition, Hughes et al. demonstrated similar and greater effects on quadriceps strength after LL-

International Journal of Sports Physical Therapy

Effect of Low-Load Blood Flow Restriction Training After Anterior Cruciate Ligament Reconstruction: A Systematic Review

BFR compared to non-BFR training.35 Ohta. at al used lowload resistance training (LLR) training as non-BFR training, while Hughes et al. used heavy-load resistance training (HLR) training as non-BFR training. Therefore, the findings of the present review are consistent with current literature comparing LL-BFR training to LLR and HLR training in healthy and postoperative patients.40–46 In regard to quadriceps mass, two studies demonstrated that LL-BFR training was more beneficial on quadriceps cross-sectional area (CSA) compared to non-BFR training.37,38 In contrast, Iversen et al. observed no difference in quadriceps CSA between LL-BFR and non-BFR training.39 The authors acknowledged that subtherapeutic training (e.g. training duration of 12 days) and LL-BFR application (e.g. no personalized BFR pressures) were possible reasons for this difference.39 Current evidence recommends training durations of 6-12 weeks and the use of personalized LL-BFR pressures (80% of limb occlusion pressure [LOP]) to achieve muscle strength and hypertrophy.23–25 In contrast to the previous studies, the non-BFR group of Hughes et al. did not consist of LLR but HLR training.35 In their study, ultrasound was used to examine vastus lateralis muscle thickness and no difference in muscle thickness was observed between LL-BFR and non-BFR training groups.35 Thus, the results of the present review are consistent with literature showing that LL-BFR training may be beneficial on quadriceps mass compared to LLR training and equally effective when compared to HLR training in healthy and postoperative patients.40–46 The application of LL-BFR has generally been indicated for the elderly or injured/postoperative patients who cannot tolerate high external loads.43,47–50 This review adds evidence on the application of LL-BFR as three studies assessing pain observed improved pain relief with LL-BFR compared to non-BFR training in patients following ACL surgery.18,35,36 This is in contrast with a recent systematic review that observed no significant difference in pain relief between LL-BFR and non-BFR training in individuals with knee joint pain.51 The study participants were heterogeneous and included individuals with patellofemoral pain, risk of symptomatic knee osteoarthritis, anterior knee pain and post knee arthroscopy.51 Furthermore, the heterogeneity in LL-BFR pressures and cuff width could explain the lack of effect on knee joint pain.51 Current evidence suggests that therapeutic restriction (defined as 80% of LOP) is achieved at lower LL-BFR pressures with wide compared to narrow cuffs.52–56 Furthermore, lower LL-BFR pressures are associated with less discomfort and greater safety.52–56 Thus, the use of non-personalized pressures without calculating the LOP may cause pain.52–56 In the present systematic review, all studies on knee joint pain used wide cuffs with an automatic personalized tourniquet system to calculate the LOP.18,35,36 Furthermore, all studies used HLR training as non-BFR training. Thus, pain relief may be the result of low external loads and hypoalgesia effects of LLBFR training compared to HLR training.47,48,57,58 A major challenge in the rehabilitation after an ACL re-

construction is optimizing muscle strength while minimizing mechanical stress to the knee joint.59–61 The importance is represented by the remodeling process of the ACL graft. The remodeling process consists of three phases and the restructuring towards the properties of an intact (noninjured) ACL takes more than six months after reconstruction.21,62 Thereby, accelerated rehabilitation protocols and high load resistance training may compromise graft remodeling and may result in increased ACL graft laxity.19–21,63 BFR training in combination with low external loads has the advantage of minimizing mechanical stress to the knee joint compared to HLR training.47,48 However, in the present systematic review only two studies evaluated ACL graft laxity and showed no significant difference on ACL graft laxity with LL-BFR compared to non-BFR training.35,37 Therefore, more randomized controlled trials are needed to evaluate the effect of LL-BFR training on ACL graft laxity compared to HLR training.

The present systematic review has several limitations.

First of all, due to the heterogeneity in intervention protocols and outcome measurements no meta-analysis could be performed. Secondly, differences in LL-BFR and non-BFR protocols affect the results of the present systematic review. Three studies compared LL-BFR training to HLR training, while three other studies compared LL-BFR training to LLR training.18,35–39 Furthermore, three of the six studies used LL-BFR protocols as recommended by current evidence.18,35,36 Thirdly, blinding of participants and personnel could not be performed or was unclear in the included studies.18,35–39 This could affect the results, as the patients may have experienced a nonspecific effect or a placebo effect due to the novel nature of LL-BFR training. Overall, the methodological quality of the included studies ranged from moderate to good. Lastly, no long-term effects of LL-BFR training after ACL reconstruction were reported.

CONCLUSION The results of this systematic review indicate that LL-BFR training after ACL reconstruction may be beneficial on quadriceps strength, quadriceps mass, and knee joint pain compared to non-BFR training with non-detrimental effects on ACL graft laxity. However, more randomized controlled trials with operational definitions, standardized intervention protocols and outcome measurements are needed to add evidence on the clinical value of LL-BFR training.

CONFLICTS OF INTEREST

The authors declare no conflicts.

Submitted: July 26, 2021 CDT, Accepted: January 23, 2022 CDT

This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CCBY-NC-4.0). View this license’s legal deed at https://creativecommons.org/licenses/by-nc/4.0 and legal code at https://creativecommons.org/licenses/by-nc/4.0/legalcode for more information.

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Effect of Low-Load Blood Flow Restriction Training After Anterior Cruciate Ligament Reconstruction: A Systematic Review

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2017;24(2):319-328. doi:10.1016/j.knee.2016.11.003 3. Piussi R, Broman D, Musslinder E, Beischer S, Thomeé R, Hamrin Senorski E. Recovery of preoperative absolute knee extension and flexion strength after ACL reconstruction. BMC Sports Sci Med Rehabil. 2020;12(1):77-84. doi:10.1186/s13102-0 20-00222-8 4. Harput G, Tunay VB, Ithurburn M. Quadriceps and hamstring strength symmetry after anterior cruciate ligament reconstruction: a prospective study. J Sports Rehabil. 2020;30:1-8.

5. Birchmeier T, Lisee C, Kane K, Brazier B, Triplett A, Kuenze C. Quadriceps muscle size following ACL injury and reconstruction: a systematic review. J Orthop Res. 2020;38(3):598-608. doi:10.1002/jor.2448 9 6. Garcia SA, Curran MT, Palmieri-Smith RM. Longitudinal assessment of quadriceps muscle morphology before and after anterior cruciate ligament reconstruction and its associations with patient-reported outcomes. Sports Health.

2020;12(3):271-278. doi:10.1177/1941738119898210 7. Fukunaga T, Johnson CD, Nicholas SJ, McHugh MP. Muscle hypotrophy, not inhibition, is responsible for quadriceps weakness during rehabilitation after anterior cruciate ligament reconstruction. Knee Surg Sports Traumatol Arthrosc. 2019;27(2):573-579. doi:1 0.1007/s00167-018-5166-1 8. Kuenze CM, Blemker SS, Hart JM. Quadriceps function relates to muscle size following ACL reconstruction. J Orthop Res. 2016;34(9):1656-1662. d oi:10.1002/jor.23166 9. Thomas AC, Wojtys EM, Brandon C, Palmieri-Smith RM. Muscle atrophy contributes to quadriceps weakness after anterior cruciate ligament reconstruction. J Sci Med Sport. 2016;19(1):7-11. doi:1 0.1016/j.jsams.2014.12.009

10. Lepley AS, Pietrosimone B, Cormier ML. Quadriceps function, knee pain, and self-reported outcomes in patients with anterior cruciate ligament reconstruction. J Athl Train. 2018;53(4):337-346. doi:1 0.4085/1062-6050-245-16 11. Welling W, Benjaminse A, Seil R, Lemmink K, Zaffagnini S, Gokeler A. Low rates of patients meeting return to sport criteria 9 months after anterior cruciate ligament reconstruction: a prospective longitudinal study. Knee Surg Sports Traumatol Arthrosc. 2018;26(12):3636-3644. doi:10.1007/s0016 7-018-4916-4 12. Pua YH, Mentiplay BF, Clark RA, Ho JY. Associations among quadriceps strength and rate of torque development 6 weeks post anterior cruciate ligament reconstruction and future hop and vertical jump performance: a prospective cohort study. J Orthop Sports Phys Ther. 2017;47:845-852. doi:10.251 9/jospt.2017.7133 13. Ithurburn MP, Paterno MV, Ford KR, Hewett TE, Schmitt LC. Young athletes with quadriceps femoris strength asymmetry at return to sport after anterior cruciate ligament reconstruction demonstrate asymmetric single-leg drop-landing mechanics. Am J Sports Med. 2015;43(11):2727-2737. doi:10.1177/0363 546515602016 14. Shi H, Huang H, Ren S, et al. The relationship between quadriceps strength asymmetry and knee biomechanics asymmetry during walking in individuals with anterior cruciate ligament reconstruction. Gait Posture. 2019;73:74-79. doi:10.10 16/j.gaitpost.2019.07.151 15. Kyritsis P, Bahr R, Landreau P, Miladi R, Witvrouw E. Likelihood of ACL graft rupture: not meeting six clinical discharge criteria before return to sport is associated with a four times greater risk of rupture. Br J Sports Med. 2016;50(15):946-951. doi:10.1136/bjspor ts-2015-095908 16. Grindem H, Snyder-Mackler L, Moksnes H, Engebretsen L, Risberg MA. Simple decision rules can reduce reinjury risk by 84% after ACL reconstruction: the Delaware-Oslo ACL cohort study. Br J Sports Med. 2016;50(13):804-808. doi:10.1136/bjsports-2016-0960 31 17. American College of Sports Medicine. Progression models in resistance training for healthy adults. Med Sci Sports Exerc. 2009;41(3):687-708. doi:10.1249/ms s.0b013e3181915670

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Effect of Low-Load Blood Flow Restriction Training After Anterior Cruciate Ligament Reconstruction: A Systematic Review

18. Hughes L, Patterson SD, Haddad F, et al.

Examination of the comfort and pain experienced with blood flow restriction training during postsurgery rehabilitation of anterior cruciate ligament reconstruction patients: a UK national health service trial. Phys Ther Sport. 2019;39:90-98. doi:10.1016/j.pt sp.2019.06.014 19. Fujimoto E, Sumen Y, Urabe Y, et al. An early return to vigorous activity may destabilize anterior cruciate ligaments reconstructed with hamstring grafts. Arch Phys Med Rehabil. 2004;85(2):298-302. do i:10.1016/s0003-9993(03)00621-x 20. Ménétrey J, Duthon VB, Laumonier T, Fritschy D. “Biological failure” of the anterior cruciate ligament graft. Knee Surg Sports Traumatol Arthr.

2008;16(3):224-231. doi:10.1007/s00167-007-0474-x 21. Janssen RPA, Scheffler SU. Intra-articular remodelling of hamstring tendon grafts after anterior cruciate ligament reconstruction. Knee Surg Sports Traumatol Arthrosc. 2014;22(9):2102-2108. doi:10.100 7/s00167-013-2634-5 22. Beynnon BD, Uh BS, Johnson RJ, et al.

Rehabilitation after anterior cruciate ligament reconstruction: a prospective, randomized, doubleblind comparison of programs administered over 2 different time intervals. Am J Sports Med. 2005;33(3):347-359. doi:10.1177/0363546504268406 23. DePhillipo NN, Kennedy MI, Aman ZS, Bernhardson AS, O’Brien LT, LaPrade RF. The role of blood flow restriction therapy following knee surgery: expert opinion. Arthroscopy. 2018;34(8):2506-2510. d oi:10.1016/j.arthro.2018.05.038 24. Humes C, Aguero S, Chahla J, Foad A. Blood flow restriction and its function in post-operative anterior cruciate ligament reconstruction therapy: expert opinion. Arch Bone Jt Surg. 2020;8:570-574.

25. Vopat BG, Vopat LM, Bechtold MM, Hodge KA. Blood flow restriction therapy: where we are and where we are going. J Am Acad Orthop Surg.

2020;28(12):e493-e500. doi:10.5435/jaaos-d-19-0034 7 26. Pearson SJ, Hussain SR. A review on the mechanisms of blood-flow restriction resistance training-induced muscle hypertrophy. Sports Med. 2015;45(2):187-200. doi:10.1007/s40279-014-0264-9 27. Hwang PS, Willoughby DS. Mechanisms behind blood flow-restricted training and its effect toward muscle growth. J Strength Cond Res. 2019;33(1):S167-S179. doi:10.1519/jsc.000000000000 2384

28. Charles D, White R, Reyes C, Palmer D. A systematic review of the effects of blood flow restriction training on muscle atrophy and circumference post ACL reconstruction. Intl J Sports Phys Ther. 2020;15(6):882-891. doi:10.26603/ijspt202 00882 29. Shamseer L, Moher D, Clarke M, et al. Preferred reporting items for systematic review and metaanalysis protocols (PRISMA-P) 2015: elaboration and explanation. BMJ. 2015;349:g7647. doi:10.1136/bmj.g 7647 30. RefWorks Ann Arbour. Proquest LLC. Accessed February 2021. https://www.refworks.com/refworks2/ 31. Review Manager (RevMan) 5.4. Accessed February 2021. https://training.cochrane.org/ 32. Sterne JA, Hernán MA, Reeves BC, et al. ROBINSI: a tool for assessing risk of bias in non-randomised studies of interventions. BMJ. 2016;355:i4919. doi:1 0.1136/bmj.i4919 33. Higgins JPT, Altman DG, Gotzsche PC, et al. The Cochrane Collaboration’s tool for assessing risk of bias in randomised trials. BMJ. 2011;343(oct18 2):d5928-d5928. doi:10.1136/bmj.d5928 34. Cumpston M, Li T, Page MJ, et al. Updated guidance for trusted systematic reviews: a new edition of the Cochrane Handbook for Systematic Reviews of Interventions. Cochrane Editorial Unit, ed.

Cochrane Database of Systematic Reviews.

2019;10:ed000142. doi:10.1002/14651858.ed000142 35. Hughes L, Rosenblatt B, Haddad F, et al.

Comparing the effectiveness of blood flow restriction and traditional heavy load resistance training in the post-surgery rehabilitation of anterior cruciate ligament reconstruction patients: a UK national health service randomised controlled trial. Sports Med. 2019;49(11):1787-1805. doi:10.1007/s40279-01 9-01137-2 36. Hughes L, Paton B, Haddad F, Rosenblatt B, Gissane C, Patterson SD. Comparison of the acute perceptual and blood pressure response to heavy load and light load blood flow restriction resistance exercise in anterior cruciate ligament reconstruction patients and non-injured populations. Phys Ther Sport. 2018;33:54-61. doi:10.1016/j.ptsp.2018.07.002 37. Ohta H, Kurosawa H, Ikeda H, Iwase Y, Satou N, Nakamura S. Low-load resistance muscular training with moderate restriction of blood flow after anterior cruciate ligament reconstruction. Acta Orthop Scand.

2003;74(1):62-68. doi:10.1080/00016470310013680

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38. Takarada Y, Takazawa H, Ishii N. Applications of vascular occlusion diminish disuse atrophy of knee extensor muscles. Med Sci Sports Exerc.

2000;32(12):2035-2039. doi:10.1097/00005768-20001 2000-00011

48. Bryk FF, dos Reis AC, Fingerhut D, et al. Exercises with partial vascular occlusion in patients with knee osteoarthritis: a randomized clinical trial. Knee Surg Sports Traumatol Arthrosc. 2016;24(5):1580-1586. do i:10.1007/s00167-016-4064-7

39. Iversen E, Røstad V, Larmo A. Intermittent blood flow restriction does not reduce atrophy following anterior cruciate ligament reconstruction. J Sports Health Sci. 2016;5(1):115-118. doi:10.1016/j.jshs.201 4.12.005

49. Ladlow P, Coppack RJ, Dharm-Datta S, et al. Lowload resistance training with blood flow restriction improves clinical outcomes in musculoskeletal rehabilitation: a single-blind randomized controlled Trial. Front Physiol. 2018;9:1269. doi:10.3389/fphys.2 018.01269

40. Van Cant J, Dawe-Coz A, Aoun E, Esculier JF. Quadriceps strengthening with blood flow restriction for the rehabilitation of patients with knee conditions: a systematic review with meta-analysis. J Back Musculoskelet Rehabil. 2020;33(4):529-544. doi:1 0.3233/bmr-191684 41. Ferlito JV, Pecce SAP, Oselame L, De Marchi T. The blood flow restriction training effect in knee osteoarthritis people: a systematic review and metaanalysis. Clin Rehabil. 2020;34(11):1378-1390. doi:1 0.1177/0269215520943650 42. Grønfeldt BM, Lindberg Nielsen J, Mieritz RM, Lund H, Aagaard P. Effect of blood‐flow restricted vs heavy‐load strength training on muscle strength: systematic review and meta‐analysis. Scand J Med Sci Sports. 2020;30(5):837-848. doi:10.1111/sms.13632 43. Barber-Westin S, Noyes FR. Blood flow-restricted training for lower extremity muscle weakness due to knee pathology: a systematic review. Sports Health.

2019;11(1):69-83. doi:10.1177/1941738118811337 44. Centner C, Wiegel P, Gollhofer A, König D. Effects of blood flow restriction training on muscular strength and hypertrophy in older individuals: a systematic review and meta-Analysis. Sports Med. 2019;49(1):95-108. doi:10.1007/s40279-018-0994-1 45. Hughes L, Paton B, Rosenblatt B, Gissane C, Patterson SD. Blood flow restriction training in clinical musculoskeletal rehabilitation: a systematic review and meta-analysis. Br J Sports Med. 2017;51(13):1003-1011. doi:10.1136/bjsports-2016-09 7071 46. Lixandrão ME, Ugrinowitsch C, Berton R, et al.

Magnitude of muscle strength and mass adaptations between high-load resistance training versus lowload resistance training associate with blood-flow restriction: a systematic review and meta-analysis.

Sports Med. 2018;48(2):361-378. doi:10.1007/s4027 9-017-0795-y 47. Ferraz RB, Gualano B, Rodrigues R, et al. Benefits of resistance training with blood flow restriction in knee osteoarthritis. Med Sci Sports Exerc.

2018;50(5):897-905. doi:10.1249/mss.0000000000001 530

50. Tennent DJ, Hylden CM, Johnson AE, Burns TC, Wilken JM, Owens JG. Blood flow restriction training after knee arthroscopy: a randomized controlled pilot study. Clin J Sport Med. 2017;27(3):245-252. doi:10.10 97/jsm.0000000000000377 51. Cuyul-Vásquez I, Leiva-Sepúlveda A, CatalánMedalla O, Araya-Quintanilla F, Gutiérrez-Espinoza H. The addition of blood flow restriction to resistance exercise in individuals with knee pain: a systematic review and meta-analysis. Braz J Phys Ther.

2020;24(6):465-478. doi:10.1016/j.bjpt.2020.03.001 52. Spitz RW, Chatakondi RN, Bell ZW, et al. Blood flow restriction exercise: effects of sex, cuff width, and cuff pressure on perceived lower body discomfort.

Percept Mot Skills. 2021;128(1):353-374. doi:10.1177/0 031512520948295 53. Weatherholt AM, Vanwye WR, Lohmann J, Owens JG. The effect of cuff width for determining limb occlusion pressure: a comparison of blood flow restriction devices. J Exerc Sci. 2019;12:136-143.

54. Jessee MB, Buckner SL, Dankel SJ, Counts BR, Abe T, Loenneke JP. The Influence of cuff width, sex, and race on arterial occlusion: implications for blood flow restriction research. Sports Med. 2016;46(6):913-921. doi:10.1007/s40279-016-0473-5 55. Loenneke JP, Fahs CA, Rossow LM, et al. Effects of cuff width on arterial occlusion: implications for blood flow restricted exercise. Eur J Appl Physiol.

2012;112(8):2903-2912. doi:10.1007/s00421-011-226 6-8 56. Spitz RW, Wong V, Bell ZW, et al. Blood flow restricted exercise and discomfort: a review. J Strength Cond Res. 2022;36(3):871-879. doi:10.1519/jsc.000000 0000003525 57. Korakakis V, Whiteley R, Epameinontidis K. Blood flow restriction induces hypoalgesia in recreationally active adult male anterior knee pain patients allowing therapeutic exercise loading. Phys Ther Sport.

2018;32:235-243. doi:10.1016/j.ptsp.2018.05.021

International Journal of Sports Physical Therapy

Effect of Low-Load Blood Flow Restriction Training After Anterior Cruciate Ligament Reconstruction: A Systematic Review

58. Korakakis V, Whiteley R, Giakas G. Low load resistance training with blood flow restriction decreases anterior knee pain more than resistance training alone. a pilot randomised controlled trial.

Phys Ther Sport. 2018;34:121-128. doi:10.1016/j.pts p.2018.09.007 59. Janssen RPA, van Melick N, van Mourik JBA, Reijman M, van Rhijn LW. ACL reconstruction with hamstring tendon autograft and accelerated bracefree rehabilitation: a systematic review of clinical outcomes. BMJ Open Sport Exerc Med. 2018;4(1):2017-20000301. doi:10.1136/bmjsem-201 7-000301 60. Kruse LM, Gray B, Wright RW. Rehabilitation after anterior cruciate ligament reconstruction: a systematic review. J Bone Joint Surg Am. 2012;94(19):1737-1748. doi:10.2106/jbjs.k.01246

61. Smith AH, Capin JJ, Zarzycki R, Snyder-Mackler L. Athletes with bone-patellar tendon bone autograft for anterior cruciate ligament reconstruction were slower to meet rehabilitation milestones and return-to-sport criteria than athletes with hamstring tendon autograft or soft tissue allograft: secondary analysis from the ACL-SPORTS trial. J Orthop Sports Phys Ther.

2020;50(5):259-266. doi:10.2519/jospt.2020.9111 62. van Groningen B, van der Steen MC, Janssen DM, van Rhijn LW, van der Linden AN, Janssen RPA. Assessment of graft maturity after anterior cruciate ligament reconstruction using autografts: a systematic review of biopsy and magnetic resonance imaging studies. Arthrosc Sports Med Rehabil.

2020;2(4):377-388. doi:10.1016/j.asmr.2020.02.008 63. Beynnon BD, Johnson RJ, Naud S, et al.

Accelerated versus nonaccelerated rehabilitation after anterior cruciate ligament reconstruction: a prospective, randomized, double-blind investigation evaluating knee joint laxity using roentgen stereophotogrammetric analysis. Am J Sports Med. 2011;39(12):2536-2548. doi:10.1177/03635465114223 49

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Effect of Low-Load Blood Flow Restriction Training After Anterior Cruciate Ligament Reconstruction: A Systematic Review

SUPPLEMENTARY MATERIALS Appendix 1 Download: https://ijspt.scholasticahq.com/article/33151-effect-of-low-load-blood-flow-restriction-training-afteranterior-cruciate-ligament-reconstruction-a-systematic-review/attachment/84051.docx?auth_token=b6MQtixLkIEJovi9K4V

International Journal of Sports Physical Therapy

Prue J, Roman DP, Giampetruzzi NG, et al. Side Effects and Patient Tolerance with the Use of Blood Flow Restriction Training after ACL Reconstruction in Adolescents: A Pilot Study. IJSPT. 2022;17(3):347-354.

Original Research

Side Effects and Patient Tolerance with the Use of Blood Flow Restriction Training after ACL Reconstruction in Adolescents: A Pilot Study Jennifer Prue 1, Dylan P Roman 1 , Nicholas G Giampetruzzi 1, Arthur Fredericks 1, Adel Lolic 1, Allison Crepeau 2, J. Lee a Pace 3, Adam P Weaver 1 1

Sports Physical Therapy, Connecticut Children's, 2 Elite Sports Medicine, Connecticut Children's, 3 Department of Orthopedics & Sports Medicine, Children's Health Andrews Institute Keywords: Reported Side Effects, Patient Tolerance, Blood Flow Restriction, ACL, Safety https://doi.org/10.26603/001c.32479

International Journal of Sports Physical Therapy Vol. 17, Issue 3, 2022

Background Blood flow restriction training (BFRT) has gained popularity in rehabilitation due to its benefits in reducing muscle atrophy and mitigating strength deficits following anterior cruciate ligament reconstruction (ACLR). While the effectiveness and safety of BFRT has been well studied in healthy adult subjects, there is limited information about the use of BFRT in the adolescent population, specifically related to patient tolerance and reported side effects post ACLR.

Purpose To investigate and record reported side effects and patient tolerance to BFRT during ACLR rehabilitation in adolescents.

Study Design Prospective Cohort Study

Methods Patients between 12 and 18 years of age who underwent ACLR at Connecticut Children’s were included. Patients utilized an automatic personalized tourniquet system and followed a standardized BFRT exercise protocol over 12 weeks starting 8.72 ± 3.32 days post-op. Upon completion of exercise while using BFRT, patients reported side effects and any adverse events were logged. Descriptive statistics were used to describe the reported side effects and adverse events associated with BFRT and calculate the frequencies of those events over a 12-week period.

Results Five hundred and thirty-five total BFRT sessions were completed between 29 patients (15.39 ± 1.61 years of age). There were zero reports of subcutaneous hemorrhage (SubQ hemorrhage) and deep vein thrombosis (DVT). Reported minor side effects to BFRT included itchiness of the occluded limb (7.85%), lower extremity paresthesia (2.81%), and dizziness (0.75%). A total of 10.47% of BFR treatment sessions were unable to be completed due to tolerance, and 3.5% of sessions required a reduction in limb occlusion pressure (LOP).

a

Corresponding Author: Adam Weaver, PT, DPT Connecticut Children’s 399 Farmington Avenue Farmington, CT 06032 Email: aweaver@connecticutchildren.org Phone: 410-474-4550 Fax: 860-837-9341

Side Effects and Patient Tolerance with the Use of Blood Flow Restriction Training after ACL Reconstruction in...

Conclusion These preliminary data suggest that BFRT is safe with only minor side effects noted in the adolescent population after ACLR. Further investigations are warranted to continue to evaluate patient tolerance and safety with BFRT, because while these preliminary results suggest a positive safety profile and good tolerance in the adolescent population after ACLR, they represent the experiences of only a small sample.

Level of Evidence Level 3

INTRODUCTION Anterior cruciate ligament (ACL) injury is common in adolescents and young adults with over 200,000 ACL injuries reported in the United States each year.1 It has been reported that greater than 75% of all young athletes who suffer an ACL tear undergo ACL reconstruction (ACLR).2 Deficits in quadriceps strength and muscle atrophy are common both early in rehabilitation and long-term after ACLR.3 Quadriceps weakness after ACLR has been associated with altered gait,4 altered biomechanics,5 and osteoarthritis.6 Prior reports of return to sport (RTS) rates have been reported to be as low as 33% twelve months after ACLR.7 Even more concerning is the rate of a second ACL injury, reported to be as high as 35% for young athletes.8,9 While these issues are likely multifactorial, one significant reason for these RTS rates and re-injury rates may be the failure to obtain sufficient lower extremity function and muscle strength.10 One of the most common and effective methods for increasing muscle strength and mass is through heavy-load resistance training (HL-RT).11 The American College of Sports Medicine recommends performing resistance exercise at an intensity greater than 70% of maximum strength in healthy adults in order to achieve muscle adaptations in both size and strength.12 In the first 12 weeks after ACLR, the use of HL-RT is not feasible, as high levels of musculoskeletal loading may be contraindicated in post-surgical individuals. Low load resistance training (LL-RT) is often indicated during early stages of rehabilitation, but is often insufficient to invoke adequate muscular adaptations.

There is mounting evidence that performing LL-RT with blood flow restriction to the exercising muscles provides a potent stimulus for increasing muscle strength and mass after ACLR in adults.13,14 Blood flow restriction training (BFRT) is a technique increasingly used in physical therapy and rehabilitation settings as an alternative to HL-RT. BFRT consist of exercising using a surgical grade pneumatic cuff or tourniquet that partially restricts arterial inflow, and fully restricts venous outflow from the working musculature during exercise.15,16 The clinical value of BFRT that has been suggested in the literature is that it allows increased muscle adaptation and hypertrophy with LL-RT,17 making BFRT a potentially advantageous tool to implement in the early post-operative population. The utilization of BFRT in conjunction with current rehabilitation standards of care has shown potential with respect to muscle adaptations and performance. A meta-analysis comparing BFRT on musculoskeletal rehabilitation versus traditional LL-RT, reported low load BFRT

training to be more effective in helping patients regain strength than traditional LL-RT.17 A common point of discussion regarding BFRT is the potential safety risk, specifically in the post-surgical population. Possible concerns include the effects of BFRT on the cardiovascular system such as blood pressure responses, potential thrombolytic events and damage to the vascular system.16 Despite these concerns, there have been several extensive reviews published demonstrating that the side effects are minimal,18,19 and BFRT when compared with traditional methods of strength training shows no greater risk in adults.20 Hughes et al. described BFRT to be as effective at improving strength and more effective at improving function, pain, and swelling compared to HL-RT in ACLR patients,13 as well as more comfortable for patients during the early phases of post-surgery rehabilitation.21 The ability to improve strength and function with BFRT with mild patient discomfort makes for an appealing tool during the early post-surgical phases of rehabilitation.

While the effectiveness and safety of BFRT has been explored in the healthy adult population, there is limited information about the tolerance and side effects of BFRT in the adolescent population post ACLR. Given that a large proportion of ACLR occur in the adolescent population and also recognizing that young22 and active patients are the most at risk for re-injury, BFRT has significant potential to aid in rehabilitation of these individuals after ACLR. Therefore, the purpose of this study was to investigate and record patient reported/observed side effects and tolerance to BFRT during post-surgical ACL rehabilitation in adolescents. It was hypothesized that adverse events and patient tolerance to BFRT will be consistent with previously published literature.

MATERIALS AND METHODS ETHICAL APPROVAL

Ethical approval was granted from an Institutional Review Board.

STUDY DESIGN

Prospective Cohort Study CONSENT

All potential patients that were scheduled to undergo ACL reconstruction at Connecticut Children’s were approached for participation for the study. Patients were pre-screened based on inclusion and exclusion criteria. Once identified as

International Journal of Sports Physical Therapy

Side Effects and Patient Tolerance with the Use of Blood Flow Restriction Training after ACL Reconstruction in...

Table 1. Exercise Protocol

Phase 1

Phase 2

Phase 3

Phase 4

Phase 5

Phase 6

Weeks 1 to 2

Weeks 3 to 4

Weeks 5 to 6

Weeks 7 to 8

Weeks 9 to 12

Weeks 11 to 12

Quad Set

Long Arc Quad (90-30deg)

Long Arc Quad (90-30deg)

Step Up

Split Squat

Split Squat

10 second on, 10 second rest

30/15/15/15

30/15/15/15

30/15/15/15

30/15/15/15

30/15/15/15 80% occlusion

80% occlusion

80% occlusion

80% occlusion

80% occlusion

80% occlusion

Side Lying Hip Abduction

Side Lying Hip Abduction

Bilateral Hip Bridge

Bilateral Hip Bridge

Medial Step Down

Medial Step Down

30/15/15/15

30/15/15/15

30/15/15/15

30/15/15/15

30/15/15/15

30/15/15/15

80% occlusion

80% occlusion

80% occlusion

80% occlusion

80% occlusion

80% occlusion

Prone Hip Extension

Leg Press (shuttle)

Leg Press (shuttle)

Leg Press (shuttle)

Leg Press (shuttle)

Leg Press (shuttle)

30/15/15/15

30/15/15/15

30/15/15/15

30/15/15/15

30/15/15/15

30/15/15/15

80% occlusion

80% occlusion

80% occlusion

80% occlusion

80% occlusion

80% occlusion

a potential candidate, the study purpose and protocol were explained and a brief summary of the study was provided to the patient/parent. Once patient/parent agreed to participate in the study, all patient guardians and patients provided signed informed consent/assent at the pre-operative visit.

exercises per session as part of their physical therapy session twice per week.

BLOOD FLOW RESTRICTION

Participants in this study were those between 12 and 18 years of age already enrolled in an ongoing IRB approved registered clinical trial investigating the impact of BFRT after primary ACLR at Connecticut Children’s from January 2020 to present. All study participants underwent ACL reconstruction using quadriceps tendon autograft by two sports fellowship trained orthopedic surgeons. All participants had no known history of central or peripheral neurological impairment and were free of any cardiac, pulmonary or metabolic conditions. Other exclusion criteria included: previous surgical intervention either on the ipsilateral or contralateral knee, history of deep vein thrombosis, multiligament rupture or trauma, chondral pathology and any additional lower extremity injury at time of knee injury requiring treatment. Additionally, meniscal root and complex tears requiring weight bearing restrictions greater than two weeks after surgery were also excluded.

All patients utilized a personalized tourniquet system (Delfi Medical), which has been shown to calculate limb occlusion pressure (LOP) reliably and accurately. LOP is defined as the minimum pressure required for full arterial occlusion.24 This device automatically increases cuff pressure in stepwise increments by analyzing arterial pressure pulsations at each cuff pressure increment, and then uses these values to determine LOP. Variable contour cuffs,25 either 24 or 34 inches in length and 4.5" wide, were utilized based on thigh circumference with a protective barrier between the skin and cuff.26 Prior to exercise, the cuff was placed on the most proximal portion of the involved lower limb. Measurement of LOP can help minimize tourniquet pressures and pressure gradients.25 LOP was calculated for each limb individually in the supine position at the beginning of every training session and BFR pressure was set at 80% of the patient’s LOP for exercise completion. LOP at 80% provides high levels of fast twitch fiber recruitment and maximize muscle adaptation.27 Patients were provided instruction that they were allowed to request reduction of LOP during exercise based on their tolerance.

POSTOPERATIVE REHABILITATION

EXERCISE PROGRESSION AND PATIENT TOLERANCE

All patients initiated formal physical therapy within one week of surgery. All participants were instructed in a standardized postoperative rehabilitation protocol adapted from Adams et al.23 The early rehabilitation phase (up to 12 weeks from surgery) consisted of acute symptom management, restoring range of motion and normalizing gait. In addition to the rehabilitation protocol, all patients followed a standardized BFRT exercise protocol over the 12-week early rehabilitation phases (Table 1). This included three

To determine the appropriate resistance for each exercise, patients performed the exercise with a weight they could comfortably lift for several repetitions. The patient’s perceived exertion of a one rep maximum (RM) was estimated using the modified OMNI-RES scale and starting load for each exercise was 20-30% of their 1RM.28 Bodyweight resistance was used when loading was not feasible. The standard repetition scheme used in this study was a set of 30 repetitions followed by a 30 second rest followed by three more

PARTICIPANTS

International Journal of Sports Physical Therapy

Side Effects and Patient Tolerance with the Use of Blood Flow Restriction Training after ACL Reconstruction in...

Table 2. Demographic Information for Participant (n=29)

Sex, n (%) Male

14 (48)

Female

15 (52)

Age, yr (mean ± SD)

15.39 ± 1.61

Height, cm

168.02 ± 7.59

Weight, kg (mean ± SD)

64.43 ± 14.31

Baseline Tegner Score

8.43± 1.89

BMI, kg/m2 (mean ± SD)

23.65 ± 3.90

Number of BFR Sessions per Patient (mean ± SD)

18.45 ± 6.47

Days Post-op to Start of BFRT (mean ± SD)

8.72 ± 3.32

Total # of BFR Sessions Across All Patients

535

sets of 15 with 30 second rests in between.29 Patients had eight minutes to complete the target of 75 repetitions for each of the three exercises per session. The BFRT cuff remained inflated for the entire time until all 75 repetitions were completed, or until the eight minutes elapsed. At the conclusion of each exercise, the cuff was deflated for one minute, and the patient’s rating of perceived exertion (RPE) was recorded prior to initiating the next exercise. Patients were instructed to report any side effects or adverse events during or immediately after exercise completion. For the purposes of this study, monitoring for the following side effects included: subcutaneous hemorrhage (SubQ), deep vein thrombosis (DVT), fainting, dizziness, lower extremity paresthesia, and itching as previously described by Yasuda et al.17 To monitor and record patient tolerance, it was documented if patients requested a reduction of LOP or were unable to finish the exercise. The inability to finish an exercise was defined as voluntary stoppage of exercise by the patient, or the inability to complete all 75 repetitions in eight minutes.

ANALYSIS

Results were analyzed using Microsoft Excel. Descriptive statistics were used to calculate the means and standard deviations for height, weight, BMI, age, and average number of BFRT sessions per patient. Adverse event occurrences were tallied for weeks one to four, five to eight, nine to twelve, and cumulatively over the 12-week period. Percentage of occurrences were found by dividing total number of reported occurrences by total number of BFRT sessions. Because of the descriptive nature of this research, no other comparisons were made.

RESULTS Twenty-nine patients between the ages of 12 and 18 years (15.39±1.62 years of age) at the time of surgery were included in the study. Seven participants were unable to complete the intended 12 weeks of BFRT for various reasons after surgery (Figure 1).

Additional demographic information can be found in

Figure 1. Patients unable to complete prescribed 12 weeks of BFRT

Table 2. Five hundred and thirty-five total BFRT sessions were completed between all patients, with each patient completing an average of 18.45±6.47 sessions over 12 weeks. There were zero reports of deep vein thrombosis (DVT), subcutaneous hemorrhage (SubQ hemorrhage), and fainting across all patients (Table 3), considered as major adverse events. Reported minor side effects to BFRT included itchiness of the occluded limb (7.85%), lower extremity paresthesia (2.81%), and dizziness (0.75%) (Table 4). 10.47% of BFR treatment sessions were unable to be finished due to tolerance, and 3.55% of sessions required a reduction in LOP (Table 5).

DISCUSSION In this study, out of 535 sessions of BFRT, there were no reported major adverse events (DVT, SubQ hemorrhage, and fainting), and minor reported side effects to BFRT were reported a total of 11.41% of the time. BFRT in adolescents appears to be well tolerated, as patients were able to finish the prescribed exercise 89.53% of the time and reduction of limb occlusion pressure occurred 3.55% of the time.

BFRT pressure, duration of inflation, and cuff width are three modifiable variables that may influence the likelihood of reported adverse events with BFRT. Variable contour cuffs that are 4.5 inches in width with a protective barrier between the skin and cuff were used for each patient. Due to the tapered shape of limbs, variable-contour cuffs have

International Journal of Sports Physical Therapy

Side Effects and Patient Tolerance with the Use of Blood Flow Restriction Training after ACL Reconstruction in...

Table 3. Major Side Effects Reported with BFRT (n=535)

Event

Number Reported

Percentage per Total Treatments

SubQ Hemorrhage

0

0%

DVT

0

0%

Fainting

0

0%

Table 4. Minor Side Effects Reported with BFRT (n=535)

Event

Number Reported

Percentage per Total Treatments

Dizziness

4

0.75%

Lower Extremity Paresthesias

15

2.81%

Itching

42

7.59%

Table 5. Patient Tolerance to BFRT (n=535)

Event

Number Reported

Percentage per Total Treatments

Inability to Finish

56

10.47%

Decrease in Pressure

19

3.55%

been shown to enhance patient comfort and further decrease the risk of mechanical shearing, as well as allow for occlusion at lower pressures.20 Prior authors have reported on adverse events after BFRT with the use of narrow diameter cuffs (∼3 cm) and with high pressures (160 to 200 mm Hg).16 A higher rate of adverse side effects were reported utilizing a narrow diameter cuff and high pressures, consistent with Estebe et al. who concluded that a 14 cm cuff needed significantly less pressure to occlude blood flow compared to a 7 cm cuff that caused significantly more pain after reaching arterial occlusion.30 Additionally, LOP was calculated for each limb individually at every training session. The personalized tourniquet pressure for each patient plays a role in patient comfort.

Lower pressures are needed to stop venous outflow, compared to the amount of pressure needed to stop arterial inflow. If the occlusion pressure is too high, blood supply to the exercising limb can be eliminated. If the pressure is too low, there may be too much arterial inflow causing venous congestion in the limb, which can be very painful for patients.20 While a small percentage reported the need to reduce LOP, the majority of patients in this study tolerated 80% LOP. There is some evidence to suggest that lower occlusion pressures may produce similar adaptations31, but 80% LOP appears to be the optimal pressure to induce the greatest muscular adaptation.27,32 In this study, there were no reports of major adverse events of DVT or subcutaneous hemorrhage. The perception that short duration tourniquet use poses significant thrombus risk appears to be unsupported. While there is risk of DVT after post-operative orthopedic extremity surgery,

there is evidence to suggest that the use of a tourniquet is not an independent risk factor for DVT and is correlated with anti-thrombolytic factors in the surgical population.33 It has been well established that short duration tourniquet use has fibrinolytic potential, and does not seem to pose an increased thrombus risk. Additionally, several studies have found no increase in markers for thrombus formation after BFR with exercise.34,35 Survey studies have also reported very low or no occurrences of thrombolytic complications (0.055%),18,36 and Nakajima et al reported that 13% of adults experienced subQ hemorrhage which is in contrast to the current findings. These reports of occurrences were often in an adult population, as well as without the use of standardized limb occlusion pressure, or variable contour cuffs.

In 7.85% of sessions, patients in this study reported transient itching, but it is important to note that all patients were able to complete exercises. Of the 29 patients in the study, two patients accounted for all reported events of itchiness. Prior research regarding patient tolerance to BFRT has not reported on the sensation of itching. The pathophysiology of itch is not well understood, but it has been categorized into four clinical categories: psychogenic, neurogenic, neuropathic, and pruritoceptive.37 It is unknown if itch after BFR follows the same physiology. There is also some evidence to suggest that itch after BFRT is related to the histamine release that occurs during exercise.38 Exercise will result in the activation of histamine receptors in the exercised muscle and triggers vasodilation, as well as a broad range of responses to exercise.

Previous reports of other adverse events such as fainting/

International Journal of Sports Physical Therapy

Side Effects and Patient Tolerance with the Use of Blood Flow Restriction Training after ACL Reconstruction in...

dizziness, and lower extremity paresthesias after BFRT have varied. In this study, there were no reports of fainting, and very low occurrences of paresthesias. Tourniquet compression may cause paresthesias due to ischemia or altered nerve conduction, however all reports of paresthesias in this study were transient and normal sensation was restored immediately following cuff deflation. Patterson et al reported fainting and dizziness in 14.6% of subjects, however, this included a wide range of ages, several different types of tourniquets or hand held pumps, and non-standardized occlusion pressures.36 Careful monitoring and feedback from patients, as well as subtle adjustments of tourniquet placement on the proximal limb may help minimize these side effects. It is possible that as this study continues and the number of enrollees grows, fainting may be encountered. Based on the findings in this preliminary report, it appears this will be an infrequent occurrence and will likely not be a contraindication to BFRT for adolescents after ACLR

LIMITATIONS The relatively small sample size of only 29 participants is the principal limitation in this study, and this report should only be interpreted as a preliminary report. Further, while patients between the ages of 12 and 18 were recruited for this study, most patients were on the upper end of this age scale so the younger adolescent population was not equally represented. This is expected in the ACLR population as most of these injuries occur after the onset of puberty, but it represents a limitation nonetheless. Additionally, by defining “inability to finish” as voluntary stoppage of exercise by the patient or the inability to complete all 75 repetitions in eight minutes, patient intolerance may have been overestimated. Load progressions in this study were based on the patient’s ability to successfully complete 75 repetitions.

Therefore, it is unknown whether the inability to finish was

a result of adequate loading or voluntary stoppage because of intolerance. Future studies will better define these differences. Lastly, because of the focus on immediate side effects/responses to BFRT, there may have been a failure to capture long term side effects like delayed onset muscle soreness (DOMS).

CONCLUSION This preliminary report shows a very low and minor side effect profile as well as generally good tolerance to BFRT in the adolescent population after ACLR. Major reported side effects to BFRT such as a DVT, SubQ hemorrhage, and fainting were not seen in this study, and minor side effects of BFRT including paresthesias and itching of the occluded limb were infrequent. As always, all populations should be assessed for possible risks and contraindications before performing BFRT. Further data is needed for a definitive determination of the safety of this intervention in this population, however, the early results are promising.

CONFLICTS OF INTEREST

JP, DR, NG, AL and AW have no conflicts of interest to disclose. AC has a leadership role for Pro Papa Missions America, Pediatric Orthopedic Society of North America, and Pediatric Research in Sports Medicine. JLP receives consulting fees and grants from Arthrex, JRF Ortho, and the American Orthopedic Society for Sports Medicine.

Submitted: November 01, 2021 CDT, Accepted: December 20, 2021 CDT

This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CCBY-NC-4.0). View this license’s legal deed at https://creativecommons.org/licenses/by-nc/4.0 and legal code at https://creativecommons.org/licenses/by-nc/4.0/legalcode for more information.

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Side Effects and Patient Tolerance with the Use of Blood Flow Restriction Training after ACL Reconstruction in...

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2013;48(6):810-817. doi:10.4085/1062-6050-48.6.03 3. Thomas AC, Wojtys EM, Brandon C, Palmieri-Smith RM. Muscle atrophy contributes to quadriceps weakness after anterior cruciate ligament reconstruction. J Sci Med Sport. 2016;19(1):7-11. doi:1 0.1016/j.jsams.2014.12.009 4. Butler RJ, Minick KI, Ferber R, Underwood F. Gait mechanics after ACL reconstruction: implications for the early onset of knee osteoarthritis. Br J Sports Med. 2009;43(5):366-370. doi:10.1136/bjsm.2008.052522 5. Shimizu T, Samaan MA, Tanaka MS, et al.

Abnormal biomechanics at 6 months are associated with cartilage degeneration at 3 years after anterior cruciate ligament reconstruction. Arthroscopy.

2019;35(2):511-520. doi:10.1016/j.arthro.2018.07.033 6. Lohmander LS, Englund PM, Dahl LL, Roos EM. The long-term consequence of anterior cruciate ligament and meniscus injuries. Am J Sports Med. 2007;35(10):1756-1769. doi:10.1177/03635465073073 96 7. Ardern CL, Webster KE, Taylor NF, Feller JA. Return to the preinjury level of competitive sport after anterior cruciate ligament reconstruction surgery. Am J Sports Med. 2011;39(3):538-543. doi:10.1177/036354 6510384798 8. Webster KE, Feller JA. Exploring the high reinjury rate in younger patients undergoing anterior cruciate ligament reconstruction. Am J Sports Med. 2016;44(11):2827-2832. doi:10.1177/03635465166518 45 9. Paterno MV, Rauh MJ, Schmitt LC, Ford KR, Hewett TE. Incidence of second ACL injuries 2 years after primary ACL reconstruction and return to sport. Am J Sports Med. 2014;42(7):1567-1573. doi:10.1177/03635 46514530088

10. Welling W, Benjaminse A, Seil R, Lemmink K, Zaffagnini S, Gokeler A. Low rates of patients meeting return to sport criteria 9 months after anterior cruciate ligament reconstruction: a prospective longitudinal study. Knee Surg Sports Traumatol Arthrosc. 2018;26(12):3636-3644. doi:10.1007/s0016 7-018-4916-4 11. Campos G, Luecke T, Wendeln H, et al. Muscular adaptations in response to three different resistancetraining regimens: specificity of repetition maximum training zones. Eur J Appl Physiol. 2002;88(1-2):50-60. doi:10.1007/s00421-002-0681-6 12. American College of Sports Medicine. American College of Sports Medicine position stand. progression models in resistance training for healthy adults. Med Sci Sports Exerc. 2009;41(3):687-708. do i:10.1249/MSS.0b013e3181915670 13. Hughes L, Rosenblatt B, Haddad F, et al.

Comparing the effectiveness of blood flow restriction and traditional heavy load resistance training in the post-surgery rehabilitation of anterior cruciate ligament reconstruction patients: A UK national health service randomised controlled trial. Sports Med. 2019;49(11):1787-1805. doi:10.1007/s40279-01 9-01137-2 14. Takarada Y, Takazawa H, Ishii N. Applications of vascular occlusion diminish disuse atrophy of knee extensor muscles. Med Sci Sports Exerc.

2000;32(12):2035-2039. doi:10.1097/00005768-20001 2000-00011 15. Scott BR, Loenneke JP, Slattery KM, Dascombe BJ. Exercise with blood flow restriction: an updated evidence-based approach for enhanced muscular development. Sports Med. 2015;45(3):313-325. doi:1 0.1007/s40279-014-0288-1 16. Brandner C, May AK, Clarkson M, Warmington S. Reported side-effects and safety considerations for the use of blood flow restriction during exercise in practice and research. Tech Orthop.

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17. Hughes L, Paton B, Rosenblatt B, Gissane C, Patterson SD. Blood flow restriction training in clinical musculoskeletal rehabilitation: a systematic review and meta-analysis. Br J Sports Med. 2017;51(13):1003-1011. doi:10.1136/bjsports-2016-09 7071 18. Nakajima KM. Use and safety of KAATSU training: results of a national survey. Int J KAATSU Training.

2006;2:5-13.

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19. Yasuda T, Meguro M, Sato Y, Nakajima T. Use and safety of KAATSU training: results of a national survey in 2016. Int J of KAATSU Train. 2017;13(1):1-9. doi:10.3806/ijktr.13.1 20. Loenneke JP, Wilson JM, Wilson GJ, Pujol TJ, Bemben MG. Potential safety issues with blood flow restriction training. Scand J Med Sci Sports.

2011;21(4):510-518. doi:10.1111/j.1600-0838.2010.01 290.x 21. Hughes L, Patterson SD, Haddad F, et al.

Examination of the comfort and pain experienced with blood flow restriction training during postsurgery rehabilitation of anterior cruciate ligament reconstruction patients: A UK National Health Service trial. Phys Ther Sport. 2019;39:90-98. doi:10.1 016/j.ptsp.2019.06.014 22. Sanders TL, Maradit Kremers H, Bryan AJ, et al.

Incidence of anterior cruciate ligament tears and reconstruction. Am J Sports Med. 2016;44(6):1502-1507. doi:10.1177/036354651662994 4 23. Adams D, Logerstedt DS, Hunter-Giordano A, Axe MJ, Snyder-Mackler L. Current concepts for anterior cruciate ligament reconstruction: a criterion-based rehabilitation progression. J Orthop Sports Phys Ther.

2012;42(7):601-614. doi:10.2519/jospt.2012.3871 24. Aorn Recommended Practices Committee.

Recommended practices for the use of the pneumatic tourniquet in the perioperative practice setting.

AORN J. 2007;86(4):640-655. doi:10.1016/j.aorn.200 7.09.004 25. Noordin S, McEwen JA, Kragh JF Jr, Eisen A, Masri BA. Surgical tourniquets in orthopaedics. J Bone Joint Surg Am. 2009;91(12):2958-2967. doi:10.2106/JBJS.I.0 0634 26. Delfi Medical Innovations Inc. PTS for Blood Flow Restriction System:Operator & Maintenance Manual.

Delfi Medical Innovations Inc. Published online 2019.

27. Lixandrão ME, Ugrinowitsch C, Laurentino G, et al. Effects of exercise intensity and occlusion pressure after 12 weeks of resistance training with blood-flow restriction. Eur J Appl Physiol.

2015;115(12):2471-2480. doi:10.1007/s00421-015-32 53-2 28. Robertson RJ, Goss FL, Andreacci JL, et al.

Validation of the children’s OMNI-Resistance exercise scale of perceived exertion. Med Sci Sports Exerc.

2005;37(5):819-826. doi:10.1249/01.mss.000016261 9.33236.f1

29. Owens J. Personalized blood flow restriction rehabilitation. Owens Recovery Science.

30. Estebe JP, Le Naoures A, Chemaly L, Ecoffey C. Tourniquet pain in a volunteer study: effect of changes in cuff width and pressure. Anaesthesia.

2000;55(1):21-26. doi:10.1046/j.1365-2044.2000.0112 8.x 31. Ilett MJ, Rantalainen T, Keske MA, May AK, Warmington SA. The effects of restriction pressures on the acute responses to blood flow restriction exercise. Front Physiol. 2019;10:1018. doi:10.3389/fph ys.2019.01018 32. Fatela P, Reis JF, Mendonca GV, Avela J, MilHomens P. Acute effects of exercise under different levels of blood-flow restriction on muscle activation and fatigue. Eur J Appl Physiol. 2016;116(5):985-995. doi:10.1007/s00421-016-3359-1 33. Jarrett PM, Ritchie I, Albadran L, Glen SK, Bridges AB, Ely M. Do thigh tourniquets contribute to the formation of intra-operative venous emboli? Acta Orthop Belg. 2004;70(3):253-259.

34. Madarame H, Kurano M, Takano H, et al. Effects of low-intensity resistance exercise with blood flow restriction on coagulation system in healthy subjects.

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2010;30(3):210-213. doi:10.1111/j.1475-097x.2010.00 927.x 35. Clark BC, Manini TM, Hoffman RL, et al. Relative safety of 4 weeks of blood flow-restricted resistance exercise in young, healthy adults. Scand J Med Sci Sports. 2011;21(5):653-662. doi:10.1111/j.1600-083 8.2010.01100.x 36. Patterson SD, Brandner CR. The role of blood flow restriction training for applied practitioners: A questionnaire-based survey. J Sports Sci. 2018;36(2):123-130. doi:10.1080/02640414.2017.1284 341 37. Garibyan L, Rheingold CG, Lerner EA. Understanding the pathophysiology of itch.

Dermatologic Therapy. 2013;26(2):84-91. doi:10.1111/ dth.12025 38. Luttrell MJ, Halliwill JR. The intriguing role of histamine in exercise responses. Exerc Sport Sci Rev. 2017;45(1):16-23. doi:10.1249/JES.0000000000000093

International Journal of Sports Physical Therapy

Kieffer EE, Brolinson PG, Rowson S. Dual-Task Gait Performance Following Head Impact Exposure in Male and Female Collegiate Rugby Players. IJSPT. 2022;17(3):355-365.

Original Research

Dual-Task Gait Performance Following Head Impact Exposure in Male and Female Collegiate Rugby Players a

Emily E Kieffer 1 1

, Per Gunnar Brolinson 2, Steven Rowson 1

Biomedical Engineering, Virginia Tech, 2 Edward Via College of Osteopathic Medicine

Keywords: sex-specific, gait, concussion, dual-task https://doi.org/10.26603/001c.32591

International Journal of Sports Physical Therapy Vol. 17, Issue 3, 2022

Background Gait impairments have been well-studied in concussed athletes. However, the sex-specific effect of cumulative head impacts on gait is not well understood. When a cognitive task is added to a walking task, dual-task gait assessments can help amplify deficits in gait and are representative of tasks in everyday life. Dual-task cost is the difference in performance from walking (single-task) to walking with a cognitive load (dual-task).

Purpose The objectives of this study were to explore the differences between sexes in 1) dual-task gait metrics, 2) gait metric changes from pre-season to post-concussion and post-season, and 3) the dual-task costs associated with gait metrics.

Study Design Cross-sectional study

Methods Over two seasons, 77 female athlete-seasons and 64 male athlete-seasons from collegiate club rugby teams participated in this study. Subjects wore inertial sensors and completed walking trials with and without a cognitive test at pre-season, post-season, and post-concussion (if applicable).

Results Females athletes showed improvement in cadence (mean = 2.7 step/min increase), double support time (mean = -0.8% gait cycle time decrease), gait speed (mean = 0.1 m/s increase), and stride length (mean = 0.2 m increase) in both task conditions over the course of the season (p < 0.030). Male athletes showed no differences in gait metrics over the course of the season, except for faster gait speeds and longer stride lengths in the dual-task condition (p < 0.034). In all four gait characteristics, at baseline and post-season, females had higher dual-task costs (mean difference = 4.4, p < 0.003) than the males.

Conclusions This results of this study showed little evidence suggesting a relationship between repetitive head impact exposure and gait deficits. However, there are sex-specific differences that should be considered during the diagnosis and management of sports-related concussion.

a

Corresponding author: Emily E. Kieffer 343 Kelly Hall 325 Stanger Street Blacksburg, VA 24061 Email: kieffere@vt.edu

Dual-Task Gait Performance Following Head Impact Exposure in Male and Female Collegiate Rugby Players

Level of Evidence Level 2b

INTRODUCTION Concussions are diffuse injuries to the brain,1 affecting various brain functions, including neurocognition and motor control.2 Gait research has advanced the understanding of the effect of concussions on motor control; altered gait patterns have been observed as a result of sports-related concussions.3–6 Dual-task walking involves locomotion while performing a concurrent cognitive task. Concussions usually affect motor and cognitive functions, so the divided attention required in dual-tasks may be more sensitive to post-concussion impairments than single-tasks.7 The addition of a cognitive load while walking also allows the evaluation of more subtle motor impairments due to the increase in processing demands required and decrease in available attention.8,9 Dual-task cost quantifies the change in a specific variable with the addition of the load (the difference in the variable from single-task to dual-task).10 Assessing the effects of dual-task is also advantageous as most sport and daily living activities require both a motor and cognitive component. Understanding their interaction in concussion may provide helpful information in injury recovery.

Researchers have observed that a full recovery in gait performance post-concussion required months to years, especially when the participant’s attention is divided.3,4,11,12 More traditional markers of recovery, like symptom surveys or neurocognitive test performance, typically analyze recovery on a shorter timeline.13,14 Assessing gait is advantageous because it is a non-novel task and can be objectively measured,3,4,12,15 unlike more obsolete methods of measuring balance16,17 or less mobile methods.18 Gait can be measured in-lab, but also on-field, using portable inertial measurement units.19,20 Accelerometry can be used to quantify gait and the incorporation of accelerometers into these body-worn portable sensors allow for an assessment of gait that allows for widespread use.19 Including a gait assessment in post-concussion protocols may provide an objective and sensitive measurement that can be assessed throughout return-to-play to monitor progress and management. Because limited sexspecific normative data exist for single and dual-task gait characteristics,7,21 baseline measurements are recommended22 as gait is unique to individuals and varies based on body size,23 concussion history,6,24 and sex.25 Females generally report more symptoms post-concussion26 and take a longer time to fully recover27 than males. Due to the differences in the presentation of concussions, it is interesting to understand any sex-specific gait changes. Understanding the effect of sex on the presentation and recovery of concussion will hopefully provide helpful information to drive sex-specific interventions.

Athletes with a history of concussion have been shown to have a more conservative pattern in their gait,6 including decreased walking speed, decreased cadence, decreased stride length, and increased double-leg support time compared with control subjects during dual-task walking.12 It is unknown how a season worth of cumulative head impacts

in a contact sport affects gait. The aims of this study were to explore the differences between sexes in 1) dual-task gait metrics, 2) gait metric changes from pre-season to postconcussion and post-season, and 3) the dual-task costs associated with gait metrics.

METHODS STUDY PARTICIPANTS

In Spring 2019, Fall 2019, and Spring 2020, athletes from women’s and men’s collegiate club rugby teams were recruited for this study. Written informed consent was obtained from each participant after explaining the purpose, associated benefits, and risks of the study according to the ethical guidelines of Virginia Tech’s Institutional Review Board (IRB). Seventy-seven female athlete-seasons (age: 20.7 ± 1.2 years, height: 1.7 ± 0.1 m, weight: 75.1 ± 17.6 kg) and 64 male athlete-seasons (age: 21.0 ± 1.2 years, height: 1.8 ± 0.1 m, weight: 89.5 ± 17.5 kg) participated in the study.

If an athlete participated for two seasons, their data are treated as two unique athlete-seasons, and they completed the full dual-task gait protocol each season. Athletes reported suspected concussions to the research team. Not all concussions were clinically diagnosed.

DUAL-TASK GAIT PROTOCOL

The gait protocol was completed pre-season (baseline), post-season, and post-concussion (if applicable). Athletes were not tested if they had a lower extremity injury. Those who sustained concussions were evaluated an average of 2.7 days after injury (range = 1 - 4 days). There were no postseason data collected for Spring 2020, as the season was interrupted due to COVID-19.

The gait protocol included two conditions: walking without a cognitive task (single-task) and walking while completing a cognitive task (dual-task). Five trials were conducted for each condition.21 The subject walked at a self-selected, comfortable pace, barefoot or in socks. They were instructed to walk towards an object 8 m in front of them, walk around it, and return to the starting point.21 For the dual-task trials, the test administrator explained the task before the start of the walk and the athlete began walking when cued by an auditory beep. The test administrator did not instruct the athlete to prioritize the motor or cognitive task, only to continue walking while responding to the task as best as possible.21 The dual-task consisted of a Mini-Mental Status Examination (MMSE), which has been shown to detect differences in dual-task walking after concussion.28 The MMSE contained three tasks: spelling a 5-letter word backward,15,29 subtracting by 6s or 7s from a randomly presented 2-digit number,30 and reciting the months in reverse order starting from a randomly chosen month.31 This cognitive test is similar to the Standardized Concussion Assessment Tool, Version 3, which is used for on-field concussion diagnosis.22,32 The tasks were randomly ordered to reduce learning effects from one trial to

International Journal of Sports Physical Therapy

Dual-Task Gait Performance Following Head Impact Exposure in Male and Female Collegiate Rugby Players

the next.

During the walking protocols, athletes wore inertial measurement units (Opal Sensor, APDM Inc. Portland, OR) attached with an elastic strap on the lumbar spine, at the lumbosacral junction, and on the dorsal surfaces of the left and right feet (Figure 1). This system has been validated33 and utilized in clinical evaluations of gait through the completion of motor tasks.20 Data were collected at a sampling frequency of 128 Hz and wirelessly synced to a computer during each trial. Temporal-distance measurements were calculated using Mobility Lab software20 and variables of interest included gait speed, cadence, double support time, and stride length, previously shown to differentiate healthy from concussed subjects.21,28,34 OUTCOME VARIABLES

Gait speed, cadence, double support time, and stride length were measured for each athlete under both task conditions at each time point. Gait speed was calculated as the average velocity for the left and right foot across all gait cycles in each trial (m/s). Cadence was defined as the rate of steps per minute (steps/min). Double support time is the percentage of time that both feet were on the ground in each gait cycle, reported as percent of gait cycle time (%GCT). Stride length is the average distance for each foot between consecutive steps in each trial (m). The changes in each metric were computed from baseline to post-season and baseline to post-concussion (if applicable). Dual-task cost, the percent change between single and dual-task conditions, was calculated for each athlete to normalize their dual-task performance to their single-task performance.34,35 Dualtask cost was calculated as (dual-task value – single-task value)/(single-task value) and reported as a percentage.

Dual-task cost was measured for each gait characteristic of interest.

STATISTICAL ANALYSIS

Shapiro-Wilk tests were used to confirm the normality of the gait metrics. Paired Welch two-sample t-tests were used to compare the magnitudes and estimate the effect size and precision of cadence, double support time, gait speed, and stride length from baseline to post-season within each task condition. The same paired comparisons were completed for athletes with baseline and post-concussion time point data. These comparisons were paired per athlete and compared within sex. Welch two-sample t-tests were completed to compare the differences in metrics between sexes from baseline to post-season for each task condition. Because there was only one concussion for the males, only females’ data were compared from baseline to post-concussion time points.

Dual-task costs were not normally distributed, so paired Wilcoxon rank-sum tests were used to compare dual-task costs from baseline to post-season within sex for each gait characteristic. Welch two-sample t-tests were used to estimate effect size and precision. Unpaired Wilcoxon ranksum tests compared dual-task cost for each metric at each time. Again, only the females’ data were compared for the differences in baseline to post-concussion change, and be-

Figure 1. Opal Sensors are attached to elastic straps around the athlete’s waist and feet to measure gait characteristics.

tween sex differences were not. Welch two-sample t-tests were used to estimate the effect size and precision of the comparisons. An α = 0.05 was used as a level of significance for all statistics.

RESULTS Gait metrics are presented from both task conditions at each time point (where applicable) for all athletes (Table 1). All comparisons within sex were paired, i.e., only athletes with both time points were included in this particular analysis.

Females walked with faster cadences at both task conditions at baseline and post-season than males (p < 0.032).

Males walked with longer stride length in dual-task conditions at baseline and post-season (p < 0.023) and greater double support time in single-task conditions at baseline (p = 0.020). All other conditions were similar between sexes.

The addition of the dual-task negatively impacted all gait metrics for both sexes at each time point (p < 0.001). Mean percent differences and 95th percentile confidence intervals between sex are shown in Figure 2. The females walked with greater cadence and a shorter stride length for the males in both task conditions. For each, mean differences were normalized to the males’ mean so each gait metric could be scaled for the sake of visualization. All baseline and postseason data that were collected were included in this comparison.

Paired t-tests showed improvement in cadence (increase), double support time (decrease), gait speed (increase), and stride length (increase) in both task conditions among the female athletes over the course of the season (Table 2) (p < 0.030). There was no change in stride length from baseline to post-season in dual-task (p = 0.071). The same tests for the males showed no differences in the metrics over the course of the season, except for faster gait speeds and longer stride lengths in the dual-task condition by the end of the season (p < 0.034). In general, cadence, gait speed, and stride length increased while double support

International Journal of Sports Physical Therapy

Dual-Task Gait Performance Following Head Impact Exposure in Male and Female Collegiate Rugby Players

Table 1. Summary table for the mean values ± the standard deviation for the four primary gait metrics from all athletes from baseline, post-concussion (CX), post-season, and at single and dual-task conditions. Count is the number of athlete-seasons in each category.

Sex

Time Point

Task

Count

Cadence (steps/min)

Double Support Time (%GCT)

Gait Speed (m/s)

Stride Length (m)

Female

Baseline

Dual

77

105.5 ± 10.1

22.3 ± 3.2

0.9 ± 0.2

1.1 ± 0.1

Single

77

113.0 ± 9.0

20.1 ± 2.9

1.1 ± 0.2

1.1 ± 0.1

Dual

14

102.4 ± 11.1

23.2 ± 3.2

0.9 ± 0.2

1.1 ± 0.1

Single

14

110.3 ± 11.1

20.8 ± 3.0

1.1 ± 0.2

1.1 ± 0.1

Dual

39

106.9 ± 10.3

21.8 ± 3.5

0.9 ± 0.2

1.1 ± 0.1

Single

39

114.5 ± 9.2

19.4 ± 3.3

1.1 ± 0.2

1.2 ± 0.1

Dual

64

102.3 ± 7.0

22.3 ± 3.0

0.9 ± 0.1

1.1 ± 0.1

Single

64

106.5 ± 5.6

20.8 ± 2.7

1.0 ± 0.1

1.1 ± 0.1

Dual

1

90.6

25.1

0.8

1.1

Single

1

96.1

24.2

0.9

1.1

Dual

37

102.4 ± 7.5

22.4 ± 2.7

1.0 ± 0.1

1.1 ± 0.1

Single

37

106.3 ± 6.1

21.0 ± 2.5

1.1 ± 0.1

1.2 ± 0.1

Post-CX PostSeason Male

Baseline Post-CX PostSeason

Table 2. Summary table for changes in the four primary gait metrics and the 95% confidence interval from athletes who completed baseline and post-season gait tests. The change is the difference from baseline to postseason.

Sex

Task

Count

∆ Cadence (steps/min)

∆ Double Support Time (%GCT)

∆ Gait Speed (m/s)

∆ Stride Length (m)

Female

Dual

39

3.3 [1.2, 5.4]

-0.8 [-1.6, -0.1]

0.1 [0.0, 0.1]

0.0 [0.0, 0.0]

Single

39

2.1 [0.5, 3.6]

-0.7 [-1.1, -0.2]

0.0 [0.0, 0.1]

0.0 [0.0, 0.0]

Dual

37

0.9 [-0.8, 2.5]

-0.2 [-0.6, 0.3]

0.0 [0.0, 0.1]

0.0 [0.0, 0.0]

Single

37

0.1 [-1.3, 1.5]

0.0 [-0.4, 0.5]

0.0 [0.0, 0.0]

0.0 [0.0, 0.0]

Male

time decreased by the end of the season, improving all characteristics. Females showed greater improvement in all gait metrics over the course of the season compared to males.

The females performed worse at post-concussion compared to their baseline in each metric. Mean percent differences and 95th percentile confidence intervals between time points are shown in Figure 3. For each, mean differences are normalized to the baseline mean so each gait metric could be scaled for the sake of visualization. Only athlete-paired data were included in this comparison (Appendix Table A1).

The metrics from baseline to post-concussion were similarly compared to provide context to the changes over the course of the season (Figure 3). Post-concussion changes (Table 3) are opposite in magnitude to those seen in postseason (Table 2), with cadence, gait speed, and stride length increasing, and most double support times decreasing. Consistent with prior literature, cadence, gait speed, and stride length decrease while double support time increases after concussion. All characteristics showed deficits in the females in both task conditions (p < 0.042) with the exceptions of double support time and stride length during the

Figure 2. The mean difference gait metrics between the sexes. The tails of each point represent the 95% CI from a t-test. Points to the right of 0 indicate a positive difference – that the males’ mean was greater than the females’. Points to the left of 0 indicate a negative difference – that the males’ mean was less than the females’.

dual-task condition (p > 0.083). It is impossible to general-

International Journal of Sports Physical Therapy

Dual-Task Gait Performance Following Head Impact Exposure in Male and Female Collegiate Rugby Players

Table 3. Summary table for changes in the four primary gait metrics and the 95% confidence interval from athletes who completed baseline and post-concussion gait tests.

Sex

Task

Count

∆ Cadence (steps/min)

∆ Double Support Time (%GCT)

∆ Gait Speed (m/s)

∆ Stride Length (m)

Female

Dual

14

-2.2 [-4.3, -0.1]

0.7 [-0.2, 1.6]

0.0 [-0.1, 0.0]

0.0 [0.0, 0.0]

Single

14

-3.1 [-4.8, -1.4]

0.7 [0.0, 1.4]

-0.1 [-0.1, 0.0]

0.0 [0.0, 0.0]

Dual

1

-6.5

1.7

-0.1

0.0

Single

1

-5.8

1.9

-0.1

-0.1

Male

Table 4. Summary table for mean dual-task cost of the four gait metrics in athletes at each time point.

Count

Cadence Cost (%)

Double Support Cost (%)

Gait Speed Cost (%)

Stride Length Cost (%)

Baseline

77

-6.6 ± 4.0

11.3 ± 7.7

-12.9 ± 6.8

-6.9 ± 4.3

PostConcussion

14

-7.2 ± 2.9

11.9 ± 6.2

-13.0 ± 5.4

-6.2 ± 3.6

Post-Season

39

-6.7 ± 3.7

12.5 ± 5.8

-13.4 ± 5.9

-7.4 ± 3.9

Baseline

64

-4.0 ± 3.6

7.4 ± 5.5

-8.6 ± 6.0

-4.9 ± 3.7

PostConcussion

1

-5.7

3.7

-8.8

-3.6

Post-Season

37

-3.6 ± 4.2

6.7 ± 5.6

-7.7 ± 6.8

-4.5 ± 3.7

Sex

Time Point

Female

Male

ize the males’ responses because post-concussion gait data were only collected from one male athlete.

The costs for cadence, gait speed, and stride length are all negative and double support time is positive because gait becomes more conservative with the addition of the cognitive load in the dual-task condition (Table 4). In all four gait characteristics, at baseline and post-season, females had higher dual-task costs (p < 0.003) than males (Figure 4).

Females had a greater cost for each gait metric both at baseline and post-season. All baseline and post-season data that were collected were included in this comparison (Table 4).

Paired Wilcox test showed cadence and gait speed had higher dual-task costs at baseline compared to post-season for both males and females (p < 0.049) (Figure 5). Across all conditions, gait speed had the highest cost. Dual-task cost for double support time and stride length were not different at baseline or post-season for males or females (p > 0.059) (Figure 5). When comparing the post-concussion data to the paired baseline data for the females, there were no differences in cost between the two time points (p > 0.384) (Figure 5). Dual-task cost did not change much from baseline to post-season or post-concussion for either sex. Only athlete-paired data were included in this comparison (Appendix Table A2).

DISCUSSION The goal of including a dual-task condition in gait tests is to identify deficits that may not be as prevalent when the attention is focused on gait. In this study, the addition of the mental load at each time point decreased cadence, gait

Figure 3. The mean difference of the post-season (PS) (and post-concussion (PCX), for the females) gait characteristic at the specified task from the baseline (B) timepoint. The tails of each point represent the 95% CI from a paired t-test. Points to the right of 0 indicate a positive difference – that the baseline mean was greater than the post-season (and post-concussion). Points to the left of 0 indicate a negative difference – that the baseline mean was less than the post-season (and postconcussion).

speed, and stride length and increased double support time for both sexes, in line with other studies.21 Compared to the males, females walked with faster cadences and shorter stride lengths, similar to previous research.7,34 It has been suggested that females’ dual-task gait velocity is higher because females may be better than males at executing two tasks at once.36 This also may explain the females’ improvement in all four gait variables (except for stride length in

International Journal of Sports Physical Therapy

Dual-Task Gait Performance Following Head Impact Exposure in Male and Female Collegiate Rugby Players

dual-task) over the course of the season. Males improved their gait speed and stride length in dual-tasks only; the rest of their metrics were not different from their baseline values. In this study, collegiate rugby players did not exhibit similar deficits in gait post-season to those they, or other studies have shown, post-concussion.12,37–40 Compared to a similar study by Howell, the athletes in this study spent much less time in double support (mean range 34.0 – 38.2 for concussed and control males and females),34 but there lacks a body of sex-specific normative value for comparison.

The changes the females showed post-concussion are consistent with post-concussion gait tests in the literature.7,34 Their cadence, gait speed, and stride length increased, and most double support times decreased. Previous work has shown a decrease in these metrics post-concussion,34,35 indicating a more conservative gait pattern, with the athletes walking slower with smaller steps post-concussion.

At baseline and post-season, females had higher dualtask costs than the males in all four variables. In general, gait speed had the largest dual-task cost. Dual-task costs for gait speed have been used as a predictor of prolonged recovery time in concussed athletes.41 Previous literature has shown a more significant cadence cost in females compared to males post-concussion.34 In the same study, they did not notice any dual-task cost difference between male and female controls,34 which is inconsistent with these results at baseline. They did not see a difference in dual-task cost from control males to concussed males either,34 which follows the same trend as the male athletes at baseline and post-season in this study.

It was expected that females would have a higher cost than males and that cost would be higher at post-concussion compared to baseline.4,35,42 The additional cognitive load was expected to reflect functional changes post-concussion and decreased interhemispheric brain connectivity,43 forcing the brain to reorganize to perform the challenging task while simultaneously providing resources for walking. In concussed athletes, this resource allocation is expected to be hindered,44,45 and appropriately reflected in dual-task costs. However, in this study, there were no differences in cost between the paired baseline and post-concussion data. Previous work has shown dual-task deficits at days 5-6,46 or in the year following,40 which is after all of the athletes in this study were tested. Additionally, as gait metrics in athletes in the current study improved over the season, cadence and gait speed had higher dual-task costs at baseline compared to post-season for both sexes.

No study has quantified cost after a season of impacts for comparison.

The overall improvement in gait and decrease in dualtask cost could result from a learning effect of the tests.

Still, there does not appear to be a deficit in gait or more conservative gait pattern that accumulated over the season.

A study examining acute postural control effects after a simulated match load of rugby impacts also suggested no changes following subconcussive impacts.47 The learning effect is likely noticeable in this study as athletes completed the protocol multiple times in a season, and many participated in multiple seasons. Other studies compared concussed athletes to controls,34,35,48 which reduces the over-

Figure 4. The mean difference of the female dualtask cost at the specified gait variable from the males’. The tails of each point represent the 95% CI from a t-test. The absolute value of double support time was taken as the cost for the females was greater in magnitude but a negative value. Points to the right of 0 indicate a positive difference – that the males’ mean cost was greater than the females’.

Figure 5. The mean difference of the post-season (PS) (and post-concussion (PCX), for the females) dual-task cost at each gait characteristic from the baseline (B) timepoint. The tails of each point represent the 95% CI from a paired t-test. The magnitude of double support was taken to be consistent with the other metrics. Points to the left of 0 indicate a negative difference – that the baseline mean was less than the post-season (and post-concussion).

all number of times an athlete would complete the dual-task protocol. Additionally, a season’s worth of exercise and training in their sport may have contributed to gait metrics improving.

There were several limitations to this study. Only one male post-concussion time point was collected, making it impossible to generalize about males’ responses post-concussion, compare them to the females at post-concussion, or compare them to males at baseline and post-season. Additionally, age, height, weight, or prior concussion history were not included in the comparisons in this analysis. Although likely the differences in sizes between males and females may contribute to the four gait variables, BMIs from the two groups are similar, and the dual-task cost normalizes performance individually. The environment in which the tests were conducted was not always consistent. They were conducted in the lab or the hallway, but sometimes the lab was busier than others, and the other distractions

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Dual-Task Gait Performance Following Head Impact Exposure in Male and Female Collegiate Rugby Players

may have confounded the subject’s attention. However, the accuracy of these dual-task tests was not checked because the divided attention should be enough to elucidate differences; their performance on the MMSE should not matter.

It has been shown that females prioritize the accuracy of their answers over their gait compared to their male counterparts.49

CONCLUSION The results of this study indicate that collegiate rugby players do not exhibit post-season gait deficits, but show postconcussion gait deficits, similar to previous work.12,37–40 This suggests that although gait is affected by a concussive impact, it may not be affected by a season’s worth of head impacts. Contrary to other studies,40,46 the female athletes in this cohort did not exhibit differences in dual-task cost from baseline to post-concussion. Although the results of this study are mixed, dual-task gait can be used to uncover functional deficits in athletes who may be asymptomatic

and do not exhibit neuropsychological dysfunction.45 Still, it is important to use dual-task gait in the context of other diagnostic tools. The sex-specific differences in gait metrics and dual-task cost at each time point suggest a need to consider the sex of the athlete in concussion diagnostics and therapies. Including dual-task gait assessments is also relevant given the implication of concussion on musculoskeletal injuries,50 and therefore should be incorporated into future clinical assessments and sex-specific concussion interventions.

CONFLICTS OF INTEREST

The authors have no conflicts to disclose.

Submitted: June 30, 2021 CDT, Accepted: January 09, 2022 CDT

This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CCBY-NC-4.0). View this license’s legal deed at https://creativecommons.org/licenses/by-nc/4.0 and legal code at https://creativecommons.org/licenses/by-nc/4.0/legalcode for more information.

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Dual-Task Gait Performance Following Head Impact Exposure in Male and Female Collegiate Rugby Players

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SUPPLEMENTARY MATERIALS Appendix Download: https://ijspt.scholasticahq.com/article/32591-dual-task-gait-performance-following-head-impactexposure-in-male-and-female-collegiate-rugby-players/attachment/ 82278.pdf?auth_token=XpmgWaFzQXFBOCRQfF7y

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Henry NE, Weart AN, Miller EM, Feltner LD, Goss DL. Normative Data for the NeuroCom Sensory Organization Test in United States Military Academy Boxers. IJSPT. 2022;17(3):366-377.

Original Research

Normative Data for the NeuroCom Sensory Organization Test in United States Military Academy Boxers a

Nathan E Henry 1 , Amy N Weart 2, Erin M Miller 3, Lisa D Feltner 2, Donald L Goss 4 1

Physical Therapist, 4th Infantry Division, Fort Carson, CO, USA; Distance Lecturer, Indiana State University, Department of Physical Therapy, Terre Haute, IN, USA; Senior Instructor, American Academy of Manipulative Therapy, Fellowship in Orthopaedic Manual Physical Therapy, Montgomery, AL, USA, 2 Keller Army Community Hospital, Department of Physical Therapy, West Point, NY, USA, 3 Baylor University - Keller Army Community Hospital Division I Sports Physical Therapy Fellowship, West Point, NY, USA, 4 Physical Therapy, High Point University, Department of Physical Therapy, High Point, NC, USA Keywords: concussion, balance, neurocom, sensory organization test, normative data https://doi.org/10.26603/001c.32547

International Journal of Sports Physical Therapy Vol. 17, Issue 3, 2022

Background Balance function is a key indicator in the identification of and recovery from concussion.

The NeuroCom Sensory Organization Test (SOT) is used to objectively quantify balance using input from the visual, vestibular, and somatosensory systems. Baseline tests are necessary for comparison post-concussion.

Purpose The primary purpose of this study was to establish baseline SOT measures for the population that will be useful in the concussion assessment, diagnosis, and return to duty decisions following a concussion. Secondary aims were to compare females and males as well as concussed versus non-concussed. To the knowledge of the authors these are the only published normative data for a highly-active military population ages 17-23.

Study Design Cross-sectional study

Methods Two hundred fifty-three (70 female and 183 male) cadets in a boxing course at a service academy were enrolled. The participants were evaluated on the SOT using the NeuroCom Balance Manager (Natus Medical Inc., Seattle, WA) and each condition, composite (COMP) score, and ratio score were recorded.

Results No significant differences were observed in SOT COMP scores between females (COMP = 76.67 ± 7.25) and males (COMP = 76.57 ± 7.77), nor between participants with history of concussion (COMP = 75.83 ± 7.90) versus those never concussed (COMP = 76.75 ± 7.57).

Conclusion This study provides SOT reference values for young, healthy, active individuals, which will assist in the interpretation of individual scores for concussion diagnosis and recovery, as well as serve as baseline data for future studies. These data on 17-23-year-olds will add to the currently available normative values of 14-15-year-olds and 20-59-year-olds.

a

Corresponding author: Nate Henry 463 Mountain Pass View Colorado Springs, CO 80906 253-651-6958 EPdrNate@gmail.com

Normative Data for the NeuroCom Sensory Organization Test in United States Military Academy Boxers

Level of Evidence 4

INTRODUCTION PREVALENCE

Awareness of concussions is at an all-time high. Since 2000, more than 360,000 traumatic brain injuries (TBI) have been diagnosed within the Department of Defense (DoD), and over 315,000 of those are considered to be mild TBI (mTBI), otherwise known as concussion.1,2 Over a five-year period these injuries accumulate medical and disability costs to the DoD exceeding $700,000,000.3 Concussion injury, diagnosis, and care are being closely monitored by a network of DoD and National Collegiate Athlete Association (NCAA) entities operating with a renewed grant of $22,500,000.4 At a military service academy, about two cadets per 100 are reported concussed each year during boxing class, a required 20-hour instructional course.5 In a systematic review by Koh et al the greatest frequencies of concussive episodes were observed with recreational male boxers and female taekwondo participants.6 Boxing has been demonstrated to cause half the impact but twice the rotational force as contact injuries in football.7 The rotational and shearing forces applied to the brain during head trauma can be detrimental resulting in concussion.8 These are forces such as a whiplash effect in the sagittal plane or rotation in the transverse plane. There are concerns that repeated episodes of concussion may lead to cumulative and worsening effects including increased neuropsychological deficits and decreased postural stability.9–12 Impaired postural stability following concussion may be a result of inaccurately processing information from the somatosensory, visual, and vestibular systems manifesting as balance deficits.10,13–16 Considering the multiple repercussions of concussion injury to include affecting somatosensory, visual, and vestibular components of balance, it is important for clinicians to incorporate balance assessment.

NEED FOR STANDARDIZED ASSESSMENT

As concussion evaluation becomes more commonplace, the need for a standardized assessment tool or protocol becomes apparent. A major factor of a concussive episode, and the recovery from it, is vestibular function.8,17,18 The vestibular system, consisting of semi-circular canals which sense rotational movements and otolith organs that sense linear acceleration, provide a sense of balance and spatial orientation for the purpose of coordinating movement.

Vestibular function is best measured by caloric testing as the gold standard.19 Rotary chair or vestibular-evoked myogenic potentials are also reliable tests of vestibular function.20 However, a more practical approach may be to evaluate an individual’s balance instead. Although not an exact measure of vestibular function, balance is a component that may be easily quantified.21 Vestibular testing is a critical part of determining the extent of a concussive episode and several tests have been proposed as possible solutions including Vestibular Ocular Motor Screening Assessment (VOMS), Balance Error Scoring System (BESS), and the Post-

Concussion Symptom Scale (PCSS).22–24 Balance has been observed to recover quickly, and the timing of recovery has been serially studied by quantifying postural sway with BESS and Sensory Organization Test (SOT) by Guskiewicz et al.25 Another study observed that acute mild head injury produced decreased stability until approximately three days post injury.10 While useful, the BESS, VOMS, and PCSS may be subject to the concussed individual’s perceptions with moderate to poor reliability and are prone to human error dependent upon the experience and ability of the evaluator.10,24,26–29 BASELINE TESTING

The NeuroCom SOT is computer-controlled balance machine used to objectively quantify the balance component of the vestibular system’s functionality and impairment.

Because it is computerized, it reduces chance for human error. It has demonstrated test-retest reliability for the measure of balance function in several studies, although Broglio et al questioned whether the NeuroCom could be used as a sole measure of vestibular function.23,30,31 Ferber-Viart et al observed SOT scores for 64 participants 20 years of age, and current manufacturer baseline measures for the SOT were established for 195 participants age 20-79.32,33 However, these sample sizes are too small in number and age ranges used for baseline measurements are too broad to determine generalizable normative values for this population.

The young, active, healthy military population that will be expected to lead future armed forces requires its own normative values.

NEED FOR RELIABILITY MEASURES

The SOT has previously been utilized in highly-trained groups of experienced special operations military personnel with the intent to establish baseline results, provide data for future studies, and to identify those at risk for lower extremity injury.30 Since the SOT measures balance from visual, vestibular, and somatosensory contributions, it may be more suited to concussion evaluation than prediction of musculoskeletal injury. Clinically, the SOT has been shown to be sensitive to functional deficiencies in the visual, vestibular, and somatosensory systems often seen after concussion, and has been used to track recovery from concussion.34,35 The primary outcome of the SOT is the equilibrium score, a composite (COMP) of all three balance components.

To the knowledge of the authors, baseline SOT measures for balance function of young, healthy, active, military 17-23-year-old individuals have not been previously reported. The primary purpose of this study was to establish baseline SOT measures for the population that will be useful in the concussion assessment, diagnosis, and return to duty decisions following a concussion. Furthermore, secondary aims are to determine if there are differences in SOT scores between females and males, or in those with and without a concussive history. Females are grossly un-

International Journal of Sports Physical Therapy

Normative Data for the NeuroCom Sensory Organization Test in United States Military Academy Boxers

Table 1. Sensory Organization Test conditions.30,36 Test Condition

Eyes

Surroundings

Platform

Sensory System Used

Disadvantaged Sensory System

1

Open

Fixed

Fixed

Somatosensory

—

2

Closed

—

Fixed

Somatosensory

Visual

3

Open

Sway referenced

Fixed

Somatosensory

Visual

4

Open

Fixed

Sway referenced

Visual

Somatosensory

5

Closed

—

Sway referenced

Vestibular

Somatosensory/Visual

6

Open

Sway referenced

Sway referenced

Vestibular

Somatosensory/Visual

Note: Each condition uses a primary sensory system based on the eyes open or closed, the surroundings fixed or swayed, and the platform fixed or swayed. Each trial of each condition receives a score. Adapted from the Balance Manager Clinical Operation Guide, NeuroCom.33 (Used by Permission.)

der-represented in the available concussion literature.6 In a time where females are included in combat arms and exposed to increased possibility of head injury, more data of baseline balance function in women may prove useful in the evaluation and recovery of concussion.

METHODS This study was a cross-sectional design for obtaining normative values. The authors established baseline measures for this group in preparation for future studies of balance associated with concussion.

PARTICIPANTS

All participants were screened for the following inclusion criteria: 1) between the ages of 17-26 years old, 2) enrolled in boxing class at this service academy, and 3) read and speak English well enough to provide informed consent and follow study instructions. If a cadet had a lower extremity, low back, or concussion injury that precluded NeuroCom testing they were excluded. All participants were informed of the testing procedures and signed a written consent form approved by the institutional review board. All testing was conducted at the physical therapy clinic at this service academy.

PROCEDURES

Participants were recruited from a required boxing class at the academy. This service academy conducted 16 boxing classes of 16-22 cadets twice every semester beginning in August, October, January, and March of the 2018-2019 academic year. Participants were recruited by direct contact during the first two days of class, prior to any striking taking place. Data were collected by four members of the research team, all trained in operation of the NeuroCom Balance Manager by the same NeuroCom continuing education instructor. Prior to testing, each participant completed a short questionnaire regarding their concussion history and demographic information to include age, height, mass, and

year in college. Participants were placed in a safety harness and positioned barefoot on the NeuroCom Balance Manager with standardized foot placement relative to their height.

Data collectors followed standardized written instruction following the SOT protocol to include verbal cues for each trial of each condition.33 Participants stood with arms relaxed at the side, looking straight forward as still as possible. The participants performed all six of the SOT conditions repeating each 20-second trial three times. Each person completed testing as shown in Figure 1 and Table 1.30,33 INSTRUMENTATION

A NeuroCom Balance Manager (Natus Medical Inc., Seattle, WA) equipped with SMART EquiTest/InVision/HS-SOT (software version 9.2, 2014) was used to assess postural stability. The Balance Manager is equipped with two 9 x 18 inches (23 x 46 centimeters) force plates connected by a pin joint.37 Both the support surface and the visual surroundings rotate in the sagittal plane referenced to the participant’s sway and sway velocity. Visual stabilization synchronizes center of gravity (COG) movement in the sagittal plane with the participant’s visual surround. Somatosensory stabilization tilts the support surface about a sagittal axis parallel to the axis through the ankle joints.38 The individual is presented with six conditions of varying sensory input including eyes open with fixed support (Condition 1), eyes closed with fixed support (Condition 2) , sway surround with fixed support (Condition 3), eyes open with sway support (Condition 4), eyes closed with sway support (Condition 5), and sway surround with sway support (Condition 6). This test is used to evaluate the individual’s use of somatosensory, visual, and vestibular input to maintain their balance.30 In this way, the SOT conditions create sensory-conflict situations.30 Participants need to compensate for these sensory conflicts and maintain their balance. An equilibrium score is given based on staying within 8.5 degrees in the anterior direction and 4 degrees in the posterior direction as previously established on the SOT and measured by the automated device. Less postural sway indicates better

International Journal of Sports Physical Therapy

Normative Data for the NeuroCom Sensory Organization Test in United States Military Academy Boxers

Figure 1. Sensory Organization Test Conditions.36 Six testing conditions are used during the Sensory Organizational Test. The first three involve a fixed platform for the three visual conditions (eyes open, eyes closed, sway referenced), and the last three involve a sway referenced platform for the same three visual conditions. Adapted from the Balance Manager Clinical Operation Guide, NeuroCom.33 (Used by permission.)

postural stability in the sagittal plane, producing a commensurate equilibrium score (greater is better). If the participant falls (lifts the toes or heels from contact with the force plate, takes a step, touches the surround, or falls to the point of the harness taking weight) or receives a negative value by swaying outside 12.5 total degrees, they receive an equilibrium score of 0 for that trial. The more difficult conditions (3-6) receive greater weights, and an overall composite equilibrium (COMP) score uses the weighted average of all scores (see Figure 2).30,39 A greater composite score indicates better postural control. Specific sensory systems are identified by using ratio combinations of average equilibrium scores for each condition (see Table 2).30,33 The sensory analysis ratio scores for the somatosensory, visual, and vestibular systems express how well a participant is able to use those specific cues for balance. The somatosensory ratio (SOM) compares Condition 2 with Condition 1 and reflects the participant’s ability to use input from the somatosensory system to maintain balance. The visual ratio (VIS) is obtained by comparing Condition 4 with Condition 1. The VIS ratio reflects a participant’s ability to use input from the visual system to maintain balance.

The vestibular ratio (VEST) is computed from scores obtained in Condition 5 and Condition 1. This ratio indicates the relative reduction in postural stability when visual and somatosensory inputs are simultaneously disrupted. The preference ratio (PREF) compares Conditions 3 and 6 with Conditions 2 and 5. The PREF ratio indicates the extent to which the participant relies on visual information to maintain balance, even when this information is incorrect.33

STATISTICAL ANALYSIS

Descriptive statistics for all participants were computed.

Means and standard deviations, as well as medians and interquartile ranges, for the descriptive evaluation and the normative SOT data were produced for females and males separately, concussive history and never concussed separately, and for all participants combined. Normality was examined with a Shapiro-Wilk test. Levene’s test was utilized to measure homogeneity of variance. Skewness and kurtosis were calculated. SOT output was collected and electronically imported into Excel (Microsoft Office 2016). Data include equilibrium scores as described above. These data were entered in the statistical package R version x64 (3.4.4.) and SPSS version 25. The non-parametric Mann-Whitney U test (known as two-sample Wilcoxon test in R) was used for comparison of SOT condition scores and ratio scores between genders, as well as between those with concussive history and those never concussed. A Bonferroni-Holm correction was planned to mitigate risks associated with multiple comparisons (α = 0.002).

RESULTS Participants included 253 cadets ages 17-23, 70 females (mean age 18.77 ± 1.00 years, height 173.55 ± 9.86 centimeters, mass 74.89 ± 13.74 kilograms) and 183 males (mean age 18.85 ± 1.12 years, height 175.66 ± 9.05 centimeters, mass 76.07 ± 12.81 kilograms). Male and female populations were proportionally represented, as the freshman class at the service academy approached 25% female in the 2018-2019 academic year. Forty-one participants (16%) re-

International Journal of Sports Physical Therapy

Normative Data for the NeuroCom Sensory Organization Test in United States Military Academy Boxers

Table 3. Descriptive Statistics. n

Age (yrs)

Height (cm)

Mass (kg)

Body Mass Index (kg/m2)

253

18.83 ± 1.08

175.08 ± 9.31

75.75 ± 13.06

24.57 ± 2.68

Females

70

18.77 ± 1.00

173.55 ± 9.86

74.89 ± 13.74

24.71 ± 2.85

Males

183

18.85 ± 1.12

175.66 ± 9.05

76.07 ± 12.81

24.51 ± 2.61

Yes

41

18.87 ± 1.10

174.76 ± 9.11

75.27 ± 14.64

24.47 ± 2.88

No

212

18.82 ± 1.08

175.14 ± 9.37

75.84 ± 12.77

24.58 ± 2.64

Group Total Gender

Concussion History

Adapted from Pletcher et al.30 (Used by permission.)

Figure 2. Examples of a SOT report.

These examples include an equilibrium report of three trials for each condition: (A) a passing composite score, and (B) a failing composite score.36 Adapted from the Balance Manager Clinical Operation Guide, NeuroCom.33 (Used by permission.)

ported a lifetime history of concussion prior to the study, five of which had had a concussive episode within the previous six months, and 212 had never experienced a concussion. Descriptive statistics for demographics of the sample are reported in Table 3. The combined group COMP score on the SOT was 76.60 ± 7.61. Mean scores between females (COMP = 76.67 ± 7.25) and males (COMP = 76.57 ± 7.77) were not different (p = 0.76, see Table 4). The COMP score was not different between those with history of concussion (75.83 ± 7.90) and for those never concussed (76.75 ± 7.57; p = 0.55, see Table 4). Mean scores and standard deviations for the descriptive evaluation and normative SOT data are reported in Table 4. Although NeuroCom reports normative values by means and standard deviations, it is also appropriate to report normative values by medians and interquartile range (Appendix Table A-6).30,33,40 Due to lack of randomization and an abnormal distribution of data (see Shapiro-Wilk results in Appendix Tables A-1 and A-2 and skewness and kurtosis in Appendix Table

A-5), non-parametric tests were used for between group comparisons. Groups were largely homogenous (see Levene’s test scores in Appendix Tables A-3 and A-4). Significant differences were observed only between males and females in Condition 3 of the SOT (p = 0.04). However, this was after 22 comparisons were made. A Bonferroni-Holm correction was performed to control for Type I error, and α was set at 0.002. No significant differences were observed in SOT condition, composite, or ratio scores between groups by gender or by history of concussion (see Table 5).

SOT ratio and condition scores from previously-published work are reported in Table 4.33 Additional data from two previous studies are visualized in comparison to SOT ratio and condition data from this study in Figures 3 and 4.30,33

DISCUSSION To the knowledge of the authors, there have been no refer-

International Journal of Sports Physical Therapy

Normative Data for the NeuroCom Sensory Organization Test in United States Military Academy Boxers

Table 4. Means and standard deviations for all Sensory Organization Test scores for all groups.

TOTAL

Females

Males

Concussive History

Never Concussed

NeuroCom Ages 20-59

NeuroCom Ages 14-19

253

70

183

41

212

112

—

1

94.81 ±1.94

94.75 ±1.82

94.83 ±1.99

94.86 ±2.20

94.80 ±1.90

93.99 ±2.53

87.2

2

92.44 ±2.67

91.87 ±3.41

92.66 ±2.29

92.20 ±2.62

92.49 ±2.68

92.05 ±4.22

86.8

3

92.44 ±2.67

90.11 ±3.78

90.86 ±4.60

90.81 ±3.94

90.63 ±4.49

91.49 ±3.34

83.3

4

78.84 ±10.27

78.41 ±9.45

79.01 ±10.58

78.34 ±11.91

78.94 ±9.95

82.45 ±7.55

67.5

5

64.44 ±13.94

66.33 ±10.64

63.71 ±14.97

62.61 ±15.97

64.79 ±13.53

69.20 ±10.44

28.7

6

61.04 ±17.27

60.62 ±16.07

61.20 ±17.75

59.39 ±18.97

61.36 ±16.96

67.19 ±11.58

29.9

COMP

76.60 ±7.61

76.67 ±7.25

76.57 ±7.77

75.83 ±7.90

76.75 ±7.57

79.79 ±5.63

63.9

SOM

97.64 ±2.51

97.07 ±2.87

97.85 ±2.33

97.37 ±2.90

97.69 ±2.43

98.00 ±0.05

—

VIS

83.17 ±10.74

82.74 ±9.78

83.33 ±11.10

82.41 ±12.47

83.31 ±10.39

87.7 ±8.0

—

VEST

67.99 ±14.66

70.01 ±11.02

67.21 ±15.79

65.98 ±16.68

68.37 ±14.25

73.6 ±11.1

—

PREF

96.97 ±11.05

95.30 ±9.04

97.61 ±11.69

97.49 ±11.45

96.87 ±11.00

98.1 ±7.1

—

n Conditions

Ratios

Females were compared to males, and those with history of concussion were compared to those with no history of concussion. COMP = composite, SOM = somatosensory, VIS = visual, VEST = vestibular, PREF = preference. Normative scores for the group are presented with the NeuroCom normative values for 20-59-year-olds and limited reported data of 14-19-yearolds (n, standard deviations, and ratio scores unavailable for this group). Adapted from the Balance Manager Clinical Operation Guide, NeuroCom.33 (Used by permission.)

ence data collected previously to assist clinicians to interpret and compare individual SOT data measures of a young, healthy, active, military population. Vander Vegt et al reported similar COMP scores (females = 76.85, males = 76.09, concussion history = 76.00, no concussion history = 76.47) for 207 collegiate athletes with mean age of 19.3 years (female = 72, male = 135) with and without history of concussion (no concussion history = 155, concussion history = 52).41 Average SOT scores for this sample were COMP = 76.60 (females = 76.67, males = 76.57, concussion history = 75.83, no concussion history = 76.75), SOM = 97.64, VIS = 83.17, VEST = 67.99, and PREF = 96.97 (see Table 4). Surprisingly, this young, healthy, active sample scored less than the NeuroCom normative data comparison population ages 20-59 (see Table 4 and Figures 3 and 4).33 Pletcher et al reported normative values for Special Operations personnel with an average age of 35 years old, and their sample also scored greater comparatively excepting the SOM score (Figure 3).30 For the six conditions, This study sample scored best in Conditions 1 and 2, but Conditions 3 through 6 were in between the younger and older samples of NeuroCom data, as well as less than the Special Operator scores (see Figure 4). One reason for this may be due to natural history of vestibular system development. Although Steindl et

Table 2. Sensory Analysis Ratios.30,33 Ratio

Condition Comparison

Description

Somatosensory

2 to 1

Ability to utilize somatosensory input

Visual

4 to 1

Ability to utilize visual input

Vestibular

5 to 1

Ability to utilize vestibular input

Preference

(3 + 6) to (2 + 5)

Reliance on visual input, even if incorrect

Note: The preference ratio defines how well a participant can ignore inaccurate visual clues in a situation of visual conflict. Adapted from the Balance Manager Clinical Operation Guide, NeuroCom.33 (Used by permission.)

al assumed complete maturation of the vestibular system in adolescents, Hirabayashi and Iwasaki demonstrated that complete integration of vestibular function with visual and somatosensory inputs seemed to remain in developmental

International Journal of Sports Physical Therapy

Normative Data for the NeuroCom Sensory Organization Test in United States Military Academy Boxers

Table 5. Comparisons between sexes and concussion statues (using the Mann-Whitney U Test).

Concussive History

Never Concussed

41

212

0.53

95.33

95.33

0.56

0.30

93.00

93.00

0.57

91.67

0.04

92.00

91.33

0.65

80.33

81.67

0.37

81.67

81.17

0.85

68.50

67.33

0.51

67.33

68.00

0.48

63.83

65.00

0.50

65.00

64.67

0.72

COMP

77.50

78.00

0.76

78.00

78.00

0.55

SOM

98.00

98.00

0.19

97.00

98.00

0.35

VIS

85.00

86.00

0.43

85.00

86.00

0.67

VEST

72.00

71.00

0.46

71.00

72.00

0.44

PREF

96.00

98.00

0.08

99.00

97.00

0.48

Females

Males

70

183

1

95.17

95.33

2

92.67

93.00

3

90.17

4 5 6

n

p value

p value

Condition

Ratios

COMP = composite, SOM = somatosensory, VIS = visual, VEST = vestibular, PREF = preference.

Note: No differences were observed between composite scores (α = 0.05). A Bonferroni-Holm correction was calculated for the remaining 20 comparisons of SOT median scores between genders and between concussion history groups. No significant differences were observed (α = 0.002).

stages through ages 14-15, and they did not observe ≥16-year-olds.42,43 These data suggest that balance function may still be under development for 17-23-year-olds, especially visual and vestibular inputs as observed with conditions 4, 5, and 6 (Table 4) which are more dependent on visual and vestibular inputs (Table 1).

These data fit naturally between the available normative values for 14-15-year-olds and 20-59-year-olds. Current NeuroCom normative values include age ranges of 3-4, 5-6, 7-8, 9-10, 11-13, 14-15, 20-59, 60-69, and 70-79.33,43 Data for ages 16-19 are lacking. The number of participants reported in each age group is unclear, however for ages 20-59 the normative values are based on 112 participants, and for ages 14-15 they are based on 19 participants.33,43 This study informs the community of normative values of young, healthy, active, military individuals ages 17-23, a demographic not previously observed for normative values.

These data bridge the gap between 14-15-year-olds and 20-59-year-olds, and they demonstrate that ages 17-23 persist as a period of balance skill development.

Another reason for resultant scores being less than 20-59-year-olds may be due to different sway strategies.

Younger people in general possess greater ankle range of motion and may tolerate sway parameters outside of 12 degrees total. Younger athletic people may develop balance strategies based on sport-specific training. Chow et al observed that amateur rugby players may have developed more hip-centered balance strategies that tend towards lower scores on the SOT.13 Their balance strategies caused them to score lower than their non-rugby-playing counterparts. This sample of cadets is required to play intercollegiate and intramural sports and may have developed sportspecific balance strategies. Pletcher et al reported that the Special Operations sample demonstrated between-group

Figure 3. Scaled View of SOT Ratio Scores.

SOT ratio scores across studies comparing data from this study sample to data from NeuroCom and Pletcher et al.30,33 (Used by permission.) NeuroCom 14-15 COMP is only score available for that group. (SOT=Sensory Organization Test, COMP = composite, SOM = somatosensory, VIS = visual, VEST = vestibular, PREF = preference)

differences in SOT scores that may have been due to their task-specific balance strategies given the weightbearing and athletic nature of their duties.30 Minimal detectable change (MDC) for SOT COMP scores has been reported as 3.97 points, and a learning effect for SOT COMP scores has been reported at 8 points.44,45 Comparing post-concussion patients to these baseline measures will assist in returning them to full duty, affecting deployability and readiness. Additionally, these data may be used for comparison in future studies and against other devices.

(NeuroCom support will be available until 2026, at which time Bertec devices will supersede.)46 These data contain performance specific to female par-

International Journal of Sports Physical Therapy

Normative Data for the NeuroCom Sensory Organization Test in United States Military Academy Boxers

ticipants that may enter the combat arms branches where they are more likely to be exposed to head trauma. Females comprised 28% of this sample. Although no significant differences were demonstrated in comparison to males, this large sample of the age group provides baseline data for future comparisons.

This study has a few limitations. Although four different clinicians were simultaneously trained to evaluate participants on the SOT, inter-rater reliability for fall criteria was not tested. To limit this bias, clinicians referred to the NeuroCom manual for fall criteria. Motion artifact may have affected individual scores. Most participants were generally still in the upper body during testing. However, occasionally a participant adjusted their glasses or scratched their face during testing. Others flexed or extended at the spine or the knees without a frank fall. This may have produced less accurate measures on each test, but this is described in the NeuroCom Manual and is a primary reason for three trials for each condition.33 A possible confounding variable may have been the time of day in which testing took place. Cadets are fully scheduled each day so they were tested according to their availability, no matter the time of day. Heinbaugh et al observed that although time of day did not affect dynamic balance testing, a significant difference exists when testing for static balance in the morning versus the afternoon.47 Those tested in the morning tend to perform better with static balance evaluation. However, the authers did not encounter literature that suggests dynamic balance is affected by time of day. Also, it should be noted that the clinic in which the NeuroCom was located for this study is much busier and noisier in the afternoon. Due to scheduling constraints for the cadets, not all participants could attend in-clinic testing at the quiet hours of the morning. Time of day and atmosphere may have confounded some of the results.

Figure 4. Scaled View of SOT Condition Scores.

SOT condition scores 1-6 across studies comparing data from this study sample to data from NeuroCom and Pletcher et al.30,33 (Used by permission.) (SOT = Sensory Organization Test)

SOT in a young, active, healthy, military population. The sample size exceeds those used to provide the current normative values for all other age groups.32,33 These data may stand as a reference standard for military providers to allow meaningful comparisons in future studies and possibly against other devices.

DISCLOSURE

The authors declare no conflicts of interest, remuneratively or otherwise, with regards to this publication.

IRB APPROVAL

CONCLUSION

Granted by Keller Army Community Hospital Institutional Review Board

This study is the first to provide normative values for the

Submitted: August 15, 2021 CDT, Accepted: November 09, 2021 CDT

This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CCBY-NC-4.0). View this license’s legal deed at https://creativecommons.org/licenses/by-nc/4.0 and legal code at https://creativecommons.org/licenses/by-nc/4.0/legalcode for more information.

International Journal of Sports Physical Therapy

Normative Data for the NeuroCom Sensory Organization Test in United States Military Academy Boxers

REFERENCES 1. Holtkamp MD, Grimes J, Ling G. Concussion in the military: an evidence-based review of mTBI in US military personnel focused on posttraumatic headache. Curr Pain Headache Rep. 2016;20(6):37. do i:10.1007/s11916-016-0572-x 2. DVBIC. Department of Defense Numbers for Traumatic Brain Injury Worldwide - Totals. DVBIC; 2018. Accessed April 20, 2019. https://dvbic.dcoe.mil/ files/tbi-numbers/worldwide-totals-2000-2018Q1-tot al_jun-21-2018_v1.0_2018-07-26_0.pdf 3. Denning JH, Shura RD. Cost of malingering mild traumatic brain injury-related cognitive deficits during compensation and pension evaluations in the veterans benefits administration. Appl Neuropsychol Adult. 2019;26(1):1-16. doi:10.1080/23279095.2017.13 50684 4. CARE-Consortium. NCAA-DoD Grand Alliance CARE Consortium. CARE-Consortium. Published 2019. Accessed April 20, 2019. http://www.careconsor tium.net/ 5. Palmer J. Concussion data for West Point USMA boxing Ccass, memorandum for record; 2018.

6. Koh JO, Cassidy JD, Watkinson EJ. Incidence of concussion in contact sports: a systematic review of the evidence. Brain Inj. 2003;17(10):901-917. doi:10.1 080/0269905031000088869 7. Viano DC, Casson IR, Pellman EJ, et al. Concussion in professional football: comparison with boxing head impacts—part 10. Neurosurgery.

2005;57(6):1154-1172. doi:10.1227/01.NEU.00001875 41.87937.D9 8. Ommaya AK, Gennarelli TA. Cerebral concussion and traumatic unconsciousness. Correlation of experimental and clinical observations of blunt head injuries. Brain. 1974;97(4):633-654.

9. Collins MW, Grindel SH, Lovell MR, et al.

Relationship between concussion and neuropsychological performance in college football players. JAMA. 1999;282(10):964-970.

10. Guskiewicz KM, Ross SE, Marshall SW. Postural stability and neuropsychological deficits after concussion in collegiate athletes. J Athl Train.

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11. Iverson GL, Gaetz M, Lovell MR, Collins MW. Cumulative effects of concussion in amateur athletes.

Brain Inj. 2004;18(5):433-443. doi:10.1080/026990503 10001617352

12. Rabadi MH, Jordan BD. The cumulative effect of repetitive concussion in sports. Clin J Sport Med. 2001;11(3):194.

13. Chow GC, Fong SS, Chung JW, Chung LM, Ma AW, Macfarlane DJ. Determinants of sport-specific postural control strategy and balance performance of amateur rugby players. J Sci Med Sport.

2016;19(11):946-950. doi:10.1016/j.jsams.2016.02.01 6 14. Dickin DC, Clark S. Generalizability of the sensory organization test in college-aged males: obtaining a reliable performance measure. Clin J Sport Med. 2007;17(2):109-115. doi:10.1097/JSM.0b013e31803bf 647 15. Gottshall KR, Hoffer ME. Tracking recovery of vestibular function in individuals with blast-induced head trauma using vestibular-visual-cognitive interaction tests. J Neurol Phys Ther.

2010;34(2):94-97. doi:10.1097/NPT.0b013e3181dead1 2 16. Guskiewicz KM, Mihalik JP, Shankar V, et al.

Measurement of head impacts in collegiate football players: relationship between head impact biomechanics and acute clinical outcome after concussion. Neurosurgery. 2007;61(6):1244-1252; discussion 1252-3. doi:10.1227/01.neu.0000306103.6 8635.1a 17. Ommaya AK. Head injury mechanisms and the concept of preventive management: a review and critical synthesis. J Neurotrauma. 1995;12(4):527-546. doi:10.1089/neu.1995.12.527 18. Yarnell P, Ommaya AK. Experimental cerebral concussion in the rhesus monkey. Bull N Y Acad Med. 1969;45(1):39-45.

19. Goncalves DU, Felipe L, Lima TM. Interpretation and use of caloric testing. Braz J Otorhinolaryngol.

2008;74(3):440-446.

20. Baloh RW, Honrubia V, Yee RD, Hess K. Changes in the human vestibulo-ocular reflex after loss of peripheral sensitivity. Ann Neurol.

1984;16(2):222-228. doi:10.1002/ana.410160209 21. Dickin DC. Obtaining reliable performance measures on the sensory organization test: altered testing sequences in young adults. Clin J Sport Med. 2010;20(4):278-285. doi:10.1097/JSM.0b013e3181e8f 8b1

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Normative Data for the NeuroCom Sensory Organization Test in United States Military Academy Boxers

22. Mucha A, Collins MW, Elbin RJ, et al. A brief Vestibular/Ocular Motor Screening (VOMS) assessment to evaluate concussions: preliminary findings. Am J Sports Med. 2014;42(10):2479-2486. do i:10.1177/0363546514543775

34. Alberts JL, Hirsch JR, Koop MM, et al. Using accelerometer and gyroscopic measures to quantify postural stability. J Athl Train. 2015;50(6):578-588. do i:10.4085/1062-6050-50.2.01

23. Riemann BL, Guskiewicz KM. Effects of mild head injury on postural stability as measured through clinical balance testing. J Athl Train.

2000;35(1):19-25.

35. Alsalaheen BA, Mucha A, Morris LO, et al.

Vestibular rehabilitation for dizziness and balance disorders after concussion. J Neurol Phys Ther.

2010;34(2):87-93. doi:10.1097/NPT.0b013e3181dde56 8

24. Lovell MR, Collins MW. Neuropsychological assessment of the college football player. J Head Trauma Rehabil. 1998;13(2):9-26.

36. NeuroCom. Balance manager Sensory Organization Test. Seattle, WA: Natus Medical, Inc.; 2016.

25. Guskiewicz KM, Riemann BL, Perrin DH, Nashner LM. Alternative approaches to the assessment of mild head injury in athletes. Med Sci Sports Exerc.

1997;29(7 Suppl):S213-21.

37. NeuroCom. Balance manager systems instructions for use: SMART EquiTest. Seattle, WA: Natus Medical, Inc.; 2014.

26. Clark S, Iltis PW. Effects of dynamic head tilts on sensory organization test performance: a comparison between college-age athletes and nonathletes. J Orthop Sports Phys Ther. 2008;38(5):262-268. doi:10.2 519/jospt.2008.2406 27. McGuffin T, Turner S, Case T, et al. The relationship between sway balance and self-reported symptoms following a sports-related concussion. J Athl Train. 2017;52(6):S-245.

28. Patterson JA, Amick RZ, Thummar T, Rogers ME. Validation of measures from the smartphone sway balance application: a pilot study. Int J Sports Phys Ther. 2014;9(2):135-139.

29. Lovell MR, Iverson GL, Collins MW, et al.

Measurement of symptoms following sports-related concussion: reliability and normative data for the post-concussion scale. Appl Neuropsychol.

2006;13(3):166-174. doi:10.1207/s15324826an1303_4 30. Pletcher ER, Williams VJ, Abt JP, et al. Normative data for the NeuroCom Sensory Organization Test in US military special operations forces. J Athl Train.

2017;52(2):129-136. doi:10.4085/1062-6050-52.1.05 31. Broglio SP, Ferrara MS, Sopiarz K, Kelly MS. Reliable change of the sensory organization test. Clin J Sport Med. 2008;18(2):148-154. doi:10.1097/JSM.0b0 13e318164f42a 32. Ferber-Viart C, Ionescu E, Morlet T, Froehlich P, Dubreuil C. Balance in healthy individuals assessed with Equitest: maturation and normative data for children and young adults. Int J Pediatr Otorhinolaryngol. 2007;71(7):1041-1046. doi:10.1016/ j.ijporl.2007.03.012

38. Shepard NT, Schultz A, Alexander NB, Gu MJ, Boismier T. Postural control in young and elderly adults when stance is challenged: clinical versus laboratory measurements. Ann Otol Rhinol Laryngol.

1993;102(7):508-517. doi:10.1177/0003489493102007 04 39. NeuroCom. Balance manager clinical interpretation guide. Seattle, WA: Natus Medical, Inc.; 2013.

40. Cameron KL, Thompson BS, Peck KY, Owens BD, Marshall SW, Svoboda SJ. Normative values for the KOOS and WOMAC in a young athletic population: history of knee ligament injury is associated with lower scores. Am J Sports Med. 2013;41(3):582-589. do i:10.1177/0363546512472330 41. Vander Vegt CB, Register-Mihalik JK, Ford CB, Rodrigo CJ, Guskiewicz KM, Mihalik JP. Baseline concussion clinical measures are related to sensory organization and balance. Med Sci Sports Exerc.

2019;51(2):264-270. doi:10.1249/mss.0000000000001 789 42. Steindl R, Kunz K, Schrott-Fischer A, Scholtz AW. Effect of age and sex on maturation of sensory systems and balance control. Dev Med Child Neurol.

2006;48(6):477-482. doi:10.1017/s0012162206001022 43. Hirabayashi S, Iwasaki Y. Developmental perspective of sensory organization on postural control. Brain Dev. 1995;17(2):111-113.

44. Cripps A. E.; Livingston S.C.; Desantis B. The testretest reliability and minimal detectable change of the sensory organization test and head-shake sensory organization test. Phys Ther. 2016;2(2).

33. NeuroCom. Balance manager clinical operation guide. Seattle, WA: Natus Medical, Inc.; 2014.

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Normative Data for the NeuroCom Sensory Organization Test in United States Military Academy Boxers

45. Wrisley DM, Stephens MJ, Mosley S, Wojnowski A, Duffy J, Burkard R. Learning effects of repetitive administrations of the sensory organization test in healthy young adults. Arch Phys Med Rehabil.

2007;88(8):1049-1054. doi:10.1016/j.apmr.2007.05.00 3

47. Heinbaugh EM, Smith DT, Zhu Q, Wilson MA, Dai B. The effect of time-of-day on static and dynamic balance in recreational athletes. Sports Biomech.

2015;14(3):361-373. doi:10.1080/14763141.2015.1084 036

46. Hain TC. Moving platform posturography testing Computerized Dynamic Posturography (CDP).

Published 2021. Accessed January 19, 2022. https://di zziness-and-balance.com/testing/posturography.html

International Journal of Sports Physical Therapy

Normative Data for the NeuroCom Sensory Organization Test in United States Military Academy Boxers

SUPPLEMENTARY MATERIALS Appendix Download: https://ijspt.scholasticahq.com/article/32547-normative-data-for-the-neurocom-sensory-organizationtest-in-united-states-military-academy-boxers/attachment/82042.docx?auth_token=WpaylTaCB-QZjIctLcoo

International Journal of Sports Physical Therapy

Shepherd HA, van Rassel CR, Black AM, et al. Feasibility and Reliability of a Novel GameBased Test of Neurological Function in Youth: The Equilibrium Test Battery. IJSPT. 2022;17(3):378-389.

Original Research

Feasibility and Reliability of a Novel Game-Based Test of Neurological Function in Youth: The Equilibrium Test Battery a

Heather A Shepherd 1 , Cody R van Rassel 2 , Amanda M Black 1 , Robert F Graham 3, Keith Owen Yeates 4 , 5 Carolyn A Emery , Kathryn J Schneider 6 1

Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada; Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, AB, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 4N1, Canada; O’Brien Institute for Public Health, University of Calgary, Calgary, AB, Canada, 2 Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada; Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, AB, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 4N1, Canada; O’Brien Institute for Public Health, University of Calgary, Calgary, AB, Canada; Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada, 3 Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada, 4 Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, AB, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 4N1, Canada; Department of Psychology, University of Calgary, Calgary, AB, Canada, 5 Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada; Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, AB, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 4N1, Canada; O’Brien Institute for Public Health, University of Calgary, Calgary, AB, Canada; Pediatrics, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Community Health Sciences, Department of Pediatrics, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada, 6 Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada; Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, AB, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 4N1, Canada; Sport Medicine Centre, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada; Evidence Sport and Spine, Calgary, AB, Canada Keywords: assessment, concussion, digital technology, feasibility, adolescents https://doi.org/10.26603/001c.32527

International Journal of Sports Physical Therapy Vol. 17, Issue 3, 2022

Background An estimated 11% of Canadian adolescents will sustain a sport-related concussion each year. However, diagnostic tools to detect and monitor concussive outcomes are limited.

Purpose To evaluate the feasibility and test-retest reliability of the Highmark Interactive Equilibrium (HIEQ) test battery in uninjured adolescents.

Study Design Observational study with repeated measurements.

Methods Participants completed the HIEQ test battery, a game-based platform on an iPad application, that assesses balance, cognitive function, and visual function, for up to 15 consecutive school days in a group classroom setting. Feasibility for use of the HIEQ was evaluated by (1) recruitment rates; (2) retention rates; (3) test completion without assistance; and (4) adverse events. Test-retest reliability was examined using Bland Altman 95% limits of agreement and intraclass correlation coefficients comparing the first and second and second and third obtained scores. Reliability across multiple baseline assessments was also analyzed using intraclass correlations for the second to sixth and seventh to eleventh obtained scores.

a

Corresponding author: Heather Shepherd Heather.shepherd@ucalgary.ca 403.220.5332 Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary Calgary, AB T2N 1N4 Canada

Feasibility and Reliability of a Novel Game-Based Test of Neurological Function in Youth: The Equilibrium Test Battery

Results Fifty-five uninjured high school students (31 females and 24 males, mean age = 16.24 [1.09]) from three high schools participated in the study. Three participants (5%) completed all 15 days of testing, and 73% completed at least 10 of 15 test days. No adverse events were reported. Although the test was feasible, all subtests showed wide limits of agreement from first to second and from second to third testing occasions.

Results indicate poor-to-moderate reliability (<0.50 to 0.75) across those intervals, as well as across the second to sixth and seventh to eleventh testing occasions.

Conclusion The HIEQ is feasible in high school students; however, performance was characterized by wide limits of agreement and poor-to-moderate reliability across test occasions. Future evaluation of the HIEQ in visual and auditory distraction free individual testing settings is warranted.

Level of Evidence Level 3.

INTRODUCTION In Canada, approximately one in nine adolescents will sustain a sport-related concussion each year.1 Concussion signs and symptoms are heterogenous and may involve a variety of domains, including physical (e.g. headache, dizziness), emotional (e.g. irritability, anxiety), sleep, and cognitive (e.g. difficulty remembering, difficulty concentrating).2 Concussion assessments should be multifaceted, incorporating multiple domains of functioning.3 Once a concussion has been diagnosed, decisions regarding recovery and clearance to return to school or to sport are made on an individual, case-by-case basis. An objective tool that assesses multiple domains at baseline and throughout the recovery process may help make informed diagnostic, management, and recovery decisions for individuals who sustain a concussion.

Current computerized neuropsychological assessment batteries used for concussion assessment (e.g., ImPACT, Axon Sports CogState Test) demonstrate variable levels of reliability,4,5 which may be attributed, in part, to natural variation in an individual’s performance on a given performance task. However, variable performance may reduce reliability and limit a test battery’s clinical utility.6 This has resulted in a shift towards conducting multiple baselines, in order to better understand normative variation in performance across multiple domains of function.6 Multiple baselines may help to yield a more reliable estimate of baseline performance, and may support clinicians in detecting change in an athlete’s functioning following a concussion.6 The Highmark Interactive Equilibrium (HIEQ) test battery is a game-based platform that draws on existing clinical tools, including the Sport Concussion Assessment Tool (SCAT), King-Devick Test, and Trail Making Test Part B.7–11 The HIEQ assesses multiple domains of functioning including balance, vision, and cognition (i.e., immediate verbal recognition memory, delayed verbal recognition memory, cognitive flexibility and inhibitory control, and attention and working memory).12 The HIEQ is unique in that it is self-administered by the participant, as opposed to requiring the expertise of a clinician to administer, and hence needs minimal supervision.13

The feasibility of the HIEQ, as well as its test-retest reliability, has not been studied extensively in healthy adolescents. Therefore, the purpose of this study was to evaluate the feasibility and test-retest reliability of the HIEQ test battery in uninjured adolescents.

MATERIALS AND METHODS STUDY DESIGN AND PARTICIPANTS

This was an observational study that involved repeated measurements in a sample of high school students. Students enrolled in three high schools in Calgary, Alberta, Canada were invited to participate in the study. Recruitment initially occurred at the school level with school administrators. Once administrators agreed to allow the research team to approach teachers within a school, students enrolled in sport medicine, sports performance, and biology classes were invited to participate in the study. Two of the schools enrolled students who were focused on sport, including athletes participating at highly competitive levels.

Some of the students were remembers of National teams or other high-performance levels of sport. The third school was a regular public high school.

Participants were eligible for inclusion if they met the following criteria: 1) age 14-19 years; 2) high school student in one of the participating classes; 3) uninjured at the start of the study; and 4) provided written participant and/or guardian informed consent and participant assent. Participants were excluded if they had any musculoskeletal injuries or other medical conditions that would hinder completion of the test battery, or if they had any planned absences from school during the study period that would preclude completion of the test battery daily for three consecutive weeks.

PROCEDURES

This study was approved by University of Calgary Conjoint Health Research Ethics Board (REB18-1482) and participating schools. Data were collected over a three-week period in each school (April-June 2019). Participants were provided detailed instructions and a demonstration of the HIEQ ap-

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Feasibility and Reliability of a Novel Game-Based Test of Neurological Function in Youth: The Equilibrium Test Battery

plication test battery (EQ Active, v. 1.1.3, Highmark Interactive, Toronto, ON, Canada), as well as instruction on how to complete the baseline questionnaire.

Participants were asked to complete the HIEQ once per school day for 15 school days. They completed the testing in their classroom under the supervision of the teacher during class time. Schools were provided with a set of iPads, managed by the teachers. Each participant was provided a unique study e-mail address to login to the application and wired headphones to reduce distractions and to minimize delays between sounds from the application and participant response times (i.e. to reduce the delay in auditory stimulus that may occur with wireless/Bluetooth headphones).

Members of the research team followed up with the sites once weekly to ensure that the test was being completed and to answer any questions from students or teachers at the schools. The research team also followed up with the teachers between visits via e-mail, as needed.

The HIEQ test battery required an internet connection to complete and send the data to a secure third-party online server (Cloud66, San Francisco, CA, US) for data storage.

MongoDB Compass (Mongo DB, Inc., New York City, NY, USA) and Sequel Pro (v1.1.2, Sequelpro.com) were used to access data stored on the Cloud66 sever. Access to the HIEQ test battery data was limited to the research team. Highmark Interactive was blinded to the test data from the HIEQ application throughout the study.

MATERIALS BASELINE QUESTIONNAIRE

The baseline questionnaire included questions pertaining to demographics, history of concussion, history of other injuries, and history of learning disabilities or participantidentified learning concerns. Participants completed the baseline questionnaire at the onset of study participation via a survey link through Research Electronic Data Capture (REDCap).

HIGHMARK INTERACTIVE EQUILIBRIUM APPLICATION

The HIEQ application contained seven subtests. Details on each subtest and scoring is described below. Each participant self-administered the HIEQ application and was instructed to complete the “Full Check-In”, or all seven subtests, on each testing day. The test battery took approximately 20 minutes to complete initially, but only 10-15 minutes once participants became familiar with the test.

HIGHMARK EQ APPLICATION

– SUBTESTS

VISUAL FUNCTION

The visual function subtest, “Dance Off,” was designed to assess binocular vision and visual processing using a rapid, timed task. It was developed to be analogous to the KingDevick Test.10,11 The subtest consisted of a randomized presentation of arrows on the screen of the device that were to be scanned visually from left to right. The participant indicated the direction of each arrow by swiping in the di-

rection of the arrow on the device. Participants were asked to complete each card (trial) as quickly as possible, without incurring any errors. If an error occurred, the participant started the card again. The task involves three cards increasing in difficulty (i.e., changes in spacing between arrows). Time to complete each card was recorded in seconds.

Completion times were averaged to yield a score in seconds.

Higher scores indicated worse performance.

BALANCE

The balance subtest, “Tire Toss,” was designed to capture balance in five different positions: 1) Romberg (feet together); 2) Tandem stance /sharpened Romberg (right leg forward); 3) Tandem stance/sharpened Romberg (left leg forward); 4) single leg stance (right leg); and 5) single leg stance (left leg).14,15 The positions are the same as those used in the Balance Error Scoring System (BESS) that is part of the SCAT.7,16 Participants were instructed to keep their eyes closed and to keep the device (iPad) level and flat against their chest. Participants held each position for 10 seconds. The balance subtest used the internal accelerometer, which measures the orientation of the iPad with respect to the participant’s initial position, to determine a participant’s tilt, or deviation from the centre of mass, to a maximum deviation of 15° from centre. A balance score was calculated using the cumulative tilt of the iPad as an approximation of the movement of the participant’s centre of mass during the test, averaged across the five balance positions. Scores range from 0 to 100, with 100 indicating better balance, or a lower deviation from the centre of mass, and 0 a higher deviation from centre of mass. If a participant deviated 15° or more from centre, then they were assigned a score of 0 for that position. If a participant lost their balance, they were instructed to resume the initial position as soon as safely able.

COGNITIVE FUNCTION

Cognitive function was measured using five tests, four of which are similar to components of the Standardized Assessment of Concussion, which is a widely accepted screening test of concussion that is part of the SCAT.7,8 The five tests are named Recipe Recall, Recipe Recall with Delay, Jersey Reversey, Fast Ball, and Pylon Pivot.

“Recipe Recall” evaluated immediate verbal recognition memory, similar to immediate memory on the SCAT5.7 Participants were presented with an auditory list of 20 words (foods) as part of a grocery list and were instructed to remember the grocery items. They were presented with this list twice. Then, they were presented with 40 words, 20 of which were previously heard and 20 novel words, in random order. Participants selected “yes” or “no” based on whether the presented word was on the grocery list. Scores were calculated as correct out of a total of 40. Higher scores indicated better performance.

“Recipe Recall with Delay” evaluated delayed verbal recognition memory, similar to delayed recall on the SCAT5.7 This subtest included a similar presentation to Recipe Recall. Participants selected “yes” or “no” based on whether the presented word was on the initial grocery list (Recipe Recall). Scores were calculated as correct out of a

International Journal of Sports Physical Therapy

Feasibility and Reliability of a Novel Game-Based Test of Neurological Function in Youth: The Equilibrium Test Battery

total of 20. Higher scores indicated better performance.

“Jersey Reversey” evaluated working memory and attention, similar to Digits Backwards on the SCAT5.7 Participants were presented with an auditory list of single-digit (1-9) numbers and were instructed to reverse the presented numbers. They selected the intended numbers presented on the screen. The subtest started with three numbers and progressed to a maximum of nine numbers. If participants were successful on a given level, then they progressed to the next level, increasing the number of digits by one. Participants had two trials to complete each level. If they were incorrect on both trials at a given level, then the subtest ended. Presentation of numbers was randomized. Scores were calculated as successful level achieved, out of a maximum score of seven (i.e., highest level completed). Higher scores on this subtest indicated better performance.

“Fastball” evaluated reaction time. It included five trials where participants tapped the screen as soon as a stimulus (a baseball) appeared. The timing between stimuli presentations was randomized, and stimuli could occur from oneto-three seconds apart. The subtest was scored by averaging the reaction time of the five trials, measured in milliseconds. Higher reaction time scores were indicative of worse performance. Reaction times below 100 milliseconds were considered invalid and excluded from the average. If a participant missed a trial, they were assigned a score of 1500 milliseconds, which was included in the average of the five trials.

The final subtest, “Pylon Pivot,” is analogous to the Trail Making Test Part B and evaluates inhibitory control and flexibility.9 Participants completed the subtest by selecting a series of numbers and letters in ascending order (e.g. 1-A, 2-B, 3-C). The locations of letters and numbers were randomized. Scoring was calculated as time to completion in seconds. If a participant made an error, they received haptic feedback and then selected the correct next number or letter in the series before progressing. Higher time scores indicated worse performance.

STATISTICAL ANALYSIS

The feasibility of the test battery was evaluated using the following metrics: 1) recruitment rates; 2) retention rates; 3) completion of test without assistance; and 4) adverse events reported. Boxplots were completed for each subtest to demonstrate medians and ranges of scores across testing days.

TEST-RETEST RELIABILITY

Test-retest reliability was assessed using Bland Altman 95% limits of agreement. Comparisons were conducted for the first versus second score and the second versus third score.

Scores were adjusted for start time (i.e. if a participant’s first day of test administration was testing day 2, then that score [and all subsequent scores] would be adjusted – day 2 would equal score 1). This procedure was used to calculate missing data points for variables on Days 1, 2, and 3, with adjusted days varying up to five days (i.e., Score 1 could be from Day 1, 2, 3, 4, or 5). The Shapiro-Wilk test of normality was used to check for the assumption of normality of dif-

ference scores for each subtest comparison. Where assumptions of normality were not met, data were logarithmically transformed. Ratios, geometric means, and 95% confidence intervals were calculated for back-transformed logarithmic data. Intraclass correlations (ICCs) and 95% confidence intervals also were used to calculate test-retest reliability for scores 1-2 and scores 2-3 based on a mean rating (k=2), twoway mixed-effects model with absolute agreement. Scores 1-2 and scores 2-3 were selected to consider initial test familiarization (scores 1-2) and to determine if test-retest reliability differs after the first two test administrations (scores 2-3). ICC values of less than 0.50 were categorized as poor, 0.50-0.75 as moderate, 0.76-0.90 as good, and above 0.90 as excellent.17 To evaluate test-retest reliability across multiple baseline periods, ICCs and 95% confidence intervals were calculated for intra-individual scores 2 to 6 and scores 7 to 11 based on a mean rating (k=5), two-way mixed-effects model with absolute agreement. Score bands 2 to 6 and 7 to 11 were used as five-day multiple baselines as recommended clinically. Score 1 was not included to minimize any potential learning effects from the first-to-second test administration. The Shapiro-Wilk test of normality was used to check for the assumption of normality of difference scores for each subtest comparison. All analyses were performed using Stata v. 15.0 and Microsoft Excel.

RESULTS Participants included 55 14–19-year-old high school students (mean = 16.24 [1.09]; 31 females and 24 males), ranging from grades 10 through 12. Twenty-eight of the participants had a prior history of concussion, and 27 had a prior history of a non-concussive injury. Of those with prior injury history, 15 participants reported a prior history of both a concussion and a non-concussive injury. Sixteen of the students self-reported a history of learning disabilities or participant-identified learning concerns. Demographic characteristics are presented Table 1.

FEASIBILITY

Three participants (5%) completed the HIEQ on all test dates. Most participants (n = 40; 73%) completed the battery for at least 10 of 15 testing days. The number of participants who completed the HIEQ test battery decreased as the number of testing days increased. All participants were able to complete the HIEQ test battery without assistance, and no adverse events were reported. Due to unexpected events, including school closures and loss of internet service, participation numbers were especially low on Days 8 and 9. Figure 1 outlines the proportion of participants who completed a given number of testing days, out of a possible 15 days.

Figure 2 shows the ranges of scores for each subtest across each testing day.

TEST-RETEST RELIABILITY

Bland Altman 95% limits of agreement are presented in Figures 3 and 4 and Table 2. Plots for Recipe Recall (score 1 to score 2, score 2 to score 3) and Pylon Pivot (score 1 to

International Journal of Sports Physical Therapy

Feasibility and Reliability of a Novel Game-Based Test of Neurological Function in Youth: The Equilibrium Test Battery

Table 1. Participant Demographics Females (n=31)

Males (n=24)

Age (years), Standard deviation

Mean = 16.13 (1.02)

Mean = 16.38 (1.17)

Previous history of concussion

Yes = 14 (45%) No = 15 (48%) Missing = 2 (7%)

Yes = 14 (58%) No = 8 (33%) Missing = 2 (9%)

Previous history of injury other than concussion

Yes = 18 (58%) No = 11 (35%) Missing = 2 (7%)

Yes = 9 (38%) No = 12 (50%) Missing = 3 (12%)

score 2, score 2 to score 3) were logarithmically transformed to improve dispersion of scores (in which case ratios are reported). Overall, wide 95% limits of agreement and ratios were apparent across all testing points. Timed subtests (Dance Off, Pylon Pivot, Fast Ball) showed improved performance, or a decrease in mean scores, from score 1 to score 2, with two (Pylon Pivot and Fast Ball) also showing improvement from score 2 to score 3.

ICCs were calculated for test-retest reliability for score 1 to score 2 and score 2 to score 3 across subtests. Reliability ranged from poor-to-moderate, where ICCs were calculated (see Table 3).17 For score 1 to score 2, moderate test-retest reliability was found for Jersey Reversey (ICC 0.52) and Tire Toss (ICC 0.61), and poor test-retest reliability for Recipe Recall (ICC 0.18). For score 2 to score 3, moderate testretest reliability was observed for Pylon Pivot (ICC 0.64), Jersey Reversey (ICC 0.68, Tire Toss (ICC 0.57), and Fast Ball (ICC 0.66). For score 2 to score 3, poor test-retest reliability was observed for Recipe Recall score 2 to score 3 (ICC 0.44).

ICCs were not reported for score 1 to score 2 for Dance Off, Pylon Pivot, Recipe Recall with Delay, or Fast Ball, or for score 2 to score 3 for Dance Off or Recipe Recall with Delay, as normality assumptions were violated.

ICCs for scores 2 through 6 and scores 7 through 11 are presented in Table 4. ICCs ranged from 0.34 to 0.55 for score 2 to score 6 and from 0.33 to 0.53 for score 7 to score 11, or from poor-to-moderate for both intervals. ICCs were not reported where assumptions were violated.

DISCUSSION The purpose of the current study was to evaluate the feasibility and test-retest reliability of the HIEQ application, a game-based test battery designed to assess neurological functioning, including balance, visual function, and cognition, in adolescents.

FEASIBILITY

Participants were recruited from four classes in three Calgary, Alberta, Canada high schools, with most students in the eligible classes electing to participate in the study. Because the sample included students who attended high-performance sports programs (n=29), some participants were absent from school for large portions of the data collection period. Thus, none of the subtests had 100% participation on any given testing day. This is highlighted in Figure 1, where four participants completed five or less days of test-

Figure 1. Number of testing days completed by participants.

ing, and only three participants completed all 15 days. Nevertheless, despite these circumstances, most participants completed the battery for at least 10 of 15 testing days.

In contrast to other computer-based assessments (e.g. ImPACT) or pen-and-paper assessments (e.g. SCAT5), the HIEQ does not need a health care professional to be present during administration. Instead, adolescents can complete the assessment independently. This may increase the likelihood of repeat testing that enables multiple baseline assessments.

To the authors’ knowledge, this was the first study that has evaluated multiple baselines across 15 days. Anecdotal reports from participants and teachers suggested that participants found the application engaging initially, with interest decreasing after the initial one-to-two weeks of test administration. This was also seen when examining participation rates, which were highest at the start of the study and declined after testing day seven, suggesting a possible limit to the desirable number of baseline test administrations. Participant fatigue has been identified as a factor which may affect reliability in studies using computerized neurocognitive tests, similar to HIEQ.4 However, this was noted to be more of a concern when multiple computerized neurocognitive tests were conducted concurrently, not specific to one test conducted across multiple days.

RELIABILITY

It was anticipated that the most improvement in mean test performance would occur from score 1 to score 2, with less improvement from score 2 to score 3. Descriptively, improvement in test performance was observed from score 1 to score 2 for timed subtests (Dance Off, Pylon Pivot, Fast Ball) and Jersey Reversey and Tire Toss. Box plots (Figure 2)

International Journal of Sports Physical Therapy

Feasibility and Reliability of a Novel Game-Based Test of Neurological Function in Youth: The Equilibrium Test Battery

Figure 2. Scores, per subtest, across Testing Days 1-15. Whiskers identify minimum and maximum values.

International Journal of Sports Physical Therapy

Feasibility and Reliability of a Novel Game-Based Test of Neurological Function in Youth: The Equilibrium Test Battery

Figure 3. Bland Altman 95% Limits of Agreement plots for score 1 to score 2. Scores were adjusted for start time, indicating each individual’s first and second testing administrations. Males are represented by black circles.

Females are represented by white diamonds. Where assumptions were violated, scores were logarithmically transformed and logarithmic values are presented (Recipe Recall, Pylon Pivot).

International Journal of Sports Physical Therapy

Feasibility and Reliability of a Novel Game-Based Test of Neurological Function in Youth: The Equilibrium Test Battery

Figure 4. Bland Altman 95% Limits of Agreement plots for score 2 to score 3. Scores were adjusted for start time, indicating each individual’s second and third testing administrations. Males are represented by black circles.

Females are represented by white diamonds. Where assumptions were violated, scores were logarithmically transformed and logarithmic values are presented (Recipe Recall, Pylon Pivot).

International Journal of Sports Physical Therapy

Feasibility and Reliability of a Novel Game-Based Test of Neurological Function in Youth: The Equilibrium Test Battery

Table 2. Bland Altman 95% Limits of Agreement Subtest

Scores

Participant (n)

Range of Scores

Mean Difference (95% Confidence Interval)

Limits of Agreement

Dance Off

1–2

55

16.23 to 28.45

-2.46 (CI -3.25 to -1.68)

-8.38 to 3.35

2–3

53

14.50 to 25.70

-0.47 (CI -1.27 to 0.33)

-6.28 to 5.34

1–2

53

1.00 to 7.00

0.45 (CI 0.10 to 0.81)

-2.12 to 3.04

2–3

51

1.50 to 7.00

0.16 (CI -0.19 to 0.50)

-2.29 to 2.60

1–2

53

14.50 to 20.00

-1.51 (CI -2.22 to -0.80)

-6.69 to 3.67

2–3

51

12.50 to 20.00

0.43 (CI -0.29 to 1.15)

-4.68 to 5.54

1–2

54

32.34 to 94.63

1.48 (CI -2.13 to 5.09)

-24.97 to 27.92

2–3

51

22.68 to 92.36

-1.78 (CI -5.85 to 2.29)

-30.72 to 27.16

1–2

55

260.21 to 537.01

-41.11 (CI -62.02 to -20.20)

-195.81 to 113.59

2–3

53

263.45 to 520.44

-33.23 (CI -44.40 to -22.07)

-114.26 to 47.78

1–2

54

30.50 to 39.50

0.97 (0.95 to 0.99)*

0.81 to 1.16**

2–3

51

28.00 to 39.50

0.99 (0.97 to 1.02)*

0.82 to 1.20**

1–2

55

24.46 to 97.35

0.93 (0.87 to 0.99)*

0.59 to 1.46**

2–3

54

25.02 to 83.93

0.90 (0.85 to 0.96)*

0.58 to 1.40**

Jersey Reversey

Recipe Recall with Delay

Tire Toss

Fast Ball

Recipe Recall

Pylon Pivot

* Geometric mean with 95% confidence interval presented when Bland and Altman plots did not meet the assumptions that the differences are normally distributed ** Limits of agreement are ratios for anti-log values presented (e.g., 0.81 to 1.16 interpreted as 95% of the time score 2 is 19% lower to 16% higher than score 1) † Subtest Scoring: a. Dance Off scores are calculated in seconds. Lower scores indicate better performance. b. Jersey Reversey scores are calculated as number correct out of a possible 7. Higher scores indicate better performance. c. Recipe Recall with Delay scores are calculated as number correct out of a possible 20. Higher scores indicate better performance. d. Tire Toss scores are calculated as deviation from centre, in degrees, with a maximum score of 100. Higher scores indicate better performance. e. Pylon Pivot scores are calculated in seconds. Lower scores indicate better performance. f. Recipe Recall scores are calculated as number correct out of a possible 40. Higher scores indicate better performance. g. Fast Ball scores are calculated in milliseconds. Lower scores indicate better performance.

were used to describe test performance over days, and suggested that mean performance on timed subtests stabilized at day 3 for Dance Off and Fast Ball and day 4 for Pylon Pivot. This is similar to results described by Hinton-Bayre and colleagues, who noted that practice effects levelled off after a second baseline assessment.18 Further, repeat testing may have resulted in motor learning on balance tests (Pylon Pivot).19 Bland-Altman limits of agreement were wide, and where ICCs were calculated, results indicated poor-to-moderate reliability between scores 1 and 2 (Figure 3) and scores 2 and 3 (Figure 4).17 Scores for some subtests violated statistical assumptions, limiting the ability to quantify testretest reliability. However, on the whole, the reliability of the HIEQ test battery across the first several administrations was limited. These results are similar to studies of other computerized test batteries used for concussion assessment, many of which have also demonstrated limited

reliability of test scores.4,5 Together with improvements in mean performance on some tests, the results also suggest that the first one or two assessments might need to be disregarded when establishing a multiple testing baseline.19 The findings of this study would also suggest that the first completion of the test should not be included in the calculation of a multiple baseline score given the potential for a learning effect.

To examine the reliability of multiple baselines, ICCs for each subtest were examined in two score bands (i.e., scores 2 through 6 and 7 through 11). The score bands were selected to reduce potential learning effects (score 1 to score 2) and to capture as many participant scores as possible.

Where ICCs were calculated, results indicated poor-tomoderate reliability for both score bands. Thus, in this group administration setting, scores on the HIEQ showed only modest reliability over time.

Some authors have reported substantial individual vari-

International Journal of Sports Physical Therapy

Feasibility and Reliability of a Novel Game-Based Test of Neurological Function in Youth: The Equilibrium Test Battery

Table 3. Intraclass Correlations for Test-Retest Reliability – Score 1 to Score 2 and Score 2 to Score 3 Subtest

Scores

Dance Off

1-2

ICC

95% Confidence Interval

F-Test

Lower

Upper

df1

df2

F

p-value

2-3 Recipe Recall

Pylon Pivot

Jersey Reversey

Recipe Recall with Delay

1-2

0.18

0-.06

0.42

53

53

1.50

0.073

2-3

0.44

0.18

0.64

50

50

2.54

0.001

2-3

0.64

0.40

0.79

53

53

5.30

<0.001

1-2

0.52

0.29

0.70

52

52

3.42

<0.001

2-3

0.68

0.51

0.82

50

50

5.34

<0.001

1-2

0.61

0.42

0.76

53

53

4.16

<0.001

2-3

0.57

0.35

0.73

50

50

3.61

<0.001

0.66

0.21

0.84

52

52

7.50

<0.001

1-2

1-2 2-3

Tire Toss

Fast Ball

1-2 2-3

Table 4. Intraclass Correlations for Reliability – Score 2 to Score 6 and Score 7 to Score 11 Subtest

Scores

Dance Off

2–6

ICC

95% Confidence Interval

F-Test

Lower

Upper

Df1

Df2

F

p-value

7 – 11 Recipe Recall

Pylon Pivot

Jersey Reversey

Recipe Recall with Delay

Tire Toss

2–6

0.34

0.21

.50

44

176

3.71

<0.0001

7 – 11

0.51

0.34

.68

29

116

6.06

<0.001

7 – 11

0.49

0.33

.66

31

124

5.85

<0.001

2–6

0.55

0.41

.68

44

176

7.26

<0.001

7 – 11

0.33

0.17

.52

29

116

3.41

<0.001

7 – 11

0.49

0.32

.67

28

112

5.71

<0.001

2–6

0.53

0.40

.67

43

172

6.67

<0.001

0.40

0.23

.61

25

100

4.53

<0.001

2–6

2–6

7 – 11 Fast Ball

2–6 7 – 11

ability on the Standardized Assessment of Concussion and the modified Balance Error Scoring Scale subtests of the SCAT5, with moderate reliability in a two-week test-retest reliability study.15,20 These findings suggest that multiple baselines may better capture the variability of performance in an uninjured athlete, and this may eventually facilitate better detection and management should an athlete sustain a concussion. Further investigation into normative ranges for each individual, as part of a comprehensive multiple baseline assessment, may help to identify expected variability across differing domains (i.e. cognitive, balance, vi-

sual function) and may help to inform the optimal number of baseline testing days required for the different domains.

SPECIFIC SUBTEST CONSIDERATIONS

Scores on the memory subtests (Recipe Recall and Recipe Recall with Delay) were characterized by a ceiling effect, with many participants reaching the maximum score (40/40 or 20/20). This is similar to a ceiling effect identified when a five-word recall list was used for the memory components on the SCAT3 and on verbal memory subtests on the ImPACT test.21,22

International Journal of Sports Physical Therapy

Feasibility and Reliability of a Novel Game-Based Test of Neurological Function in Youth: The Equilibrium Test Battery

An interference effect also may have affected scores on memory subtests as participants completed the test over 15 testing days, with words presented on previous testing days interfering and affecting memory for current words, and thus resulting in a decrease in performance. Although these subtests were developed as a more functional task (grocery shopping list) and may be more applicable to daily life settings, a larger or more varied word bank may help to prevent interference effects.

LIMITATIONS

The study had several limitations. School barriers, such as school closure, personal activity days, exams, and lost internet connections hampered completion of the HIEQ on some testing days. The test was performed in a classroom setting; therefore, the participants may have been distracted or given less effort than they would have in a distraction-free setting without others present. This may have led to increased variability in test scores, although the use of headphones would reduce distraction. Evaluation of reliability of repeat testing in visual and auditory distraction free individual testing environments is warranted and is in keeping with current testing recommendations. Participants were asked to complete the test for 15 consecutive school days; the number of consecutive days may have decreased engagement and also contributed to variability in test scores, although reliability was not noticeably different across the two testing bands. In addition, some participants elected to complete only certain subtests or some subtests repeatedly, which may have influenced their exposure to certain subtests, and thus the reliability of their performance. Randomizing the order of the subtests may increase engagement with the HIEQ test battery. Further, two schools in the study included high-performance studentathletes. The performance of adolescents attending highperformance schools may differ from that of adolescents attending a typical high school. As participation in the study was voluntary and recruitment happened through specific schools and classes a selection bias may have occurred where the students who performed at a higher level or were more likely to perform well on the tests may have chosen to participate. The study was not adequately powered to permit evaluation of differences in performance between schools.

CONCLUSIONS While the HIEQ appears to be feasible in high school students, test-retest reliability is poor-to-moderate when the tests are administered in a group setting. Fifteen days of repeated baseline testing may be burdensome to adolescents.

Further research evaluating five-day multiple baseline testing of individuals in visual and auditory distraction free individual testing settings may provide greater insight into the reliability of the HIEQ in uninjured adolescents athletes.

DECLARATION OF INTEREST

Kathryn Schneider is a physiotherapist consultant at Evidence Sport and Spinal Therapy and at University of Calgary Sport Medicine Centre.

FUNDING

We acknowledge funding through Highmark Innovations Inc. (Toronto, Canada) for the support of this project and the studentship of HAS. CONFLICTS OF INTEREST

There are no conflicts of interest to declare.

APPROVAL

This study was approved by the University of Calgary Conjoint Health Research Ethics Board for human subject research.

ACKNOWLEDGEMENTS

The Sport Injury Prevention Research Centre is one of the International Research Centres for Prevention of Injury and Protection of Athlete Health supported by the International Olympic Committee. We acknowledge funding from Highmark Innovations Inc. (Toronto, Canada) for the support of this project. We acknowledge Vineetha K. Warryiar for her contributions to the project. Keith Yeates holds the Ronald and Irene Ware Chair in Pediatric Brain Injury, funded by the Alberta Children’s Hospital Foundation. Carolyn Emery holds a Canada Research Chair (Tier 1) in Concussion. We acknowledge the support of the students, teachers, and schools who participated in this study.

AUTHOR CONTRIBUTIONS

All authors contributed to the conceptualization and design of the study. HAS, CRVR, and KJS led the protocol development for data collection and HAS, CRVR, and RFG conducted all data collection and data cleaning. HAS conducted all data analysis with mentorship from all team members in particular AMB, KOY, and CAE. The paper was initially drafted by HAS. HAS and KJS take responsibility for the integrity of the data and the accuracy of the data analysis and manuscript. KJS takes responsibility for funding acquisition. All authors critically reviewed and edited the manuscript before submission.

Submitted: September 13, 2021 CDT, Accepted: December 08, 2021 CDT

This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CCBY-NC-4.0). View this license’s legal deed at https://creativecommons.org/licenses/by-nc/4.0 and legal code at https://creativecommons.org/licenses/by-nc/4.0/legalcode for more information.

International Journal of Sports Physical Therapy

Feasibility and Reliability of a Novel Game-Based Test of Neurological Function in Youth: The Equilibrium Test Battery

REFERENCES 1. Black A, McCallum J, Eliason PE, Hagel BE, Emery CA. The burden of sport-related concussion in high school students: lifetime prevalence, 1-year incidence and persistent symptoms. Clin J Sport Med. 2020;30(3):e89. doi:10.1097/JSM.0000000000000844 2. McCrory P, Meeuwisse W, Dvořák J, et al.

Consensus Statement on Concussion in Sport—the 5th International Conference on Concussion in Sport held in Berlin, October 2016. Br J Sports Med. 2017;51(11):838. doi:10.1136/bjsports-2017-097699 3. Feddermann-Demont N, Echemendia RJ, Schneider KJ, et al. What domains of clinical function should be assessed after sport-related concussion? A systematic review. Br J Sports Med. 2017;51(11):903. doi:10.1136/ bjsports-2016-097403 4. Farnsworth JL, Dargo L, Ragan BG, Kang M. Reliability of computerized neurocognitive tests for concussion assessment: A meta-analysis. J Athl Train.

2017;52(9):826-833. doi:10.4085/1062-6050-52.6.03 5. Kontos A, Sufrinko A, Womble M, Kegel N. Neuropsychological assessment following concussion: An evidence-based review of the role of neuropsychological assessment pre- and postconcussion. Curr Pain Headache Rep. 2016;20(6):1-7. d oi:10.1007/s11916-016-0571-y 6. Bruce J, Echemendia R, Tangeman L, et al. Two baselines are better than one: Improving the reliability of computerized testing in sports neuropsychology. Appl Neuropsychol Adult.

2016;23(5):336-342. doi:10.1080/23279095.2015.1064 002 7. Echemendia RJ, Meeuwisse W, Mccrory P, et al. The Sport Concussion Assessment Tool 5th Edition (SCAT5): Background and rationale. Br J Sports Med. 2017;51(11):848. doi:10.1136/bjsports-2017-097506 8. Mccrea M. Standardized mental status testing on the sideline after sport-related concussion. J Athl Train. 2001;36(3):274-279.

9. Partington JE, Leiter RG. Partington’s Pathways Test. Psychol Serv Cent J. 1949;1:11-20.

10. Galetta KM, Liu M, Leong DF, Ventura RE, Galetta SL, Balcer LJ. The King-Devick Test of rapid number naming for concussion detection: Meta-analysis and systematic review of the literature. Concussion.

2016;1(2):cnc.15.8. doi:10.2217/cnc.15.8 11. King-Devick Technologies, Inc. Accessed April 9, 2021. https://kingdevicktest.com/

12. Highmark Interactive. EQ Science . Published 2020. Accessed August 5, 2020. https://www.highmar k.tech/science/ 13. Highmark Interactive. EQ Active. Published 2020.

Accessed August 5, 2020. https://www.highmark.tech/ eqactive/ 14. Gokula KA. Romberg’s Test. J Postgrad Med. 2003;49:169-172.

15. Bell DR, Guskiewicz KM, Clark MA, Padua DA. Systematic review of the Balance Error Scoring System. Sports Health. 2011;3(3):287-295. doi:10.117 7/1941738111403122 16. Khanna NK, Baumgartner K, Labella CR. Balance Error Scoring System performance in children and adolescents with no history of concussion. Sports Health. 2015;7(4):341-345. doi:10.1177/19417381155 71508 17. Koo TK, Li MY. A guideline of selecting and reporting intraclass correlation coefficients for reliability research. J Chiropr Med. 2016;15(2):155-163. doi:10.1016/j.jcm.2016.02.012 18. Hinton-Bayre AD, Geffen GM, Geffen LB, Mcfarland KA, Frijs P. Concussion in contact sports: Reliable change indices of impairment and recovery. J Clin Exp Neuropsychol. 1999;21(1):70-86. doi:10.1076/ jcen.21.1.70.945 19. Manaseer TS, Whittaker JL, Isaac C, Schneider K, Roberts MR, Gross DP. The reliability of clinical balance tests under single-task and dual-task testing paradigms in uninjured active youth and young adults. Int J Sports Phys Ther. 2020;15(4):487. doi:10.2 6603/ijspt20200487 20. Luoto T, Parkkari J, Seppänen A, Palola V, Tuominen M, Iverson GL. Reliability of the Sport Concussion Assessment Tool 5 baseline testing: A 2-week test-retest study. 2019;(March):2-3. doi:10.26 226/MORRESSIER.5C7E3E2129D813000CB41BA0 21. Snedden TR, Brooks MA, Hetzel S, McGuine T. Normative values of the Sport Concussion Assessment Tool 3 (SCAT3) in high school athletes.

Clin J Sport Med. 2017;27(5):462-467. doi:10.1097/JS M.0000000000000389 22. Gaudet CE, Konin J, Faust D. Immediate Postconcussion and Cognitive Testing: Ceiling effects, reliability, and implications for interpretation. Arch Clin Neuropsychol. 2021;36(4):561-569. doi:10.1093/A RCLIN/ACAA074

International Journal of Sports Physical Therapy

Bullock GS, Thigpen CA, Collins GS, et al. Machine Learning Does Not Improve Humeral Torsion Prediction Compared to Regression in Baseball Pitchers. IJSPT. 2022;17(3):390-399.

Original Research

Machine Learning Does Not Improve Humeral Torsion Prediction Compared to Regression in Baseball Pitchers a

Garrett S Bullock 1 , Charles A Thigpen 2, Gary S Collins 3, Nigel K Arden 1, Thomas K Noonan 4, Michael J Kissenberth 5, Ellen Shanley 2 1

Department of Orthopaedic Surgery, Wake Forest School of Medicine; Centre for Sport, Exercise and Osteoarthritis Research Versus Arthritis, University of Oxford, 2 University of South Carolina Center for Rehabilitation and Reconstruction Sciences; ATI Physical Therapy, 3 Centre for Statistics in Medicine, Nuffield Department of Orthopaedics, Rheumatology, and Musculoskeletal Sciences, University of Oxford; Oxford University Hospitals NHS Foundation Trust, 4 Department of Orthopaedic Surgery, University of Colorado School of Medicine; University of Colorado Health, Steadman Hawkins Clinic, 5 Steadman Hawkins Clinic of the Carolinas Keywords: humeral retrotorsion, deep learning, gradient boosting machines, non-linear transformations https://doi.org/10.26603/001c.32380

International Journal of Sports Physical Therapy Vol. 17, Issue 3, 2022

Background Humeral torsion is an important osseous adaptation in throwing athletes that can contribute to arm injuries. Currently there are no cheap and easy to use clinical tools to measure humeral torsion, inhibiting clinical assessment. Models with low error and “good” calibration slope may be helpful for prediction.

Hypothesis/Purpose To develop prediction models using a range of machine learning methods to predict humeral torsion in professional baseball pitchers and compare these models to a previously developed regression-based prediction model.

Study Design Prospective cohort

Methods An eleven-year professional baseball cohort was recruited from 2009-2019. Age, arm dominance, injury history, and continent of origin were collected as well as preseason shoulder external and internal rotation, horizontal adduction passive range of motion, and humeral torsion were collected each season. Regression and machine learning models were developed to predict humeral torsion followed by internal validation with 10-fold cross validation. Root mean square error (RMSE), which is reported in degrees (°) and calibration slope (agreement of predicted and actual outcome; best = 1.00) were assessed.

Results Four hundred and seven pitchers (Age: 23.2 +/-2.4 years, body mass index: 25.1 +/-2.3 km/ m2, Left-Handed: 17%) participated. Regression model RMSE was 12° and calibration was 1.00 (95% CI: 0.94, 1.06). Random Forest RMSE was 9° and calibration was 1.33 (95% CI: 1.29, 1.37). Gradient boosting machine RMSE was 9° and calibration was 1.09 (95% CI: 1.04, 1.14). Support vector machine RMSE was 10° and calibration was 1.13 (95% CI: 1.08, 1.18). Artificial neural network RMSE was 15° and calibration was 1.03 (95% CI: 0.97, 1.09).

Conclusion This is the first study to show that machine learning models do not improve baseball

a

Corresponding Author: Garrett Bullock, PT, DPT, DPhil Department of Orthopaedic Surgery and Rehabilitation Wake Forest School of Medicine email: gbllock@wakehealth.edu

Machine Learning Does Not Improve Humeral Torsion Prediction Compared to Regression in Baseball Pitchers

humeral torsion prediction compared to a traditional regression model. While machine learning models demonstrated improved RMSE compared to the regression, the machine learning models displayed poorer calibration compared to regression. Based on these results it is recommended to use a simple equation from a statistical model which can be quickly and efficiently integrated within a clinical setting.

Levels of Evidence 2

INTRODUCTION

models to a traditional regression-based prediction model.

Baseball throwing generates high velocity and forces through the arm,1–3 which contribute to unique osseous and soft tissue glenohumeral joint adaptations.4,5 These shoulder adaptations contribute to changes in shoulder range of motion, specifically to increased external rotation and decreased internal rotation in comparison to the nondominant arm.6 These unique throwing specific shoulder adaptations have been associated with arm injuries in baseball players.4,7 While soft tissue adaptations affect throwing specific shoulder range of motion,8 the underlying osseous structural transformations also contribute to throwing shoulder range of motion.9 These osseous shoulder structural adaptations are termed humeral torsion (HT). HT is measured through the line that bisects the humeral head articular surface and the transepicondylar axis.10 During youth and adolescence, the high humeral forces generated during pitching effect osseous growth and development, contributing to the diminution of humeral anatomical neck and head antetorsion that occurs with aging.11 These structural adaptations are important for throwing development12; however, they are also linked to arm injury risk.9 Within clinical practice, HT can be calculated indirectly through ultrasonic methods.5 However, this equipment is expensive, preventing many clinics and clinicians from assessing HT, hindering clinical examination. One way to arrive at clinical measures is through prediction modelling.13 Statistical prediction modelling uses traditional regression based methods to obtain a risk or probability.14 More recently, machine learning algorithms (such as random forests, gradient boosting machines, support vector machines, and neural networks) have been purported to offer increased flexibility to capture nonlinearities and higher order interactions.15,16 Machine learning uses general purpose algorithms that identify data patterns, using minimal data assumptions,17 and are being increasingly used in the medical setting.18,19 As a result, there is widespread interest in exploring the usefulness of modern machine learning methods for increasing prediction accuracy compared to more regression based statistical approaches.20 Humeral torsion is an important osseous adaptation in throwing athletes that can contribute to arm injuries.9 Machine learning algorithms offer an alternative strategy to predict outcomes in data with high complexity. Comparing and contrasting regression based statistical and machine learning approaches can help identify the most promising prediction model to be implemented in the clinical setting.

Therefore, the purpose of this study was to develop prediction models using a range of machine learning methods to predict professional baseball pitcher HT and compare these

METHODS STUDY DESIGN

A prospective cohort study was conducted from 2009 to 2019 on Minor League pitchers in one Major League Baseball organization. Only preseason data were utilized in this study and pitchers were only included once within the dataset. Participants were excluded from the study if 1) the athlete played a primary position other than pitcher, 2) they were being treated for a shoulder or elbow injury at the beginning of the season, or 3) they were unable to participate on the first day of practice because of upper extremity injury. Prior to data collection, all participants were informed of the risks and benefits of study participation and participants gave verbal and written consent to study participation. The PRISMA health system Institutional Review Board approved this study.

DATA COLLECTION

Before the beginning of the season, all baseball players were questioned for arm dominance, prior baseball experience, injury history, and position(s) played. Participants were then examined for current height (cm) and mass (kg). Participants were then examined for passive shoulder PROM and HT. Shoulder PROM testing was randomized for each participant, and examiners were blinded to hand dominance throughout the study.21 Two examiners performed all measurements for the entire cohort.

PREDICTORS

Predictors included player demographics (age, hand dominance, previous baseball participation, injury history, position played, and continent of origin), shoulder PROM, and injury history. Shoulder ROM and injury history are further described below.

SHOULDER RANGE OF MOTION

All shoulder PROM (external rotation [ER], internal rotation [IR] and horizontal adduction [HA]) was measured supine on a standardized plinth table by two examiners using a digital inclinometer per previously described methods.22–25 Two trials were performed per shoulder measurement, and the average of these two trials was used for data analysis.

Shoulder PROM was calculated on 10 participants prior to data collection for the two examiners. Shoulder PROM intra- and inter-rater reliability was excellent for ER and IR (ICC(2,1) and ICC (2,k) = 0.92-0.99) and HA (ICC(2,1) and ICC

International Journal of Sports Physical Therapy

Machine Learning Does Not Improve Humeral Torsion Prediction Compared to Regression in Baseball Pitchers

(2,k)

= 0.92-0.99), and the standard error of measurement was 2°-4° for shoulder ER, IR, and HA.

model for individual prognosis or diagnosis (TRIPOD) were followed for all model development.28

INJURY HISTORY

STATISTICAL MODEL

A shoulder or elbow injury was defined as any traumatic or overuse injury that occurred during any baseball team sponsored activity (from the beginning of preseason through the last post season game) to any muscle, joint, tendon, ligament, bone, or nerve that required medical attention.26 Injuries were further designated by dominant and nondominant arm. An independent examiner, blinded to physical measurements, reviewed medical documents to determine the diagnosis, duration of treatment, and the time to clearance for return to full sport participation.

A linear regression model to predict HT was developed, using predictor variables including: Predictor variables included: (1) age,29 (2) arm dominance (Left or Right handed),30,31 (3) shoulder IR,9 (4) shoulder ER,9 (5) shoulder HA,32 (6) continent of origin (North America or Latin America),33 (7) previous shoulder or elbow injury.34 Linearity was not assumed; as a result, continuous predictors were assessed for non-linearity with restricted cubic splines. Restricted cubic splines were calculated with three, four, and five knots with the R package rms. All continuous predictors demonstrated a linear relationship to HT. Interactions were also analyzed, with no predictors observed to have an interaction relationship with HT. Internal validation was performed with a 10-fold cross validation. Internal validation is performed to reduce optimism bias, as models are overly optimistic on the developed dataset.35,36 The R package caret was used to performed cross validation.

Four machine learning models (Random Forest, Gradient Boosting Machine [GBM], Support Vector Machine Regression [SVM], and Artificial Neural Networks [ANN]) were developed to predict HT using an iterative hyperparameter tuning process. Hyperparamter tuning consisted of using a grid search process. All machine learning models incorporated all the same predictors used to develop the linear regression model. The R packages randomForest, gbm, kernlab and e1071, and neuralnet were used for random forest, GBM, SVM, and ANN models. For full description of the machine learning models, tuning variables, final hyperparameters, and complete code, please refer to the Appendix. Following model development, all machine learning models, besides ANN, were internally validated with a 10-fold cross validation. The ANN model was replicated 100 times.

Model performance was assessed with root mean square error (RMSE), calibration and R2. Root mean square error is the error of the model reported in outcome units (i.e., degrees), with lower error demonstrating improved prediction performance. Calibration is the agreement of predicted and actual outcome (i.e., HT), with a calibration of 1 equalling best calibration.35,36

OUTCOME HUMERAL TORSION (HT)

Dominant HT was measured supine on a standardized plinth table with the shoulder in 90° of abduction. One examiner, using a 5 mHz ultrasonographic transducer (Sonosite Inc, Bothell, WA, USA) measured HT. The ultrasonographic transducer was placed level, confirmed with a bubble level, on the anterior shoulder, perpendicular to the long axis of the humerus. The humerus was then rotated until the apexes of the greater and lesser tubercles could be visualized parallel to the horizontal plane. The second examiner placed a digital inclinometer on the ulnar side of the forearm, measuring the forearm inclination angle with respect to the horizontal, which indirectly measures HT.5 Two trials were performed per HT measurement, and the average of these two trials was used for data analysis. HT reliability was calculated on 10 participants prior to data collection for the two examiners. Humeral torsion intra- and inter-rater reliability was excellent (ICC(2,1) and ICC (2,k) 0.93-0.97) and the standard error of measure was 2-4°.

STATISTICAL ANALYSES

All data were investigated for missingness prior to analyses, using the R package naniar. Missing data were low (Shoulder ROM: 3%, age: <1%, HT: 2%), thus complete case analyses were performed. Descriptive statistics were reported by mean (standard deviation), median (interquartile range), and frequencies and percentages for categorical variables.

SAMPLE SIZE CONSIDERATIONS

For the statistical modelling, an a priori sample size calculation was performed with the R package pmsampsize.27 Referencing a previous meta-analysis and meta-regression,9 mean HT was 28°, standard deviation was 4°, and R2 was 0.38. The a priori statistical regression prediction model was determined to incorporate ten degrees of freedom (i.e., parameters). As a result, a total of 246 baseball players were required to reduce the risk of overfitting.

MODEL DEVELOPMENT

RESULTS A total of 407 pitchers with a mean age of 23.2 years (sd = 2.4), BMI of 25.1 km/m2 (sd = 2.3) were eligible and included (Table 1).

GENERALIZED LINEAR REGRESSION MODEL

Final model RMSE was 12°, calibration was 1.00 (95% CI: 0.94, 1.06); Table 2; Figure 1A), and R2 was 0.41. The mean distribution of the final model linear predictors was 17°, the standard deviation was 10°, the minimum was -19°, and the maximum was 48°. For full model report, please refer to the Appendix.

The transparent reporting of a multivariable prediction

International Journal of Sports Physical Therapy

Machine Learning Does Not Improve Humeral Torsion Prediction Compared to Regression in Baseball Pitchers

Table 1. Pitcher demographics, presented as mean (SD) or percentage.

Professional Pitchers (n = 407) Age (years)

23.2 (2.4)

Hand Dominance Left Right

17% 83%

BMI (kg/m2)

25.1 (2.3)

Arm Injury History Prevalence

43%

Dominant Humeral Torsion (°)

8.2 (12.7)

Dominant Internal Rotation (°)

35.2 (11.4)

Dominant External Rotation (°)

126.9 (10.9)

Dominant Horizontal Adduction (°)

-1.4 (13)

Nondominant Humeral Torsion (°)

25.7 (13.0)

Nondominant Internal Rotation (°)

48.1 (10.6)

Nondominant External Rotation (°)

118.3 (11.6)

Nondominant Horizontal Adduction (°)

16.5 (14.6)

Table 2. Statistical and Machine Prediction Model Performance Prediction Model

Root Mean Square Error

Calibration Slope

Generalized Linear Regression

12°

1.00 (95% CI: 0.94, 1.06)

Random Forest

9°

1.33 (95%CI: 1.29, 1.37)

Gradient Boosting Machine

9°

1.09 (95% CI: 1.04, 1.14)

Support Vector Machine Regression

10°

1.13 (95% CI: 1.08, 1.18)

Artificial Neural Network

15°

1.03 (95% CI: 0.97, 1.09)

MACHINE LEARNING MODELS

The random forest and GBM demonstrated the best RMSE (Table 2). The random forest demonstrated the worst calibration (Table 2) and the ANN demonstrated the best calibration (Table 2; Figure 1B). The mean distribution of the final model linear predictors was 16° to 17°, the standard deviation was ranged from 9° to 10°, the minimum ranged from -2°1 to -11°, and the maximum was ranged from 44° to 52°. For each calibration plot and a full pictorial description of the final ANN architecture, please refer to the Appendix.

DISCUSSION The machine learning models, besides ANN, demonstrated improved RMSE, compared to the statistical prediction model. Interestingly, the random forest and GBM RMSE difference compared to the linear regression model was similar to the HT standard error of measure (2-4°). However, all machine learning models demonstrated poor calibration compared to the linear regression prediction model. All prediction models demonstrated similar mean and variance calculations for predicted values. These findings suggest

that prediction model performance should be evaluated through multiple performance metrics.

The machine learning models demonstrated decreased RMSE compared to the linear regression model. RMSE reports the average prediction model error in the units of the outcome of interest, which in this case is degrees of HT.37 This allows for a clinically pertinent and interpretable comparison of model performance. The random forest and GBM demonstrated decreased RMSE similar to the reliability HT standard error of measure, which may demonstrate a clinically significant difference. Both the random forest and GBM methods employ ensemble methods to generate prediction models.38,39 Ensemble methods have been shown to increase overall prediction precision due to the meta-aggregation of multiple models, allowing for increased generalizability in highly complex data.40 Further, the SVM model demonstrated a RMSE difference just below to the standard error of measure in comparison to the statistical model.

SVMs utilize spatial kernel-based methods to inform predictions. Due to the individuality affecting HT development,12 the visual hyperplane demarcation methods used

by SVM may generate improved HT prediction.

Although ML methods demonstrated decreased RMSE, calibration was poor. All machine learning methods demon-

International Journal of Sports Physical Therapy

Machine Learning Does Not Improve Humeral Torsion Prediction Compared to Regression in Baseball Pitchers

strated worse calibration compared to the statistical model, with the ANN a three-point slope difference. Calibration assesses the prediction outcome versus the actual outcome, and is important in understanding the accuracy of predictions.41 Over calibration has been reported as potentially harmful in the clinical setting, with miscalibration above 5% potentially affecting clinical decisions.42 These worse calibration performing machine learning methods, besides the ANN model, demonstrated a calibration slope in excess of 1.09, with the random forest model having a calibration slope of 1.33. Upon visual inspection of the calibration plots, all three models had significant demarcation at both tails of the calibration slope. These calibration discrepancies may be due to the biological volatility of individual outliers. Baseball players may have different genetic, environmental, and overall baseball loading factors, which all contribute to HT. Due to the algorithmic nature of machine learning, these outliers may have indiscriminately affected overall calibration. However, the ANN model had similar calibration compared to the statistical mode. ANN’s are high performers in predictions involving complex and multiple interaction data.43 As stated above, the complex issue individual variability, may allow for ANN’s to demonstrate high calibration performance.

All machine learning and linear regression models demonstrated similar mean and variance of predicted outcomes. These predictions are greater than those reported in a previous meta-analysis.9 While all models demonstrated similar prediction HT outcomes, there were distinct differences in model performance parameters. These findings highlight that model performance should be evaluated on multiple parameters, and not just on one specific performance finding. Clinicians need to integrate multiple prediction model performance outcomes, including discrimination, calibration, and model error, where appropriate, when evaluating the efficacy of a prediction model.41 These findings warrant future research. External validation is required to evaluate the generalizability of these models. HT development may be influenced by the volume and speed of throwing.12 Further research is needed to decipher if incorporating lifetime baseball exposure and throwing velocity could aid in prediction model precision. Other genetic factors such as collagen phenotype and familial history may also affect HT. Incorporating these predictors would be beneficial in evaluating the prediction ability of these models. Finally, the clinical utility of these prediction models needs to be evaluated. Understanding how these models may affect clinical practice and decisions in comparison to standard evidence-based practice is needed.

CLINICAL IMPLICATIONS

Model RMSE ranged from 9° to 15° for all models, with the statistical regression model RMSE was 12. The HT standard error of measure in professional pitchers is 2 degrees.44 Professional pitchers with 5 degrees HT difference between their throwing and non-throwing arms has been previously determined to pose greater risk for arm injury.45 As RMSE was reported in degrees, the RMSE may be beyond the clinically important error, and affect pitching arm risk assessment.5 However, arm injury examination encompasses mul-

Figure 1. Calibration Plot for Regression (A) and Artificial Neural Network (B) The blue line depicts perfect calibration, while the red line reports actual calibration.

tiple factors,4,46,47 and this HT prediction model could be used in conjunction of multiple other clinical tests and measures in order to prescribe a personalized injury mitigation program.

PRACTICAL EXAMPLE

To aid in clinical applicability an example is described. As the machine learning models did not improve HT prediction, the ease of use and interpretability of the statistical model is recommended for clinical implementation. The statistical model is calculated through a mathematical equation to predict HT. This equation can be inputted into a standardized Excel or other basic computer program. For example, consider a 22-year-old right-handed pitcher from North America, with 35 degrees of IR, 103 degrees of ER, and 2 degrees of HA. During the clinical interview, the pitcher did not report any current or prior arm injuries. Using the equation reported in the supplement: 33.01 (The Intercept) + 22*0.15 (Age) – 1.83 (Right-Handed) + 35*0.37 (IR) - 103*0.30 (ER) + 2*0.31 (HA) + 0 (North America) + 0 (No Injury History) the model predicts this pitcher’s right HT is 18 degrees.48

International Journal of Sports Physical Therapy

Machine Learning Does Not Improve Humeral Torsion Prediction Compared to Regression in Baseball Pitchers

STRENGTHS AND POTENTIAL LIMITATIONS

This study utilized a large sample of professional baseball pitchers that exceeded the a priori required sample size which increases the precision of these results. Multiple models were performed, incorporating both machine learning and statistical prediction model techniques, which increases the comparability of these findings. Internal validation was performed on all findings, allowing for a realistic optimism corrected model estimate, increasing the validity of these results. External validation was not performed on these models, decreasing the generalizability of these models. While many machine learning methods suggest splitting data into training and testing sets,49,50 this decreases the power and precision of these models.51,52 While this data met the a priori sample size calculations for linear regression, this sample size calculation may be too small for machine learning models.53 Further, these data did not allow for a training and testing split to maintain proper power. Previous authors51,52,54 have recommended to utilize all data during model development, and use robust internal validation methods to correct for optimism. As a result, cross-validation was used for internal validation on these prediction models.

statistical model. Machine learning did not improve HT prediction in professional baseball players compared to a traditional statistical model. The root mean square error of all models was greater than the standard error of measure and clinically important difference, which may hinder the clinical usefulness of these models. It is recommended that clinicians use the statistical model in practice in conjunction with other examination factors, as this model provides an easy-to-use equation, that can quickly and efficiency be integrated within a clinical setting. Future research is needed to evaluate if environmental and genetic factors can improve HT prediction.

DECLARATIONS OF INTEREST

The authors declare no conflicts of interest.

FUNDING

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Submitted: September 14, 2021 CDT, Accepted: December 20,

CONCLUSIONS

Machine learning models demonstrated improved root mean square error and poorer calibration compared to the

2021 CDT

This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CCBY-NC-4.0). View this license’s legal deed at https://creativecommons.org/licenses/by-nc/4.0 and legal code at https://creativecommons.org/licenses/by-nc/4.0/legalcode for more information.

International Journal of Sports Physical Therapy

Machine Learning Does Not Improve Humeral Torsion Prediction Compared to Regression in Baseball Pitchers

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Machine Learning Does Not Improve Humeral Torsion Prediction Compared to Regression in Baseball Pitchers

SUPPLEMENTARY MATERIALS Appendix 1 Download: https://ijspt.scholasticahq.com/article/32380-machine-learning-does-not-improve-humeral-torsionprediction-compared-to-regression-in-baseball-pitchers/attachment/81315.docx?auth_token=aV-iOWv4B1Z_VbB7F4o

International Journal of Sports Physical Therapy

Fukunaga T, Fedge C, Tyler T, et al. Band Pull-Apart Exercise: Effects of Movement Direction and Hand Position on Shoulder Muscle Activity. IJSPT. 2022;17(3):400-408.

Original Research

Band Pull-Apart Exercise: Effects of Movement Direction and Hand Position on Shoulder Muscle Activity a

Takumi Fukunaga, DPT, SCS, ATC, CSCS 1 , Connor Fedge, DPT, MS, CSCS 1, Timothy Tyler, PT, ATC 1, Michael Mullaney, DPT, SCS 1, Brandon Schmitt, DPT, ATC 1, Karl Orishimo, MS, CSCS 1, Malachy McHugh, PhD 1, Stephen Nicholas, MD 1 1

Nicholas Institute of Sports Medicine and Athletic Trauma

Keywords: shoulder, emg, rehabilitation https://doi.org/10.26603/001c.33026

International Journal of Sports Physical Therapy Vol. 17, Issue 3, 2022

Background/Purpose The Elastic band pull-apart exercise is commonly used in rehabilitation. It involves pulling an elastic resistance band with both hands in horizontal abduction or diagonal arm movements. The extent of muscle activation during this exercise is unknown. The purpose of this study was to measure the electromyographic (EMG) activity of shoulder-girdle muscles during the pull-apart exercise using resistance bands and to determine the effects of arm position and movement direction on shoulder-girdle muscle activity.

Materials/Methods Surface EMG activity was measured on the infraspinatus, upper trapezius, middle trapezius, lower trapezius and posterior deltoid of the dominant shoulder. After measurement of maximal voluntary contraction (MVC) for each muscle, subjects performed the band pull-apart exercise in three hand positions (palm up, neutral, palm down) and three movement directions (diagonal up, horizontal, diagonal down). Elastic band resistance was chosen to elicit moderate exertion (5/10 on the Borg CR10 scale). The order of the exercises was randomized and three repetitions of each exercise were performed. Mean peak EMG activity in each muscle across the repetitions was calculated and expressed as a percentage of MVC. Peak normalized EMG activity in each muscle was compared in two-way (hand position x direction) repeated-measures ANOVA.

Results Data were collected from 10 healthy subjects (all males, age 36±12 years). Peak muscle activity ranged from 15.3% to 72.6% of MVC across muscles and exercise conditions.

There was a significant main effect of hand position for the infraspinatus and lower trapezius, where muscle activity was highest with the palm up hand position (p < 0.001), and for the upper trapezius and posterior deltoid, where muscle activity was highest with the palm down position (p-value range < 0.001-0.004). There was a significant main effect of movement direction, where the diagonal up direction demonstrated the highest muscle activity for the infraspinatus, upper trapezius, lower trapezius, and posterior deltoid (p-value range < 0.001-0.02).

Conclusion Altering hand position and movement direction during performance of an elastic band pull-apart exercise can affect magnitudes of shoulder-girdle muscle activity. Clinicians may alter a patient’s hand position and movement direction while performing the band pull-apart exercise in order to increase muscle activity in target muscles or diminish

a

Corresponding author: Takumi Fukunaga, DPT, SCS, ATC, CSCS Nicholas Institute of Sports Medicine and Athletic Trauma, Lenox Hill Hospital 210 East 64th Street, 5th Floor, New York, NY 10065 USA E-mail: tak@nismat.org

Band Pull-Apart Exercise: Effects of Movement Direction and Hand Position on Shoulder Muscle Activity

muscle activity in other muscles.

Level of Evidence 2b

INTRODUCTION Glenohumeral joint pain is widely prevalent in the general population and exerts a large burden on society.1,2 One reason for the high prevalence of shoulder pathology is related to its anatomical structure. The glenohumeral joint’s osseous anatomy provides little stability3,4 and it is well established that the glenohumeral joint is reliant on muscular support for dynamic stability.4–7 Specifically, the muscles of the rotator cuff (RTC), the supraspinatus, infraspinatus, teres minor, and subscapularis, are vital to collectively compress the humeral head into the glenoid for stabilization.4–9 In order for the RTC muscles to function properly, there must be adequate scapular stabilization,5,6,10,11 which is accomplished by muscular contributions from the periscapular muscles.4,12,13 Deficiencies in periscapular muscle function and scapular motion have been detected in patients with shoulder pathology.5,6,14–21 Therefore, both RTC and periscapular strengthening exercises are established interventions for patients with shoulder pathology.6,11,20,22,23 Since muscular imbalance is a potential cause for shoulder pathology, it has been suggested that exercises should aim to preferentially target the middle trapezius, lower trapezius, and posterior RTC, with lower contributions from the upper trapezius and deltoid muscles.14,16,19,24–26 Commonly performed strengthening exercises targeted at periscapular and RTC muscles include shoulder horizontal abduction27 and diagonal arm movements.6,8,28,29 These exercises are often performed with dumbbell or cable resistance; however, equipment such as dumbbells and a cable column machine may not be readily available for all individuals during home exercise. When these motions are performed with an elastic resistance band, with both hands in horizontal abduction or diagonal arm movements they are often referred to as band pull-apart exercises. Elastic band is an extremely convenient tool for exercise, as it is portable and the patient does not require any additional equipment. Although clinicians are widely aware of the utility of these band pull-apart exercises, no information regarding the extent of shoulder-girdle muscle activity during these exercises is available to guide clinical decision making.

Band pull-apart exercises can be performed with varying degrees of arm rotation. Previous authors have demonstrated that changes in glenohumeral internal and external rotation alter scapular and RTC muscle activity in a number of shoulder exercises utilizing electromyography (EMG).24–26,30–35 These exercises are frequently performed in the prone position,11,30 however, a standing position is more functional, and due to the muscular attachments on the scapula, performing strengthening exercises with hip and trunk extension may be beneficial,6,8 suggesting advantages of the resistance band pull-apart exercise. The effects of movement direction and arm rotation position on shoulder muscle activity during performance of the pull-apart ex-

ercise in standing are currently unknown. Therefore, the purpose of this study was to measure the EMG activity of shoulder-girdle muscles during the pull-apart exercise using resistance bands and to determine the effects of arm position and movement direction on shoulder-girdle muscle activity.

METHODS PARTICIPANTS

A sample of convenience was recruited from the local community. Potential subjects were included if they were healthy at the time of testing and did not have any history of shoulder pathology. Before participation, each subject provided written informed consent in accordance with institutional review board regulations.

PROCEDURES

A 16-channel BTS FREEEMG 300 system, CMRR: >110 dB at 50–60 Hz; input impedance: >10 GΩ (BTS Bioengineering, Milan, Italy) was utilized for EMG data collection during this study.

Previously described anatomical landmarks for surface EMG placement were identified for five muscles of interest: upper trapezius, posterior deltoid, infraspinatus, middle trapezius and lower trapezius.36,37 The subject’s exposed skin was prepared by shaving, cleaning, and lightly abrading. Disposable Ag/AgCl passive dual surface EMG electrodes (2.0 cm interelectrode distance; Noraxon, Scottsdale, AZ) were placed on the identified landmarks on the right shoulder of each subject (Figure 1). Muscle activity was sampled at 1000 Hz. Once surface electrodes were attached to the subject, a maximum voluntary contraction (MVC) was performed in the previously described manual muscle testing (MMT) position for each muscle.38 A single tester, a board-certified sports physical therapist with over 20 years of clinical experience, provided MMT resistance for all subjects. One trial lasting five seconds was performed for each MMT for each muscle tested. Once peak activity from the MVC trials were calculated, it was verified that the highest peak activity for a muscle occurred during its intended MVC and not during the MVC intended for another muscle.

Subjects then determined which resistance level they would use by performing shoulder horizontal abduction with a neutral grip for five repetitions while holding a resistance band. Resistance level was standardized across subjects to self-reported moderate exertion (5/10 on Borg CR10 Scale).39 As the tension of a resistance band is affected by the amount of elongation, subjects were instructed to hold the band without slack or tension at the beginning of each exercise movement.

A total of nine exercise conditions existed between the variations of hand position (palm up, neutral, palm down) and movement direction (diagonal up, horizontal, diagonal

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Band Pull-Apart Exercise: Effects of Movement Direction and Hand Position on Shoulder Muscle Activity

Table 1. Mean normalized peak muscle activity during band pull-apart exercise for all muscles, movement directions, and glenohumeral rotation positions tested.

Direction:

Diagonal Up

Horizontal

Diagonal Down

Hand Position:

Palm Up

Neutral

Palm Down

Palm Up

Neutral

Palm Down

Palm Up

Neutral

Palm Down

Infraspinatus

49.5 ± 29.1

41.6 ± 24.5

40.7 ± 28.5

42.5 ± 20.3

35.0 ± 20.3

31.4 ± 20.7

36.3 ± 15.7

25.7 ± 10.2

23.0 ± 10.0

Upper Trapezius

60.8 ± 24.5

64.3 ± 25.0

72.6 ± 39.3

44.7 ± 21.5

53.0 ± 26.5

59.6 ± 26.3

26.4 ± 14.2

28.9 ± 12.7

33.0 ± 14.1

Middle Trapezius

62.9 ± 32.1

58.4 ± 24.7

63.4 ± 27.2

56.0 ± 25.0

55.8 ± 25.0

61.5 ± 24.8

32.0 ± 10.9

29.9 ± 9.4

28.0 ± 9.9

Lower Trapezius

62.4 ± 28.3

52.2 ± 24.9

47.8 ± 23.8

52.4 ± 22.4

39.5 ± 15.1

36.9 ± 15.4

25.2 ± 10.5

17.1 ± 7.7

15.3 ± 7.7

Posterior Deltoid

42.8 ± 31.2

51.2 ± 40.5

62.9 ± 46.3

33.2 ± 24.4

38.3 ± 19.6

48.3 ± 24.2

29.4 ± 20.1

31.0 ± 15.1

34.6 ± 16.9

All values expressed as % maximal voluntary contraction ± SD. See results section for significant differences in muscle activation among movement directions and glenohumeral rotation positions.

down) (Figures 2-4). Order of exercise condition was randomized for each subject using a random number generator.

Three repetitions of each exercise condition were performed. Pace of movement was standardized to three seconds for each phase of movement (i.e., concentric and eccentric) guided by a metronome set to 20 beats per minute.

DATA PROCESSING

Electromyographic data were processed and analyzed using previously described methods.40 All EMG data were highpass filtered at 10 Hz, full-wave rectified and smoothed using an RMS filter with a 100-ms window. For each muscle, the peak EMG activation level was identified during each exercise. The mean activation level of each muscle during a window from 250 milliseconds before the peak to 250 milliseconds after the peak was calculated. This was then averaged over the three repetitions for each exercise and each muscle. This mean peak EMG activity was normalized to the maximum EMG activity recorded during maximal voluntary isometric contraction (MVIC) and expressed as a percent.

STATISTICAL ANALYSIS

Descriptive statistics were calculated for mean normalized peak EMG activity for each muscle and each exercise condition. Shapiro-Wilk test for normal distribution of the data and Mauchly’s test for sphericity were conducted to confirm that assumptions were met for conducting a parametric test for these data. For each muscle, mean normalized peak EMG activity was compared across exercise conditions using twoway (hand position x movement direction) repeated-measures ANOVA. If a significant interaction or main effect was found with the ANOVA, post-hoc simple main effects or pairwise comparisons, respectively, was performed. Where a main effect was found for either hand position or direction, post-hoc pairwise comparisons of marginal means were performed with a Bonferroni correction, in which p values for the pairwise comparisons were adjusted by the number of pairwise comparisons performed per main effect

Figure 1. Electrode placement for EMG: (A) upper trapezius, (C) posterior deltoid, (D) infraspinatus, (F) middle trapezius, (G) lower trapezius, (B) and (E) were not used for analysis.

per muscle. Familywise significance level was set at p=0.05.

All statistical analyses were performed using IBM SPSS Statistics 25 (IBM Corp, Armonk, NY).

RESULTS Ten male subjects (age 36 ± 12 years) volunteered to be included in this study. Mean normalized peak muscle activity ranged from 15.3% to 72.6% of MVC across muscles and exercise conditions (Table 1). No significant interaction effect was found between hand position and movement direction on mean normalized peak muscle activity in any of the muscles analyzed (p-value range 0.18-0.85).

There was a significant main effect of hand position on infraspinatus activity (p<0.001), where the palm up position

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Band Pull-Apart Exercise: Effects of Movement Direction and Hand Position on Shoulder Muscle Activity

Figure 2. Palm up hand position: (A) diagonal up, (B) horizontal, (C) diagonal down, named by the dominant upper extremity, in this case, the right upper extremity.

Figure 3. Neutral hand position: (A) diagonal up, (B) horizontal, (C) diagonal down.

Figure 4. Palm down hand position: (A) diagonal up, (B) horizontal, (C) diagonal down.

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Band Pull-Apart Exercise: Effects of Movement Direction and Hand Position on Shoulder Muscle Activity

elicited 11.1% higher activity compared to palm down (p=0.029) and 8.7% higher activity compared to neutral position (p=0.031). There was also a significant main effect of movement direction (p=0.011), however, post-hoc pairwise comparisons did not yield any significant differences.

Upper trapezius activity showed a significant main effect of hand position (p=0.004), where the palm down position elicited 6.3% higher activity compared to the neutral position (p=0.036). A significant main effect of movement direction was also found (p<0.001), where the highest activity was in the diagonal up direction (mean difference vs. diagonal down 36.4%, p=0.003; mean difference vs. horizontal 13.5%, p=0.02), followed by horizontal (mean difference vs. diagonal down 23.0%, p=0.005).

Middle trapezius activity was significantly affected by movement direction (p<0.001), where the normalized activity was 31.6% higher in the diagonal up direction (p=0.003) and 27.8% higher in the horizontal direction (p=0.017) compared to the diagonal down direction. Hand position did not have a significant effect on middle trapezius activity.

There was a significant main effect of hand position on lower trapezius activity (p<0.001), where palm up position elicited 13.3% higher activity than palm down position (p=0.001) and 10.4% higher activity than neutral position (p=0.011). Movement direction also had a significant effect on lower trapezius activity, where the highest activity was seen in the diagonal up direction (mean difference vs. diagonal down 34.9%, p=0.003; mean difference vs. horizontal 11.2%, p=0.019), followed by horizontal (mean difference vs. diagonal down 23.7%, p=0.004).

Posterior deltoid activity showed a main effect of hand position (p=0.001), where the palm down position elicited 13.5% higher activity compared to the palm up position (p=0.02) and 8.4% higher activity compared to the neutral position (p=0.002). There was also a significant main effect of movement direction (p=0.02), however, post-hoc pairwise comparisons for the effect of movement direction did not show any significant differences.

DISCUSSION The principle finding of this research study was that the resistance band pull-apart exercise effectively recruited scapular and RTC muscles, demonstrated by mean peak muscle activity levels of 15% to 73% of MVC. The results also demonstrated that hand position and movement direction had significant effects on scapular and RTC muscle activity.

Horizontal abduction and diagonal movement patterns are common shoulder ans scapular strengthening exercises.6,8,27–29 Additionally, varying glenohumeral rotation has consistently demonstrated the ability to alter muscle activity during arm movements and exercises.24–26,30–35 The current research study adds to this body of evidence by showing that infraspinatus activity can be increased by using the palm up position over the neutral or palm down positions, and upper trapezius, middle trapezius, and lower trapezius activity can be increased by using the diagonal up direction over the horizontal or diagonal down directions.

The mean difference in muscle activity between the palm up and palm down positions was 11%, which exceeded pre-

viously reported minimally detectable change for surface EMG of infraspinatus (8.2% of MVC).41 Therefore, using the palm up hand position over the palm down position during the pull-apart exercise resulted in a significant and clinically meaningful increase in infraspinatus muscle activity.

There was a significant main effect of movement direction for the infraspinatus, upper trapezius, middle trapezius, lower trapezius, and posterior deltoid. Moreover, the diagonal up direction facilitated significantly higher muscle activity than one or both of the other movement directions for the upper trapezius, middle trapezius, and lower trapezius muscles. The diagonal up movement showing the highest shoulder-girdle muscle activity is understandable as the arm is moving against gravity, resulting in higher overall load when the same level of resistance band is used as the other movement directions.

The ability to facilitate or inhibit muscle activity during the pull-apart exercises by changing hand position and/or movement direction is desirable, as this enables a clinician to adjust and prescribe appropriate exercise load by adjusting these parameters. Exercises targeting shoulder-girdle muscles often aim to minimize upper trapezius and deltoid activity, and to increase lower trapezius and RTC activity for individuals that have shoulder pathology.14,16,19,24–26 Based on the results of this research study, activation of the infraspinatus may be maximized by performing the pullapart exercise in the palms-up hand position. This information could influence clinical decision making, as it may be useful to utilize the GH ER (palms up) grip during the pullapart exercises, to selectively maximize the infraspinatus and lower trapezius. Additionally, the findings that RTC and periscapular muscles can be activated to a high degree with a resistance band further demonstrates the convenience of this exercise apparatus.

There is concern about the palm down hand position, especially when combined with the diagonal up movement, as this may put the shoulder in position of glenohumeral internal rotation, which has been shown to decrease subacromial space42 and is considered a risk for pathologic impingement of the RTC.43 Therefore, the palm up hand position during the diagonal up movement may offer the maximal benefit for muscle recruitment while minimizing potential adverse effects of subacromial impingement. In cases where subacromial impingement or selective muscle activation is not of concern, all hand positions and movement angles may be used to maximize activation of all periscapular and rotator cuff muscles.

This research study has several limitations. A sample of convenience was used and only data from healthy male participants were collected. As patients with shoulder symptoms demonstrate alterations in their muscular activity,6,15,16 results of this study may not be generalizable to a patient population. Surface EMG is prone to signal crosstalk from surrounding musculature and surrounding noise.

The instrumentation and signal processing procedures used in this study were intended to suppress noise in the data, however, signal cross-talk cannot be completely eliminated with surface EMG. In addition, it was not possible to accurately measure supraspinatus activity via surface EMG due to the overlying upper trapezius muscle and since surface EMG signals are most impacted by motor units closest to

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Band Pull-Apart Exercise: Effects of Movement Direction and Hand Position on Shoulder Muscle Activity

the recording electrode.44 This was clearly a limitation of this research study as supraspinatus activity is of strong clinical interest in studying shoulder exercises. Future research could study the supraspinatus using fine-wire EMG. Finally, EMG data do not fully represent force production of the involved muscles, tension across tendons, or the training effects of the exercises. To provide a more robust support for the use of the pull-apart exercises, future studies are needed to show training effects and clinical outcomes in patients with shoulder pathology.

tivity for the upper trapezius, middle trapezius, and lower trapezius muscles. Additionally, the palm up hand position demonstrated increased levels of activation of the infraspinatus and lower trapezius, and decreased activity of the upper trapezius and posterior deltoid. Thus, the diagonal up motion, with the palm up hand position, may be most beneficial to maximize desirable levels of RTC and scapular muscle activation during the pull-apart exercise.

CONCLUSION

CONFLICTS OF INTEREST

The findings of the current study suggest that movement direction and hand position may alter level of muscle activity in the RTC and scapular muscles. The diagonal up movement demonstrated the highest levels of muscular ac-

The authors report no conflicts of interest related to this manuscript.

Submitted: August 19, 2021 CDT, Accepted: January 09, 2022 CDT

This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CCBY-NC-4.0). View this license’s legal deed at https://creativecommons.org/licenses/by-nc/4.0 and legal code at https://creativecommons.org/licenses/by-nc/4.0/legalcode for more information.

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34. Schoenfeld B, Sonmez RGT, Kolber MJ, Contreras B, Harris R, Ozen S. Effect of hand position on EMG activity of the posterior shoulder musculature during a horizontal abduction exercise. J Strength Cond Res. 2013;27(10):2644-2649. doi:10.1519/jsc.0b013e31828 1e1e9 35. Edwards PK, Ebert JR, Littlewood C, Ackland T, Wang A. A systematic review of electromyography studies in normal shoulders to inform postoperative rehabilitation following rotator cuff repair. J Orthop Sports Phys Ther. 2017;47(12):931-944. doi:10.2519/jo spt.2017.7271 36. Waite DL, Brookham RL, Dickerson CR. On the suitability of using surface electrode placements to estimate muscle activity of the rotator cuff as recorded by intramuscular electrodes. J Electromyogr Kinesiol. 2010;20(5):903-911. doi:10.1016/j.jelekin.20 09.10.003 37. Muscles SEftN-IAo. SENIAM Project. Accessed June 27, 2019. http://www.seniam.org 38. Kendall FP, Kendall McCreary E, Provance PG, Rodgers M, Romani W. Muscles: Testing and Function, with Posture and Pain. Philadelphia, PA: Wolters Kluwer Health; 2014.

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Kaizu Y, Oyama Y, Ishihara Y, Honma Y. Survey with Innovations to Increase Response Rate Reveals Low Compliance with Guidelines among Youth Baseball Coaches Including a Survey of Differences between Cities -. IJSPT. 2022;17(3):409-419.

Original Research

Survey with Innovations to Increase Response Rate Reveals Low Compliance with Guidelines among Youth Baseball Coaches Including a Survey of Differences between Cities Yoichi Kaizu, RPT, MSc 1

a

, Yuki Oyama, RPT, PhD 2, Yamato Ishihara, RPT 3, Yusuke Honma, RPT, MSc 2

1

Department of Rehabilitation Center, Hidaka Hospital, Takasaki, Gunma, Japan; Department of Rehabilitation Sciences, Gunma University Graduate School of Health Sciences, Maebashi, Gunma, Japan, 2 Department of Rehabilitation Center, Hidaka Rehabilitation Hospital, Takasaki, Gunma, Japan, 3 Department of Rehabilitation Center, Hidaka Hospital, Takasaki, Gunma, Japan Keywords: little league, coach, injury prevention, pitcher, non-respondent bias https://doi.org/10.26603/001c.32978

International Journal of Sports Physical Therapy Vol. 17, Issue 3, 2022

Background Compliance rates of youth baseball team coaches with guidelines regarding pitch count limits have been reported, but response rates from previous surveys have not been high, which may introduce substantial non-response bias. In addition, differences between cities in guideline compliance rates have remained unclear.

Purpose The aim of the present study was to obtain data on coach compliance with guidelines for pitch count limits with a high survey response rate. Secondary aims were to determine compliance with guidelines other than pitch count limits, and to determine whether differences in compliance exists between cities.

Methods A questionnaire was developed for coaches of youth baseball teams in Gunma to assess knowledge of and compliance with the Japan Softball Baseball Association’s recommendations for preventing injuries. In the preparation, distribution, and collection of the questionnaire, four strategies were applied to increase the response rate. The questionnaire surveyed basic descriptive information about the team and coach and coaches compliance with guidelines. Survey items were compared between compliant and non-compliant groups for pitch count limits, and by city.

Results Valid responses to the questionnaire were obtained from coaches of 58 of 62 teams surveyed for a response rate of 93.5%. Despite the fact that almost all coaches were aware of the recommendations regarding pitch count limits and felt these limits were needed, only 15.5% were compliant. For guidelines other than the pitch count limits, the recommended values were exceeded for practice time on holidays. Differences between cities were evident in the compliance rate with the pitch count limit, but no differences between cities in other items were observed.

Conclusion The results of this research revealed that compliance with pitch count limits in this sample of youth baseball coaches was much lower than previously reported. Differences between cities were identified in rates of compliance with pitch count limits. These

a

Corresponding author: Yoichi Kaizu RPT, M.Sc. 886 Nakao-machi, Takasaki, Gunma 370-0001, Japan Phone: +81 27-362-2005 FAX: +81 27-362-0217 E-mail: kaiduyoichi@yahoo.co.jp

Survey with Innovations to Increase Response Rate Reveals Low Compliance with Guidelines among Youth Baseball Coaches -...

results suggest a need to increase compliance rates with guidelines for pitch count limits and to address differences between cities.

Level of Evidence Cross-sectional survey study, 3b

INTRODUCTION Approximately one-third of Little League baseball players experience shoulder or elbow pain during the season.1 Of great concern is the high rate at which these young athletes sustain serious injuries that may require surgery.2 Guidelines have been issued in various countries to prevent injury,3,4 and compliance with these guidelines is reportedly effective in preventing the development of elbow pain.5 Bohne et al. found that 85% of youth baseball players were unaware of the guidelines and that 62% disagreed with “the more you throw, the more likely you are to get hurt”.6 Player perceptions may increase the risk of pitching injury, and environmental factors such as influence of caregivers and team coaches are also important. Caregivers also reported that 83% did not know that the guidelines existed.7 Compliance of coaches with guidelines regarding pitch count limits have been reported to be 56–73% in the United States,8,9 and 28.3% in Japan,10 indicating that coach compliance with guidelines is low in Japan. However, the response rate for these questionnaires ranged from 41.4% to 56%,8–10 which is comparable or slightly lower than the typical general response rate of 52.7% for surveys targeting individuals.11 As non-respondents show different psychological characteristics compared to respondents,12 a high number of non-respondents has been suggested to bias results towards reduced frequencies of problems.13 Coach compliance with guidelines may thus be lower than reported, and research that achieves a higher response rate is clearly desirable. Further, the guidelines3 refer to warm-up, cool-down, and practice days and time, but few reports have provided data on compliance with these guidelines.

Medical checks and awareness-raising activities have been undertaken by doctors and physiotherapists with the aim of improving coach compliance with guidelines and preventing injury to players.14 These activities are often carried out on a local authority or hospital basis. Differences between cities in coach compliance may thus occur depending on the status of these activities.

The aim of the present study was to obtain low nonresponse bias data on coach compliance with guidelines for pitch count limits with a high response rate. Secondary aims were to determine compliance with guidelines other than pitch count limits, and to determine whether differences in compliance exists between cities.

METHODS PARTICIPANTS AND DATA COLLECTION

This investigation comprised a cross-sectional study of coaches for youth baseball teams in Japan. Participants were the coaches of 66 teams belonging to the Gunma Prefecture Western Region Youth Baseball League (a response was requested from one representative per team). The sur-

vey was conducted between December 2017 and February 2018. All study protocols were approved by the institutional review board at Hidaka Hospital (approval no. 187). The purpose and methods of this study were orally explained in detail, and written informed consent was obtained. The players on each team coached by the respondents were at the Little League level (ages 6 to 12).

In developing, handing out, and collecting the questionnaires, efforts were made to maximize the response rate. In addition, all survey items were designed to be closed-ended rather than open-ended.15 To conduct this questionnaire survey, the youth baseball leagues in each of the three municipalities (City A, City B, and City C) cooperated.16 Prior to the distribution of the questionnaires, the co-researcher participated in meetings with youth baseball federations in each area where the representatives of each team met, and explained the research in advance.16 This co-researcher then handed out questionnaires to the coach of each team at the meeting.17,18 Questionnaires were completed by one representative coach from each team and hand-delivered to the youth baseball league to which each team belonged, and the co-researcher then received the questionnaires from the representatives of each youth baseball league.

Note that, according to studies that have investigated the level of response rates to questionnaires, a response rate of 73.1% (mean + 1 standard deviation [SD]) or higher is defined as a “high response rate”, and a response rate of 93.5% (mean + 2 SD) or higher is defined as a “very high response rate”.11 INSTRUMENT

The questionnaire for team representative coaches included basic information about the team and items related to the various recommendations of the guidelines (see Appendix for the text of the questionnaire). Basic information obtained included the age, baseball coaching experience, and baseball experience of the coach, the area of the team, number of coaches, number of members, number of pitchers, and total number of games played per year. Guideline recommendations were: 1) no more than 50 pitch counts; 2) conduct of both a warm-up and a cool-down; and 3) less than three days of practice per week and less than two hours of practice per day (Table 1).3 Note that these guidelines were in place at the time the study was conducted and that revised guidelines are currently available.3 For recommendations 1-3), respondents were asked to rate their knowledge of the recommendations in the guidelines. For recommendations 1–3), the necessity for each recommendation in the guidelines was rated on a 4-point scale (warm-up/cooldown was not rated because 100% of respondents complied with the guidelines). For recommendation 1), respondents were asked to indicate the number of pitches players give their best effort per day; and for recommendation 3), the number of practice days per week and the amount of time

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Survey with Innovations to Increase Response Rate Reveals Low Compliance with Guidelines among Youth Baseball Coaches -...

Table 1. Recommendations for baseball injuries in youth (referred to Japan Softball Baseball Association).

1

The incidence of baseball elbow injury peaks at 11 and 12 years of age. Therefore, baseball coaches should pay particular attention to elbow pain and limitation of movement in players at this age.

2

The incidence of baseball elbow and baseball shoulder injury is overwhelmingly high in pitchers and catchers. Therefore, each team should have at least 2 pitchers and 2 catchers.

3

As for the number of days and hours of practice, elementary school students (ages 6 to 12) should practice no more than three days a week and no more than two hours a day.

4

The number of pitches thrown should be no more than 50 per day for elementary school students and no more than 200 per week, including games. In addition, pitching two games in one day should be prohibited.

5

Adequate warm-up and cool-down shoud be performed before and after practice.

6

The off-season is desirable time to provide opportunities to enjoy sports other than baseball.

This table only includes the part for elementary school students (ages 6 to 12).

spent in practice on weekdays and holidays. Weekdays were defined as days with school attendance, and holidays were defined as days without school attendance. The reason for asking about the practice time separately for weekdays and holidays is that the practice time on weekdays is presumably shorter than that on holidays because of the afterschool practice.

DATA ANALYSIS

For continuous variables, mean, SD, median and interquartile range (25th–75th percentiles) are presented. Categorical variables are indicated by the number of participants.

Basic information and questions on pitch count limits were compared between groups that complied with pitch count limit recommendations and those that did not. The level of compliance with practice time (weekdays) was compared according to the knowledge and necessity of the guideline recommendations regarding practice days and times. Note that “absolutely necessary” and “necessary” were defined as necessary, while “not really necessary” and " Not necessary at all" were defined as not necessary. A Student’s t-test was used to compare continuous variables with a normal distribution, and a Mann-Whitney test was used for variables showing a non-parametric distribution. A chi-square test was used to compare categorical variables. Mean difference and 95% confidence interval was calculated in the case of comparison of continuous variables. Groups for each city (City A, City B, and City C) were compared regarding basic team information and questions about various recommendations of the guidelines. Analysis of variance (ANOVA) was used to compare continuous variables with a normal distribution, and a Kruskal-Wallis test was used for variables showing a non-parametric distribution. A chi-square test was used to compare categorical variables.

Two-tailed p-values less than 0.05 were considered significant. Statistical analysis was performed using IBM SPSS version 26 statistical software (IBM Corp., Armonk, NY, USA).

RESULTS The questionnaire received valid responses from coaches of 58 of 62 teams (response rate, 93.5%). The descriptive in-

Figure 1a. Percentage of coaches with or without knowledge of the restriction guideline regarding practice days and time (n=58).

Figure 1b. Percentage of coaches’ perceived necessity of restrictions on practice days and times (n=58).

formation for all teams, compliance with each guideline and perceptions of the team are shown in Table 2.

With regard to limits on pitch counts, nine of 58 teams (15.5%) were compliant with the guidelines. Almost all

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Survey with Innovations to Increase Response Rate Reveals Low Compliance with Guidelines among Youth Baseball Coaches -...

Table 2. Descriptive information on coaches and teams, as well as coach-reported compliance with each guideline.

All teams (n = 58) Basic information Age of representative coach

44.8±6.8 (44, 41-49)

Coaching experience of representative coach, months

66.7±66.4 (48, 24-85)

Baseball experience of the representative coach, yes/no

56/2

Area of the team, City A/City B/City C

38/9/11

Number of coaches

3.4±0.9 (3, 3-3)

Number of members, ≤15/16-30

20/38

Number of pitchers

3.5±1 (4, 3-4)

Number of games, ≤25/26-50/51-75/76-100/>100

5/16/28/9

Pitch counts Compliance with guidelines, yes/no

9/49

Number of pitches thrown in a day, ≤50/51-100/101-150

9/35/14

Knowledge of guidelines, yes/no

57/1

Necessity of restriction, absolutely necessary/necessary

32/26

Warm-up/cool-down Conducting warm-up, yes/no

58/0

Conducting cool-down, yes/no

58/0

Practice days and time Compliance with practice day guidelines, yes/no

49/9

Compliance with guidelines for practice time (weekdays), yes/no

40/18

Compliance with guidelines for practice time (holidays), yes/no

0/58

teams were knowledgeable regarding the guidelines, and all coaches answered that restrictions were either “absolutely necessary” or “necessary”. All teams used a warm up and cool down as part of their practice schedule. Regarding the limitation on the number of practice days, coaches of 49 teams (84.5%) reported being compliant with the guidelines. Regarding the limitation on practice time, coaches of 40 teams (69%) reported being compliant with the guidelines on weekdays, while all teams were not compliant with the guidelines on holidays. Coaches of twenty-eight teams (48.3%) were not knowledgeable regarding guidelines for limitations on practice days and time (Figure 1a), and coaches of 20 teams (34.5%) responded that the limitations were “not really necessary” (Figure 1b). Not knowledgeable teams of the guidelines for practice days and time limits showed no difference in practice time (weekday) compliance compared to knowledgeable teams (57.1% vs. 80%, p = 0.089). Futhermore, there was no difference in guideline compliance with practice time (weekdays) among the teams

that did not feel the necessity to restriction the number of days and hours of practice compared to those that did (80% vs. 63.2%, p = 0.241).

Table 3 provides a comparison of the two groups according to compliance with the guidelines on pitch count limits.

In the non-compliant group, 14 of 49 teams (28.6%) threw between 101 and 150 pitches per day.

Comparisons of data for descriptive team information, compliance with guidelines on pitch count limit, limits on practice days and limits on practice time by city are shown in Table 4. Descriptive team information did not differ by city. With regard to pitch count limits, City C showed the lowest rate of compliance with guidelines (0%, compared to 13.1% in City A and 44.4% in City B), and 5 of 11 teams (45.5%) threw 101–150 pitches (21.1% in City A and 11.1% in City B). No differences between cities were observed in terms of limitations on practice days or time.

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Table 3. Comparison between groups according to compliance with guidelines on number of pitches.

Compliant group n=9

Non-compliant group n=49

Compliant vs non-compliant group MD (95% CI)

p-value

Basic information Age of coach

44±5.9 (44, 40-52)

44.8±7 (44, 41-49)

0.24 (-4.76 to 5.24)

0.924a

Coaching experience of coach, months

46±44.3 (22, 12-84)

70.4±70.5 (48, 25-85)

24.44 (-13.35 to 62.24)

0.19b

9/0

47/2

-

1c

5/4/0

33/5/11

-

0.019c*

3.1±0.3 (3, 3-3)

3.5±1 (3, 3-4)

0.36 (-0.01 to 0.72)

0.055b

5/4

15/34

-

0.251c

3.1±0.8 (3, 3-4)

3.6±1 (4, 3-4)

0.46 (-0.18 to 1.1)

0.143b

2/1/4/2

3/15/24/7

-

0.299c

9/0/0

0/35/14

-

<0.001c**

Knowledge of guidelines, yes/no

9/0

48/1

-

1c

Necessity of restriction, absolutely necessary/necessary

6/3

26/23

-

0.495c

Baseball experience of coach, yes/no Area of team, City A/City B/City C Number of coaches Number of members, ≤15/16-30 Number of pitchers Number of games, ≤25/26-50/51-75/76-100/>100 Pitch counts Number of pitches thrown in a day, ≤50/51-100/101-150

Values are shown as mean±standard deviation (median, interquartile range).

MD: mean difference, CI: confidence interval. a Student’s t-test; b Mann-Whitney U test; c chi-squared test. * p &lt; 0.05, ** p &lt; 0.01

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Survey with Innovations to Increase Response Rate Reveals Low Compliance with Guidelines among Youth Baseball Coaches -...

Table 4. Comparison between cities of basic team information, compliance with each guideline and perceptions.

City A n=38

City B n=9

City C n=11

p-value

Age of coach

44.5±7.4 (44, 40-49)

44.9±6.8 (44, 40-49)

45.5±5.1 (45, 43-49)

0.545a

Coaching experience of the coach, months

67.7±75.9 (42, 24-84)

45.6±35.7 (36, 17-66)

80.2±54.1 (60, 33-147)

0.25b

36/2

9/0

11/0

0.58c

3.5±1 (3, 3-4)

3±0 (3, 3-3)

3.6±1.2 (3, 3-3)

0.321b

13/25

5/4

2/9

0.216c

3.5±0.9 (4, 3-4)

3.6±0.9 (4, 3-4)

3.7±1.1 (4, 3-5)

0.618b

3/12/18/5

2/1/4/2

0/3/6/2

0.599c

5/33

4/5

0/11

0.019c*

5/25/8

4/4/1

0/6/5

0.038c*

Knowledge of guidelines, yes/no

37/1

9/0

11/0

0.765c

Necessity of restriction, absolutely necessary/necessary

21/17

6/3

5/6

0.637c

Compliance with practice day guidelines, yes/no

13/7

8/1

10/1

0.696c

Compliance with the guidelines for practice time (weekdays), yes/no

26/12

6/3

8/3

0.951c

Basic information

Baseball experience of the coach, yes/no Number of coaches Number of members, ≤15/16-30 Number of pitchers Number of games, ≤25/26-50/51-75/76-100/>100 Pitch counts Compliance with guidelines, yes/no Number of pitches thrown in a day, ≤50/51-100/101-150

Practice days and time

Values are shown as mean±standard deviation (median, interquartile range). a Analysis of variance; b Kruskal-Wallis test; c chi-squared test. * p < 0.05, ** p < 0.01

International Journal of Sports Physical Therapy

Survey with Innovations to Increase Response Rate Reveals Low Compliance with Guidelines among Youth Baseball Coaches -...

DISCUSSION The present study utilized a questionnaire survey with several measures taken to improve the response rate, achieving a very high response rate of 93.5% by coaches of youth baseball teams. The results indicate that although knowledge about and perception of the necessity of pitch count limits were both almost 100%, the actual compliance rate was as low as 15.5%. Further, 28.6% of teams that did not comply with pitch count limits threw more than 100 pitches per day. Although differences between cities were observed in the percentage of teams complying with pitch count limits, none of the descriptive information for teams showed any differences between the cities. In addition, all teams (100%) were complying with guidelines on warm-up/cooldown, but no teams were complying with time limits for practice on holidays. These results suggest that compliance with guidelines for pitch count limits is lower than previously reported, suggesting a need for raising awareness among youth baseball coaches regarding the risk of pitching injury.

In previous studies of questionnaires for youth baseball coaches, response rates ranged from 41.4% to 56%,8–10 comparable or slightly lower than the general response rate of 52.7% for surveys targeting individuals,11 and non-response bias may thus have been present in the results obtained. The present study showed a very high response rate perhaps due to the measures that were taken: 1) the use of closed-ended items;15 2) prior explanation of the study;16 3) hand-delivery and collection of questionnaires;17,18 and 4) selection of organizations for distribution16 with little possibility of non-response bias.

The compliance rate of 15.5% for the pitch count limit in this study was remarkably low compared with previous reports, which have described rates of 44–56% in the United States8,9 and 28.3% in Japan.10 The compliance rate found in this study was the lowest guideline compliance rate that the authors found. The low compliance rate might be largely attributable to the removal of non-response bias.13 In this study, 28.3% of the non-compliant group routinely threw more than 100 pitches, in stark contrast with the guideline recommendation of no more than 50. These results suggest that youth baseball players in Japan are exposed to environments likely to increase the risk of pitching injury more than previously thought. Intergroup comparisons revealed differences between cities in compliance with pitch count limits. The difference in compliance rates between the cities was very large (44.4% difference between City B and City C). This large difference between City B and City C needs to be clarified. However, none of the comparisons of descriptive team information, knowledge of pitch count limit, or need for pitch count limit by city revealed significant differences, and no reason for the differences between cities in compliance rates could be identified.

The percentage compliance with the guidelines was found to be 100% for warm-up/cool-down, 84.5% for the limitation on the number of practice days and 69% for the limitation of practice time (weekdays), showing no major problems. However, all teams were non-compliant with restrictions on practice time for holidays, with 48.3% lacking knowledge regarding the recommendations and 34.5% stat-

ing that the limits were “not really necessary”. These results suggest that practice time is likely to be exceeded, especially during holidays. Although no reports on compliance rates or the perceptions of coaches regarding practice time limits are available for comparison, practice time of 13.5~21.7 hours/week19–21 has been reported for baseball players of similar age groups. Excessive practice time has been shown to lead to problems such as medial epicondyle apophysitis19 and lower limb tightness20 and represents an issue needing attention. The compliance rate of the guideline regarding practice time did not differ depending on the knowledge of the guideline or the necessity of the guideline, and the results of this study made it difficult to identify the factors that reduced the compliance rate of the guideline.

Since the non-compliant group for pitch counts showed a high level of knowledge and perception of the necessity of the guidelines, methods other than imparting knowledge may be needed to increase compliance rates. Monitoring pitches from the mound using systems that utilize pitch tracking, such as PITCHf/x (Sportvision, Chicago, IL), TrackMan (Vedbæk, Denmark), and Rapsodo (St Louis, MO), to monitor changes in workload intensity and fatigue during games and practices may be useful.22 On the other hand, knowledge regarding the guidelines and perception of their necessity were both low with regard to practice time limits, so educational activities such as disseminating knowledge of the guideline to coaches may be effective in increasing compliance rates. In addition, although workload monitoring during games has been emphasized in the past, Lazu et al. reported that the average only 12% of all pitches were thrown during games compared to practice and games combined.23 Therefore, one of the issues to be addressed is to examine the method of workload monitoring during practice. Keeping records of the number of pitches during practice, the number of practice days, and practice hours during practice are may be effective, but the effectiveness of these method should be verified in the future.

Furthermore, since differences between cities were observed, optimal methods of achieving changes may change depending on the city. However, since the reasons for differences between cities could not be clarified from this study, further work is needed in the future.

This study had a number of limitations. First, the number of teams in the compliant group was small, making comparisons between groups less reliable and multiple analyses impossible. Second, the symptoms of players could not be linked to team compliance with the guidelines because only coaches were surveyed. Third, it is assumed that they often threw from the flat ground in practice and from the mound in games, but the details such as the height of the mound are unknown since the authors did not actually investigate it. Finally, because the number of participants and variables specific to the city were small, factors contributing to differences between cities could not be identified. In the future, factors contributing to guideline compliance rates should be examined in the context of city-specific variables, such as the number of nearby medical institutions and municipal initiatives.

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ACKNOWLEDGEMENTS

CONCLUSION The results of this research revealed considerably lower compliance with guidelines on pitch count limits than previously reported. In addition, for guidelines other than the pitch count limits, the recommended values were exceeded for practice time on holidays. Differences between cities in compliance with the pitch count limits were found. The low compliance rate with the guidelines by youth baseball coaches needs to be further keenly aware and to address the differences between cities in compliance rates.

We would like to thank the Gunma Prefecture Western Region Youth Baseball League for their cooperation in the collection of data.

CONFLICTS OF INTEREST

The authors report no potential conflicts of interest in the development and publication of this manuscript.

Submitted: August 14, 2021 CDT, Accepted: January 09, 2022 CDT

This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CCBY-NC-4.0). View this license’s legal deed at https://creativecommons.org/licenses/by-nc/4.0 and legal code at https://creativecommons.org/licenses/by-nc/4.0/legalcode for more information.

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7. Reintgen C, Zeppieri Jr G, Bruner M, et al. Youth baseball caregiver understanding of safe pitching guidelines and player injury. Int J Sports Phys Ther.

2021;16(3):807-815. doi:10.26603/001c.22532 8. Fazarale JJ, Magnussen RA, Pedroza AD, Kaeding CC. Knowledge of and compliance with pitch count recommendations: a survey of youth baseball coaches. Sports Health. 2012;4(3):202-204. doi:10.117 7/1941738111435632 9. Knapik DM, Continenza SM, Hoffman K, Gilmore A. Youth baseball coach awareness of pitch count guidelines and overuse throwing injuries remains deficient. J Pediatr Orthop. 2018;38(10):e623-e628. do i:10.1097/bpo.0000000000001244 10. Yukutake T, Yamada M, Aoyama T. A survey examining the correlations between Japanese Little League baseball coaches’ knowledge of and compliance with pitch count recommendations and player elbow pain. Sports Health. 2013;5(3):239-243. d oi:10.1177/1941738113480341 11. Baruch Y, Holtom BC. Survey response rate levels and trends in organizational research. Hum Relat.

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Relationships between physical characteristics and ultrasound and physical examination.

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21. Huang YH, Wu TY, Learman KE, Tsai YS. A comparison of throwing kinematics between youth baseball players with and without a history of medial elbow pain. Chin J Physiol. 2010;53(3):160-166.

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SUPPLEMENTARY MATERIALS Appendix Download: https://ijspt.scholasticahq.com/article/32978-survey-with-innovations-to-increase-response-rate-revealslow-compliance-with-guidelines-among-youth-baseball-coaches-including-a-survey-of-differen/attachment/ 83128.docx?auth_token=v0AIVUkCzUvs3hHU4op7

International Journal of Sports Physical Therapy

Kelly S, Pollock N, Polglass G, Clarsen B. Injury and Illness in Elite Athletics: A Prospective Cohort Study Over Three Seasons. IJSPT. 2022;17(3):420-433.

Original Research

Injury and Illness in Elite Athletics: A Prospective Cohort Study Over Three Seasons Shane Kelly 1

a

, Noel Pollock 2

, George Polglass 3 , Ben Clarsen 4

1

Ballet Healthcare, The Royal Ballet, London, UK, 2 British Athletics, National Performance Institute, Loughborough, UK; Institute of Sport Exercise and Health, London, UK, 3 British Athletics, National Performance Institute, Loughborough, UK, 4 Oslo Sports Trauma Research Center, Department of Sports Medicine, Norwegian School of Sports Sciences, Oslo, Norway; Centre for Disease Burden, Norwegian Institute of Public Health, Bergen, Norway Keywords: injury, illness, epidemiology, athletics, track and field, elite, hamstring, achilles, soleus https://doi.org/10.26603/001c.32589

International Journal of Sports Physical Therapy Vol. 17, Issue 3, 2022

Background Athletics (also known as track and field) is one of the most popular sports in the world and is the centrepiece of the Summer Olympic Games. Participation in athletics training and competition involves a risk of illness and injury.

Purpose To describe injury and illness in British Olympic track and field athletes over three full training and competition seasons.

Study Design Descriptive Epidemiology Study

Methods A total of 111 athletes on the British national program were followed prospectively for three consecutive seasons between 2015-2018. Team medical personnel recorded all injuries and illnesses during this time, following current consensus-based methods. All data pertaining to these records were reviewed and analyzed for sports injury and illness epidemiological descriptive statistics.

Results The average age of the athletes was 24 years for both males and females (24 years, +/- 4).

Total exposure for the three seasons was 79 205 athlete days (217 athlete years). Overuse injuries (56.4%) were more frequent than acute injuries (43.6%). The thigh was the most common injury location (0.6 per athlete year), followed by the lower leg (0.4 per athlete year) and foot (0.3 per athlete year). Muscle and tendon were the most commonly injured tissues, while strains and tears were the most common pathology type. Hamstring muscle strain was the most common diagnosis causing time loss, followed by Achilles tendinopathy and soleus muscle strain. Respiratory illness was the most common illness type (0.3 per athlete year).

Conclusion Hamstring strains, Achilles tendinopathy, and soleus strains are the most common injuries in athletics and have highest burden. Respiratory illness is the most common illness and has the highest burden. Knowledge of this injury and illness profile within athletics could be utilised for the development of targeted prevention measures within

a

Corresponding author: Shane Kelly Ballet Healthcare, The Royal Ballet The Royal Opera House, Bow Street London, WC2E 9DD, United Kingdom email: shane.kelly@roh.org.uk

Injury and Illness in Elite Athletics: A Prospective Cohort Study Over Three Seasons

the sport at the elite level.

Level of Evidence 3

INTRODUCTION Participation in track and field (athletics) training and competition is associated with a risk of injury and illness.1–5 The risk and burden of injury can differ depending on the event, discipline, age, gender and time of season. 1–3,6,7 Injury has a detrimental impact on performance, with high levels of time lost from training being associated with athletes not reaching their performance goals.8 Robust data is required on injury and illness to inform the development of effective prevention measures within a sport.9,10 Across 16 major international athletics championships, muscle injuries were the most common injury type, representing 41% of all injuries.11 Of these, hamstring muscle injuries were the most common, representing 17% of all injuries.1,11 In a prospective study of elite Swedish track and field athletes conducted over one season, Achilles tendon injuries were most common, closely followed by thigh strains.4 Bone stress injuries are also common in athletics, with one cohort study reporting an annual cumulative incidence of 20% with no difference between males and females or between event groups.2 Currently, there are gaps in the evidence on the patterns of injury and illness in elite level track and field. Epidemiological studies of elite level athletics have been conducted during short-term competitions.1,11–14 Studies over a longer time frame (maximum one season) have assessed mixed cohorts of junior elite, college and amateur athletes and have only investigated injury.3,4 It is unknown whether their findings can be applied to adult athletes at the elite level. No study has followed an elite cohort of track and field athletes over multiple seasons, recording both illness and injury.

The study presents three seasons of injury and illness surveillance data for athletes on the British Athletics Olympic World Class Performance Programme (WCP). The primary aim was to describe injury and illness in British Olympic track and field athletes over three full training and competition seasons. The secondary aim of the study was to identify areas for future research for injury and illness prevention programs in elite athletics.

METHODS STUDY DESIGN

ber 2018. Ethical approval for the study was granted by the University College of London (UCL) research ethics committee.

PARTICIPANTS AND SETTING

All athletes that were part of the WCP in each season were eligible to be included in this study. Athletes on the WCP can be based anywhere around the world, although a majority train at the two main training centers in England – the National Performance Institute in Loughborough and Lee Valley Athletics Center, London, United Kingdom. British Athletics full time medical staff are located at both centers and are available to support all WCP athletes at both centers and, on occasion, at other venues.

DATA COLLECTION PROCEDURES

All injuries and illnesses sustained by WCP athletes during the data collection period were recorded and coded by team medical personnel, using the British Athletics electronic medical record (EMR) system (Smartabase, Fusion Sport, Brisbane, Australia). All injuries and illnesses that required medical attention were recorded, irrespective of their impact on athletic participation or performance.

For athletes based at the two training centers, electronic medical records were created for all injury and illness presentations as part of their normal care. Athletes that were off-site were contacted regularly by medical personnel to inform the WCP of injury, illness and training status. When athletes became ill or injured it was required that they inform the medical team or senior coach on the programme which would initiate an injury/illness record being created.

Medical and therapy personnel created new injury and illness records as they occurred.

The injury or illness progress and training status were recorded in the EMR by medical and therapy practitioners, based on their clinical assessment of the athlete. Staff were asked to review records weekly to ensure all athletes’ training status was updated. Cases were recorded as resolved when the athlete had returned to full training or competition. When new injury and illness records were entered into the EMR the number of days of time loss and non-time loss were calculated until the complaint was resolved.

DATA PROCESSING AND SUMMARY

This was a prospective cohort study of Olympic athletes on the British WCP. Every year, the WCP invites athletes of track and field disciplines to be part of the program. Invitation to the WCP is made by the Performance Director and Head Coaches who determine the athlete has a realistic chance of a medal at a future World Championships or Olympic Games. Athletes are included on the 1st of December each year and supported until the 30th of November the following year. Data for this study were collected over three consecutive seasons, from December 2015 to Novem-

All injury and illness classification within the EMR were recorded using the Orchard Sports Injury Classification System (OSIICS), Version 10 and subsequently translated to OSIICS-13 prior to analysis.15 At the end of the three seasons the data were processed for input and computational errors by two authors. Injury and illness data processing involved double checking that all WCP athletes were included in analysis and removing any athletes that should not be included for analysis (in

International Journal of Sports Physical Therapy

Injury and Illness in Elite Athletics: A Prospective Cohort Study Over Three Seasons

Table 1. Number of athletes included in the British Athletics WCP by sex and season.

2015-16 Sex

2016-17

2017-18

Males

Females

Males

Females

Males

Females

40

40

35

38

36

28

some seasons the software had included athletes not officially on the WCP). Missing data were then accounted for using practitioner and EMR follow up. Further specific analysis and EMR follow up was performed for any injury records that had more than 80 days of time loss. This was an arbitrary number used to identify cases that may not have been closed appropriately on return to full training. If this was the case, a consensus was reached on the appropriate time loss based on the available information.

All data were summarized by an external investigator who was provided with three seasons of anonymous surveillance data. Key variables and outcomes included cohort demographics, event group characteristics, injury mode of onset (acute and overuse), time loss, incidence of injury and illness and burden of injury by tissue type and body area.

EVENT GROUP CATEGORIES

Event group classification was based on the athletics consensus statement16 (Fig.1). Due to performance selection for the WCP not all events or event groups were represented in every year.

Figure 1. Event group classification Adapted from Timpka et al (2014).16 All events that are supported by the British Athletics World Class Programme.

1. Sprints (60, 100, 200 and 400 m) and relays (4 100 and 4 400) 2. Middle distance runs (800–1500 m) 3. Long-distance runs (3000–10 000 m) including steeplechase (3000 m steeplechase) 4. Marathon 5. Race walking (20 and 50 km) 6. Hurdles (60, 100, 110 and 400 m hurdles) 7. Jumps (high, long, triple and pole vault) 8. Throws (discus, javelin, hammer and shot put) 9. Combined events (decathlon, heptathlon)

CALCULATION OF EXPOSURE, INCIDENCE AND BURDEN

Exposure – On the WCP, collection of training data is not systematic, and it is not always comparable across or within event groups. Therefore, exposure was calculated individually for each athlete as the number of days on the WCP. Incidence – Incidence was calculated as the number for

time loss cases per athlete year (365 days).17 Burden – Burden was calculated as number of time loss days per athlete per year.17 This definition was decided on as other measures of exposure are inconsistent between different track and field disciplines.17 The operational injury definition was: “Any new physical complaint sustained by an athlete that required assessment and/or treatment and was entered into the British Athletics Medical Records System by a British Athletics or affiliated medical practitioner” Illnesses were defined as: ''Any new medical complaint, physical or psychological, sustained by an athlete that required assessment and/or treatment and was entered into the British Athletics Medical Records System by a British Athletics or affiliated medical doctor" All new injuries and illnesses that satisfied these definitions were recorded in the EMR, irrespective of whether they were associated with time loss from athletics training or competition.

For each case, the resultant time loss (TL) was recorded as the number of days completely unavailable for training or competition, irrespective of the season period and irrespective of whether training was planned each day. Timeloss days were counted from the day after the onset, as per current recommendations.5 Cases were categorized as non-time-loss injuries (NTL) if they did not lead to any days of unavailability from training or competition.

Injuries were classified as an acute if they ‘resulted from a specific identifiable event and had a rapid onset of experienced distress or disability’.16 Injuries were classified as overuse injuries if they had a ‘gradual onset, without a single identifiable event being responsible for the condition’.16

RESULTS A total of 111 athletes were included in the surveillance program over the three seasons: 80 in 2015/16, 73 in 2016/ 17 and 64 in 2017/18. Forty-three athletes were included for a single year, 31 for two seasons and 37 athletes for all three years. Across the three seasons, the overall exposure was 79 205 athlete days (217 athlete years). The average age was 24 years each year for both males and females (+/- 4, Range 18-35) The largest event groups were sprints and middle-distance, which represented 41% and 19% of the cohort, respectively, over the three seasons.

The number of athletes included each season is shown is shown in Table 1. Females represented 50%, 52% and 44% of athletes in each of the three seasons.

A total of 347 TL overuse injuries were recorded over the

International Journal of Sports Physical Therapy

Injury and Illness in Elite Athletics: A Prospective Cohort Study Over Three Seasons

Table 2. Number of cases, incidence and time loss by health problem type.

Health problem type

Number of cases

Incidence* [95% CI]

TL loss days

Mean TL days [95% CI]

Acute injury

150

0.7 [0.6, 0.8]

2822

18.8 [13.9, 24.5]

Overuse injury

347

1.6 [1.44, 1.77]

3656

10.5 [7.6, 14.0]

Illness

178

0.8 [0.7, 1.0]

864

4.9 [1.3, 11.1]

* Incidence expressed as number of new cases per 365 athlete days, CI=confidence interval, TL= time loss

three seasons, leading to a total of 3656 days of time loss (50% of all time loss). The incidence of overuse injury was 1.6 cases per athlete year (Table 2).

There were 150 cases of acute injury over the three seasons, leading to a total of 2822 days of time loss (38% of all time loss). The average the time loss for an acute injury was 18.8 days with an incidence of 0.7 per athlete year (Table 2).

A total of 178 illnesses were recorded over the three years, leading to 864 days of time loss (12% of all time loss).

The incidence of illness was 0.8 cases per athlete year (Table 2).

Most injuries were in the lower limb (Table 3), particularly in the thigh (128 cases), lower leg (84 cases) and foot (61 cases).

Muscle tears were most common, with an incidence of 0.8 per athlete year. There were relatively few bone injuries; however, due to their high severity (particularly bone stress injuries), their burden remained substantial (Table 4, Figure 2).

The most common illnesses were respiratory and gastrointestinal illness (Table 5). Respiratory illness was most common, with an incidence of 0.3 per athlete year and total of 100 time-loss days. Gastrointestinal illness had an incidence of 0.1 per athlete year and a total of 72 time-loss days.

Table 6 shows the five most commonly recorded specific injury diagnoses during the three-year data collection period and ranks these according to time loss and time loss/ cases combined. Hamstring, Achilles tendinopathy and soleus strain rank the top three most common diagnoses in both scenarios.

International Journal of Sports Physical Therapy

Injury and Illness in Elite Athletics: A Prospective Cohort Study Over Three Seasons

Table 3. Number of cases, incidence, time loss and burden by injury location. Greater detail is provided for selected (common) diagnoses.

Body Area

OSICS 13 Diagnosis

Cases

Total TL days

TL mean

95% CI mean

TL SD

Incidence

95% CI

Head

All

4.0

0.0

0.0

[0.0-0.0]

0.0

0.0

[0.0,0.0]

Neck

All

8.0

35.0

4.4

[0.0-11.6]

10.2

0.0

[0.0, 0.1]

Shoulder

All

11.0

15.0

1.4

[0.0-4.0]

4.2

0.1

[0.0-0.1]

Elbow

All

3.0

100.0

33.3

[0.0-100.0]

57.7

0.0

[0.0-0.0]

Wrist

All

8.0

52.0

6.5

[0.0-19.5]

18.4

0.0

[0.0-0.0]

Hand

All

4.0

0.0

0.0

[0.0-0.0]

0.0

0.0

[0.0-0.0]

Chest

All

5.0

21.0

4.2

[0.0-12.6]

9.4

0.0

[0.0-0.1]

Thoracic spine

All

6.0

101.0

16.8

[0.2-49.2]

39.3

0.0

[0.0-0.1]

Lumbosacral

All

43.0

419.0

9.7

[1.5-22.6]

37.6

0.2

[0.2-0.3]

Abdomen

All

2.0

1.0

-

-

0.7

0.0

[0.0-0.0]

Hip/groin

All

41.0

755.0

18.4

[6.5-33.9]

45.2

0.2

[0.1-0.3]

Hip flexor muscle strain

7.0

76.0

10.9

[5.1-17.1]

8.8

0.0

[0.0-0.1]

Hip and Groin Muscle Strain/ Tear

3.0

3.0

1.0

[0.0-3.0]

1.7

0.0

[0.0-0.0]

Iliopsoas tendinopathy/ bursitis

3.0

40.0

13.3

[0.0-27.0]

13.5

0.0

[0.0-0.0]

Osteitis pubis

3.0

233.0

77.7

[0.0-233.0]

134.5

0.0

[0.0-0.0]

Hip joint sprain/jar

4.0

18.0

4.5

[0.0-13.5]

9.0

0.0

[0.0-0.0]

All

128.0

1830.0

14.3

[10.6-18.6]

23.5

0.6

[0.5-0.7]

Hamstring strain/tear

62.0

1165.0

18.8

[15.4-22.2]

13.8

0.3

[0.0-0.0]

Thigh Muscle Spasm/Trigger Points

12.0

2.0

0.2

[0.0-0.5]

0.6

0.1

[0.0-0.1]

Rectus femoris strain

5.0

193.0

38.6

[1.4-99.6]

66.8

0.0

[0.0-0.1]

Adductor longus strain

4.0

174.0

43.5

[2.0-92.5]

56.7

0.0

[0.0-0.0]

Hamstring origin tendinopathy

7.0

8.0

1.1

[0.0-3.4]

3.0

0.0

[0.0-0.1]

All

51.0

406.0

8.0

[2.7-14.9]

22.8

0.2

[0.2-0.3]

Patellar tendinopathy

6.0

106.0

17.7

[0.0-53.0]

43.3

0.0

[0.0-0.1]

Iliotibial band syndrome

4.0

121.0

30.2

[0.0-90.8]

60.5

0.0

[0.0-0.0]

Patellofemoral joint chondral pain

5.0

0.0

0.0

[0.0-0.0]

0.0

0.0

[0.0-0.1]

Knee posterolateral complex str/ tear

3.0

10.0

3.3

[0.0-6.0]

3.1

0.0

[0.0-0.0]

All

84.0

1183.0

14.1

[8.4-20.7]

29.7

0.4

[0.3-0.5]

Gastrocnemius muscle injury/

6.0

46.0

7.7

[1.0-16.4]

10.9

0.0

[0.0-0.0]

Thigh

Knee

Lower leg

International Journal of Sports Physical Therapy

Injury and Illness in Elite Athletics: A Prospective Cohort Study Over Three Seasons

strain

Ankle

Foot

Soleus muscle strain

19.0

476.0

25.1

[15.0-37.1]

24.8

0.1

[0.1-0.1]

Calf muscle cramps/spasm

9.0

12.0

1.3

[0.0-2.9]

2.4

0.0

[0.0-0.1]

Medial Tibial Stress Syndrome

4.0

0.0

0.0

[0.0-0.0]

0.0

0.0

[0.0-0.0]

Achilles tendinopathy

25.0

461.0

18.4

[5.2-34.8]

38.8

0.1

[0.1-0.2]

All

36.0

771.0

21.4

[7.4-39.9]

51.4

0.2

[0.1-0.2]

Ankle anterior impingement

5.0

91.0

18.2

[0.0-47.4]

31.6

0.0

[0.0-0.1]

Posterior impingement ankle

6.0

0.0

0.0

[0.0-0.0]

0.0

0.0

[0.0-0.1]

Ankle synovitis/ Impingement/ Bursitis

2.0

6.0

-

-

4.2

0.0

[0.0-0.0]

All

61.0

766.0

12.4

[5.4-21.0]

32.5

0.3

[0.2-0.4]

Tibialis posterior tendinopathy

5.0

42.0

8.4

[0.0-23.2]

16.1

0.0

[0.0-0.1]

Stress reactions/ fractures in foot

9.0

335

37.2

[3.3-71.1]

51.9

0.0

[0.0-0.0]

* Incidence expressed as number of new cases per 365 athlete days, CI=confidence interval, TL=time loss, SD=standard deviation.

International Journal of Sports Physical Therapy

Injury and Illness in Elite Athletics: A Prospective Cohort Study Over Three Seasons

Table 4. Number of cases, incidence, time loss and burden of injuries by tissue type and pathology.

OSIICS 13 Tissue Type

OSIICS 13 Pathology Type

Cases

Total TL

TL Mean

TL SD

95% CI

Incidence

95% CI

Burden

275.0

3748.0

13.6

26.1

[10.7-16.9]

1.3

[1.1-1.4]

17.3

Muscle injury

176.0

2505.0

14.2

22.7

[11.1-17.8]

0.8

[0.7-0.9]

11.5

Muscle contusion

2.0

0.0

NA

0.0

NA

0.0

[0.0-0.0]

NA

Muscle compartment syndrome

3.0

0.0

0.0

0.0

[0.0-0.0]

0.0

[0.0-0.0]

0.0

Tendinopathy

89.0

1011.0

11.4

29.3

[5.8-18.0]

0.4

[0.3-0.5]

4.7

Tendon rupture

5.0

232.0

46.4

58.7

[5.8-97.0]

0.0

[0.0-0.1]

0.9

Muscle/ tendon

Nervous

9.0

0.0

0.0

0.0

[0.0-0.0]

0.0

[0.0-0.1]

0.0

Brain & spinal cord injury

1.0

0.0

NA

NA

NA

0.0

[0.0-0.0]

NA

Peripheral nerve Injury

8.0

0.0

0.0

0.0

[0.0-0.0]

0.0

[0.0-0.1]

0.0

Bone

29.0

1501.0

51.8

73.4

[27.0-78.9]

0.1

[0.1-0.2]

6.7

Fracture

7.0

182.0

26.0

43.5

[2.1-58.4]

0.0

[0.0-0.1]

0.8

Bone stress injury (inc. stress fracture)

22.0

1319.0

60.0

79.7

[28.8-93.5]

0.1

[0.1-0.2]

6.0

48.0

434.0

9.0

36.2

[1.9-20.7]

0.2

[0.2-0.3]

2.0

Cartilage

20.0

307.0

15.4

53.7

[1.3-40.7]

0.1

[0.1-0.3]

1.4

Arthritis

1.0

0.0

NA

NA

NA

0.0

[0.0-0.0]

NA

Synovitis / capsulitis

24.0

98.0

4.1

15.2

[0.0-10.9]

0.1

[0.1-0.2]

0.4

Bursitis

3.0

29.0

9.7

9.5

[0.0-19.0]

0.0

[0.0-0.0]

0.1

61.0

592.0

9.7

23.5

[4.5-16.4]

0.3

[0.2-0.4]

2.7

Joint sprain (ligament tear, acute instability episode)

52.0

556.0

10.7

25.2

[4.7-18.4]

0.2

[0.2-0.3]

2.6

Chronic instability

9.0

36.0

4.0

8.0

[0.0-9.9]

0.0

[0.0-0.1]

0.2

66.0

203.0

3.1

11.9

[0.7-6.4]

0.3

[0.2-0.4]

0.9

Injury without tissue type specified

25.0

97.0

3.9

17.0

[0.1-11.0]

0.1

[0.1-0.2]

0.5

Unknown

41.0

106.0

2.6

7.6

[0.6-5.2]

0.2

[0.1-0.3]

0.5

Cartilage/ synovium/ bursa

Ligament/ joint capsule

Nonspecific

*Burden is defined as the number of time loss days per athlete-year (365 athlete-days), Incidence expressed as number of new cases per 365 athlete days, CI=confidence interval, TL=time loss, SD=standard deviation, OSIICS= Orchard Sports Injury and Illness coding system

International Journal of Sports Physical Therapy

Injury and Illness in Elite Athletics: A Prospective Cohort Study Over Three Seasons

Table 5. Number of cases, incidence, time loss and burden of illnesses by organ system/region. Greater detail is provided for selected (common) aetiologies.

Illness type

Illness

Cases

Total TL

TL Mean

SD

95% CI

incidence

95% CI

burden

Cardiovascular

All

4.0

27.0

6.8

13.5

[0.0-20.2]

0.0

[0.0-0.0]

0.1

Gastrointestinal

All

30.0

72.0

2.4

7.0

[0.4-5.2]

0.1

[0.1-0.2]

0.3

Gastritis

3.0

0.0

0.0

0.0

[0.0-0.0]

0.0

[0.0-0.0]

0.0

Appendicitis

1.0

39.0

39.0

0.0

0.0

0.0

[0.0-0.0]

0.0

Gastrointestinal Illness

18.0

29.0

2.4

6.2

[0.0-6.4]

0.1

[0.0-0.1]

0.1

Genitourinary/Gynaecological

All

11.0

14.0

1.3

4.2

[0.0-3.8]

0.1

[0.0-0.1]

0.1

Neurological

All

3.0

3.0

1.0

1.7

[0.0-3.0]

0.0

[0.0-0.0]

0.0

Otological

All

4.0

6.0

1.5

1.9

[0.0-3.0]

0.0

[0.0-0.0]

0.0

Psychiatric/psychological

All

4.0

526.0

132.0

254.4

[0.0-385.0]

0.0

[0.0-0.0]

2.6

Respiratory

All

63.0

100.0

1.6

4.2

[0.7-2.7]

0.3

[0.2-0.4]

0.5

Infection

38.0

80.0

2.1

4.5

[0.9-3.7]

0.2

[0.1-0.2]

0.4

Allergic

14.0

18.0

1.3

4.8

[0.0-3.9]

0.1

[0.0-0.1]

0.1

Other

11.0

2.0

0.2

0.7

[0.0-0.7]

0.0

[0.0-0.1]

0.0

All

18.0

116.0

6.4

14.1

[0.4-13.6]

0.1

[0.1-0.1]

0.5

Multiple systems

*Burden is defined as the number of time loss days per athlete-year (365 athlete-days), Incidence expressed as number of new cases per 365 athlete days CI=confidence interval, TL=time loss, SD=standard deviation

International Journal of Sports Physical Therapy

Injury and Illness in Elite Athletics: A Prospective Cohort Study Over Three Seasons

Table 6. Top 5 injury diagnoses by cases and time loss.

Cases

TL total days

Mean TL days

SD

incidence

95% CI

Burden

Hamstring strain/tear

62

1165

18.8

13.8

0.3

[0.0-0.0]

5.3

Achilles tendinopathy

25

461

18.4

38.8

0.1

[0.1-0.2]

2.2

Soleus muscle strain

19

476

25.1

24.8

0.1

[0.1-0.1]

2.2

Pars stress fracture L5

2

295

NA

122.3

0.0

[0.0-0.0]

NA

Navicular stress fracture

3

255

85.0

71.0

0.0

[0.0-0.0]

0.9

Hamstring strain/tear

62

1165

18.8

13.8

0.3

[0.0-0.0]

5.3

Achilles tendinopathy

25

461

18.4

38.8

0.1

[0.1-0.2]

2.2

Soleus muscle strain

19

476

25.1

24.8

0.1

[0.1-0.1]

2.2

Hip flexor muscle strain

7

76

10.9

8.8

0.0

[0.0-0.1]

0.3

Patellar tendinopathy

6

106

17.7

43.3

0.0

[0.0-0.1]

0.5

OSIICs 13 diagnosis Top 5 rank by TL

Top 5 rank by cases and TL

*Burden is defined as the number of time loss days per athlete-year (365 athlete-days), Incidence expressed as number of new cases per 365 athlete days CI=confidence interval, TL=time loss, SD=standard deviation, OSIICS= Orchard Sports Injury and Illness coding system

DISCUSSION In recent years there have been multiple high-quality injury and illness surveillance studies of elite track and field athletes performed during major international competitions.1,7,11,12,14,18 However, information on the health problems sustained by these elite athletes outside of competition remains limited. Presented in this study is three seasons of high-quality surveillance data from one of the leading national athletics teams in the world, recently contributing seven medals to a record medal tally for Great Britain at the Rio Summer Olympic Games and finishing 6th on the medal table in Doha, 2019 IAAF World Championships. This data may be valuable to guide future efforts to prevent injuries and illnesses among elite track and field athletes.

Overuse injuries represented the greatest burden, followed by acute injuries, then illness. This finding is similar to a study of elite Swedish track and field athletes.4 However, in the current study, the proportion of overuse injuries was relatively lower (70% of all injuries) than the Swedish study (96%). The discrepancy may be explained by differences in overuse and acute injury definitions in the two studies. Specifically, Jacobsson et al. subcategorized overuse injuries into those with a gradual onset and a sudden onset, whereas the current study classified all suddenonset injuries, such as sudden onset bone stress, as acute injuries. Nonetheless, the findings from both studies clearly show that overuse injuries are an important type of health problem in elite athletics, and that efforts need to be focussed on their prevention. In particular, research across multiple seasons on the relationship between athletics training loads and injury are necessary, to facilitate the development of effective load management principles.19–21 Over 25% of all injuries were to the thigh, with hamstring

Figure 2. Risk matrix of body area burden in three years of consecutive surveillance data. Injuries to the thigh and lower leg represent the highest burden. Severity is in calculated as mean days of time loss, incidence is cases per athlete year.

strain the most frequent diagnosis. This is consistent with previous studies of elite track and field athletes, and other sports involving regular high-speed or fatiguing running.1,4,11,22–26 The findings of this research are conclusive in establishing that hamstring injury is the most common injury in athletics for both training and competition exposure where commonly high speed, or fatiguing running is

International Journal of Sports Physical Therapy

Injury and Illness in Elite Athletics: A Prospective Cohort Study Over Three Seasons

required. Reducing hamstring burden has been a strategic focus of the British Athletics medical team.27,28 The exposure to high speed running in this cohort is a necessary demand of the sport therefore injury prevention strategies need to focus on the speed/fatigue/exposure relationship and how this factored into training and competition programming.20,29 Furthermore, the use of specific conditioning exercises in the primary and tertiary prevention of hamstring injuries, as seen in other sports, should be tested in injury prevention studies in athletics.27,30–33 More research is required on specific mechanisms of thigh injury and risk factors in elite level track and field particularly regarding biomechanical risk factors in sprinting.28 Achilles injury was the second most common injury in this cohort and the most common in the Jacobssen study.4 In an athletics championship setting Achilles tendon rupture is a serious but rare occurrence and other forms of Achilles pathology are not that common.1 Lower incidence of Achilles tendinopathy within the in-competition studies is not surprising as the definitions and timeframes involved with these studies may limit the capture of this presentation. It is important to note that in this study the term ‘Achilles tendinopathy’ could represent other forms of Achilles region pain thereby potentially inflating the incidence of this injury diagnosis. In future surveillance studies the authors of this study would recommend a more specific diagnosis and coding of Achilles tendon related presentations. The OSIICs 13 definition of tendinopathy is limited in its application in elite level athletics and the authors would advocate a sub-categorisation diagnostic approach.

The high incidence of acute soleus injuries in this cohort is a unique finding within elite track and field.1–4 The calf, and specifically the soleus, has a large role in force production in all modes of locomotion with the highest demand on the muscle occurring at higher speeds and therefore ‘reduced strength’ of the calf complex is likely a risk factor for calf muscle injury or Achilles tendon pathology.34–36 O’Neil et al found a strong association with weak ankle plantarflexors, particularly the soleus muscle, and the presence of Achilles tendinopathy in non-elite runners.37 Due to the critical role of soleus and gastrocnemius at all running speeds, injury prevention research relating to the lower leg is likely to be as important as hamstring injury prevention efforts in this sport.35,36,38,39 Furthermore, investigation into how training load volumes and intensities interact with intrinsic factors of the lower leg would be a suggested focus for future research.40,41 Bone stress injuries were not common in this cohort, but they still represented a substantial burden due to high levels of associated time loss. There was a similar finding to Bennel et al., who found that bone stress injuries were a significant problem in athletics.2 There is relevant work on the multitude of risk factors for bone stress injury that should be considered by all practitioners working in elite track and field.42 These specifically should include a thorough knowledge of the importance of relative energy deficiency in sport (RED-S).43 Given the high burden and potential health and performance costs this is certainly an injury category that warrants further injury prevention research. Understanding the mechanisms and training etiology of this sort of injury specifically in an elite cohort is needed.

Figure 3. Risk matrix tissue type burden in three years of consecutive surveillance data. Injuries to muscle, tendon and bone tissue had the highest burden. Incidence was calculated as cases per athlete year, severity was calculated using mean time loss days.

Two injury specific injury diagnoses (rectus femoris and adductor longus muscle strain) had low incidence yet high impact regarding time loss days. Both these muscle injury types had a longer mean return to performance and review of the cases highlights three of the rectus femoris injuries were surgical cases which extended the recovery period and skewed mean recovery time. There was one adductor longus case which is likely to have skewed the mean and this was due to a complicated rehabilitation. For both these injury types a median value may have statistically represented the recovery times better and given a more accurate reflection of recovery from these specific injuries. Rectus femoris and adductor longus strain mean recovery time may have been shortened if it was not for these complicated or surgical cases.

Illness had the second highest incidence of all of presentations and was third in terms of time loss days, representing 12% of total time loss. In major international athletics competitions upper respiratory tract infection was the most common illness.12–14 This was comparable to the current study’s cohort establishing upper respiratory symptoms and infection as the most common medical presentation in competition and out-of-competition setting.

Strategies to prevent respiratory illness and transmission should be an integral part of sports medicine provision for elite athletes and teams.44,45 Mental illness represented the highest burden of all illness. Despite there only being four cases, the mean time loss was large compared to other illnesses. Due to medical confidentiality the cases and specific presentations are not

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Injury and Illness in Elite Athletics: A Prospective Cohort Study Over Three Seasons

discussed in this research but the burden of mental health with respect to performance should be recognized.46 The understanding of mental health generally in elite sport is increasing and there is increasing mental health support for athletes at the Olympic level.47 All athletes currently on the WCP have 24/7 access to mental health support which highlights elite sports’ increasing awareness and support for athletes at the elite level. An area of future research would be to understand the specific mental health presentation in in elite level athletics to inform future prevention strategies.47 METHODOLOGICAL CONSIDERATIONS

There are several methodological limitations to this study.

Due to the small number of athletes in some event groups in this study the researchers were unable to present data separately for each subgroup. To do this, larger studies would be necessary. While most athletes on the WCP train at the two national training centres, a number are based elsewhere in the United Kingdom or in other countries. Outside of competition periods and organised training camps, these athletes are followed remotely by British Athletics medical personnel. This may have reduced the accuracy and specificity of their surveillance data as some of these athletes may have consulted with other medical practitioners.

The incidence of injury and illness was expressed per 365 athlete days because other forms of exposure measurement are not comparable across athletics disciplines (e.g. 1000 h of high jumping is not comparable to 1000h of distance running). While this is the recommended approach when dealing with heterogenous cohorts, athlete-days is a blunt measure of exposure which fails to account for differences in athletes’ training volume or intensity within each training day.17 To be able to use more specific exposure measures in epidemiological studies of athletics, it would be necessary to include a larger number of athletes or limit the cohort to comparable disciplines.

For consistency with historical athlete records, we applied injury and illness definitions that are slightly different

to those recommended by the athletics and IOC consensus statements on epidemiological methodology.17 Specifically, the authors only recorded health problems that led to medical attention from medical personnel. Our data, therefore, are not directly comparable to data collected using an “all complaints” definition.

CONCLUSION The results of this study provide new insights into the injury and illness patterns of athletes at the highest level of competitive athletics. Future preventative attention should be focused on hamstring muscle strains, soleus muscle strains, Achilles tendinopathy, and bone stress injuries.

Practitioners working in elite athletics should consider employing risk reduction measures for the three biggest time loss injuries in the sport: hamstring, Achilles tendinopathy and soleus injury

CONFLICT OF INTEREST

The authors declare no conflicts of interest ACKNOWLEDGEMENTS

The authors would like to thank all members of the British Athletics medical and therapy team for developing of and recording in of medical notes data into the EMR during the surveillance period. The authors would like to thank the British Athletics World Class Performance programme senior and performance management and athletes for the support of this study. We would like to thank Ben Stone for his specific inputs regarding some supplementary statistical analysis during the project.

Submitted: July 27, 2021 CDT, Accepted: December 01, 2021 CDT

This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CCBY-NC-4.0). View this license’s legal deed at https://creativecommons.org/licenses/by-nc/4.0 and legal code at https://creativecommons.org/licenses/by-nc/4.0/legalcode for more information.

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Injury and Illness in Elite Athletics: A Prospective Cohort Study Over Three Seasons

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19. Soligard T, Schwellnus M, Alonso JM, et al. How much is too much? (Part 1) International Olympic Committee consensus statement on load in sport and risk of injury. Br J Sports Med. 2016;50(17):1030-1041. doi:10.1136/bjsports-2016-096581 20. Kalkhoven JT, Watsford ML, Coutts AJ, Edwards WB, Impellizzeri FM. Training load and injury: causal pathways and future directions. Sports Med. 2021;51(6):1137-1150. doi:10.1007/s40279-020-0141 3-6 21. Impellizzeri FM, Menaspà P, Coutts AJ, Kalkhoven J, Menaspà MJ. Training load and its role in injury prevention, Part I: Back to the future. J Athl Train.

2020;55(9):885-892. doi:10.4085/1062-6050-500-19 22. Pollock N, Patel A, Chakraverty J, Suokas A, James SLJ, Chakraverty R. Time to return to full training is delayed and recurrence rate is higher in intratendinous (‘c’) acute hamstring injury in elite track and field athletes: clinical application of the British Athletics Muscle Injury Classification. Br J Sports Med. 2016;50(5):305-310. doi:10.1136/bjsport s-2015-094657 23. Duhig S, Shield AJ, Opar D, Gabbett TJ, Ferguson C, Williams M. Effect of high-speed running on hamstring strain injury risk. Br J Sports Med. 2016;50(24):1536-1540. doi:10.1136/bjsports-2015-09 5679 24. Malone S, Owen A, Mendes B, Hughes B, Collins K, Gabbett TJ. High-speed running and sprinting as an injury risk factor in soccer: can well-developed physical qualities reduce the risk? J Sci Med Sport.

2018;21(3):257-262. doi:10.1016/j.jsams.2017.05.016 25. Liu H, Garrett WE, Moorman CT, Yu B. Injury rate, mechanism, and risk factors of hamstring strain injuries in sports: a review of the literature. J Sport Heal Sci. 2012;1(2):92-101. doi:10.1016/j.jshs.2012.0 7.003 26. Saw R, Finch CF, Samra D, et al. Injuries in Australian Rules Football: an overview of injury rates, patterns, and mechanisms across all levels of play.

Sports Health. 2018;10(3):208-216. doi:10.1177/19417 38117726070 27. MacDonald B, McAleer S, Kelly S, Chakraverty R, Johnston M, Pollock N. Hamstring rehabilitation in elite track and field athletes: applying the British Athletics Muscle Injury Classification in clinical practice. Br J Sports Med. 2019;53(23):1464-1473. do i:10.1136/bjsports-2017-098971 28. Pollock N, Kelly S, Lee J, et al. A 4-year study of hamstring injury outcomes in elite track and field using the British Athletics rehabilitation approach. Br J Sports Med. 2021;14:bjsports-2020-103791. doi:10.1 136/bjsports-2020-103791

29. Gabbett TJ. The training-injury prevention paradox: should athletes be training smarter and harder? Br J Sports Med. 2016;50(5):273-280. doi:10.1 136/bjsports-2015-095788 30. Tillaar R, Asmund J, Solheim B. Original research comparison of hamstring muscle activation during high-speed running and various hamstring stenghthening exercises. Int J Sports Phys Ther.

2017;12(5):718-727. doi:10.16603/ijspt20170718 31. van Dyk N, Behan FP, Whiteley R. Including the Nordic hamstring exercise in injury prevention programmes halves the rate of hamstring injuries: a systematic review and meta-analysis of 8459 athletes.

Br J Sports Med. 2019;53(21):1362-1370. doi:10.1136/ bjsports-2018-100045 32. Bourne MN, Timmins RG, Opar DA, et al. An evidence-based framework for strengthening exercises to prevent hamstring injury. Sports Med. 2018;48(2):251-267. doi:10.1007/s40279-017-0796-x 33. Giakoumis M, Pollock N, Mias E, et al. Eccentric hamstring strength in elite track and field athletes on the British Athletics world class performance program. Phys Ther Sport. 2020;43:217-223. doi:10.10 16/j.ptsp.2020.03.008 34. Cronin NJ, Peltonen JT, Finni T, Avela J. Differences in contractile behaviour between the soleus and medial gastrocnemius muscles during human walking. J Exp Biol. 2012;216(5):909-914. doi:1 0.1242/jeb.078196 35. Schache AG, Dorn TW, Williams GP, Brown NAT, Pandy MG. Lower-limb muscular strategies for increasing running speed. J Orthop Sports Phys Ther.

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Phys Ther Sport. 2019;37:69-76. doi:10.1016/j.ptsp.20 19.03.002 38. Dorn TW, Schache AG, Pandy MG. Muscular strategy shift in human running: dependence of running speed on hip and ankle muscle performance.

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39. Lai A, Lichtwark GA, Schache AG, Lin YC, Brown NAT, Pandy MG. In vivo behavior of the human soleus muscle with increasing walking and running speeds. J Appl Physiol. 2015;118(10):1266-1275. doi:10.1152/ja pplphysiol.00128.2015 40. Kink S, Johnson A. Achilles tendinopathy. Pocket Foot Ankle Med Surg. 2018;17(2):8-20. doi:10.1007/97 8-3-642-36801-1_181-1 41. Windt J, Gabbett TJ. How do training and competition workloads relate to injury? the workload—injury aetiology model. Br J Sports Med. 2017;51(5):428-435. doi:10.1136/bjsports-2016-09604 0 42. Warden SJ, Davis IS, Fredericson M. Management and prevention of bone stress injuries in longdistance runners. J Orthop Sports Phys Ther.

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44. Gleeson M, Pyne DB. Respiratory inflammation and infections in high‐performance athletes. Immunol Cell Biol. 2016;94(2):124-131. doi:10.1038/icb.2015.10 0 45. Hull JH, Jackson AR, Ranson C, Brown F, Wootten M, Loosemore M. The benefits of a systematic assessment of respiratory health in illnesssusceptible athletes. Eur Respir J. 2020;57(6):03722-02020. doi:10.1183/13993003.0372 2-2020 46. Reardon CL, Hainline B, Aron CM, et al. Mental health in elite athletes: International Olympic Committee consensus statement (2019). Br J Sports Med. 2019;53(11):667-699. doi:10.1136/bjsports-201 9-100715 47. Currie A, Blauwet C, Bindra A, Budget R, Campriani N, et al. Athlete mental health: future directions. Br J Sports Med. 2021;55:1243-1244.

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Schwery NA, Kiely MT, Larson CM, et al. Quadriceps Strength following Anterior Cruciate Ligament Reconstruction: Normative Values based on Sex, Graft Type and Meniscal Status at 3, 6 & 9 Months. IJSPT. 2022;17(3):434-444.

Original Research

Quadriceps Strength following Anterior Cruciate Ligament Reconstruction: Normative Values based on Sex, Graft Type and Meniscal Status at 3, 6 & 9 Months a

Nicole A. Schwery, MS, CSCS 1 , Michael T. Kiely, MS, SCCC 1, Christopher M. Larson, MD 2, Corey A. Wulf, MD 2, Christie S. Heikes, MD 2, Ryan W. Hess, MD 3, M. Russell Giveans, PhD 4, Braidy S. Solie, DPT, SCS, CSCS 1, Chrisopher P. Doney, MS, LAT, ATC 1 1

Training HAUS at Twin Cities Orthopedics, Eagan, MN, USA, 2 Twin Cities Orthopedics, Edina, MN, USA, 3 Twin Cities Orthopedics, Robbinsdale, MN, USA, 4 Training HAUS at Twin Cities Orthopedics, Eagan, MN, USA; Twin Cities Orthopedics, Edina, MN, USA Keywords: quadriceps, strength, isometric, meniscus, anterior cruciate ligament reconstruction https://doi.org/10.26603/001c.32378

International Journal of Sports Physical Therapy Vol. 17, Issue 3, 2022

Background Higher postoperative quadriceps function has been positively associated with surgical outcomes after anterior cruciate ligament reconstruction (ACLR). However, the impact of autograft harvest and/or a concomitant meniscal procedure on the recovery of quadriceps strength is not well defined.

Purpose To describe postoperative recovery of quadriceps strength following ACLR related to autograft selection, meniscal status, and sex.

Study Design Retrospective Cohort.

Methods One hundred and twenty-five participants who underwent ACLR with either a hamstring tendon (HT), bone-patellar tendon-bone (BPTB) or quadriceps tendon (QT) autograft were included. At postoperative months 3, 6 and 9, each participant completed an isometric quadriceps strength testing protocol at 90-degrees of knee flexion. Participants’ quadriceps average peak torque (Q-AvgPKT), average peak torque relative to body weight (Q-RPKT), and calculated limb symmetry index (Q-LSI) were collected and used for data analysis. Patients were placed in groups based on sex, graft type, and whether they had a concomitant meniscal procedure at the time of ACLR. At each time point, One-way ANOVAs, independent samples t-test and chi-square analyses were used to test for any between-group differences in strength outcomes.

Results At three months after ACLR, Q-RPKT was significantly higher in those with the HT compared to the QT. At all time points, males had significantly greater Q-RPKT than females and HT Q-LSI was significantly higher than BPTB and QT. A concomitant meniscal procedure at the time of ACLR did not significantly affect Q-LSI or Q-RPKT at any testing point.

a

Corresponding author: Nicole Schwery, MS, CSCS Training HAUS at Twin Cities Orthopedics 2645 Vikings Circle, Suite 200 Eagan, MN 55121 952-456-7650 NicoleSchwery@TrainingHAUS.com

Quadriceps Strength following Anterior Cruciate Ligament Reconstruction: Normative Values based on Sex, Graft Type and...

Conclusion This study provides outcomes that are procedure specific as well as highlights the objective progression of quadriceps strength after ACLR. This information may help better-define the normal recovery of function, as well as guide rehabilitation strategies after ACLR.

Level of Evidence 3

INTRODUCTION Anterior cruciate ligament reconstruction (ACLR) is the primary surgical procedure for restoring anatomic knee stability after an anterior cruciate ligament injury. Despite improvements in ACLR indications, techniques, and postoperative rehabilitation,1–3 a large proportion of patients continue to report long-term reductions in physical function.4 Stronger and more symmetrical quadriceps strength has consistently been associated with better surgical outcomes.5–12 Prior ACLR studies have highlighted a positive correlation between higher quadriceps strength and improved knee function within the surgical limb, as well as a reduced risk of recurrent knee injuries.12–15 In reference to long-term joint health after ACLR, poor postoperative quadriceps function may be an intervening risk factor in the development of post-traumatic osteoarthritis within the knee.16,17 There are a number of considerations for ACLR graft harvest selection with each option having advantages and disadvantages, but research is limited on graft specific objective performance outcomes. Bone-patellar tendon-bone autograft (BPTB) has been reported as the superior graft choice for athletes,18,19 but carries an increased risk of patellar fracture,20 kneeling difficulty,21 and anterior knee pain.19,22–24 Compared to the BPTB, the hamstring tendon (HT) autograft may produce fewer graft harvest site complications,25 but yield an increase prevalence of joint laxity and delayed graft maturation.26–28 More recently, outcomes for the quadriceps tendon (QT) autograft have been reported to be comparable to the BPTB and HT autograft,22,24,29 but the QT produces significantly less initial quadriceps weakness than the BPTB autograft.23 Current evidence suggests no significant difference in graft failure rates between BPTB, HT and QT autografts, 19,24 but studies have suggested graft-specific impairments in muscle function after ACLR, to which the recovery of postoperative quadriceps strength is partially dictated by graft selection itself.30–32 Specifically, ACLR with a BPTB may produce larger reductions in quadriceps function, require more time to recover quadriceps strength, and be slower to achieve rehabilitation milestones compared to the HT autograft or an allograft procedure.33 The above observations are paralleled by research highlighting persistent impairments in quadriceps function at longer-term follow up, independent of graft type.17,34–37 Regardless of graft selection for ACLR, higher postoperative quadriceps strength at mid-term follow-up has been consistently correlated with better knee function at longer-term follow up.38–40 Although greater quadriceps strength may facilitate a better ACLR outcome10,11, the majority of these

studies have reported the between-limb, level of quadriceps strength-symmetry as the outcome of interest rather than the actual quadriceps strength relative to the participants’ body weight.41 The quadriceps limb symmetry index (QLSI) approach to quantifying muscle strength assumes the non-surgical limb’s strength-value is an adequate benchmark from which to compare the reconstructed knee’s muscles. Most of the recent literature has reported that athletes achieve a Q-LSI anywhere between 73% and 95% at their time of return to activities, which has been measured both isometrically and isokinetically.5,11,13,41–43 However, data published by Chung et al37 has highlighted the fact unilateral ACL injury can produce reductions in muscle strength within the uninjured limb, and suboptimal muscle function is still present at the time of return to sport. For this reason, the use of Q-LSI without consideration of the individual’s relative strength levels when assessing functional status should be questioned. To the authors’ knowledge, two studies to date have investigated the ability of Q-LSI and relative strength values to predict patient-reported knee function.44,45 Kuenze et al44 suggest an isometric relative quadriceps strength value ≥ 3.00 newton-meters/kilogram (Nm/kg) is an acceptable indicator of good patient-reported knee function 2.5 years after ACLR, whereas a Q-LSI ≥ 84.7% is less indicative of higher outcome scores. With similar methods, Pietrosimone et al45 established an isokinetic relative quadriceps strength value of >3.10 Nm/kg as a good indicator of higher patient reported outcome at three years post ACLR. The potential for inconsistency in quadriceps strength and muscle recovery exists after ACLR, necessitates more detailed reporting of strength outcomes which are specific to the ACLR procedure. Few studies comment on the progression of quadriceps strength relative to the participant’s body weight,46–50 but these studies are limited to only reporting isokinetic data and lack procedure-specific comparisons. Specifically, no study has presented the progression of isometric quadriceps strength within a population of BPTB, HT, and QT autografts at 3, 6, and 9 months after ACLR. Studies with this level of procedure-specific detail can help better define the normal recovery of quadriceps strength after ACLR. Therefore, the purpose of this study was to describe postoperative recovery of quadriceps strength following ACLR related to autograft selection, meniscal status, and sex.

MATERIALS AND METHODS Between September 2018 and May 2020, 125 competitive and recreational athletes who underwent an ACLR procedure were included in this study; 85% of the participants

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Quadriceps Strength following Anterior Cruciate Ligament Reconstruction: Normative Values based on Sex, Graft Type and...

were involved in either Level I or II cutting, pivoting, jumping, and lateral movement.51 Participants were included if they had undergone ACLR with either a HT, BPTB or QT autograft. Patients who underwent ACLR with a concomitant meniscal repair or meniscectomy were also included. Those with meniscectomies were included in the non-meniscus group for analysis due to lack of weight bearing and range of motion restrictions. Exclusion criteria included those having undergone a contralateral ACLR, a revision ACLR; having a multi-ligament knee injury or graft harvest from the contralateral limb; or any previous knee surgeries on either limb. The study was conducted under institutional review board approval (Advarra, 08.19.2019 NS_HAUS). All testing procedures were explained to each participant and an informed consent document was signed prior to testing.

Parental consent and youth assent were obtained for all participants under the age of 18 years. All data was collected at the Training HAUS Sports Science Lab at Twin Cities Orthopedics (Eagan, MN).

All participants underwent quadriceps strength testing between three and nine months after ACLR. Participants completed testing at three separate time points within 1.5 months of their 3, 6 and 9-month postoperative date. For three month testing, no participants were tested earlier than 2.4 months after ACLR. Isometric quadriceps strength tests were all performed using an isokinetic dynamometer (Biodex Medical Systems, Inc., Shirley, NY). Due to the varying postoperative precautions present during the early stages of recovery after an ACLR, isometric contractions at 90-degrees where utilized to test quadriceps strength instead of an isokinetic protocol.20,27,45,52,53 Before testing, participants were taken through a dynamic warm-up led by a physical therapist, athletic trainer or sports performance coach. For strength testing, participants were seated with the knee positioned so that the lateral femoral epicondyle aligned with the dynamometer’s axis of rotation. Thigh, waist, and two chest straps were used to secure the participant to the chair. The dynamometer’s force-arm was secured superior to the lateral malleolus of the ankle. Each participant completed a warm-up protocol on the dynamometer consisting of four, isokinetic knee extensions through a self-selected range of motion. For isometric testing, the knee was positioned at 90-degrees of flexion and all participants were asked to apply as much force as possible against the fixed arm of the dynamometer throughout the duration of the test. One maximal voluntary isometric contraction (MVIC) torque for the quadriceps, recorded in Nm, was completed against the arm of the dynamometer; this was done to practice the subsequent isometric strength test. Three, MVICs were completed for fiveseconds in duration, with a 30-second rest interval in between each repetition. For all participants, testing was completed on the non-surgical limb first, followed by testing of the surgical limb. The average of the three peak torque values was calculated (Q-AvgPKT) and normalized to body mass in kilograms (Q-RPKT). Q-LSI was calculated at each time point utilizing Q-AvgPKT with the following equation: (Q-AvgPKT surgical limb/ Q-AvgPKT non-surgical limb) x 100. The variables used in analysis were Q-RPKT and Q-LSI. An a priori power analysis was completed for three inde-

pendent groups, a medium effect size and a power of 0.80.

For the data set to be adequately powered, a total sample size of 115 patients would be needed with a minimum of 15 patients within each group. Kolmogorov-Smirnov and Shapiro-Wilk tests were used to confirm normality within the collected data set for this study. When applicable, oneway ANOVAs, as well as independent samples t-tests and chi-square tests were used to determine mean differences between the three groups. Statistical analyses were performed with SPSS version 24 (IBM Corp., Armonk, NY, USA), and significance was set at p < 0.05.

RESULTS Patient demographics are presented in Table 1. Procedurespecific quadriceps strength variables, organized by postoperative time point, are presented in Table 2. The testing protocol used in this study did not result in any surgical complications when implemented as early as three months after ACLR, suggesting an isometric testing protocol on an isokinetic dynamometer is a safe and clinically reasonable way to assess quadriceps strength during the early stages of rehabilitation after ACLR. At postoperative months 3, 6 and 9, quadriceps Q-LSI was found to be significantly higher in patients who had undergone ACLR with the HT autograft than with the BPTB and QT (p< .001). At three months after ACLR, Q-RPKT was found to be significantly higher in those with the HT compared to the QT (p<.05). There were no significant differences in Q-RPKT between graft types at six and nine months after ACLR. At all three postoperative time points, males had significantly greater Q-RPKT than females (p<.01) but no differences in Q-LSI was observed between sexes. Compared to those who received an isolated ACLR procedure, no significant difference in Q-LSI or QRPKT was found in those with a concomitant meniscal procedure at the time of ACLR.

DISCUSSION The purpose of this study was to describe the postoperative recovery of quadriceps strength after ACLR. Before determining the clinical significance of any findings, the reader must first acknowledge the observed distribution of quadriceps strength within the cohort. At all three testing points, those receiving the BPTB and QT autografts for ACLR presented with a wider distribution of Q-LSI values than was observed in the HT group (Figure 1. d-f).

Additionally, those receiving the BPTB autograft tended to have a more consistent improvement in Q-LSI throughout the postoperative testing period, which is reflected in the higher absolute BPTB frequency-distribution percentages compared to the QT autograft at the six and nine month testing points. Collectively, these observations suggest that at three months after ACLR, a larger distribution in Q-LSI may be expected in those receiving the BPTB or QT for ACLR, compared to the HT autograft.

This study’s findings also suggest individuals receiving the HT autograft for ACLR may exhibit a greater Q-LSI throughout the postoperative rehabilitation period, compared to those receiving the BPTB and QT autografts. This

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Quadriceps Strength following Anterior Cruciate Ligament Reconstruction: Normative Values based on Sex, Graft Type and...

Table 1. Participant Demographicsa Demographic

Measure

Sex

Female: 74 Male: 51

Age (y)

18.52 (5.08)

Height (m)

1.71 (0.09)

Weight (kg)

69.57 (14.37)

Testing Time Post-Op (months)

Early: 3.48 (0.57) Mid: 6.37 (0.61) Late: 9.23 (0.64)

Sport Levels51

Level I: 97 Level II: 23 Level III: 5

Limb Involved

Right: 51 Left: 74

Graft Type

BPTB: 87 HT: 21 QT: 17

Meniscal Involvement

Yes: 45 No: 80

aValues are presented as mean (SD) or number

BPTB = bone-patellar tendon-bone, HT = hamstring tendon, QT = quadriceps tendon

finding is not a novel contribution to the ACLR literature, as prior studies have reported graft-specific reductions in muscle strength after ACLR. Fischer et al54 reported a difference in muscle strength between the HT and the QT autografts used for ACLR, to which a similarly higher level of Q-LSI was observed in those with the HT compared to the QT. Considering this, this study’s findings further suggest that graft harvest site is a relevant functional consideration for Q-LSI after ACLR, as graft specific impairments in quadriceps symmetry between limbs may be expected with the BPTB and QT autografts, compared to the HT. At three months after ACLR, this study suggests individuals receiving the HT may expect a statistically greater level of Q-RPKT than those receiving the QT autograft. BPTB QRPKT was less than HT and greater than QT, but these differences were not statistically different. These decreased QRPKT values in QT and BTB may be present due to graft harvest from the knee extensor mechanics resulting in decreased tendon capacity. At postoperative months six and nine, no between-graft differences in Q-RPKT were found between any of the three autograft types (Table 2). Prior research has suggested any between-graft differences in quadriceps strength may only be clinically distinguishable during the early phases of rehabilitation after ACLR;55 a notion which these findings support. These findings may

support the idea that factors other than graft harvest site are responsible for relative strength values not reaching previously reported values for higher outcomes by nine months.44,45 Further research is needed to assess the relevance and relationship of Q-RPKT to the timing of returnto-sport (RTS) and graft rupture rates.

The statistically lower Q-LSI values observed after ACLR with the BPTB and QT, compared to the HT autograft, may be partially explained by the body’s protective response to donor site morbidity. Previously published biomechanical research has highlighted a 25% and 34% relative reduction in the absolute tensile strength of the patellar and quadriceps tendons after autograft harvest, respectively.56 It also appears having a concomitant meniscal procedure at the time of ACLR does not impact Q-RPKT or Q-LSI levels, and although males presented with a greater Q-RPKT than females, sex did not significantly impact Q-LSI levels. Collectively, these findings may suggest the low Q-LSI observed with the BPTB and QT, and Q-RPKT with the QT autograft at three months, is partially due to trauma to the extensor mechanism during graft harvest rather than any additional meniscal procedure at the time of ACLR.

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Quadriceps Strength following Anterior Cruciate Ligament Reconstruction: Normative Values based on Sex, Graft Type and...

Table 2. Mean Values of Strength & Symmetry over Stages of Rehabilitation, all data presented mean (SD) 3 month

6 month

9 month

n

Non-Surgical QRPKT (Nm/kg)

Surgical QRPKT (Nm/kg)

Q-LSI (%)

Non-Surgical QRPKT (Nm/kg)

Surgical QRPKT (Nm/kg)

Q-LSI (%)

Non-Surgical QRPKT (Nm/kg)

Surgical QRPKT (Nm/kg)

Q-LSI (%)

BPTB

87

2.75 (0.60)

1.64 (0.50)

60% (0.13)

2.88 (0.68)

2.12 (0.59)

74% (0.13)

2.93 (0.67)

2.46 (0.66)

84% (0.14)

HT

21

2.41 (0.42)

1.83 (0.42)

76% (0.12)

2.45 (0.46)

2.25 (0.54)

92% (0.13)

2.74 (0.54)

2.61 (0.59)

96% (0.16)

QT

17

2.63 (0.69)

1.39 (0.67)

52% (0.17)

2.79 (0.61)

1.87 (0.70)

67% (0.20)

2.85 (.044)

2.24 (0.78)

77% (0.19)

p=.059

p=.035†

p<.001‡§

p=.025*

p=.146

p<.001‡§

p=.443

p=.237

p<.001†§

p value Meniscus

45

2.77 (0.57)

1.72 (0.40)

63% (0.13)

2.85 (0.63)

2.16 (0.49)

76% (0.14)

2.94 (0.56)

2.49 (0.60)

85% (0.15)

No Meniscus

80

2.62 (0.59)

1.59 (0.58)

60% (0.60)

2.76 (0.67)

2.09 (0.68)

76% (0.17)

2.86 (0.64)

2.44 (0.73)

85% (0.17)

p=.170

p=.185

p=.285

p=.463

p=.545

p=.999

p=.485

p=.697

p=.999

p value Male

51

2.94 (0.61)

1.88 (0.58)

64% (0.15)

3.15 (0.70)

2.42 (0.69)

77% (0.16)

3.18 (0.61)

2.78 (0.74)

87% (0.16)

Female

74

2.49 (0.50)

1.47 (0.41)

60% (0.14)

2.55 (0.50)

1.9 (0.45)

75% (0.16)

2.68 (0.52)

2.23 (0.54)

84% (0.16)

p<.001

p<.001

p=.130

p<.001

p<.001

p=.494

p<.001

p<.001

p=.305

p value

* Statistically significant difference between BPTB & HT (p< 0.05), † Statistically significant difference between HT & QT (p< 0.05), ‡ Statistically significant difference between HT & QT (p< 0.001), §Statistically significant difference between BPTB & HT (p< 0.0001), Q-RPKT = quadriceps average peak torque normalized to body mass, Q-LSI = quadriceps limb symmetry index, BPTB = bone-patellar tendon-bone, HT = hamstring tendon, QT = quadriceps tendon

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Quadriceps Strength following Anterior Cruciate Ligament Reconstruction: Normative Values based on Sex, Graft Type and...

Figure 1a-f. Quadriceps Relative Peak Torque and Limb Symmetry Index Frequency Distribution by Graft Type: 3, 6 and 9 month postoperative. (a-c RPKT; d-f LSI)

When discussing RTS after ACLR, recent authors have shown that only 65% of athletes return to their pre-injury level of sports participation.57 An improved understanding of the contextual factors associated with RTS has shown a greater subjective report of knee function is positively correlated with an improving likelihood of an athlete returning to their pre-injury level of sport.58 Prior research has highlighted a positive relationship between greater Q-LSI and patient reported knee function, but fewer studies have investigated the relationship between Q-RPKT and subjective knee function. Kuenze et al44 reported an isometric relative strength cut-off value of ≥ 3.00 Nm/kg may be a more sensitive predictor of good patient-reported knee function in recreational athletes than Q-LSI. This however, was collected in recreational individuals beyond traditional time points of returning to sport. The majority of this current study’s population participated in Level I/II sports with 52% of HT, 22% of BPTB and 35% of QT achieving the previously mentioned Q-RPKT ≥ 3.00Nm/kg by the nine month post-

surgery time point (Figure 1. a-c). These findings suggest that at nine months after ACLR, a relatively low proportion of this cohort achieved the level of Q-RPKT that may be assumed to present with a high self-report of knee function.

Smith et al33 have previously highlighted a discrepancy between subjective reporting of knee function and objective functional status within a cohort of athletes after ACLR. Athletes who had an ACLR with the BPTB were slower to achieve rehabilitation milestones and functional criteria than those with the HT or allograft, but no statistical, between-graft differences were observed in the subjective reporting of knee function. However, it is important to note that Smith et al33 used Q-LSI, rather than Q-RPKT, to quantify quadriceps function, and therefore, inferences from their study on the relationship between Q-RPKT and subjective knee function within this cohort is not directly comparable.

Q-LSI is commonly used as an objective outcome within the RTS decision-making process. Considering this, HT au-

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Quadriceps Strength following Anterior Cruciate Ligament Reconstruction: Normative Values based on Sex, Graft Type and...

tografts consistently had more individuals testing ≥ 90% Q-LSI at all three testing points, with less variability in strength testing scores than the BPTB and QT autografts.

This finding, alone, may be useful to clinicians when implementing criteria-based rehabilitation for an athlete. For instance, a medical team may elect to more closely monitor the progression of quadriceps strength throughout the postoperative rehabilitation period for athletes undergoing ACLR with the BPTB or QT compared to the HT, as well as implement a longer and more specific quadriceps strengthening program. Lastly, the procedure-specific Q-LSI and QRPKT values within this study may be used as normative data for clinicians to cross-reference when implementing criteria-based rehabilitation after ACLR for those returning to Level I and II sports, as well as recreational athletes returning to activity.

Strengths of this study include the standardization of data collection; testing of participants at multiple testing periods; and the direct comparison of quadriceps strength between the HT, BPTB, and QT autografts for ACLR. However, this study has several limitations worth mentioning.

(1) This study was a retrospective analysis of prospectively collected data, and therefore, subject to the innate limitations of a retrospective study design. (2) Wide age-range within this cohort may make it difficult to extrapolate the normative data to more specific populations, such as young athletes returning to sport. (3) Participants were recruited from a single metropolitan city, making the possibility of a regional bias reflected within the study’s outcomes. (4) ACLR procedures were completed by 36 different surgeons; specific postoperative rehabilitation protocols, number of therapy visits, quality of rehabilitation, variance in surgical techniques and supplemental training was not standardized or described. (5) Weight bearing status was not taken into account for the meniscus repair group. (6) Lastly, a relatively low number of ACLR procedures with the QT and HT, compared to the BPTB, were completed within this cohort.

CONCLUSION The results of this study outline isometric quadriceps strength progression specific to graft type, sex and meniscal involvement. Q-LSI was significantly greater in HT compared to BPTB and QT graft types at all three time points.

Q-RPKT for QT was significantly lower than HT at 3-months, postoperatively. At all time points, males presented with significantly greater Q-RPKT than females, but sex did not significantly impact Q-LSI. Lastly, receiving a concomitant meniscal procedure at the time of ACLR did not statistically impact Q-RPKT or Q-LSI. The strength data found within this paper can be used to better understand the recovery of quadriceps strength after ACLR, as well as be used to optimize the rehabilitation plan of care based on surgical procedure. Future analysis on this population from subsequent testing sessions at later time points and evaluation of self-reported function will further provide additional insight into isometric quadriceps strength progression following ACLR.

CONFLICTS OF INTEREST

The authors report no conflicts of interest.

ACKNOWLEDGEMENTS

We thank the Twin Cities Orthopedics surgeons and physical therapists who referred their patients to be participants in this study. We also acknowledge Becky Stone McGaver for her contribution to this work.

Submitted: July 26, 2021 CDT, Accepted: December 09, 2021 CDT

This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CCBY-NC-4.0). View this license’s legal deed at https://creativecommons.org/licenses/by-nc/4.0 and legal code at https://creativecommons.org/licenses/by-nc/4.0/legalcode for more information.

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Quadriceps Strength following Anterior Cruciate Ligament Reconstruction: Normative Values based on Sex, Graft Type and...

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42. Zwolski C, Schmitt LC, Thomas S, Hewett TE, Paterno MV. The utility of limb symmetry indices in return-to-sport assessment in patients with bilateral anterior cruciate ligament reconstruction. Am J Sports Med. 2016;44(8):2030-2038. doi:10.1177/0363546516 645084 43. Toole AR, Ithurburn MP, Rauh MJ, Hewett TE, Paterno MV, Schmitt LC. Young athletes after anterior cruciate ligament reconstruction cleared for sports participation: how many actually meet recommended return-to-sport criteria cutoffs? J Orthop Sport Phys Ther. Published online October 7, 2017:1-27. doi:10.2 519/jospt.2017.7227 44. Kuenze C, Hertel J, Saliba S, Diduch DR, Weltman A, Hart JM. Clinical thresholds for quadriceps assessment after anterior cruciate ligament reconstruction. J Sport Rehabil. 2015;24(1). doi:10.112 3/jsr.2013-0110 45. Pietrosimone B, Lepley AS, Harkey MS, et al.

Quadriceps strength predicts self-reported function post-ACL reconstruction. Med Sci Sports Exerc.

2016;48(9):1671-1677. doi:10.1249/MSS.00000000000 00946 46. Goto S, Garrison JC, Hannon JP, et al. Quadriceps strength changes across the continuum of care in adolescent male and female athletes with anterior cruciate ligament injury and reconstruction. Phys Ther Sport. 2020;46:214-219. doi:10.1016/j.ptsp.202 0.08.016 47. Garrison JC, Hannon J, Goto S, et al. Knee loading after ACL-R is related to quadriceps strength and knee extension differences across the continuum of care. Orthop J Sport Med. 2019;7(10):1-8. doi:10.1177/ 2325967119870155 48. Ueda Y, Matsushita T, Shibata Y, et al.

Longitudinal quadriceps strength recovery after anterior cruciate ligament reconstruction with hamstring autograft: patients stratified by preoperative quadriceps strength deficit. J Sport Rehabil. 2020;29(5):602-607. doi:10.1123/jsr.2018-023 6 49. Welling W, Benjaminse A, Seil R, Lemmink K, Zaffagnini S, Gokeler A. Low rates of patients meeting return to sport criteria 9 months after anterior cruciate ligament reconstruction: a prospective longitudinal study. Knee Surgery, Sport Traumatol Arthrosc. 2018;26(12). doi:10.1007/s00167-018-491 6-4 50. Pottkotter KA, Di Stasi SL, Schmitt LC, et al.

Timeline of gains in quadriceps strength symmetry and patient-reported function early after ACL reconstruction. Int J Sports Phys Ther.

2020;15(6):995-1005. doi:10.26603/ijspt20200995

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Quadriceps Strength following Anterior Cruciate Ligament Reconstruction: Normative Values based on Sex, Graft Type and...

51. Daniel DM, Stone ML, Dobson BE, Fithian DC, Rossman DJ, Kaufman KR. Fate of the ACL-injured patient: a prospective outcome study. Am J Sports Med. 1994;22(5):632-644. doi:10.1177/036354659402 200511 52. Maffiuletti NA, Bizzini M, Desbrosses K, Babault N, Munzinger U. Reliability of knee extension and flexion measurements using the Con-Trex isokinetic dynamometer. Clin Physiol Funct Imaging.

2007;27(6):346-353. doi:10.1111/j.1475-097X.2007.00 758.x 53. Pincivero DM, Salfetnikov Y, Campy RM, Coelho AJ. Angle- and gender-specific quadriceps femoris muscle recruitment and knee extensor torque. J Biomech. 2004;37(11). doi:10.1016/j.jbiomech.2004.0 2.005 54. Fischer F, Fink C, Herbst E, et al. Higher hamstring-to-quadriceps isokinetic strength ratio during the first post-operative months in patients with quadriceps tendon compared to hamstring tendon graft following ACL reconstruction. Knee Surgery, Sport Traumatol Arthrosc.

2018;26(2):418-425. doi:10.1007/s00167-017-4522-x

55. Johnston PT, McClelland JA, Feller JA, Webster KE. Knee muscle strength after quadriceps tendon autograft anterior cruciate ligament reconstruction: systematic review and meta-analysis. Knee Surgery, Sport Traumatol Arthrosc. 2021;29(9). doi:10.1007/s00 167-020-06311-y 56. Adams DJ, Mazzocca AD, Fulkerson JP. Residual strength of the quadriceps versus patellar tendon after harvesting a central free tendon graft. Arthrosc J Arthrosc Relat Surg. 2006;22(1):76-79. doi:10.1016/j.ar thro.2005.10.015 57. Ardern CL, Taylor NF, Feller JA, Webster KE. Fiftyfive per cent return to competitive sport following anterior cruciate ligament reconstruction surgery: an updated systematic review and meta-analysis including aspects of physical functioning and contextual factors. Br J Sports Med. 2014;48(21). doi:1 0.1136/bjsports-2013-093398 58. Ardern CL. Anterior cruciate ligament reconstruction—not exactly a one-way ticket back to the preinjury level. Sports Health. 2015;7(3):224-230. doi:10.1177/1941738115578131

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38. Decker MJ, Torry MR, Noonan TJ, Riviere A, Sterett WI. Landing adaptations after ACL reconstruction. Med Sci Sports Exerc.

2002;34(9):1408-1413. doi:10.1097/00005768-200209 000-00002

43. McPherson AL, Feller JA, Hewett TE, Webster KE. Psychological readiness to return to sport is associated with second anterior cruciate ligament injuries. Am J Sports Med. 2019;47(4):857-862. doi:1 0.1177/0363546518825258

39. Kuenze CM, Trigsted S, Lisee C, Post E, Bell DR. Sex differences on the landing error scoring system among individuals with anterior cruciate ligament reconstruction. J Athl Train. 2018;53(9):837-843. doi:1 0.4085/1062-6050-459-17

44. Dragoo JL, Braun HJ, Durham JL, Chen MR, Harris AHS. Incidence and risk factors for injuries to the anterior cruciate ligament in National Collegiate Athletic Association Football: data from the 2004-2005 through 2008-2009 National Collegiate Athletic Association injury surveillance system. Am J Sports Med. 2012;40(5):990-995. doi:10.1177/0363546 512442336

40. Grindem H, Snyder-Mackler L, Moksnes H, Engebretsen L, Risberg MA. Simple decision rules can reduce reinjury risk by 84% after ACL reconstruction: the Delaware-Oslo ACL cohort study. Br J Sports Med. 2016;50(13):804-808. doi:10.1136/bjsports-2016-0960 31 41. Kyritsis P, Bahr R, Landreau P, Miladi R, Witvrouw E. Likelihood of ACL graft rupture: not meeting six clinical discharge criteria before return to sport is associated with a four times greater risk of rupture. Br J Sports Med. 2016;50(15):946-951. doi:10.1136/bjspor ts-2015-095908 42. Paterno M, Schmitt L, Ford K, et al. Biomechanical measures during landing and postural stability predict second ACL injury after ACL reconstruction and return to sport. Am J Sports Med. 2010;38(10):1968-1978. doi:10.1177/03635465103760 53

45. DeLang MD, Hannon JP, Goto S, Bothwell JM, Garrison JC. Female adolescent soccer players utilize different neuromuscular strategies between limbs during the propulsion phase of a lateral vertical jump.

Int J Sports Phys Ther. 2021;16(3):695-703. doi:10.266 03/001c.22134 46. Malafronte J, Hannon J, Goto S, et al. Limb dominance influences energy absorption contribution (EAC) during landing after anterior cruciate ligament reconstruction. Phys Ther Sport. 2021;50:42-49. doi:1 0.1016/j.ptsp.2021.03.015 47. Dai B, Butler RJ, Garrett WE, Queen RM. Using ground reaction force to predict knee kinetic asymmetry following anterior cruciate ligament reconstruction. Scand J Med Sci Sports.

2014;24(6):974-981. doi:10.1111/sms.12118

International Journal of Sports Physical Therapy

Chaaban CR, Hearn D, Goerger B, Padua DA. Are Elite Collegiate Female Athletes PRIME for a Safe Return to Sport after ACLR? An Investigation of Physical Readiness and Integrated Movement Efficiency (PRIME). IJSPT. 2022;17(3):445-455.

Original Research

Are Elite Collegiate Female Athletes PRIME for a Safe Return to Sport after ACLR? An Investigation of Physical Readiness and Integrated Movement Efficiency (PRIME) Courtney R Chaaban, PT, DPT 1 ATC, PhD 1 1

a

, Darren Hearn, PT, PhD, MPH, OCS 2, Benjamin Goerger, ATC, PhD 1, Darin A Padua,

Exercise and Sport Science, University of North Carolina at Chapel Hill, 2 Human Performance and Sports Medicine, Fort Bragg

Keywords: return to sport, elite athlete, female athlete, anterior cruciate ligament, ACL https://doi.org/10.26603/001c.32529

International Journal of Sports Physical Therapy Vol. 17, Issue 3, 2022

Background Elite female athletes who successfully return to sport after anterior cruciate ligament reconstruction (ACLR) represent a high-risk group for secondary injury. Little is known about how the functional profile of these athletes compares to their teammates who have not sustained ACL injuries.

Purpose To compare elite collegiate female athletes who were able to successfully return to sport for at least one season following ACLR to their teammates with no history of ACLR with regard to self-reported knee function, kinetics, and kinematics during a double limb jump-landing task.

Study Design Cross-Sectional Study

Level of Evidence Level 3

Methods Eighty-two female collegiate athletes (17 ACLR, 65 control) completed the knee-specific SANE (single assessment numeric evaluation) and three trials of a jump-landing task prior to their competitive season. vGRF data on each limb and the LESS (Landing Error Scoring System) score were collected from the jump-landing task. Knee-SANE, vGRF data, and LESS scores were compared between groups. All athletes were monitored for the duration of their competitive season for ACL injuries.

Results Athletes after ACLR reported worse knee-specific function. Based on vGRF data, they unloaded their involved limb during the impact phase of the landing, and they were more asymmetrical between limbs during the propulsion phase as compared to the control group. The ACLR group, however, had lower LESS scores, indicative of better movement quality. No athletes in either group sustained ACL injuries during the following season.

a

Corresponding author: Courtney R Chaaban, PT, DPT Department of Exercise and Sport Science University of North Carolina at Chapel Hill, CB #8700, 209 Fetzer Hall, Chapel Hill, NC 27599, USA Email: rosscj@live.unc.edu

Are Elite Collegiate Female Athletes PRIME for a Safe Return to Sport after ACLR? An Investigation of Physical Readiness...

Conclusion Despite reporting worse knee function and demonstrating worse kinetics, the ACLR group demonstrated better movement quality relative to their uninjured teammates. This functional profile may correspond to short-term successful outcomes following ACLR, given that no athletes sustained ACL injuries in the competition season following assessment.

INTRODUCTION Female athletes have a higher incidence of anterior cruciate ligament (ACL) injury in both high school and collegiate levels of sports participation.1 This injury incidence is increasing at a faster rate when compared to males.2 ACL reconstruction (ACLR) is often the treatment of choice following ACL injury, and short-term goals following ACLR include return to sport and improved self-reported function.3 Females have significantly worse outcomes for both of these short-term goals: they are less likely to return to competitive sport,4 and they report significantly worse knee-related function5 compared to males. Thus, it is important to understand possible factors that may influence the inferior outcomes observed in female athletes following ACLR. A safe return to sport following ACLR is defined as the ability to return to sport without sustaining a secondary ACL injury, whether to the ACL graft or the contralateral ACL. Secondary ACLR results in a significantly lower rate of return to sport and inferior functional outcomes compared to primary ACLR,6–10 which has implications for short- and long-term knee-related quality of life. Approximately 20-25% of young athletes who return to sport after ACLR have a second ACL injury,11,12 and females after ACLR are approximately five times more likely to sustain an ACL injury compared to females without a history of ACL injury.13 Furthermore, female gender, young age, and return to high activity level all increase the odds of sustaining a second ACL injury.14 Due to the elevated injury incidence, inferior functional outcomes, and high rate of secondary ACL injury, female athletes after ACL injury represent a significant public health challenge. Efforts should be focused on understanding possible modifiable factors associated with the elevated risk of secondary injury and inferior functional outcomes observed in young female athletes who return to a high level of sport, such a Division I collegiate athletics, after ACLR. Double limb jump-landing tasks have been utilized previously both as a screening tool for ACL injury risk15 as well as a portion of a return to sport test battery following ACLR.16 During the landing phase of the task, which is often defined as the period from initial contact to maximum flexion, there are altered lower extremity biomechanics after ACLR in both limbs.17 Additionally, between limb asymmetries are more often observed following ACLR in kinetic as opposed to kinematic variables during this task, including a decrease in the peak vertical ground reaction force (vGRF) of the involved limb.18,19 The Landing Error Scoring System (LESS) is a valid and reliable composite measure of kinematics during this jump-landing-rebound task20,21 that can be combined with the Kinect camera for automated scoring.22 The LESS identifies high-risk movement patterns

(“errors”) at both initial contact and maximum flexion, and generates a cumulative score of errors, whereby a higher score (number of errors) is indicative of poorer movement quality. Prior research has shown that individuals previously cleared to return to recreational sports after ACLR have worse composite scores compared to matched control subjects.23,24 However, these recreational athletes may not have the same kinematic profile of female athletes participating at a higher level of competition after ACLR. Given that ACL injuries occur within the first 50 milliseconds after ground contact,25,26 the analysis of the landing phase temporally aligns with the occurrence of these injuries. Additional insight may be gained from examining the propulsion phase, which occurs as the athlete generates higher vGRF to propel their body into the air following maximum flexion. Analyzing the propulsion phase of this vertical jump may be of interest given that the knee performs a higher percentage of the work relative to the other lower extremity joints when compared to a horizontal jump,27 making this task functionally relevant to athletes who may have deficits in knee function after ACLR. In summary, prior research has demonstrated that following ACLR, individuals report lower function and demonstrate both kinetic asymmetry and poorer movement quality during landing tasks. However, prior research has not specifically investigated elite female athletes who have returned to sport. Given the high risk of future ACL injury within this cohort, a better understanding of those athletes who safely return to elite sport without subsequent injury, particularly in the context of their teammates, may provide insights into return to sport testing criteria and secondary injury prevention efforts.

Therefore, the purpose of this study was to compare elite collegiate female athletes who were able to successfully return to sport for at least one season following ACLR to their teammates with no history of ACLR with regard to selfreported knee function, kinetics and kinematics during a double limb jump-landing task. It was hypothesized that in comparison to their teammates, athletes post-ACLR would report worse knee-related function, demonstrate decreased peak vGRF on their involved limb during landing and propulsion, and have a higher composite LESS score, indicative of poorer movement quality.

METHODS PARTICIPANTS

All members (n=86) of the women’s field hockey, lacrosse, and soccer varsity teams at one Division I university were eligible for enrollment and were recruited to participate prior to their competitive athletic season during an academic year. These sports were selected as they represent the women’s field sports at this university. Additionally, all

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Are Elite Collegiate Female Athletes PRIME for a Safe Return to Sport after ACLR? An Investigation of Physical Readiness...

Figure 1.

Flow diagram of athletes through study. ACLR, anterior cruciate ligament reconstruction. DVJ, drop vertical jump. SANE, single assessment numeric evaluation.

three teams have won at least one national championship in the decade prior to study enrollment, suggesting these teams represent elite collegiate athletes. Athletes were classified according to self-reported injury history: ACLR (at least one prior ACLR reported, n=19), and control (no prior ACLR reported, n=67). Any athlete who had a current lower extremity injury that limited their ability to perform a jump-landing task was excused from the movement assessment described below. Following assessment, all athletes were monitored by the sports medicine staff for ACL injury for one competitive season. A successful return to sport for at least one season was operationally defined as participation in the index sport without a secondary ACL injury during a six-month monitoring period, which coincided with the competitive season, following baseline data collection.

A flow diagram of participants is depicted in Figure 1. The university’s Institutional Review Board approved the study, and written informed consent was obtained from all participants.

PROCEDURES

Demographic and anthropometric information were collected, including age, height, and weight. Participants were given a detailed knee injury history questionnaire. They were asked to report if and when they sustained any ACL injuries, including the limb that was involved and any concomitant injuries. They were asked to report the year they underwent ACLR. They also reported a knee-specific single assessment numeric evaluation (SANE), rated based on the statement: “On a scale of 0-100, how would you rate your involved knee today, with 100 being normal?” The kneespecific SANE is positively correlated with the International Knee Documentation Committee (IKDC) subjective knee

survey in individuals following ACLR28 and was selected in this study due to its time-efficiency.

All participants completed three trials of a double-limb jump-landing movement assessment as previously described.20,22 For the assessment, participants jumped from a 30 cm tall box to side-by-side force plates in front of the box, the center of which was 90 cm from the front edge of the box. They were instructed to complete a maximal vertical jump immediately after landing. A trial was deemed successful if the participant (1) jumped off the box with both feet leaving the box at the same time; (2) jumped forward, not vertically, to reach the force plates; (3) landed with one foot on each force plate; (4) jumped vertically, and not forward, during the maximal jump; and (5) completed the trials in a fluid motion.

Jump-landing trials were recorded by the Kinect camera located 335 cm in front of the front edge of the box (Kinect sensor, version 2, Microsoft Corp, Redmond, WA). The depth-sensing camera was controlled by a standard laptop computer. Concurrently, ground reaction forces were collected at a sampling rate of 1000 Hz from two embedded force plates (FP406020, Bertec Corp), collected through Nexus software (Vicon, Nexus, Oxford, UK).

DATA REDUCTION

In the ACLR group, 17 participants reported one or more prior ACL injuries on one limb only, and the involved limb was defined as the previously injured limb. Two participants in the ACLR group reported ACL injuries on both limbs, and these participants were excluded from analysis given that both limbs were involved. In the control group, the involved limb was randomly assigned as right or left for comparison to the ACLR group as healthy females do not have dif-

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Are Elite Collegiate Female Athletes PRIME for a Safe Return to Sport after ACLR? An Investigation of Physical Readiness...

Table 1. Participant demographics by group. Values are presented as mean ± SD. ACLR (n = 17)

Control (n = 65)

p value

Time from ACLR (years)

2.35 ± 1.28

Age (years)

20.38 ± 1.09

19.63 ± 1.28

0.034*

Height (m)

1.69 ± 0.06

1.66 ± 0.06

0.049*

Mass (kg)

65.47 ± 6.39

63.72 ± 7.97

0.41

ACLR, anterior cruciate ligament reconstruction. * indicates statistically significant difference at p < 0.05

ferences in peak vGRF between limbs based on limb dominance.29 Athletic Movement Assessment software (PhysiMax Technologies Ltd, Tel Aviv, Israel) was used to evaluate the Kinect camera data to score the LESS. This method of automated scoring has been validated against expert raters.22 The LESS was scored based on the scoring criteria described

by Mauntel,22 evaluating the frames of initial contact and maximum knee flexion for common kinematic “errors,” such as asymmetry. Scores were averaged across the three trials for each participant. Higher scores indicated more errors, with a minimum score of 0 errors and a maximum score of 24 errors.

A custom MATLAB (MATLAB version R2019a, The MathWorks Inc, Natick, MA) script was used to extract kinetic variables of interest from the ground reaction force data during the ground contact separately for each limb on each trial. Ground contact was defined as the period during which the vertical component of the ground reaction force (vGRF) exceeded 20 Newtons (N).30,31 Two phases of ground contact were defined: impact phase and propulsion phase. The impact phase was the first 200 milliseconds (ms) of ground contact for each limb. The time frame of the impact phase was selected as it captured all peak vGRF values.

The impact phase likely represents a subset of the landing phase, as there was not kinematic data available to indicate when maximum flexion occurred. The propulsion phase was the second half of ground contact. The peak vGRF values during the impact and propulsion phases were extracted for each limb during each trial. vGRF data were normalized to body weight (BW) in N for each subject and reported in multiples of BW. The limb symmetry index (LSI) for each variable was calculated as: (involved limb / uninvolved limb) x 100. Values were averaged across three trials for each participant for each limb (involved and uninvolved).

within-subjects factor were conducted to determine differences in kinetic variables (peak vGRF during the impact and propulsion phases). If findings were significant, four planned pairwise comparisons (between group and limb) were conducted with a Bonferroni-corrected α level of 0.0125. If parametric assumptions were not met, the Wilcoxon signed-rank test was used for within group comparisons and Mann-Whitney U test was used for between group comparisons. All statistical analyses were performed in jamovi (version 1.6.1.0, The jamovi project).

RESULTS DESCRIPTIVE DATA

The final analyses included 17 athletes in the ACLR group and 65 athletes in the control group. Participant descriptive data are presented in Table 1. All participants in the ACLR group were at least one-year post-ACLR. The mean time from ACLR to testing was 2.4 ± 1.3 years. Participants in the ACLR group were significantly older and taller than the control group. There were no significant differences in body mass between groups (p>0.05).

SANE AND LESS

The knee SANE score was significantly lower in the ACLR group compared to the control group (p=0.002), suggestive of worse self-reported function in the ACLR group, as displayed in Figure 2a. The LESS score was significantly lower in the ACLR group compared to the control group (p=0.026), indicating the ACLR group demonstrated better movement quality compared to the control group, as displayed in Figure 2b. Knee SANE and LESS summary statistics are displayed in Table 2.

VGRF-IMPACT PHASE

STATISTICAL ANALYSIS

An alpha level was set a priori at α ≤ 0.05. Independent samples t-tests were used to assess differences in knee SANE and LESS composite scores between groups (ACLR vs. control). In addition, Cohen d effect sizes and associated 95% confidence interval were calculated.32 Effect size estimates were classified as small (0.2), moderate (0.5), and large (0.8).32 Separate two-way mixed model analyses of variance (ANOVA) with group (ACLR vs. control) as the betweensubjects factor and limb (involved vs. uninvolved) as the

Individual participant means and distribution by group for the impact phase and propulsion phase are displayed in raincloud plots33 in Figure 3. During the impact phase, there was a significant interaction effect (F(1,80)=6.37, p=0.013) and a significant main effect for limb (p=0.048), but no significant main effect for injury history (p=0.51).

Based on planned pairwise comparisons, the ACLR involved limb (1.92 ± 0.49 BW) differed from the control involved limb (2.34 ± 0.57 BW), p=0.003, indicative of underloading in the ACLR group compared to the control group. No other

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Are Elite Collegiate Female Athletes PRIME for a Safe Return to Sport after ACLR? An Investigation of Physical Readiness...

Table 2. Knee SANE and LESS scores by group. Values are presented as mean ± SD. ACLR (n = 17)

Control (n = 65)

p value

Effect size [95% CI]

Knee SANE

89.41 ± 7.63

96.55 ± 8.09

0.002*

0.89 [0.33, 1.45]

LESS score

4.06 ± 1.52

5.32 ± 2.16

0.026*

0.62 [0.07, 1.16]

ACLR, anterior cruciate ligament reconstruction. LESS, Landing Error Scoring System. SANE, single assessment numeric evaluation. * indicates statistically significant difference at p < 0.05.

Table 3. vGRF by group and limb during the impact and propulsion phases. Values are presented in multiples of body weight.

Impact Phase Mean ± SD

Propulsion Phase Median [IQR]

ACLR

Control

ACLR

Control

Involved Limb

1.92 ± 0.49

2.34 ± 0.57

1.07 [1.05, 1.14]

1.19 [1.09, 1.32]

Uninvolved Limb

2.24 ± 0.53

2.30 ± 0.47

1.11 [1.09, 1.29]

1.18 [1.10, 1.37]

LSI (%)

89.2 ± 26.4

105 ± 21.8

95.3 [90.9, 99.4]

100 [94.7, 104]

The impact phase is represented as the mean ± SD. The propulsion phase is represented as the median [IQR] due to the non-normality of the distribution. ACLR, anterior cruciate ligament reconstruction. IQR, interquartile range. LSI, limb symmetry index. vGRF, vertical ground reaction force.

Figure 2.

Distribution of (a) Knee SANE scores and (b) LESS composite scores within each group. Data are represented as proportions within each group due to unequal group sizes.

ACLR, anterior cruciate ligament reconstruction. SANE, single assessment numeric evaluation. LESS, Landing Error Scoring System.

significant differences were observed (p>0.05). Group means and standard deviations are reported in Table 3.

VGRF-PROPULSION PHASE

Levene’s test was significant for the involved limb (p=0.015), suggesting a violation of the assumption of equal variance. Four non-parametric pairwise comparisons were conducted, utilizing Wilcoxon signed-rank test for within group comparisons (Limb: involved, uninvolved) and Mann-

Whitney U test for between group comparisons (Group: ACLR, control). All p-values were adjusted using Bonferroni correction based on four planned comparisons. The ACLR involved limb differed from the ACLR uninvolved limb (p=0.012), indicative of asymmetrical loading in the ACLR group. No other significant differences were observed (p>0.05). Group medians and interquartile ranges (IQRs) are reported in Table 3.

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Are Elite Collegiate Female Athletes PRIME for a Safe Return to Sport after ACLR? An Investigation of Physical Readiness...

Figure 3.

Peak vGRF during (a) impact phase and (b) propulsion phase in multiples of body weight by group and limb. From left to right, jittered dots represent individual subject means across all trials, the diamonds represent group means and 95% confidence intervals, and the violin represents the distribution within the group.33 ACLR, anterior cruciate ligament reconstruction. vGRF, vertical ground reaction force. BW, body weight.

DISCUSSION The purpose of this study was to describe the functional profile of elite collegiate female athletes who were able to successfully return to play for at least one season following ACLR compared to their teammates with no history of ACLR with regard to self-reported knee function, kinetics, and kinematics. Findings suggest that relative to their teammates, elite female athletes averaging 2.4 years after ACLR report worse knee-related function and demonstrate kinetic differences during a jump landing task, including underloading of their involved limb during the impact phase and asymmetrical loading during the propulsion phase. Despite these findings, athletes after ACLR also have lower risk kinematic movement patterns during the same landing task. Additionally, no athletes sustained an ACL injury during the competition season following assessment, suggesting that the functional profile observed was safe for shortterm return to participation.

SELF-REPORTED KNEE FUNCTION

To assess self-reported knee function, this study used the knee-specific SANE, as it is recommended for use due to simplicity of application and direct patient relevance.3 The knee-specific SANE has moderate to strong correlations with the IKDC in populations including young, active females with knee and ACL injuries,28,34,35 and thus provides a reasonable, time-efficient alternative. In support of this study’s hypothesis, there was decreased self-reported knee function in elite collegiate female athletes after ACLR compared to their teammates. Prior research has shown self-reported knee function is worse in females compared to males following ACLR,5 and that higher self-reported knee function is associated with passing return to sport batteries.4 The findings of this study are also consistent with prior research in young females one to two years post-ACLR, who continued to report significantly worse function than their uninjured peers in spite of similar levels of moderate and vigorous physical activity.36 The athletes in this study av-

eraged 2.4 years post-ACLR, suggesting that this impairment in self-reported function persists several years even amongst those who return to the same level of sports participation.

A score of 90% on the knee-specific SANE is the threshold to identify successful outcomes following ACLR.3 The mean score in the ACLR group was an 89.4, with eight of the 17 athletes (47%) rating themselves lower than 90%, and three athletes (18%) rating themselves at 90%. Despite approximately half of the athletes after ACLR in this cohort rating themselves below the 90% threshold for successful outcomes, these athletes were still able to participate at an elite level of sport without sustaining a secondary ACL injury the season following assessment.

KINETICS

In support of this study’s hypothesis, those with ACLR had lower vGRF in the involved limb during the impact phase of landing compared to controls, suggestive of underloading of the involved limb. The athletes in this study were at least 1 year post-ACLR and averaged 2.4 years post-ACLR. Interestingly, the findings of this study are consistent with athletes who are within 12 months post-ACLR,19 but contradict previous findings on individuals greater than 12 months post-ACLR.37,38 Paterno et. al. examined a cohort of recreationally active females two years following ACLR compared to a control group of female collegiate athletes. They found an increased vGRF during impact phase in the uninvolved limb of the ACLR group, while the involved limb was not different than the control limbs.37 Decker utilized a higher (60 cm box) landing task in recreational athletes at least 12 months from ACLR and found no differences in peak vGRF during impact phase between the involved limb of the ACLR group and a matched control limb, though this peak had a temporal delay in the ACLR group.38 The differences observed in this study relative to previous research may be due to the level of athletic participation: this study examined elite, collegiate athletes, in contrast to the recreational athletes utilized by both Paterno and Decker. Additionally, this control group was matched to the ACLR group given that it

International Journal of Sports Physical Therapy

Are Elite Collegiate Female Athletes PRIME for a Safe Return to Sport after ACLR? An Investigation of Physical Readiness...

utilized the teammates of the ACLR group. These findings suggest that alterations in landing kinetics, suggestive of both underloading relative to teammates and asymmetrical loading between limbs, are still present in elite female athletes who successfully return to sport without subsequent injury.

KINEMATICS/LESS

In contrast to this study’s hypothesis, those with ACLR had lower LESS scores, indicative of fewer movement errors, compared to their teammates. Previous research has shown that LESS composite scores are worse in both healthy females20 as well as females after ACLR39 when compared to male counterparts, suggestive of poorer movement quality across females overall. The assessment of landing kinematics following ACLR often takes place during the return to sport window,18,19 with only a few studies limited to recreationally active cohorts assessing later time points. These studies have shown worse LESS composite scores compared to matched control subjects.23,24 Bell found a mean LESS scores of 6.7 in an ACLR cohort compared to 5.6 in a healthy cohort.23 Accordingly, Kuenze found a mean LESS score of 6.0 in an ACLR cohort compared to 2.8 in a healthy cohort.24 The mean LESS score of 4.1 in this ACLR cohort was observationally lower than the means in previous research, and statistically lower than the mean of 5.3 observed in control subjects. Hence, this ACLR cohort of elite female athletes had better movement quality than what has been previously reported in recreational athletes following ACLR. This difference may be due, in part, to the level of athlete observed.

With regard to ACL injury risk, prior research has determined soccer athletes with LESS scores of five or higher are at heightened risk of sustaining primary ACL injuries.15 This study’s ACLR group had a mean LESS score of 4.1, with 59% of the group scoring a four or lower, suggestive of good movement quality and lower risk of ACL injury. Accordingly, no athletes in this cohort sustained a subsequent ACL injury the following season.

COMBINED FINDINGS

In combination, findings suggest that elite female athletes after ACLR have fewer kinematic errors than their teammates, despite lower self-reported function and kinetic underloading and asymmetry. All athletes were able to participate in sport the following season without subsequent ACL injury, suggesting that they were able to attain a safe shortterm return to sport, despite the deficits observed. This is particularly important given that a high proportion of secondary ACL injuries occur within the first year following return to sport.40,41 One interpretation of these findings is that elite athletes are able to learn good movement patterns following ACLR during the extensive rehabilitation process. The differences observed between this elite athlete cohort and recreational athletes23,24 may be due, in part, to differences in level of athletic participation and skill. Elite athletes attain good movement quality despite worse self-reported function and kinetic loading patterns. Given that no athletes in this cohort sustained a second ACL injury the following season,

this suggests good movement quality, indicated by a lower LESS score, may be a short-term mediator of the high-risk kinetic loading patterns observed in this cohort. The divergent kinetic and kinematic findings are supported by a recent meta-analysis that found asymmetry was more often identified in kinetics compared to kinematics during double limb landing tasks post-ACLR.19 This highlights the potential utility of including both measures as a part of an athlete’s functional assessment.

POTENTIAL STUDY LIMITATIONS

One limitation of this study is the lack of comparable data on these athletes at the time of return to sport. Both biomechanical42 and psychological43 variables at the time of return to sport are predictive of second ACL injury after return to sport in young athletes, and thus an athlete’s profile at this time provides insight to their future injury risk. It is unknown if the profile observed in these athletes upon successful reintegration to elite sport was similar to their profile at the time of return to sport. Further longitudinal research is recommended to examine if and how an athlete’s profile changes during this time period and if changes observed relate to secondary injury risk. Despite lacking serial assessments, there were no primary or secondary ACL injuries observed during the competition season following assessment.

The monitoring period of the study specifically tracked ACL injuries, as this was the primary variable of interest.

Athletes may have sustained other time-loss injuries, but these were not accounted for in the present study. Additional research could incorporate monitoring all lower extremity time-loss injuries. Additionally, exposure was not tracked during this period. While all athletes participated in sport without restriction, it is unknown how many total minutes of participation each athlete had during competition. If athletes in the ACLR group had limited playing time during competition, this may have significantly lowered their risk for a second ACL injury, especially given that these injuries may be more common in competition compared to practice.44 Additionally, longer-term implications beyond one competition season cannot be inferred. Further research is warranted to better understand how the attainment of good kinematics despite altered kinetic loading influences longer term risk of secondary ACL injury and additional long-term sequalae following ACLR. Random assignment of the “involved” limb in the control group was utilized in order to assess both limbs for comparison, meaning that there was no account for a potential influence of limb dominance on magnitude of peak vGRF between limbs. Peak vGRF does not differ in landings in healthy female athletes between the dominant and nondominant limb.29 However, recent work has shown that limb dominance influences intra-limb energy absorption both during a single limb landing task in healthy individuals45 and during a double limb landing task post-ACLR,46 though neither study reported the peak vGRF. Future research should incorporate matching based on limb dominance to control for its potential influence on kinetic symmetry.

In an effort to create a time-efficient screening assess-

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Are Elite Collegiate Female Athletes PRIME for a Safe Return to Sport after ACLR? An Investigation of Physical Readiness...

ment of these athletes, there was no three-dimensional motion capture data to allow the calculation of knee-specific loading, calling into question how the values of peak vGRF in the present study may relate to the knee in particular.

Prior research has shown that six months post-ACLR, vGRF asymmetry predicts knee sagittal plane kinetic asymmetries in both double and single limb landing tasks.47 Accordingly, a meta-analysis identified that ACLR has a large effect on asymmetry in peak vGRF and peak knee extension moment symmetry during double limb landing tasks.19 Given previous findings, it is reasonable to infer that the asymmetry of vGRF observed in the ACLR group in this study would likely correspond to an asymmetrical knee-specific load as well.

While motion capture could further detail loading across the knee, in the absence of this measurement, there is still clinical utility in the assessment of peak vGRF.

relative to teammates during double limb landing tasks despite successful return to sport without secondary ACL injury. In contrast, these athletes demonstrate fewer kinematic errors relative to their teammates. These conflicting findings suggest that incorporation of both kinetic and kinematic measurements may be important to fully understand an athlete’s functional profile. Given that these athletes did not sustain a secondary ACL injury for the monitoring period following assessment, the good movement quality observed may be protective against the functional deficits reported and kinetic differences observed. Further longitudinal research is warranted to understand how functional profiles relate to longer-term outcomes following ACLR and return to elite sport in female athletes.

CONCLUSIONS

CONFLICTS OF INTEREST

This study examined elite collegiate female athletes, a population which is under-represented in current research despite a high risk of injury. The results suggest that elite female athletes after ACLR continue to report decreased knee-related function and demonstrate kinetic differences suggestive of both asymmetrical loading and underloading

The authors report no conflicts of interest.

Submitted: April 12, 2021 CDT, Accepted: December 09, 2021 CDT

This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CCBY-NC-4.0). View this license’s legal deed at https://creativecommons.org/licenses/by-nc/4.0 and legal code at https://creativecommons.org/licenses/by-nc/4.0/legalcode for more information.

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Are Elite Collegiate Female Athletes PRIME for a Safe Return to Sport after ACLR? An Investigation of Physical Readiness...

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Am J Sports Med. 2014;42(7):1567-1573. doi:10.1177/0 363546514530088 14. Cronström A, Tengman E, Häger CK. Risk factors for contralateral secondary anterior cruciate ligament injury: a systematic review with meta-analysis. Sport Med. 2021;51(7):1419-1438. doi:10.1007/s40279-02 0-01424-3 15. Padua DA, DiStefano LJ, Beutler AI, De La Motte SJ, DiStefano MJ, Marshall SW. The landing error scoring system as a screening tool for an anterior cruciate ligament injury-prevention program in eliteyouth soccer athletes. J Athl Train.

2015;50(6):589-595. doi:10.4085/1062-6050-50.1.10 16. Gokeler A, Welling W, Zaffagnini S, Seil R, Padua D. Development of a test battery to enhance safe return to sports after anterior cruciate ligament reconstruction. Knee Surgery, Sport Traumatol Arthrosc. 2017;25(1):192-199. doi:10.1007/s00167-01 6-4246-3 17. Goerger BM, Marshall SW, Beutler AI, Blackburn JT, Wilckens JH, Padua DA. Anterior cruciate ligament injury alters preinjury lower extremity biomechanics in the injured and uninjured leg: the JUMP-ACL study. Br J Sports Med. 2015;49(3):188-195. doi:10.113 6/bjsports-2013-092982

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18. Lepley AS, Kuenze CM. Hip and knee kinematics and kinetics during landing tasks after anterior cruciate ligament reconstruction: a systematic review and meta-analysis. J Athl Train.

2018;53(2):1062-6050-334-16. doi:10.4085/1062-605 0-334-16 19. Hughes G, Musco P, Caine S, Howe L. Lower limb asymmetry after anterior cruciate ligament reconstruction in adolescent athletes: a systematic review and meta-analysis. J Athl Train.

2020;55(8):12-15. doi:10.4085/1062-6050-244-19.S1 20. Padua DA, Marshall SW, Boling MC, Thigpen CA, Garrett WE, Beutler AI. The landing error scoring system (LESS) is a valid and reliable clinical assessment tool of jump-landing biomechanics: the jump-ACL study. Am J Sports Med. 2009;37(10):1996-2002. doi:10.1177/03635465093432 00 21. Hanzlíková I, Hébert-Losier K. Is the landing error scoring system reliable and valid? a systematic review. Sports Health. 2020;12(2):181-188. doi:10.117 7/1941738119886593 22. Mauntel TC, Padua DA, Stanley LE, et al.

Automated quantification of the landing error scoring system with a markerless motion-capture system. J Athl Train. 2017;52(11):1062-6050-52.10.12. doi:10.4 085/1062-6050-52.10.12 23. Bell DR, Smith MD, Pennuto AP, Stiffler MR, Olson ME. Jump-landing mechanics after anterior cruciate ligament reconstruction: a landing error scoring system study. J Athl Train.

2014;49(4):435-441. doi:10.4085/1062-6050-49.3.21 24. Kuenze CM, Foot N, Saliba SA, Hart JM. Droplanding performance and knee-extension strength after anterior cruciate ligament reconstruction. J Athl Train. 2015;50(6):596-602. doi:10.4085/1062-6050-5 0.2.11 25. Koga H, Nakamae A, Shima Y, et al. Mechanisms for noncontact anterior cruciate ligament injuries: knee joint kinematics in 10 injury situations from female team handball and basketball. Am J Sports Med. 2010;38(11):2218-2225. doi:10.1177/036354651 0373570

28. Shelbourne KD, Barnes AF, Gray T. Correlation of a single assessment numeric evaluation (SANE) rating with modified cincinnati knee rating system and IKDC subjective total scores for patients after acl reconstruction or knee arthroscopy. Am J Sports Med. 2012;40(11):2487-2491. doi:10.1177/03635465124585 76 29. Aizawa J, Hirohata K, Ohji S, Ohmi T, Yagishita K. Limb-dominance and gender differences in the ground reaction force during single-leg lateral jumplandings. J Phys Ther Sci. 2018;30(3):387-392. doi:10.1 589/jpts.30.387 30. Pfeiffer SJ, Blackburn JT, Luc-Harkey B, et al. Peak knee biomechanics and limb symmetry following unilateral anterior cruciate ligament reconstruction: associations of walking gait and jump-landing outcomes. Clin Biomech. 2018;53(January):79-85. do i:10.1016/j.clinbiomech.2018.01.020 31. Pfeiffer SJ, Spang JT, Nissman D, et al. Association of jump-landing biomechanics with tibiofemoral articular cartilage composition 12 months after ACL reconstruction. Orthop J Sport Med. 2021;9(7). doi:1 0.1177/23259671211016424 32. Cohen. J. Statistical Power Analysis for the Behavioral Sciences. 2nd ed. L. Erlbaum Associates; 1988.

33. Allen M, Poggiali D, Whitaker K, Marshall TR, Kievit RA. Raincloud plots: a multi-platform tool for robust data visualization [version 1; peer review: 2 approved]. Wellcome Open Res. 2019;4:1-41. doi:10.12 688/wellcomeopenres.15191.1 34. Garcia AN, Cook C, Lutz A, Thigpen CA. Concurrent validity of the single assessment numerical evaluation and patient-reported functional measures in patients with musculoskeletal disorders: an observational study. Musculoskelet Sci Pract.

2019;44:102057. doi:10.1016/j.msksp.2019.102057 35. Winterstein AP, McGuine TA, Carr KE, Hetzel SJ. Comparison of IKDC and SANE outcome measures following knee injury in active female patients. Sports Health. 2013;5(6):523-529. doi:10.1177/19417381134 99300

26. Krosshaug T, Nakamae A, Boden BP, et al.

Mechanisms of anterior cruciate ligament injury in basketball: video analysis of 39 cases. Am J Sports Med. 2007;35(3):359-367. doi:10.1177/0363546506293 899

36. Ezzat AM, Brussoni M, Mâ sse LC, Emery CA. Effect of anterior cruciate ligament rupture on physical activity, sports participation, patientreported health outcomes, and physical function in young female athletes. doi:10.1177/036354652110025 30

27. Kotsifaki A, Korakakis V, Graham-Smith P, Sideris V, Whiteley R. Vertical and horizontal hop performance: contributions of the hip, knee, and ankle. Sports Health. 2021;XX(X):1941738120976363. doi:10.1177/1941738120976363

37. Paterno MV, Ford KR, Myer GD, Heyl R, Hewett TE. Limb asymmetries in landing and jumping 2 years following anterior cruciate ligament reconstruction.

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38. Decker MJ, Torry MR, Noonan TJ, Riviere A, Sterett WI. Landing adaptations after ACL reconstruction. Med Sci Sports Exerc.

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43. McPherson AL, Feller JA, Hewett TE, Webster KE. Psychological readiness to return to sport is associated with second anterior cruciate ligament injuries. Am J Sports Med. 2019;47(4):857-862. doi:1 0.1177/0363546518825258

39. Kuenze CM, Trigsted S, Lisee C, Post E, Bell DR. Sex differences on the landing error scoring system among individuals with anterior cruciate ligament reconstruction. J Athl Train. 2018;53(9):837-843. doi:1 0.4085/1062-6050-459-17

44. Dragoo JL, Braun HJ, Durham JL, Chen MR, Harris AHS. Incidence and risk factors for injuries to the anterior cruciate ligament in National Collegiate Athletic Association Football: data from the 2004-2005 through 2008-2009 National Collegiate Athletic Association injury surveillance system. Am J Sports Med. 2012;40(5):990-995. doi:10.1177/0363546 512442336

40. Grindem H, Snyder-Mackler L, Moksnes H, Engebretsen L, Risberg MA. Simple decision rules can reduce reinjury risk by 84% after ACL reconstruction: the Delaware-Oslo ACL cohort study. Br J Sports Med. 2016;50(13):804-808. doi:10.1136/bjsports-2016-0960 31 41. Kyritsis P, Bahr R, Landreau P, Miladi R, Witvrouw E. Likelihood of ACL graft rupture: not meeting six clinical discharge criteria before return to sport is associated with a four times greater risk of rupture. Br J Sports Med. 2016;50(15):946-951. doi:10.1136/bjspor ts-2015-095908 42. Paterno M, Schmitt L, Ford K, et al. Biomechanical measures during landing and postural stability predict second ACL injury after ACL reconstruction and return to sport. Am J Sports Med. 2010;38(10):1968-1978. doi:10.1177/03635465103760 53

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International Journal of Sports Physical Therapy

Waldhelm A, Allen S, Grand L, et al. Reliability and Differences Between Sexes in Landing Mechanics when Performing the Lateral Bound Test. IJSPT. 2022;17(3):466-473.

Original Research

Reliability and Differences Between Sexes in Landing Mechanics when Performing the Lateral Bound Test a

Andy Waldhelm, PT, PhD 1 , Sydney Allen, PT 2, Lacy Grand, PT 2, Carolyn Bopp, PT 2, Kristian Foster, PT 2, Ginger Muckridge, PT 2, Neil Schwarz, PhD 3 1

South College, Doctor of Physical Therapy Program, Knoxville, TN, USA; University of South Alabama, Physical Therapy Department, Mobile, AL, USA, Physical Therapy Department, University of South Alabama, Mobile, AL, USA, 3 Department of Health, Kinesiology and Sport, University of South Alabama, Mobile, AL, USA 2

Keywords: return to sports, movement systems, acl injuries https://doi.org/10.26603/001c.33067

International Journal of Sports Physical Therapy Vol. 17, Issue 3, 2022

Background and Purpose Anterior cruciate ligament injuries are prevalent among the athletic population, imposing a heavy economic burden, and the risk of re-injury. Most current biomechanical screening tasks are performed in the sagittal plane, and there is a need for more screening tools that assess sports specific movements in the frontal plane. The purpose of this study was to determine the reliability of and examine differences between sexes in the performance of the Lateral Bound Test (LBT).

Materials/Methods Each subject performed three trials of a LBT which included jumping laterally from one leg over a hurdle and landing on the opposite leg. Two cameras were placed six feet from the landing marker. Maximum dynamic knee valgus using the frontal plane projection angle and knee flexion angle at initial contact and maximal knee flexion were measured upon landing leg using 2D video analysis software. Additionally, video of 10 individuals’ trials were analyzed twice with one week between the analyses to obtain intra-rater reliability while 12 participants were retested one week later to determine test-retest reliability.

Results Thirty healthy subjects, 16 males, 14 females participated. Intra-rater reliability was determined to be excellent for all variables (ICC>0.96). In contrast, the test-retest reliability had greater disparity. Test-retest reliability ranged from poor (ICC = 0.47) to excellent (ICC > 0.90). Significant differences existed between the sexes, including males being significantly taller, weighing more, and demonstrating greater bilateral dynamic knee valgus (p < 0.05). No significant differences existed between sexes for knee flexion angles.

Conclusion The new LBT had excellent intra-rater reliability for assessing dynamic knee valgus and initial and maximum knee flexion angle when performing a functional movement in the frontal plane. Furthermore, males landed with more dynamic knee valgus than females which is contradictory to what has been observed with functional screening tools performed in the sagittal plane.

a

Corresponding author: Andy Waldhelm South College 400 Goody’s Lane, Knoxville, TN 37922 Phone: 225-328-3890 Email: awaldhelm@south.edu

Reliability and Differences Between Sexes in Landing Mechanics when Performing the Lateral Bound Test

Level of Evidence 3b (reliability study)

INTRODUCTION There are 80,000-250,000 anterior cruciate ligament (ACL) injuries per year, 70% of which are non-contact injures.1 Of all knee ligament injuries involving surgery in a fiveyear epidemiological study, 80% involved the ACL and 65% of the ACL injuries requiring surgery were the result of a sport/recreational incident.2 ACL injuries also bear a heavy economic and social burden with the cost of an ACL injury estimated at $38,121 in a lifetime, and $7.6 billion dollars across the US annually.3 Likewise, conservative treatment can cost an individual $88,583 throughout their life and $17.7 billion in the US annually.3 Also, there is a high risk for development of osteoarthritis following an ACL injury, which leads to added expenses for treatment and interventions.3 Along with direct expenses, ACL injury can have a major indirect cost to society including decreased productivity, disability, and lost wages3 and the average time off for an acute reconstruction is 56.9 days and 88.5 days for a delayed reconstruction.4 There are various reports on the incidence of ACL injuries in males and females. When observing the general population, males constitute the majority of ACL injuries but this has been attributed to males being more likely to participate in athletic tasks known to injure the ACL such as cutting, jumping and contact sports as compared to females.2 When examining ACL injuries in the perspective of the athletic population, there is a strong agreement that females are at higher risk4 with numerous studies reporting that females have approximately three to nine times greater risk of injury than males.5 Hootman et al.6 evaluated sports injuries occurring in 15 NCAA sports over a 16 year period and found 5,000 of 182,000 were ACL injuries, or 2.7%. According to their study, the three sports with the highest incidence for ACL injury were women’s’ sports, including gymnastics, soccer, and basketball.6 There are several anatomical and biomechanical risk factors associated with ACL injuries. Anatomically, a decrease in femoral notch width, a decrease in concavity depth of the medial tibial plateau, an increase in posterior-inferior-directed slope of tibial plateau, and generalized joint laxity have been noted in persons who have sustained an ACL injury.7 Biomechanically, decreased knee flexion, increased knee valgus, tibial rotation, hip adduction, and hip internal rotation during landing and/or cutting maneuvers are frequently observed during ACL injury episodes.7 Collectively, these movements are termed “dynamic knee valgus.”7 This dynamic knee valgus, along with the anatomical risk factors, is more frequently demonstrated in women and may help explain why there is a much higher rate of ACL injuries in women as compared to men.7 Compared to female soccer players, female basketball players typically have more body mass, are taller, and demonstrate larger ground reaction forces with jumping and landing activities –all of which are factors that increase the risk of an ACL injury.8,9 With an initial ACL injury comes an increased risk for reinjury of the ligament. It is reported that up to 33% of in-

dividuals who previously suffered an ACL injury sustained a second ACL injury within two years following ACL reconstruction.10 Although a second ACL tear is less common than an initial rupture, young athletes who return to sport following an initial ACL injury are at approximately 30 to 40 times greater risk of sustaining an ACL injury during sport compared to those who have not had a previous ACL injury.11 Second ACL tears can occur due to graft failure and contralateral ACL rupture, and the risk factors for these tears include young age, sex, and return to sport.10–12 Inadequate rehabilitation and participation in high-risk sports such as soccer, basketball, football, or skiing are some factors that may lead to graft failure or contralateral ACL injury.11 It is reported that 29.5% of athletes suffered a second ACL injury within two years of return to sport, with 20.5% tearing the intact contralateral ACL and 9.0% rupturing the ACL graft.10 Increased dynamic knee valgus motion during the impact phase of jumping and cutting tasks are key predictors for ACL injuries.13 Dynamic knee valgus is a combined movement of the lower extremity during an activity which includes hip adduction and internal rotation, knee abduction and tibia internal rotation14 or the medial displacement of the knee.15 Therefore, biomechanical pre-injury screenings can be performed to identify individuals who may be at risk for ACL injuries. Currently, one of the most common screening tools is assessing lower extremity mechanics during the drop vertical jump (DVJ) assessment, which requires a high level of dynamic neuromuscular control.13 While the DVJ test demonstrates high reliability (ICC greater than 0.93), this movement doesn’t accurately represent the more common mechanisms of injury for ACL tears—which includes cutting, landing and/or pivoting in the frontal plane.13 Another common screening test is the single leg (SL) squat assessment. This activity objectively shows changes in lower extremity alignment in athletes as they progress toward return to jumping or cutting sports.16 The amount of dynamic knee valgus displayed during a SL squat is reflective of the individual’s associated hip strength and neuromuscular control. Although the SL squat test may identify hip weakness that predisposes an athlete to an ACL injury,16 the SL squat does adequately mimic jumping or cutting as seen in high-risk sports such as basketball and soccer where the majority of ACL injures occur during landing and change of direction movements, respectively.8 For this reason, there needs to be a stronger emphasis on a frontal plane dynamic activity, rather than the DVJ and SL squat, to effectively screen athletes for potential ACL injury.

During return to sport decision-making there are several different factors that need to be assessed—such as range of motion, strength, pain, self-reported questionnaires and functional performance.17 Currently, functional tests commonly used include the single leg hop, triple hop, crossover hop and 6-m hop for time.17 With all functional performance tests, the examiner is observing quality of movement, signs of patient apprehension, and most importantly limb symmetry. While these tests should be included in a

International Journal of Sports Physical Therapy

Reliability and Differences Between Sexes in Landing Mechanics when Performing the Lateral Bound Test

return to sport assessment, the evidence on their ability to accurately indicate if the athlete is able to return safely is lacking.17 Furthermore, the functional tests listed only assess movement in the frontal plane. Therefore, there is a need for dynamic tests which assess neuromuscular control in the frontal plane which may assist in determining if an athlete is ready to return to sport with minimal risk of reinjury.

One functional test that does utilize frontal plane movements is the medial and lateral triple hop test for distance.

This test is used for both ACL prevention and return to sport assessment in athletes and mimics the original triple hop test, but hopping is performed in the frontal plane rather than the sagittal.8,18 The most limiting aspect of this test, however, is that a single-leg hop is rarely a movement performed in sport. Basketball players specifically, are more involved in movement such as lateral shuffling and cutting.8 While these motions do require single-leg movement, they involve transition of single leg stance on one leg to single leg stance on the contralateral leg, unlike hopping.19 ACL injuries are a growing issue, as they occur commonly in the athletic population and the consequences can be both costly and timely. A test is needed which incorporates dynamic movement in a frontal plane functionally similar to shuffling and cutting. Therefore, the purpose of this study was to determine the reliability of and examine differences between sexes in the performance of the Lateral Bound Test (LBT). It was hypothesized that the LBT will be reliable and females will demonstrate increased dynamic knee valgus and decreased knee flexion at both initial contact and maximal depth.

METHODS PARTICIPANTS

Thirty subjects, healthy, non-athletes were recruited. Participants were excluded if they participated in any sport at the collegiate level or if they had sustained an injury in the prior three months that required medical attention and/or resulted in a decrease in activity for greater than three days.

Informed verbal and written consent as well as participant demographics and injury history were taken prior to testing. This study was approved by the University of South Alabama’s Institutional Review Board.

PROCEDURE

jump from the starting position on one leg, over a 10-inch (25.4 cm) hurdle which was placed approximately 2 to 6 inches (5.08 to 15.2 cm) from the starting leg and land on the target with the opposite leg. The target was placed laterally of the starting leg to limit movement in the anterior and posterior directions and a hurdle was used to ensure the participant attained a significant amount of vertical movement. Two practice trials and three testing trials were performed for each leg with the landing leg being considered the tested leg. Rather than classifying limb as right or left, dominant/non-dominant extremity was used with the dominant lower extremity determined by the extremity selected by the participant when asked “what leg they would select to kick a soccer ball as hard as they could.”

The average of the three trials was used for data analysis.

Two 60 Hz video cameras, one anterior and one lateral of the participant, were placed 6 ft (1.82 m) from the landing target at a height of 18 inches (45.7 cm) from the ground.

The camera placed lateral to the participant camera was used to assess initial and maximum knee flexion angle during the landing, while the camera placed anterior to the participant was used to assess knee valgus angle. Video software (Dartfish Motion Analysis Software) was used to determine initial (Figure 1a) and maximum knee flexion angle (Figure 1b) and dynamic knee valgus via the Frontal Plane Projection Angle (FPPA) (Figure 2). For true dynamic knee valgus, the static FPPA was subtracted from the FPPA obtained during landing from the lateral bound. Only knee kinematics were used in this study to minimize time needed for data processing, therefore results could be obtained quickly in a clinical setting. Twelve of the participants were randomly selected and asked to return for a retest a week after of the initial trial. One trial for ten participants were randomly selected for intra-rater reliability with the primary investigator performing video analysis on two occasions, seven days apart.

STATISTICAL ANALYSIS

To determine the intra-rater and test-retest reliability of the Lateral Bound Test, Intraclass Correlation Coefficients (ICC) were performed while independent t-tests were used to compare differences between sexes in dynamic knee valgus and knee flexion angles. A p-value of 0.05 was used for all statistical analyses.

RESULTS

The participants performed a five-minute warm-up which included walking or jogging at their own preferred pace.

Markers were then placed at the greater trochanter, lateral joint line of the knee, lateral malleolus, the anterior thigh midway between the anterior superior iliac spine (ASIS) and mid patella, anterior joint line of the knee and at the anterior ankle between the tibia and fibula. To normalize bounding distance, each participant’s leg length was measured using the distance between the ASIS and the medial malleolus. Then a target "X’ was place on the landing surface which was a force plate, however, kinetics were not assessed in this study. Static knee valgus posture was assessed by having the participant stand on a single leg before they performed the LBT. The participant was then instructed to

Sixteen males and 14 females above the age of 18 participated in this study (males 23.6 ± 1.58, females 22.9 ± 1.22 years of age). Descriptive statistics from both sessions and all participants were used to determine intra-rater and testretest reliability for each of the six variables as well as ICC values (Table 1). Intra-rater reliability was determined to be excellent for all variables with ICC values all greater than 0.96. In contrast, the test-retest reliability had greater disparity. Dominant knee flexion at initial contact exhibited poor reliability (ICC = 0.47), two measurements had fair reliability, maximum non-dominant knee valgus (ICC = 0.74 and ICC = 0.71, respectively), maximum non-dominant knee flexion, (ICC = 0.88) was found to have good reliability

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Reliability and Differences Between Sexes in Landing Mechanics when Performing the Lateral Bound Test

Table 1. Descriptive Statistics (Mean ± SD) and Intra-rater and Test-Retest Reliability Intra-Rater

Test-Retest

1st Rating

2nd Rating

ICC3,1

S1

S2

ICC3,1

Max D Valgus (°)

-1.83 ± 5.02

-1.19 ± 4.42

0.96

-2.26 ± 4.18

-1.81 ± 5.23

0.92

D Knee Flexion IC (°)

22.7 ± 4.42

23.1 ± 5.00

0.99

23.9 ± 4.79

23.3 ± 2.97

0.47

Max D Knee Flexion (°)

34.5 ± 4.72

34.4 ± 4.66

0.96

36.0 ± 8.58

36.2 ± 6.46

0.90

Max ND Valgus (°)

-2.35 ± 4.90

-2.71 ± 4.46

0.97

-3.46 ± 5.64

-1.61 ± 3.01

0.74

ND Knee Flexion IC (°)

20.8 ± 4.46

21.4 ± 4.44

0.96

23.6 ± 5.10

21.1 ± 4.72

0.71

Max ND Knee Flexion (°)

30.0 ± 6.89

30.1 ± 6.96

0.98

33.1 ± 7.76

33.6 ± 9.34

0.88

ICC: D: Dominant leg; ND: Non-Dominant leg; Intraclass correlation coefficient; IC: Initial contact; Max Valgus: Maximum valgus or minimum varus recorded during landing from initial flatfoot to stoppage of movement with negative being a valgus measurement and positive being a varus measurement; SD: Standard deviation; S1: Session one; S2: Session two.

Table 2. Descriptive statistics (Mean ± Standard Deviation) and differences between sexes.

Males (n = 16)

Females (n = 14)

p-value

Age (years)

23.6 ± 1.58

22.9 ± 1.22

0.17

Height (m)

1.80 ± 0.07

1.63 ± 0.07

< 0.01

Weight (kg)

84.2 ± 15.8

60.2 ± 9.25

< 0.01

D Max Valgus (°)

-3.59 ± 4.18

0.34 ± 3.17

0.01

D Knee Flexion IC (°)

22.1 ± 5.49

23.1 ± 4.21

0.56

D Max Knee Flexion (°)

32.7 ± 9.81

31.6 ± 5.56

0.69

ND Max Valgus (°)

-3.06 ± 5.63

0.51 ± 4.18

0.05

ND Knee Flexion IC (°)

23.2 ± 4.90

22.9 ± 4.52

0.87

ND Knee Flexion (°)

31.7 ± 7.54

32.1 ± 7.38

0.87

Bold values indicate significant at 0.05 D: Dominant leg; ND: Non-dominant leg; Max Valgus: Maximum valgus or minimum varus recorded during landing from initial flatfoot to stoppage of movement with negative being a valgus measurement and positive being a varus measurement; SD: Standard deviation; IC: Initial contact.

and two tests, maximum dominant knee valgus (ICC = 0.92) and maximum dominant knee flexion (ICC = 0.90) were shown to have excellent reliability.

Means and standard deviations as well as sex-related differences are displayed in Table 2. Significant differences between sexes were noted for height, weight and bilateral maximum dynamic knee valgus. Males were significantly taller, weighed more, and exhibited greater dynamic knee valgus on both the dominant and non-dominant lower extremity upon landing from the lateral bound, while on average females landed with a slightly knee varus posture on both extremities. There were no significant differences with the degrees of knee flexion on initial contact or maximum knee flexion on either leg when comparing between sexes.

DISCUSSION The purpose of this study was to determine the reliability and differences in performance between sexes of a new test, the LBT, which assesses the quality of landing mechanics in the frontal plane. The hypothesis was partially supported by the results as the lateral bound test was found to be reliable but sex differences in landing mechanics were not accurately predicted. The lateral bound test was found to have excellent intra-rater reliability, but test-retest reliabil-

ity ranged from poor to excellent. Males surprisingly displayed significantly greater landing knee valgus than females although the difference may not be clinically relevant since the findings were less than 4˚.

Compared to other studies of similar tests, the LBT had better intra-rater reliability statistics in the current research. McKeown et al. reported moderate intra-rater reliability when screening with a similar test where female semiprofessional football players performed a maximum lateral bound and a qualitative scoring system was used to assess performance.20 These lower reliability measures could be due to the subjectivity of their study, as the scoring criteria relied on categorical observations opposed to objective numerical data. Hip/knee/ankle alignment, depth, balance/ control, and power positioning in landing were assessed and scored from one to three - one being poor execution of the task and three being perfect execution of the task.20 There are several other studies on examining the reliability of functional screens with similar results. Herrington et al. reported good intra-rater reliability when performing 2D assessment of dynamic knee valgus during a single leg squat screen and a single leg hop landing screen on active and healthy individuals.21 Redler et al. assessed ACL injury risk in young athletes via the drop vertical jump based on normalized knee separation distance, reporting it to have

International Journal of Sports Physical Therapy

Reliability and Differences Between Sexes in Landing Mechanics when Performing the Lateral Bound Test

moderate reliability.1 The LBT demonstrated excellent intra-rater reliability most likely due to the highly objective nature of the study as well as the rater’s experience with the software.

Several other studies examined the test-retest reliability of other functional screens and they had comparable results when assessing dynamic knee valgus angles.21,22 Herrington et al. reported the single leg squat and single leg hop screening tests to have good reliability (ICC= 0.79-0.87) between sessions as well.21 Werner et al. demonstrated good to excellent test-retest reliability when assessing frontal plane projection angles during the single leg squat (ICC=0.84), single leg hop (ICC=0.82), and drop jump (ICC=0.96) using 2D video analysis.22 It is possible that some of these tests demonstrated a greater test-retest reliability due to the fact that the components of the tests, such as single leg squat, were movements with which the subjects were more familiar, or had more practice performing since they may be included in an exercise program.

While the intra-rater reliability of this test was found to be excellent, due to high variability within subjects, the test-retest reliability for some measurements were less consistent. This may be due to participants not landing on the target for every attempt which may be due to many factors such as length of the target or poor athletic performance since the participants were not competitive athletes. The researchers in the current study observed that when a subject landed past the target, they exhibited increased knee valgus. This could have contributed to the participant having difficulty controlling their pelvis and having excessive lateral movement when landing past the target. Furthermore, the average knee valgus (FPPA) decreased in in session two, indicating that there may have been a learning effect in which the subjects became more familiar with the task and were able to improve their landing mechanics in session two by concentrating more on the mechanics.

As expected, there were significant differences by sex noted for height and weight. Males landed with more dynamic knee valgus (bilaterally) which is not a common finding in functional screens performed in the sagittal plane.

In a study using the drop vertical jump, female high school basketball players demonstrated significantly increased dynamic knee valgus as compared to males.23 Furthermore, females demonstrate greater knee valgus angles during a single leg squat test, as well as higher rectus femoris muscle activation, both of which can add to the stress on the ACL during jumping, landing, and cutting activities.24 Pappas et al. reported that regardless of bilateral or unilateral landings, females tend to land with greater knee valgus as compared to males.25 Since females often display greater quadriceps activation during jumping and landing activities in the sagittal plane, this greater quadriceps activation may increase knee stability and actually be beneficial in controlling knee valgus motion while performing the LBT in the frontal plane.24,26 Therefore, males potentially have greater control on knee dynamic valgus in the sagittal plane with an increase in proximal hip stabilizing muscle activation, whereas females have greater control in the frontal plane with an increase in quadriceps muscle activation.24,26 Another explanation is that in the current study the initial static knee valgus measurement was subtracted from the max-

Figure 1. Knee flexion angle during landing from Lateral Bound Test. A. Top figure, shows initial flexion angle B. Bottom figure, show maximum flexion angle.

Figure 2. Frontal plane projection ankle during landing from Lateral Bound Test

imum knee valgus measurement in order to determine the participants dynamic knee valgus during landing during the LBT The greater dynamic knee valgus shown by males, as compared to other studies, could be reflective of other studies not taking account of an initial static knee valgus measurement to determine the amount of knee valgus displayed dynamically during landings.

One limitation of this study was the inability to analyze inter-rater reliability as there was only one person who was trained to perform the video analysis. A second limitation was the inability to move the hurdle, therefore, shorter subjects were closer to the hurdle than taller subjects, but all participants stated they were able to perform the bound comfortably and aberrant techniques were not observed.

International Journal of Sports Physical Therapy

Reliability and Differences Between Sexes in Landing Mechanics when Performing the Lateral Bound Test

The height of the hurdle remained constant and was not standardized to the height of each participant making it another limitation to the study. Having an adjustable hurdle and a more dynamic testing location would allow for standardization of the hurdle height and location in reference to the participant. Finally, the cameras used to record the trials captured 60 frames per second. However, a camera capable of capturing greater number of frames per second could have allowed the recording of more accurate measurements, specifically at knee flexion during initial contact.

Future studies of the LBT should include comparisons of athletes and non-athletes, athletes of different sports, athletes of different competitive levels, and athletes with and without previous lower extremity injury such as those recovering from ACL reconstruction. These future studies would help provide normative data and determine if the LBT could be used as a predictor of lower extremity injury or as a return to sport assessment. Last, different landing lengths, shorter and greater than the leg length or maximal distance bounded should be examined in order to determine if using the participants’ leg length is truly the best distance to observe dynamic knee control in the LBT. This this may be more specific to athletes where bounding the distance of their leg length may not be challenging enough to identify impaired landing mechanics.

CONCLUSION The results of this study indicate that the LBT has excellent intra-rater reliability and varying test-retest reliability when used in healthy non-athletes. Additional research should be performed to determine validity. Unlike other tests assessing dynamic knee valgus in the sagittal plane, the current results indicate that males had statistically greater dynamic knee valgus compared to females during landing and no statistically significant difference in knee flexion angles.

CONFLICT OF INTEREST

All authors declare no conflict of interest related to this manuscript.

Submitted: August 19, 2021 CDT, Accepted: January 23, 2022 CDT

This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CCBY-NC-4.0). View this license’s legal deed at https://creativecommons.org/licenses/by-nc/4.0 and legal code at https://creativecommons.org/licenses/by-nc/4.0/legalcode for more information.

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Reliability and Differences Between Sexes in Landing Mechanics when Performing the Lateral Bound Test

REFERENCES 1. Redler LH, Watling JP, Dennis ER, Swart E, Ahmad CS. Reliability of a field-based drop vertical jump screening test for ACL injury risk assessment. Phys Sportsmed. 2016;44(1):46-52. doi:10.1080/00913847.2 016.1131107

10. Paterno MV, Rauh MJ, Schmitt LC, Ford KR, Hewett TE. Incidence of second ACL injuries 2 years after primary ACL reconstruction and return to sport.

Am J Sports Med. 2014;42(7):1567-1573. doi:10.1177/0 363546514530088

2. Gianotti SM, Marshall SW, Hume PA, Bunt L. Incidence of anterior cruciate ligament injury and other knee ligament injuries: a national populationbased study. J Sci Med Sport. 2009;12(6):622-627. do i:10.1016/j.jsams.2008.07.005

11. Wiggins AJ, Grandhi RK, Schneider DK, Stanfield D, Webster KE, Myer GD. Risk of secondary injury in younger athletes after anterior cruciate ligament reconstruction. Am J Sports Med. 2016;44(7):1861-1876. doi:10.1177/036354651562155 4

3. Mather RC, Koenig L, Kocher MS, et al. Societal and economic Impact of anterior cruciate ligament tears. J Bone Joint Surg Am. 2013;95(19):1751-1759. doi:10.21 06/jbjs.l.01705 4. von Essen C, McCallum S, Barenius B, Eriksson K. Acute reconstruction results in less sick-leave days and as such fewer indirect costs to the individual and society compared to delayed reconstruction for ACL injuries. Knee Surg Sports Traumatol Arthrosc.

2020;28(7):2044-2052. doi:10.1007/s00167-019-0539 7-3 5. Prodromos CC, Han Y, Rogowski J, Joyce B, Shi K. A meta-analysis of the incidence of anterior cruciate ligament tears as a function of gender, sport, and a knee injury-reduction regimen. Arthrosc J Arthrosc Relat Surg. 2007;23(12):1320-1325.e6. doi:10.1016/j.a rthro.2007.07.003 6. Hootman JM, Dick R, Agel J. Epidemiology of collegiate injuries for 15 sports: summary and recommendations for injury prevention initiatives. J Athl Train. 2007;42(2):311-319.

7. Smith HC, Vacek P, Johnson RJ, et al. Risk factors for anterior cruciate ligament injury. Sports Health.

2012;4(1):69-78. doi:10.1177/1941738111428281 8. Hardesty K, Hegedus EJ, Ford KR, Nguyen AD, Taylor JB. Determination of clinically relevant differences in frontal plane hop tests in women’s collegiate basketball and soccer players. Int J Sports Phys Ther. 2017;12(2):182-189.

9. Munro A, Herrington L, Comfort P. Comparison of landing knee valgus angle between female basketball and football athletes: possible implications for anterior cruciate ligament and patellofemoral joint injury rates. Phys Ther Sport. 2012;13(4):259-264. do i:10.1016/j.ptsp.2012.01.005

12. Wright RW, Dunn WR, Amendola A, et al. Risk of tearing the intact anterior cruciate ligament in the contralateral knee and rupturing the anterior cruciate ligament graft during the first 2 years after anterior cruciate ligament reconstruction: a prospective MOON Cohort Study. Am J Sports Med. 2007;35(7):1131-1134. doi:10.1177/036354650730131 8 13. Hewett TE, Myer GD, Ford KR, et al.

Biomechanical measures of neuromuscular control and valgus loading of the knee predict anterior cruciate ligament injury risk in female athletes: a prospective study. Am J Sports Med. 2005;33(4):492-501. doi:10.1177/0363546504269591 14. Dix J, Marsh S, Dingenen B, Malliaras P. The relationship between hip muscle strength and dynamic knee valgus in asymptomatic females: a systematic review. Phys Ther Sport. 2019;37:197-209. doi:10.1016/j.ptsp.2018.05.015 15. Kianifar R, Lee A, Raina S, Kulic D. Automated assessment of dynamic knee valgus and risk of knee injury during the single leg squat. IEEE J Transl Eng Health Med. 2017;5:1-13. doi:10.1109/jtehm.2017.273 6559 16. Willson JD, Ireland ML, Davis I. Core strength and lower extremity alignment during single leg squats.

Med Sci Sports Exerc. 2006;38(5):945-952. doi:10.124 9/01.mss.0000218140.05074.fa 17. Williams D, Heidloff D, Haglage E, Schumacher K, Cole BJ, Campbell KA. Anterior cruciate ligament functional sports assessment. Oper Tech Sports Med. 2016;24(1):59-64. doi:10.1053/j.otsm.2015.10.002 18. Kea J, Kramer J, Forwell L, Birmingham T. Hip abduction-adduction strength and one-leg hop tests: test-retest reliability and relationship to function in elite ice hockey players. J Orthop Sports Phys Ther.

2001;31(8):446-455. doi:10.2519/jospt.2001.31.8.446

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Reliability and Differences Between Sexes in Landing Mechanics when Performing the Lateral Bound Test

19. Taylor JB, Ford KR, Nguyen AD, Shultz SJ. Biomechanical comparison of single- and double-leg jump landings in the sagittal and frontal Plane.

Orthop J Sports Med. 2016;4(6):232596711665515. do i:10.1177/2325967116655158

23. Ford KR, Myer GD, Hewett TE. Valgus knee motion during landing in high school female and male basketball players. Med Sci Sports Exerc.

2003;35(10):1745-1750. doi:10.1249/01.mss.00000893 46.85744.d9

20. McKeown I, Taylor-McKeown K, Woods C, Ball N. Athletic ability assessment: a movement assessment protocol for athletes. Int J Sports Phys Ther.

2014;9(7):862-873.

24. Zeller BL, McCrory JL, Ben Kibler W, Uhl TL. Differences in kinematics and electromyographic activity between men and women during the singlelegged squat. Am J Sports Med. 2003;31(3):449-456. d oi:10.1177/03635465030310032101

21. Herrington L, Alenezi F, Alzhrani M, Alrayani H, Jones R. The reliability and criterion validity of 2D video assessment of single leg squat and hop landing.

J Electromyogr Kinesiol. 2017;34:80-85. doi:10.1016/j.j elekin.2017.04.004 22. Werner DM, Di Stasi S, Lewis CL, Barrios JA. Testretest reliability and minimum detectable change for various frontal plane projection angles during dynamic tasks. Phys Ther Sport. 2019;40:169-176. do i:10.1016/j.ptsp.2019.09.011

25. Pappas E, Hagins M, Sheikhzadeh A, Nordin M, Rose D. Biomechanical differences between unilateral and bilateral landings from a jump: gender differences. Clin J Sport Med. 2007;17(4):263-268. do i:10.1097/jsm.0b013e31811f415b 26. Zazulak BT, Ponce PL, Straub SJ, Medvecky MJ, Avedisian L, Hewett TE. Gender comparison of hip muscle activity during single-leg landing. Res Rep. 2005;35(5):292-299.

International Journal of Sports Physical Therapy

Butler LS, Martinez AR, Sugimoto D, et al. Reliability of the Expanded Cutting Alignment Scoring Tool (E-CAST) to Assess Trunk and Limb Alignment During a 45-Degree SideStep Cut. IJSPT. 2022;17(3):456-465.

Original Research

Reliability of the Expanded Cutting Alignment Scoring Tool (ECAST) to Assess Trunk and Limb Alignment During a 45-Degree Side-Step Cut a

Lauren S. Butler, DPT 1 , Alexa R. Martinez, DPT 1, Dai Sugimoto, PhD, ATC 2, Charles W. Wyatt, CPNP, RNFA 3, Eryn K. Milian, PT, PhD 4, Sophia Ulman, PhD 5, Ashley Erdman, MS, MBA 5, Alex Loewen, MS 5, Kristin Hayden, DPT 1, Amie DeVerna, DPT 1, Kirsten Tulchin-Francis, PhD 5, PRiSM Injury Prevention Research Interest Group 1

Nicklaus Children’s Hospital, Miami, FL, USA, 2 The Micheli Center for Sports Injury Prevention, Waltham, MA, USA; Faculty of Sport Sciences, Waseda University, Tokyo, Japan, 3 Scottish Rite for Children, Dallas, TX, USA; University of Texas Southwestern Medical Center, Dallas, TX, USA, 4 University of Miami, Miami, FL, USA, 5 Scottish Rite for Children, Dallas, TX, USA Keywords: qualitative assessment, side-step cut, movement analysis, change of direction https://doi.org/10.26603/001c.33045

International Journal of Sports Physical Therapy Vol. 17, Issue 3, 2022

Background Current clinical screening tools assessing risky movements during cutting maneuvers do not adequately address sagittal plane foot and ankle evaluations. The Cutting Alignment Scoring Tool (CAST) is reliable in evaluating frontal plane trunk and lower extremity alignment during a 45-degree side-step cut. The Expanded Cutting Alignment Scoring Tool (E-CAST) includes two new sagittal plane variables, knee flexion and ankle plantarflexion angle.

Hypothesis/Purpose To assess the inter-and intra-rater reliability of the E-CAST to evaluate trunk and lower extremity alignment during a 45-degree side-step cut.

Study Design Repeated Measures

Methods Participants included 25 healthy females (13.8 ± 1.4 years) regularly participating in cutting or pivoting sports. Participants were recorded performing a side-step cut in frontal and sagittal planes. One trial was randomly selected for analysis. Two physical therapists independently scored each video using the E-CAST on two separate occasions, with randomization and a two-week wash-out between rounds. Observed movement variables were awarded a score of “1”, with higher scores representing poorer technique.

Intraclass correlation coefficients (ICC) and 95% confident intervals (95% CI) were calculated for the total score, and a kappa coefficient (k) was calculated for each variable.

Results The cumulative intra-rater reliability was good (ICC=0.78, 95% CI 0.59-0.96) and the cumulative inter-rater reliability was moderate (ICC=0.71, 95% CI 0.50-0.91). Intra-rater kappa coefficients ranged from moderate to excellent for all variables (k= 0.50-0.84) and inter-rater kappa coefficients ranged from slight to excellent for all variables

a

Corresponding author: Lauren S. Butler Nicklaus Children’s Hospital Sports Health Center 11521 South Dixie Hwy. Miami, FL 33156 Telephone: 786-624-5133 Fax: 786-624-5106 Email: Lauren.Butler@nicklaushealth.org

Reliability of the Expanded Cutting Alignment Scoring Tool (E-CAST) to Assess Trunk and Limb Alignment During a 45-Degree...

(k=0.20-0.90).

Conclusion The addition of two sagittal plane variables resulted in lower inter-rater ICC compared to the CAST (ICC= 0.81, 95% CI 0.64-0.91). The E-CAST is a reliable tool to evaluate trunk and LE alignment during a 45-degree side-step cut, with good intra-rater and moderate inter-rater reliability.

Level of Evidence Level 2, Diagnosis

INTRODUCTION

Table 1. Subject demographics

Up to 70% of all anterior cruciate ligament (ACL) injuries occur via a non-contact mechanism.1 The most frequent movement pattern associated with non-contact ACL injuries in young female athletes includes a deceleration event paired with a change of direction on a planted foot.1 It is also known that female athletes are two to ten times more likely to rupture their ACL when compared to their male counterparts.2–7 Neuromuscular control deficits at the hip and trunk have been theorized to result in altered lower extremity (LE) neuromuscular control and subsequently higher knee abduction loads in female athletes.8–11 Specifically, lateral trunk motion with the body shifted over the stance limb has been found to be related to high knee abduction moments and medial knee collapse.12,13 Additionally, females demonstrate altered hip recruitment strategies with decreased gluteal activation, greater hip moments, and increased quadriceps activation that result in increased knee abduction moments and higher ACL injury risk.14–19 Numerous qualitative tools to assess movement quality utilizing two-dimensional (2-D) analysis have been found to be reliable and valid.20–24 However, the majority of these assessment tools only evaluate landing mechanics and do not address cutting movement. Recently, several assessment tools utilizing 2-D video have been introduced to assess cutting technique. Weir et al. assessed the reliability and validity of a 2-D video-based screening tool to predict peak knee moments during an unplanned 45-degree sidestep cut in a group of junior (age = 15.1 ± 1.2 years) and senior (age = 22.1 ± 2.3 years) elite female field hockey players.25 The screening tool involved 2-D kinematic measurement of frontal and sagittal plane variables using video analysis software and reported poor to excellent intra-rater and inter-rater reliability.26 The Cutting Movement Assessment Score (CMAS), a qualitative scoring system to evaluate a 90-degree cutting maneuver, was found to be a reliable and valid tool to assess risky movement patterns during a 90-degree cutting task in college-aged athletes.27 The Cutting Alignment Scoring Tool (CAST), demonstrates good inter-rater and intra-rater reliability for the assessment of LE and trunk alignment in young athletes (age=14.7+1.2 years).26 The CAST involves dichotomous scoring of four frontal plane movement variables observed from 2-D video during a planned 45-degree side-step cut.

However, the CAST may not sufficiently address sagittal plane foot and ankle assessments. Decreased ankle plantarflexion angles and decreased knee flexion angles have been associated with higher knee joint loads during cutting maneuvers.28–31 In an attempt to assess both frontal and

Age (years)

Height (cm*)

Weight (kg†)

BMI‡

Minimum

12.0

150.0

40.8

16.4

Maximum

16.3

172.5

72.6

26.3

Average

13.8

161.7

52.4

19.9

Standard deviation

1.4

6.0

9.3

2.6

*cm= Centimeters † kg= Kilograms ‡ BMI= body mass index

sagittal plane trunk and LE alignment during a 45-degree side-step cut, the authors of this study developed the Expanded Cutting Alignment Scoring Tool (E-CAST). The primary purpose of this study was to examine the reliability of the E-CAST among physical therapists. This study consisted of three aims: 1) to assess the inter-rater reliability of the E-CAST, 2) to assess the intra-rater reliability of the E-CAST, and 3) to examine rater agreement of each component of the E-CAST. The hypotheses were: 1) there would be good–to-excellent inter-rater reliability, 2) there would be good-to-excellent intra-rater reliability, and 3) there would be good-to-nearly perfect agreement in the E-CAST variables including; cut width, trunk lean, knee flexion and plantarflexion, and moderate agreement in knee valgus variables of the E-CAST.

METHODS STUDY DESIGN

A repeated measures study design was used. To achieve the study aims, inter-rater and intra-rater reliability were calculated based on the first and second reliability tests. The study protocol was developed based on the Declaration of Helsinki and ethical standards in sport and exercise science research.32 Institutional Review Board approval was obtained prior to commencement of the study.

PARTICIPANTS

A total of 25 adolescent female athletes (age 13.8 ± 1.4 years, mass 52.4 ± 9.3 kg, height 161.7 ± 6.0 cm) were recruited from local middle school, high school and club sport teams (Table 1).

Inclusion criteria were: 1) age between 12 and 17 years,

International Journal of Sports Physical Therapy

Reliability of the Expanded Cutting Alignment Scoring Tool (E-CAST) to Assess Trunk and Limb Alignment During a 45-Degree...

and 2) actively participating in sports requiring cutting and pivoting in the prior 12 months. The following exclusion criteria were used: 1) LE injury within the prior six months, 2) past history of LE surgery, 3) a positive response on the Physical Activity Readiness Questionnaire (PAR-Q+), and 4) history of scoliosis. The PAR-Q+ was used to determine the participants’ readiness and safety for physical activity. A positive response of the PAR-Q+ indicates the need to seek further advice from a physician prior to engaging in physical activity.33 All participants provided written informed assent, and their parent or legal guardian provided signed consent. Data collection was performed in a movement science lab at a local sports medicine center.

DATA COLLECTION

Prior to performing the 45-degree side step cut task, a fiveminute warm up on an exercise bike (Matrix Fitness, Cottage Grove, WI) was performed. Participants practiced the side step cut three times in each direction or until they felt comfortable with the procedure. They were instructed to sprint at 80% of their maximum speed in a forward direction toward the “opponent cone” and to pivot and perform the side step cut (Figure 1).

This procedure was modeled after a testing protocol described by McLean et al.34 Specifically, participants decelerated, planted on the right foot, and performed a side step cut, running in the left direction between cones placed along a 45-degree line of progression. The procedure was repeated planting on the left foot and running to the right direction (Figure 1). Then, participants completed three trials planting on the right LE and three trials planting on the left LE, with a trial considered “good” if the subject’s foot landed within the stance/pivot area necessary for successful completion of the task. The testing order was standardized for all participants following the protocol by Butler et al.26 Video data were captured at 60 frames per second with 1080p quality using three Sony RX10 IV cameras adjusted to 36 inches tall. Two cameras were positioned 136 inches from either side of the stance/pivot area, and one camera was positioned 146 inches in front of the stance/ pivot area. Participants performed a total of six cutting maneuvers with one trial randomly selected for analysis. All videos were slowed by 50% for visual analysis and participants’ faces were blurred using Corel VideoStudio.

QUALITATIVE MEASUREMENT SCALE

A clinically established checklist, E-CAST, was developed to examine the quality of trunk and LE movement during the cutting maneuver based on 2-D video. The checklist was devised based on the previously reported scoring system (CAST). It involves a dichotomous rating system, with scoring defined as “1” when a movement fault was present and “0” when optimal movement patterns were observed. The E-CAST evaluates the original frontal plane variables of the CAST including; trunk lean to the opposite direction of the cut, increased cut width, knee valgus at initial load acceptance (Static Evaluation), and knee valgus throughout the cutting task (Dynamic Evaluation) as well as two new variables that are assessed in the sagittal plane including; plan-

Figure 1. 45-degree side-step cut task

tarflexion angle and knee flexion angle. The E-CAST checklist is shown in Table 2.

RATERS

Two raters consisting of two pediatric sports medicine doctors of physical therapy were chosen because of their clinical roles in treating young athletes. The two raters were chosen from the same institution and had seven and five years of clinical experience, respectively. The raters independently viewed a total of 25 videos. All raters provided their consent to participate in the current study.

PROCEDURES

One of the six trials, which consisted of three right LE and three left LE cutting maneuvers from each of the 25 subjects, was chosen at random. A review of current research in this area led to the sample size selection. The videos were provided to each rater along with a reference sheet containing images demonstrating optimal and sub-optimal movement strategies and elaborated definitions used in the E-CAST (Appendix A). The raters were instructed to view the videos independently. They were allowed to review the videos as many times as necessary and could pause the video as needed. All videos were evaluated using each rater’s personal smart phone device. The raters were given one week to complete the first reliability session. After the first reliability session, a two-week wash-out period was given. Next, the second reliability session was performed, using the same method outlined for the first reliability session. The sequence of videos was randomized in the second reliability session.

International Journal of Sports Physical Therapy

Reliability of the Expanded Cutting Alignment Scoring Tool (E-CAST) to Assess Trunk and Limb Alignment During a 45-Degree...

Table 2. Expanded Cutting Alignment Scoring Tool (E-CAST) Item

View

Operational Definition

1. Trunk lean to opposite direction of cut

Frontal

At the time point of initial load acceptance, if the whole trunk segment appears to be deviated greater than 10 degrees from a horizontal line through the hips (ASIS* to ASIS*) score 1 (YES). If not, score 0 (NO).

2. Increased cut width

Frontal

At the time point of initial load acceptance , draw a line down from the lateral most aspect of the athlete’s stance leg hip, if the line appears to fall more than one shoe width medial to the foot score 1 (YES). If not, score 0 (NO).

3. Knee Valgus at Initial load acceptance (Static Evaluation)

Frontal

At the time point of initial load acceptance, if the weight bearing limb demonstrates valgus (thigh adduction, genu valgum, or knee abduction) score 1 (YES). If the weight bearing limb is in neutral alignment score 0 (NO).

4. Knee Valgus throughout the cutting task (Dynamic Evaluation)

Frontal

During the cutting task if the weight bearing limb demonstrates valgus (thigh adduction, genu valgum or knee abduction) score 1 (YES). If the weight bearing limb is in neutral alignment, score 0 (No).

5. Decreased knee flexion angle

Sagittal

At the time point of initial contact, if the athlete demonstrates a stiff or extended knee position score 1 (YES). If the athlete demonstrates a flexed knee position ( Approximately> 30 degrees), score 0 (NO)

6. Decreased plantar flexion angle

Sagittal

At the time point of initial contact, if the stance foot lands heel to toe score 1 (YES). If the stands foot lands toe to heel score 0 (NO)

*ASIS= Anterior Superior Iliac Spine

Table 3. Intra-rater reliability (ICC*, 95%CI†, cumulative values) and intra-rater reliability for E-CAST variables Raters

ICC*

95% CI†

Cut Width (k‡)

Trunk Lean (k‡)

Dynamic Valgus (k‡)

Static Valgus (k‡)

Knee Flexion (k‡)

Plantar Flexion (k‡)

PT #1

0.72

0.43-1.02

0.505

0.635

0.737

0.719

0.677

0.759

PT #2

0.84

0.60-1.07

0.621

0.840

0.500

0.802

0.606

0.746

Cumulative

0.78

0.5-0.96

0.555

0.750

0.646

0.758

0.642

0.759

*ICC= intraclass correlation coefficient,†CI= confidence interval, ‡k- kappa coefficient, PT= physical therapist

STATISTICAL ANALYSIS

Reliability was determined by calculating intraclass correlation coefficients (ICC) for the E-CAST total scores, with a 2-way mixed-effects model and 95% confidence intervals (95% CIs) for inter-rater and intra-rater reliability. For the first aim, the individual and cumulative inter-rater reliabilities were calculated within the first and second reliability sessions. The individual and cumulative intra-rater reliabilities were calculated between the first and second reliability sessions. ICC values less than 0.50, between 0.50 and 0.75, between 0.75 and 0.90, and greater than 0.90 were defined as poor, moderate, good and excellent reliability, respectively.35 To attain study aim 2, a kappa coefficient was calculated for each of the checklist variables using the formula; k= Pr(a) – Pr(e)/1 – Pr(e), where Pr(a)= relative observed agreement between raters and Pr(e)= hypothetic probability of chance agreement. The kappa coefficient was interpreted based on the scale of Landis and Koch36 with 0.01-0.20 being slight, 0.21-0.40 fair, 0.41-0.60 moderate, 0.61-0.80 good, and 0.81-1.00 almost perfect. All statistical analyses were conducted using SPSS Statistics 22 (IBM

Corp. Released 2013. IBM SPSS Statistics for Windows, Version 22.0. Armonk, NY: IBM Corp).

RESULTS Inter-rater reliability for the first reliability session was moderate (ICC: 0.73, 95% CI 0.43-1.20) and inter-rater reliability for the second reliability test was moderate (ICC: 0.70, 95% CI 0.39-1.01). The cumulative inter-rater reliability, a combination of first and second inter-rater reliability, was moderate (ICC: 0.71, 95% CI 0.50-0.91). Intrarater reliability for Rater 1 was moderate (ICC: 0.72, 95% CI 0.43-1.02) and intra-rater reliability for Rater 2 was good (ICC: 0.84 95% CI 0.60-1.07, Table 3). The cumulative intrarater reliability of the two raters was good (ICC: 0.78, 95% CI 0.59-0.96, Table 3). Intra-rater kappa coefficients for each variable are presented in Table 3 and ranged from moderate to excellent for all variables (k = 0.50-0.84). Interrater kappa coefficients are presented in Table 4 and ranged from slight to excellent for all variables (k = 0.20-0.90).

International Journal of Sports Physical Therapy

Reliability of the Expanded Cutting Alignment Scoring Tool (E-CAST) to Assess Trunk and Limb Alignment During a 45-Degree...

Table 4. Inter-rater reliability for E-CAST* variables Rating Session

Cut Width (k†)

Trunk Lean (k†)

Dynamic Valgus (k†)

Static Valgus (k†)

Knee Flexion (k†)

Plantar Flexion (k†)

1

0.603

0.434

0.783

0.896

0.204

0.525

2

0.503

0.593

0.545

0.818

0.426

0.531

Cumulative

0.559

0.513

0.653

0.854

0.320

0.529

*E-CAST= Expanded Cutting Alignment Scoring Tool, †k= kappa coefficient

DISCUSSION The primary purpose of this study was to assess the intrarater and inter-rater reliability of the E-CAST. The E-CAST demonstrated moderate inter-rater reliability (cumulative ICC: 0.71, 95% CI 0.50-0.91) and good intra-rater reliability (cumulative ICC: 0.78, 95% CI 0.59-0.96). The findings did not support the first hypothesis that the E-CAST would demonstrate good-excellent inter-rater reliability because only moderate inter-rater reliability was found. However, the second hypotheses was supported with the E-CAST demonstrating good-excellent intra-rater reliability. The third hypothesis was not supported as moderate agreement was found for trunk lean, cut width and plantarflexion and only fair agreement was found for knee flexion. Additionally, valgus variables demonstrated good-to-almost perfect agreement.

The findings of this study are generally in agreement with the previous work which reported good cumulative inter-rater reliability (ICC: 0.81, 95% CI 0.64-0.91) and good cumulative intra-rater reliability (ICC: 0.75, 95% CI 0.59-0.85) of the CAST. When comparing the cumulative inter-rater reliability of the E-CAST to the cumulative interrater reliability of just the two physical therapist raters for the CAST, the E-CAST demonstrated higher inter-rater reliability (ICC: 0.71, 95% CI 0.50-0.91 vs ICC: 0.46, 95% CI 0.28-0.61). This may have been a result of the raters’ greater experience with assessing cutting movement errors as the same two physical therapists were used to determine the reliability of both the CAST and the E-CAST. When comparing the cumulative intra-rater reliability of the E-CAST to the cumulative intra-rater reliability of just the two physical therapist raters for the CAST, the E-CAST (ICC: 0.78, 95% CI 0.59-0.96) demonstrated slightly higher intra-rater reliability than the CAST (ICC: 0.77, 95% CI 0.43-0.91). A study conducted by Dos’ Santos et al reported a similar finding.

According to his study, moderate inter-rater reliability (ICC =0.69) and excellent intra-rater reliability (ICC =0.95) were found when utilizing a qualitative scoring system to evaluate a 90-degree cutting maneuver in collegiate athletes.27 There are, however, several differences in study design. Dos’ Santos et al27 reported intra-rater reliability of the CMAS for only one rater. The current study reported the average of two raters which may have contributed to the lower intra-rater reliability found in the E-CAST compared to the CMAS. Additionally, Dos’ Santos et al. only used a one-week wash out period compared to a two-week washout period used in this study.27 In a another study by Weir et al., an unplanned 45-degree

side step cut was assessed in 15 junior (age 15.1 + 1.2 years) and 15 elite senior (age 22.1+ 2.3 years) female field hockey players utilizing 2-D video based measurements of whole body kinematics.26 Weir et al. found excellent intra-rater reliability (ICC: 0.99-1.00) for angular measurements including dynamic knee valgus angle, trunk lateral flexion angle, knee flexion angle, thigh abduction angle and trunk flexion angle, and poor to good reliability (ICC: 0.38-0.54) for displacement based measurements including foot placement and dynamic medial knee shift.26 Weir et al. found good to excellent inter-rater reliability (ICC: 0.66-0.97) for all angular measurements and poor to excellent inter-rater reliability (ICC: 0.22-0.87) for displacement based measurements.26 Again, several differences in study design need to be discussed between the work of Weir et al. and this study.

First, Weir et al. used an un-planned cutting task versus a planned cutting task, which was used in our study. An unplanned cutting task has been shown to result in greater knee joint loads when compared to planned cutting maneuvers.37 The work of Weir et al. utilized 2-D measurement of full body kinematics compared to the qualitative assessment used in this study.26 It is unknown if 2-D measurement is a more reliable and valid method for evaluating trunk and LE alignment during a cutting task, and further work in this area is needed. However, a primary concern of incorporating 2-D measurements is that it may increase the complexity of the tool, and therefore, time and effort for evaluators, potentially reducing ease-of-use in clinic and in the field.

The second aim of this study was to evaluate rater agreement of each component of the E-CAST. Almost perfect kappa coefficients were found for static valgus and good kappa coefficients were found for dynamic valgus. Moderate kappa coefficients were observed for trunk lean, cut width, and plantarflexion, while only fair kappa coefficients were noted for knee flexion. The hypothesis that there would be good to almost perfect agreement for trunk lean, cut width, knee flexion and plantarflexion variables was not supported. Only moderate agreement was found for trunk lean, cut width and plantarflexion and only fair agreement was found for knee flexion. The hypothesis that valgus variables would demonstrate moderate agreement was also not supported. The results were not consistent with previous work which found only fair kappa coefficients for static and dynamic valgus variables and almost perfect kappa coefficients for cut width.26 One potential explanation for the difference in results is that the CAST assessed reliability using six raters consisting of two physical therapists, two sports medicine physicians and two athletic trainers, while the

International Journal of Sports Physical Therapy

Reliability of the Expanded Cutting Alignment Scoring Tool (E-CAST) to Assess Trunk and Limb Alignment During a 45-Degree...

E-CAST only assessed the reliability between two physical therapists. Furthermore, in this study almost perfect agreement was found for static valgus and good agreement was found for dynamic valgus. In our perspective, this may be a result of having an additional sagittal plane view which may improve consistency with time point identification. The two sagittal plane variables (knee flexion angle and plantarflexion angle) demonstrated the lowest and third lowest interrater reliability (k = 0.32 and k = 0.53, respectively) which contrasted with the authors 'expectations. Initially, the authors speculated that sagittal plane variables would demonstrate higher inter-rater reliability than frontal plane variables and the addition of two sagittal plane variables in the E-CAST would increase its intra-rater and inter-rater reliability in comparison to the CAST. One explanation for this outcome may be a result of the increased range of motion that occurs in the sagittal plane. This wider range of motion in the sagittal plane compared to the more restricted range of motion that occurs in the frontal plane may increase each rater’s variability in movement fault identification.

It is currently unknown if qualitative screening tools evaluating cutting technique in young athletes are predictive of ACL injuries. Given that the two sagittal plane assessments demonstrated the lowest and third lowest interrater reliability, future work should explore the predictability of frontal plane variables alone in identifying athletes who are at high risk for ACL injury. If frontal plane variables are found to be predictive of ACL injury, sagittal plane assessments may not be needed. This would simplify the screening tool, which would likely improve its adoptability by coaches. The development of screening tools that are able to accurately identify high-risk cutting movements with one camera view may provide coaches and practitioners with an efficient and effective strategy to screen athletes for ACL injury and enhance injury prevention interventions.

LIMITATIONS

The current study had a number of limitations. First, the E-CAST only evaluated reliability of physical therapists.

Coaching staff spend the most time working with athletes; thus, determining the reliability of the E-CAST amongst coaches would greatly increase its clinical utility. Coaches are likely best positioned to perform team-based injury prevention screenings. Providing coaches with a reliable and valid screening tool to identify athletes who are at high risk for ACL injury would help them in determining who would benefit most from injury prevention interventions. Future research should aim to determine the reliability of the ECAST with coaches. Additionally, this study only assessed the reliability between two raters, future studies should evaluate the tool’s reliability between multiple raters. Next, the operational definitions for each variable were written

with varying criteria. For example, an approximate degree reference was provided for trunk lean and knee flexion, a body reference was provided for cut width and plantarflexion, and a qualitative description was provided for the knee valgus variables. This variability may have contributed to rater confusion when using the tool. Future work should consider utilizing consistent reference terminology when defining movement fault criteria. It should also be acknowledged that this study used a planned cutting task. Different outcomes may be expected with the use of an unplanned cutting task which has been shown to result in greater knee joint loads when compared to planned cutting maneuvers.37 While the use of an unplanned cut may be more generalizable, it is more difficult to capture in the lab and in both the in-clinic and on-field settings. With the use of an unplanned cut, two sagittal plane cameras would be needed in order to capture LE biomechanics on the stance limb.

An additional camera view would increase the amount of equipment needed and the complexity of the screening tool for on field or clinic use. Additionally, in the lab setting, using a planned cut allowed for reduced errors in data collection, as this allowed the athlete to line up with the force plate without having to target a spot on the floor. Lastly, it is unknown if the E-CAST is a valid tool for predicting ACL injury risk during a cutting maneuver. It is important to investigate whether or not 3-D kinematic variables are correlated with visually identified movements. Future studies should aim to determine its predictive validity and its criterion validity with 3-D motion capture.

CONCLUSION This study demonstrated that the E-CAST, a qualitative evaluation tool using frontal and sagittal plane videos to identify at-risk movements for ACL tear in side-step cutting, demonstrated moderate inter-rater and good intrarater reliability among physical therapists. However, the addition of sagittal plane variables in the E-CAST resulted in a decrease in inter-rater reliability of the tool. These findings suggest that the E-CAST can be used as a reliable tool to evaluate trunk and LE alignment in the frontal and sagittal plane during a cutting task by physical therapists. However, the use of a frontal plane assessment alone may be more reliable. Future work is recommended to determine the predictive validity of the CAST and the E-CAST in identifying individuals at risk for ACL injury.

Submitted: June 03, 2021 CDT, Accepted: January 23, 2022 CDT

This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CCBY-NC-4.0). View this license’s legal deed at https://creativecommons.org/licenses/by-nc/4.0 and legal code at https://creativecommons.org/licenses/by-nc/4.0/legalcode for more information.

International Journal of Sports Physical Therapy

Reliability of the Expanded Cutting Alignment Scoring Tool (E-CAST) to Assess Trunk and Limb Alignment During a 45-Degree...

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International Journal of Sports Physical Therapy

Reliability of the Expanded Cutting Alignment Scoring Tool (E-CAST) to Assess Trunk and Limb Alignment During a 45-Degree...

APPENDIX A

ACKNOWLEDGEMENTS

We would like to acknowledge Scottish Rite Hospital, Nicklaus Children’s Hospital and the PRiSM Injury Prevention

Research Interest Group for their support of this project. All of the named authors approved the final manuscript as submitted, and agree to be accountable for all aspects of the work.

International Journal of Sports Physical Therapy

Reliability of the Expanded Cutting Alignment Scoring Tool (E-CAST) to Assess Trunk and Limb Alignment During a 45-Degree...

FINANCIAL DISCLOSURE AND CONFLICT OF INTEREST

The authors affirm that they have no financial affiliation (including research funding) or involvement with any com-

mercial organization that has a direct financial interest in any matter included in this manuscript.

International Journal of Sports Physical Therapy

Waldhelm A, Allen S, Grand L, et al. Reliability and Differences Between Sexes in Landing Mechanics when Performing the Lateral Bound Test. IJSPT. 2022;17(3):466-473.

Original Research

Reliability and Differences Between Sexes in Landing Mechanics when Performing the Lateral Bound Test a

Andy Waldhelm, PT, PhD 1 , Sydney Allen, PT 2, Lacy Grand, PT 2, Carolyn Bopp, PT 2, Kristian Foster, PT 2, Ginger Muckridge, PT 2, Neil Schwarz, PhD 3 1

South College, Doctor of Physical Therapy Program, Knoxville, TN, USA; University of South Alabama, Physical Therapy Department, Mobile, AL, USA, Physical Therapy Department, University of South Alabama, Mobile, AL, USA, 3 Department of Health, Kinesiology and Sport, University of South Alabama, Mobile, AL, USA 2

Keywords: return to sports, movement systems, acl injuries https://doi.org/10.26603/001c.33067

International Journal of Sports Physical Therapy Vol. 17, Issue 3, 2022

Background and Purpose Anterior cruciate ligament injuries are prevalent among the athletic population, imposing a heavy economic burden, and the risk of re-injury. Most current biomechanical screening tasks are performed in the sagittal plane, and there is a need for more screening tools that assess sports specific movements in the frontal plane. The purpose of this study was to determine the reliability of and examine differences between sexes in the performance of the Lateral Bound Test (LBT).

Materials/Methods Each subject performed three trials of a LBT which included jumping laterally from one leg over a hurdle and landing on the opposite leg. Two cameras were placed six feet from the landing marker. Maximum dynamic knee valgus using the frontal plane projection angle and knee flexion angle at initial contact and maximal knee flexion were measured upon landing leg using 2D video analysis software. Additionally, video of 10 individuals’ trials were analyzed twice with one week between the analyses to obtain intra-rater reliability while 12 participants were retested one week later to determine test-retest reliability.

Results Thirty healthy subjects, 16 males, 14 females participated. Intra-rater reliability was determined to be excellent for all variables (ICC>0.96). In contrast, the test-retest reliability had greater disparity. Test-retest reliability ranged from poor (ICC = 0.47) to excellent (ICC > 0.90). Significant differences existed between the sexes, including males being significantly taller, weighing more, and demonstrating greater bilateral dynamic knee valgus (p < 0.05). No significant differences existed between sexes for knee flexion angles.

Conclusion The new LBT had excellent intra-rater reliability for assessing dynamic knee valgus and initial and maximum knee flexion angle when performing a functional movement in the frontal plane. Furthermore, males landed with more dynamic knee valgus than females which is contradictory to what has been observed with functional screening tools performed in the sagittal plane.

a

Corresponding author: Andy Waldhelm South College 400 Goody’s Lane, Knoxville, TN 37922 Phone: 225-328-3890 Email: awaldhelm@south.edu

Reliability and Differences Between Sexes in Landing Mechanics when Performing the Lateral Bound Test

Level of Evidence 3b (reliability study)

INTRODUCTION There are 80,000-250,000 anterior cruciate ligament (ACL) injuries per year, 70% of which are non-contact injures.1 Of all knee ligament injuries involving surgery in a fiveyear epidemiological study, 80% involved the ACL and 65% of the ACL injuries requiring surgery were the result of a sport/recreational incident.2 ACL injuries also bear a heavy economic and social burden with the cost of an ACL injury estimated at $38,121 in a lifetime, and $7.6 billion dollars across the US annually.3 Likewise, conservative treatment can cost an individual $88,583 throughout their life and $17.7 billion in the US annually.3 Also, there is a high risk for development of osteoarthritis following an ACL injury, which leads to added expenses for treatment and interventions.3 Along with direct expenses, ACL injury can have a major indirect cost to society including decreased productivity, disability, and lost wages3 and the average time off for an acute reconstruction is 56.9 days and 88.5 days for a delayed reconstruction.4 There are various reports on the incidence of ACL injuries in males and females. When observing the general population, males constitute the majority of ACL injuries but this has been attributed to males being more likely to participate in athletic tasks known to injure the ACL such as cutting, jumping and contact sports as compared to females.2 When examining ACL injuries in the perspective of the athletic population, there is a strong agreement that females are at higher risk4 with numerous studies reporting that females have approximately three to nine times greater risk of injury than males.5 Hootman et al.6 evaluated sports injuries occurring in 15 NCAA sports over a 16 year period and found 5,000 of 182,000 were ACL injuries, or 2.7%. According to their study, the three sports with the highest incidence for ACL injury were women’s’ sports, including gymnastics, soccer, and basketball.6 There are several anatomical and biomechanical risk factors associated with ACL injuries. Anatomically, a decrease in femoral notch width, a decrease in concavity depth of the medial tibial plateau, an increase in posterior-inferior-directed slope of tibial plateau, and generalized joint laxity have been noted in persons who have sustained an ACL injury.7 Biomechanically, decreased knee flexion, increased knee valgus, tibial rotation, hip adduction, and hip internal rotation during landing and/or cutting maneuvers are frequently observed during ACL injury episodes.7 Collectively, these movements are termed “dynamic knee valgus.”7 This dynamic knee valgus, along with the anatomical risk factors, is more frequently demonstrated in women and may help explain why there is a much higher rate of ACL injuries in women as compared to men.7 Compared to female soccer players, female basketball players typically have more body mass, are taller, and demonstrate larger ground reaction forces with jumping and landing activities –all of which are factors that increase the risk of an ACL injury.8,9 With an initial ACL injury comes an increased risk for reinjury of the ligament. It is reported that up to 33% of in-

dividuals who previously suffered an ACL injury sustained a second ACL injury within two years following ACL reconstruction.10 Although a second ACL tear is less common than an initial rupture, young athletes who return to sport following an initial ACL injury are at approximately 30 to 40 times greater risk of sustaining an ACL injury during sport compared to those who have not had a previous ACL injury.11 Second ACL tears can occur due to graft failure and contralateral ACL rupture, and the risk factors for these tears include young age, sex, and return to sport.10–12 Inadequate rehabilitation and participation in high-risk sports such as soccer, basketball, football, or skiing are some factors that may lead to graft failure or contralateral ACL injury.11 It is reported that 29.5% of athletes suffered a second ACL injury within two years of return to sport, with 20.5% tearing the intact contralateral ACL and 9.0% rupturing the ACL graft.10 Increased dynamic knee valgus motion during the impact phase of jumping and cutting tasks are key predictors for ACL injuries.13 Dynamic knee valgus is a combined movement of the lower extremity during an activity which includes hip adduction and internal rotation, knee abduction and tibia internal rotation14 or the medial displacement of the knee.15 Therefore, biomechanical pre-injury screenings can be performed to identify individuals who may be at risk for ACL injuries. Currently, one of the most common screening tools is assessing lower extremity mechanics during the drop vertical jump (DVJ) assessment, which requires a high level of dynamic neuromuscular control.13 While the DVJ test demonstrates high reliability (ICC greater than 0.93), this movement doesn’t accurately represent the more common mechanisms of injury for ACL tears—which includes cutting, landing and/or pivoting in the frontal plane.13 Another common screening test is the single leg (SL) squat assessment. This activity objectively shows changes in lower extremity alignment in athletes as they progress toward return to jumping or cutting sports.16 The amount of dynamic knee valgus displayed during a SL squat is reflective of the individual’s associated hip strength and neuromuscular control. Although the SL squat test may identify hip weakness that predisposes an athlete to an ACL injury,16 the SL squat does adequately mimic jumping or cutting as seen in high-risk sports such as basketball and soccer where the majority of ACL injures occur during landing and change of direction movements, respectively.8 For this reason, there needs to be a stronger emphasis on a frontal plane dynamic activity, rather than the DVJ and SL squat, to effectively screen athletes for potential ACL injury.

During return to sport decision-making there are several different factors that need to be assessed—such as range of motion, strength, pain, self-reported questionnaires and functional performance.17 Currently, functional tests commonly used include the single leg hop, triple hop, crossover hop and 6-m hop for time.17 With all functional performance tests, the examiner is observing quality of movement, signs of patient apprehension, and most importantly limb symmetry. While these tests should be included in a

International Journal of Sports Physical Therapy

Reliability and Differences Between Sexes in Landing Mechanics when Performing the Lateral Bound Test

return to sport assessment, the evidence on their ability to accurately indicate if the athlete is able to return safely is lacking.17 Furthermore, the functional tests listed only assess movement in the frontal plane. Therefore, there is a need for dynamic tests which assess neuromuscular control in the frontal plane which may assist in determining if an athlete is ready to return to sport with minimal risk of reinjury.

One functional test that does utilize frontal plane movements is the medial and lateral triple hop test for distance.

This test is used for both ACL prevention and return to sport assessment in athletes and mimics the original triple hop test, but hopping is performed in the frontal plane rather than the sagittal.8,18 The most limiting aspect of this test, however, is that a single-leg hop is rarely a movement performed in sport. Basketball players specifically, are more involved in movement such as lateral shuffling and cutting.8 While these motions do require single-leg movement, they involve transition of single leg stance on one leg to single leg stance on the contralateral leg, unlike hopping.19 ACL injuries are a growing issue, as they occur commonly in the athletic population and the consequences can be both costly and timely. A test is needed which incorporates dynamic movement in a frontal plane functionally similar to shuffling and cutting. Therefore, the purpose of this study was to determine the reliability of and examine differences between sexes in the performance of the Lateral Bound Test (LBT). It was hypothesized that the LBT will be reliable and females will demonstrate increased dynamic knee valgus and decreased knee flexion at both initial contact and maximal depth.

METHODS PARTICIPANTS

Thirty subjects, healthy, non-athletes were recruited. Participants were excluded if they participated in any sport at the collegiate level or if they had sustained an injury in the prior three months that required medical attention and/or resulted in a decrease in activity for greater than three days.

Informed verbal and written consent as well as participant demographics and injury history were taken prior to testing. This study was approved by the University of South Alabama’s Institutional Review Board.

PROCEDURE

jump from the starting position on one leg, over a 10-inch (25.4 cm) hurdle which was placed approximately 2 to 6 inches (5.08 to 15.2 cm) from the starting leg and land on the target with the opposite leg. The target was placed laterally of the starting leg to limit movement in the anterior and posterior directions and a hurdle was used to ensure the participant attained a significant amount of vertical movement. Two practice trials and three testing trials were performed for each leg with the landing leg being considered the tested leg. Rather than classifying limb as right or left, dominant/non-dominant extremity was used with the dominant lower extremity determined by the extremity selected by the participant when asked “what leg they would select to kick a soccer ball as hard as they could.”

The average of the three trials was used for data analysis.

Two 60 Hz video cameras, one anterior and one lateral of the participant, were placed 6 ft (1.82 m) from the landing target at a height of 18 inches (45.7 cm) from the ground.

The camera placed lateral to the participant camera was used to assess initial and maximum knee flexion angle during the landing, while the camera placed anterior to the participant was used to assess knee valgus angle. Video software (Dartfish Motion Analysis Software) was used to determine initial (Figure 1a) and maximum knee flexion angle (Figure 1b) and dynamic knee valgus via the Frontal Plane Projection Angle (FPPA) (Figure 2). For true dynamic knee valgus, the static FPPA was subtracted from the FPPA obtained during landing from the lateral bound. Only knee kinematics were used in this study to minimize time needed for data processing, therefore results could be obtained quickly in a clinical setting. Twelve of the participants were randomly selected and asked to return for a retest a week after of the initial trial. One trial for ten participants were randomly selected for intra-rater reliability with the primary investigator performing video analysis on two occasions, seven days apart.

STATISTICAL ANALYSIS

To determine the intra-rater and test-retest reliability of the Lateral Bound Test, Intraclass Correlation Coefficients (ICC) were performed while independent t-tests were used to compare differences between sexes in dynamic knee valgus and knee flexion angles. A p-value of 0.05 was used for all statistical analyses.

RESULTS

The participants performed a five-minute warm-up which included walking or jogging at their own preferred pace.

Markers were then placed at the greater trochanter, lateral joint line of the knee, lateral malleolus, the anterior thigh midway between the anterior superior iliac spine (ASIS) and mid patella, anterior joint line of the knee and at the anterior ankle between the tibia and fibula. To normalize bounding distance, each participant’s leg length was measured using the distance between the ASIS and the medial malleolus. Then a target "X’ was place on the landing surface which was a force plate, however, kinetics were not assessed in this study. Static knee valgus posture was assessed by having the participant stand on a single leg before they performed the LBT. The participant was then instructed to

Sixteen males and 14 females above the age of 18 participated in this study (males 23.6 ± 1.58, females 22.9 ± 1.22 years of age). Descriptive statistics from both sessions and all participants were used to determine intra-rater and testretest reliability for each of the six variables as well as ICC values (Table 1). Intra-rater reliability was determined to be excellent for all variables with ICC values all greater than 0.96. In contrast, the test-retest reliability had greater disparity. Dominant knee flexion at initial contact exhibited poor reliability (ICC = 0.47), two measurements had fair reliability, maximum non-dominant knee valgus (ICC = 0.74 and ICC = 0.71, respectively), maximum non-dominant knee flexion, (ICC = 0.88) was found to have good reliability

International Journal of Sports Physical Therapy

Reliability and Differences Between Sexes in Landing Mechanics when Performing the Lateral Bound Test

Table 1. Descriptive Statistics (Mean ± SD) and Intra-rater and Test-Retest Reliability Intra-Rater

Test-Retest

1st Rating

2nd Rating

ICC3,1

S1

S2

ICC3,1

Max D Valgus (°)

-1.83 ± 5.02

-1.19 ± 4.42

0.96

-2.26 ± 4.18

-1.81 ± 5.23

0.92

D Knee Flexion IC (°)

22.7 ± 4.42

23.1 ± 5.00

0.99

23.9 ± 4.79

23.3 ± 2.97

0.47

Max D Knee Flexion (°)

34.5 ± 4.72

34.4 ± 4.66

0.96

36.0 ± 8.58

36.2 ± 6.46

0.90

Max ND Valgus (°)

-2.35 ± 4.90

-2.71 ± 4.46

0.97

-3.46 ± 5.64

-1.61 ± 3.01

0.74

ND Knee Flexion IC (°)

20.8 ± 4.46

21.4 ± 4.44

0.96

23.6 ± 5.10

21.1 ± 4.72

0.71

Max ND Knee Flexion (°)

30.0 ± 6.89

30.1 ± 6.96

0.98

33.1 ± 7.76

33.6 ± 9.34

0.88

ICC: D: Dominant leg; ND: Non-Dominant leg; Intraclass correlation coefficient; IC: Initial contact; Max Valgus: Maximum valgus or minimum varus recorded during landing from initial flatfoot to stoppage of movement with negative being a valgus measurement and positive being a varus measurement; SD: Standard deviation; S1: Session one; S2: Session two.

Table 2. Descriptive statistics (Mean ± Standard Deviation) and differences between sexes.

Males (n = 16)

Females (n = 14)

p-value

Age (years)

23.6 ± 1.58

22.9 ± 1.22

0.17

Height (m)

1.80 ± 0.07

1.63 ± 0.07

< 0.01

Weight (kg)

84.2 ± 15.8

60.2 ± 9.25

< 0.01

D Max Valgus (°)

-3.59 ± 4.18

0.34 ± 3.17

0.01

D Knee Flexion IC (°)

22.1 ± 5.49

23.1 ± 4.21

0.56

D Max Knee Flexion (°)

32.7 ± 9.81

31.6 ± 5.56

0.69

ND Max Valgus (°)

-3.06 ± 5.63

0.51 ± 4.18

0.05

ND Knee Flexion IC (°)

23.2 ± 4.90

22.9 ± 4.52

0.87

ND Knee Flexion (°)

31.7 ± 7.54

32.1 ± 7.38

0.87

Bold values indicate significant at 0.05 D: Dominant leg; ND: Non-dominant leg; Max Valgus: Maximum valgus or minimum varus recorded during landing from initial flatfoot to stoppage of movement with negative being a valgus measurement and positive being a varus measurement; SD: Standard deviation; IC: Initial contact.

and two tests, maximum dominant knee valgus (ICC = 0.92) and maximum dominant knee flexion (ICC = 0.90) were shown to have excellent reliability.

Means and standard deviations as well as sex-related differences are displayed in Table 2. Significant differences between sexes were noted for height, weight and bilateral maximum dynamic knee valgus. Males were significantly taller, weighed more, and exhibited greater dynamic knee valgus on both the dominant and non-dominant lower extremity upon landing from the lateral bound, while on average females landed with a slightly knee varus posture on both extremities. There were no significant differences with the degrees of knee flexion on initial contact or maximum knee flexion on either leg when comparing between sexes.

DISCUSSION The purpose of this study was to determine the reliability and differences in performance between sexes of a new test, the LBT, which assesses the quality of landing mechanics in the frontal plane. The hypothesis was partially supported by the results as the lateral bound test was found to be reliable but sex differences in landing mechanics were not accurately predicted. The lateral bound test was found to have excellent intra-rater reliability, but test-retest reliabil-

ity ranged from poor to excellent. Males surprisingly displayed significantly greater landing knee valgus than females although the difference may not be clinically relevant since the findings were less than 4˚.

Compared to other studies of similar tests, the LBT had better intra-rater reliability statistics in the current research. McKeown et al. reported moderate intra-rater reliability when screening with a similar test where female semiprofessional football players performed a maximum lateral bound and a qualitative scoring system was used to assess performance.20 These lower reliability measures could be due to the subjectivity of their study, as the scoring criteria relied on categorical observations opposed to objective numerical data. Hip/knee/ankle alignment, depth, balance/ control, and power positioning in landing were assessed and scored from one to three - one being poor execution of the task and three being perfect execution of the task.20 There are several other studies on examining the reliability of functional screens with similar results. Herrington et al. reported good intra-rater reliability when performing 2D assessment of dynamic knee valgus during a single leg squat screen and a single leg hop landing screen on active and healthy individuals.21 Redler et al. assessed ACL injury risk in young athletes via the drop vertical jump based on normalized knee separation distance, reporting it to have

International Journal of Sports Physical Therapy

Reliability and Differences Between Sexes in Landing Mechanics when Performing the Lateral Bound Test

moderate reliability.1 The LBT demonstrated excellent intra-rater reliability most likely due to the highly objective nature of the study as well as the rater’s experience with the software.

Several other studies examined the test-retest reliability of other functional screens and they had comparable results when assessing dynamic knee valgus angles.21,22 Herrington et al. reported the single leg squat and single leg hop screening tests to have good reliability (ICC= 0.79-0.87) between sessions as well.21 Werner et al. demonstrated good to excellent test-retest reliability when assessing frontal plane projection angles during the single leg squat (ICC=0.84), single leg hop (ICC=0.82), and drop jump (ICC=0.96) using 2D video analysis.22 It is possible that some of these tests demonstrated a greater test-retest reliability due to the fact that the components of the tests, such as single leg squat, were movements with which the subjects were more familiar, or had more practice performing since they may be included in an exercise program.

While the intra-rater reliability of this test was found to be excellent, due to high variability within subjects, the test-retest reliability for some measurements were less consistent. This may be due to participants not landing on the target for every attempt which may be due to many factors such as length of the target or poor athletic performance since the participants were not competitive athletes. The researchers in the current study observed that when a subject landed past the target, they exhibited increased knee valgus. This could have contributed to the participant having difficulty controlling their pelvis and having excessive lateral movement when landing past the target. Furthermore, the average knee valgus (FPPA) decreased in in session two, indicating that there may have been a learning effect in which the subjects became more familiar with the task and were able to improve their landing mechanics in session two by concentrating more on the mechanics.

As expected, there were significant differences by sex noted for height and weight. Males landed with more dynamic knee valgus (bilaterally) which is not a common finding in functional screens performed in the sagittal plane.

In a study using the drop vertical jump, female high school basketball players demonstrated significantly increased dynamic knee valgus as compared to males.23 Furthermore, females demonstrate greater knee valgus angles during a single leg squat test, as well as higher rectus femoris muscle activation, both of which can add to the stress on the ACL during jumping, landing, and cutting activities.24 Pappas et al. reported that regardless of bilateral or unilateral landings, females tend to land with greater knee valgus as compared to males.25 Since females often display greater quadriceps activation during jumping and landing activities in the sagittal plane, this greater quadriceps activation may increase knee stability and actually be beneficial in controlling knee valgus motion while performing the LBT in the frontal plane.24,26 Therefore, males potentially have greater control on knee dynamic valgus in the sagittal plane with an increase in proximal hip stabilizing muscle activation, whereas females have greater control in the frontal plane with an increase in quadriceps muscle activation.24,26 Another explanation is that in the current study the initial static knee valgus measurement was subtracted from the max-

Figure 1. Knee flexion angle during landing from Lateral Bound Test. A. Top figure, shows initial flexion angle B. Bottom figure, show maximum flexion angle.

Figure 2. Frontal plane projection ankle during landing from Lateral Bound Test

imum knee valgus measurement in order to determine the participants dynamic knee valgus during landing during the LBT The greater dynamic knee valgus shown by males, as compared to other studies, could be reflective of other studies not taking account of an initial static knee valgus measurement to determine the amount of knee valgus displayed dynamically during landings.

One limitation of this study was the inability to analyze inter-rater reliability as there was only one person who was trained to perform the video analysis. A second limitation was the inability to move the hurdle, therefore, shorter subjects were closer to the hurdle than taller subjects, but all participants stated they were able to perform the bound comfortably and aberrant techniques were not observed.

International Journal of Sports Physical Therapy

Reliability and Differences Between Sexes in Landing Mechanics when Performing the Lateral Bound Test

The height of the hurdle remained constant and was not standardized to the height of each participant making it another limitation to the study. Having an adjustable hurdle and a more dynamic testing location would allow for standardization of the hurdle height and location in reference to the participant. Finally, the cameras used to record the trials captured 60 frames per second. However, a camera capable of capturing greater number of frames per second could have allowed the recording of more accurate measurements, specifically at knee flexion during initial contact.

Future studies of the LBT should include comparisons of athletes and non-athletes, athletes of different sports, athletes of different competitive levels, and athletes with and without previous lower extremity injury such as those recovering from ACL reconstruction. These future studies would help provide normative data and determine if the LBT could be used as a predictor of lower extremity injury or as a return to sport assessment. Last, different landing lengths, shorter and greater than the leg length or maximal distance bounded should be examined in order to determine if using the participants’ leg length is truly the best distance to observe dynamic knee control in the LBT. This this may be more specific to athletes where bounding the distance of their leg length may not be challenging enough to identify impaired landing mechanics.

CONCLUSION The results of this study indicate that the LBT has excellent intra-rater reliability and varying test-retest reliability when used in healthy non-athletes. Additional research should be performed to determine validity. Unlike other tests assessing dynamic knee valgus in the sagittal plane, the current results indicate that males had statistically greater dynamic knee valgus compared to females during landing and no statistically significant difference in knee flexion angles.

CONFLICT OF INTEREST

All authors declare no conflict of interest related to this manuscript.

Submitted: August 19, 2021 CDT, Accepted: January 23, 2022 CDT

This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CCBY-NC-4.0). View this license’s legal deed at https://creativecommons.org/licenses/by-nc/4.0 and legal code at https://creativecommons.org/licenses/by-nc/4.0/legalcode for more information.

International Journal of Sports Physical Therapy

Reliability and Differences Between Sexes in Landing Mechanics when Performing the Lateral Bound Test

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3. Mather RC, Koenig L, Kocher MS, et al. Societal and economic Impact of anterior cruciate ligament tears. J Bone Joint Surg Am. 2013;95(19):1751-1759. doi:10.21 06/jbjs.l.01705 4. von Essen C, McCallum S, Barenius B, Eriksson K. Acute reconstruction results in less sick-leave days and as such fewer indirect costs to the individual and society compared to delayed reconstruction for ACL injuries. Knee Surg Sports Traumatol Arthrosc.

2020;28(7):2044-2052. doi:10.1007/s00167-019-0539 7-3 5. Prodromos CC, Han Y, Rogowski J, Joyce B, Shi K. A meta-analysis of the incidence of anterior cruciate ligament tears as a function of gender, sport, and a knee injury-reduction regimen. Arthrosc J Arthrosc Relat Surg. 2007;23(12):1320-1325.e6. doi:10.1016/j.a rthro.2007.07.003 6. Hootman JM, Dick R, Agel J. Epidemiology of collegiate injuries for 15 sports: summary and recommendations for injury prevention initiatives. J Athl Train. 2007;42(2):311-319.

7. Smith HC, Vacek P, Johnson RJ, et al. Risk factors for anterior cruciate ligament injury. Sports Health.

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9. Munro A, Herrington L, Comfort P. Comparison of landing knee valgus angle between female basketball and football athletes: possible implications for anterior cruciate ligament and patellofemoral joint injury rates. Phys Ther Sport. 2012;13(4):259-264. do i:10.1016/j.ptsp.2012.01.005

12. Wright RW, Dunn WR, Amendola A, et al. Risk of tearing the intact anterior cruciate ligament in the contralateral knee and rupturing the anterior cruciate ligament graft during the first 2 years after anterior cruciate ligament reconstruction: a prospective MOON Cohort Study. Am J Sports Med. 2007;35(7):1131-1134. doi:10.1177/036354650730131 8 13. Hewett TE, Myer GD, Ford KR, et al.

Biomechanical measures of neuromuscular control and valgus loading of the knee predict anterior cruciate ligament injury risk in female athletes: a prospective study. Am J Sports Med. 2005;33(4):492-501. doi:10.1177/0363546504269591 14. Dix J, Marsh S, Dingenen B, Malliaras P. The relationship between hip muscle strength and dynamic knee valgus in asymptomatic females: a systematic review. Phys Ther Sport. 2019;37:197-209. doi:10.1016/j.ptsp.2018.05.015 15. Kianifar R, Lee A, Raina S, Kulic D. Automated assessment of dynamic knee valgus and risk of knee injury during the single leg squat. IEEE J Transl Eng Health Med. 2017;5:1-13. doi:10.1109/jtehm.2017.273 6559 16. Willson JD, Ireland ML, Davis I. Core strength and lower extremity alignment during single leg squats.

Med Sci Sports Exerc. 2006;38(5):945-952. doi:10.124 9/01.mss.0000218140.05074.fa 17. Williams D, Heidloff D, Haglage E, Schumacher K, Cole BJ, Campbell KA. Anterior cruciate ligament functional sports assessment. Oper Tech Sports Med. 2016;24(1):59-64. doi:10.1053/j.otsm.2015.10.002 18. Kea J, Kramer J, Forwell L, Birmingham T. Hip abduction-adduction strength and one-leg hop tests: test-retest reliability and relationship to function in elite ice hockey players. J Orthop Sports Phys Ther.

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Reliability and Differences Between Sexes in Landing Mechanics when Performing the Lateral Bound Test

19. Taylor JB, Ford KR, Nguyen AD, Shultz SJ. Biomechanical comparison of single- and double-leg jump landings in the sagittal and frontal Plane.

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International Journal of Sports Physical Therapy

Hedt CA, Le JT, Heimdal T, et al. Sex-related Anthropometrics in a Lower-Body Mobility Assessment Among Professional Soccer Athletes. IJSPT. 2022;17(3):474-482.

Original Research

Sex-related Anthropometrics in a Lower-Body Mobility Assessment Among Professional Soccer Athletes a

Corbin A. Hedt 1 , Jessica T. Le 1, Tyler Heimdal 1, Justin Vickery 1, Erin Orozco 1, Patrick C. McCulloch 1, Bradley S. Lambert 1

1

Orthopedics and Sports Medicine, Houston Methodist

Keywords: functional mobility screen, fms, balance, range of motion, injury, mobility, preseason screening https://doi.org/10.26603/001c.32595

International Journal of Sports Physical Therapy Vol. 17, Issue 3, 2022

Background The functional movement screen (FMS™) and Y-balance test (YBT) are commonly used to evaluate mobility in athletes.

Purpose The primary aim of this investigation was to determine the relationship between demographic and anthropometric factors such as sex, body composition, and skeletal dimension and scoring on YBT and FMS™ in male and female professional soccer athletes.

Study Design Cross Sectional

Methods During pre-season assessments, athletes from two professional soccer clubs were recruited and underwent body composition and skeletal dimension analysis via dual-energy X-ray absorptiometry (DEXA) scans. Balance and mobility were assessed using the YBT and FMS™. A two-tailed t-test was used to compare YBT between sexes.

Chi-square was used for sex comparisons of FMS™ scores. Correlation analysis was used to determine if body composition and/or skeletal dimensions correlated with YBT or FMS™ measures. Type-I error; α=0.05.

Results 40 Participants were successfully recruited: (24 males: 27±5yr, 79±9kg; |16 females: 25±3yr, 63±4kg). YBT: Correlations were found between anterior reach and height (r=-0.36), total lean mass (LM)(r=-0.39), and trunk LM(r=-0.39) as well as between posterolateral reach and pelvic width (PW)(r=0.42), femur length (r=0.44), and tibia length (r=0.51)(all p<0.05). FMS™: The deep squat score was correlated with height(r=-0.40), PW(r=0.40), LM(r=-0.43), and trunk LM (r =-0.40)(p<0.05). Inline lunge scores were correlated with height(r=-0.63), PW(r=0.60), LM(r=-0.77), trunk LM(r=-0.73), and leg LM(r=0.70)(all p<0.05). Straight leg raise scores were correlated with PW (r=0.45, p<0.05).

Females scored higher for the three lower body FMS™ measures where correlations were observed (p<0.05).

a

Corresponding author: Corbin Hedt, PT, DPT, SCS, CSCS Houston Methodist, Department of Orthopedics & Sports Medicine 5505 W Loop South Houston, TX 77081 Phone: 713-398-9214 Email: chedt@houstonmethodist.org

Sex-related Anthropometrics in a Lower-Body Mobility Assessment Among Professional Soccer Athletes

Conclusions Lower body FMS™ scores differ between male and female professional soccer athletes and are related to anthropometric factors that may influence screening and outcomes for the FMS™ and YBT, respectively. Thus, these anatomical factors likely need to be taken into account when assessing baseline performance and risk of injury to improve screening efficacy.

Level of Evidence Level 3b

INTRODUCTION Preseason screening for body composition, bone health, range of motion, flexibility, balance, and multidimensional hip strength have become common practice in several professional and collegiate sport settings.1 Athletic injuries and the long-term sequalae that emerge as a result remain a primary concern in athletics for coaches, trainers, physical therapists, and physicians. In particular, soccer athletes often present with higher rates of injury relative to other team based sports.2 When observing NCAA sports teams, both women’s and men’s soccer are among the highest reported rates of ankle sprains as well as quadriceps and hamstring strains.3,4 Anterior cruciate ligament tears are also common, and have a four to six times higher incidence in female soccer players compared to males.3,4 Imbalances in strength, flexibility, movement, and neuromuscular control all pose as risks for athletic injuries which may adversely affect both athletes and their teams through time lost from playing, suboptimal team performance, and difficulties returning to preinjury performance level. As a result, many professional and collegiate sports teams have adopted the practice of preseason movement and balance screening for the purpose of injury prevention.5,6 The Y-balance Test (YBT) and Functional Movement Screen (FMS™) are two common measures performed to evaluate dynamic flexibility and stability.1 The YBT can be used for evaluation of both the upper extremity and lower extremity. The lower quarter YBT (LQYBT), was derived from the Star Excursion Balance Test (SBET) used to evaluate lower extremity balance and stability with multidirectional reaches.7 The FMS™ seeks to identify functional limitations or asymmetries through the evaluation of movement patterns that together measure range of motion, stability, and balance.4,8–11 During the FMS™, athletes perform a series of seven tasks (deep squat, hurdle step, in-line lunge, shoulder mobility, rotary stability, active straight leg raise, trunk stability pushup) and are scored on a criterionbased Likert scale based on their performance for each task.9,10 These scores are used to derive a composite score.

Both assessments have been designed to provide athletic trainers, coaches, and physicians with baseline metrics for tracking player mobility and function throughout a sport season and during rehabilitation from injury.

The YBT and FMS™ have generally been utilized as onesize–fits-all assessments. While numerous studies have examined the utility of YBT and FMS™ as injury prediction tools, conclusions of these studies remain inconsistent.1,12,13 This inconsistency may be in part due the homogeneity of many of the study populations, often only includ-

ing participants of a single sport, sex, or profession without taking into account other potential variables that may influence scoring. With regard to sex, body composition, and skeletal dimensions (bone length, pelvic width, etc.) little is known about how these variables may impact the conclusions of these assessments. Such information may help refine current testing protocols and increase the clinical relevance of screening in assessment of baseline performance and injury risk. Therefore, the primary aim of this investigation was to determine the relationship between demographic and anthropometric factors such as sex, body composition, and skeletal dimension and scoring on YBT and FMS™ in male and female professional soccer athletes. The authors hypothesized that YBT and FMS™ scores would differ between male and female professional soccer athletes and that variables such as body composition and skeletal dimensions would correlate with test scoring and interpretation.

METHODS STUDY DESIGN

This study was a single timepoint cross sectional design and the following protocol was approved by the Houston Methodist Institutional Review Board for research involving human subjects. All participants provided informed consent prior to participation.

PARTICIPANTS

Professional soccer athletes (Major League Soccer, MLS®; National Women’s Soccer League, NWSL®) from two separate clubs were recruited to participate in this investigation during each team’s preseason evaluations and screening.

Both professional organizations were local to the research team. All active roster athletes without ongoing injury (lower extremity injury resulting in activity limitation < six months prior) or other limitations were offered participation to which none declined consent. These athletes were to undergo other preseason multidisciplinary screening measures on the same day, independent of this investigation.

All screening took place in the same location using the same licensed physical therapy team during all evaluations.

PROCEDURES

On the morning of the study, all subjects underwent body composition and skeletal analysis assessed with a DEXAscans (Lunar iDXA, GE®, Boston MA) scan. Full body scans were obtained. Imaging software (ImageJ, Version

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Sex-related Anthropometrics in a Lower-Body Mobility Assessment Among Professional Soccer Athletes

Figure 1. Y-Balance test performance.

1.8.0-172, NIH) was later used (in a similar manner to Stanelle et al.14) with full body DEXA scan images to quantify trunk length, pelvic width, femur length, tibia length, shoulder width, humerus length, and radius length. Bilateral measurements of the extremities were averaged and demonstrated interclass correlation coefficients of >0.95 for all measures. All measures were performed and recorded by the same team of three trained laboratory technicians.

Lower body balance and stability were assessed using standard YBT and FMS™ protocols.9,15 Dynamic balance was measured using the YBT (Figure 1) using the Y-Balance Test Kit™ (Functional Movement Systems, Chatham, VA). Athletes were instructed to balance on one leg while simultaneously reaching as far as possible in three different directions: anterior, posteromedial, and posterolateral. This was performed bilaterally, and distance reached in each direction was recorded. A sum of the total reach distance was done for each leg and normalized to the respective limb length to form a composite score.

The FMS™ was then conducted with the athletes. The seven tasks were scored individually on a scale of 0 (worst) – 3 (best) depending on athlete performance quality for each screening movement (Figure 2). Specific criteria for each movement have been previously published.9 A score of 3 indicates that the athlete was able to perform the movement as directed without compensation. A score of 2 indicates that the athlete performed the movement but with compensation or imperfection. A score of 1 indicates that the athlete was unable to perform the movement. A score of 0 was used if the athlete experienced any pain during the movement regardless of the quality.

STATISTICAL ANALYSIS

Independent samples two-tailed t-tests were used to compare body composition, YBT score, bone length, bone width, and trunk length between sexes. Chi-square analysis was used for comparison of FMS™ test scores between sexes. In instances where significant pair-wise comparisons were observed, effect sizes were calculated using either a Cohen’s d statistic (t-test) or a Phi Statistic (Chi-square)

whereby effect sizes (ES) were interpreted as follows: 0.0-0.1, Negligible (N); 0.1-0.3, Small (S); 0.3-0.5, Moderate (M); 0.5-0.7, Large (L); >0.7, Very Large (VL).16 Pearson’s correlation analysis was used to determine if body composition and bone length was correlated with Y-balance scores.

Spearman’s Rank Order correlation was used for the same analysis of ordinal FMS™ scores. Statistically significant correlational strength was defined as weak (r < 0.4), moderate (r = 0.4-0.7), and strong (r > 0.7). Type I error for all analyses was set at α=0.05. Using a minimum detectable difference of 10% in YBT scores and 30% in FMS™ classification frequency between sexes as well as a minimum overall correlation strength of 0.3 for mobility measures at a power of 0.80, it was determined a minimum sample size of 15 athletes would be required per group.

RESULTS Twenty-four male (27±5 y; 181.6 ± 8.1cm; 79.7 ± 8.8kg) and sixteen female (25±3 y; 168.1 ± 5.8cm; 63.0 ± 4.4kg) subjects participated. Baseline demographics are shown in Table 1 where differences between sexes were observed for all demographic variables (p<0.001) with the exception of BMI. SKELETAL DIMENSIONS

Comparison of skeletal dimensions between male and female athletes are shown in Table 2 where significant differences between sexes were observed for trunk length, humerus length, shoulder width, radius length, pelvic width below femoral head, femur length and tibia length (p<0.05).

No differences were observed between sexes for greatest pelvic width.

FUNCTIONAL MOVEMENT SCREEN

Variables of skeletal dimensions were observed to be significantly correlated with FMS™ scoring for the deep squat, inline lunge, and straight leg raise (p<0.05). Moderate negative correlations were found between the deep squat score and total lean mass (r = -0.43), trunk lean mass (r = -0.40),

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Sex-related Anthropometrics in a Lower-Body Mobility Assessment Among Professional Soccer Athletes

Figure 2. Functional Movement Screening Tests & Scoring Criteria.

Photo examples of each test along with scoring criteria for a top score of “3” taken on a 0 – 3 rating scale.

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Sex-related Anthropometrics in a Lower-Body Mobility Assessment Among Professional Soccer Athletes

Table 1. Athlete Demographics.

ATHLETE DEMOGRAPHICS Height (cm)

Weight (kg)

BMI (kg/m2)

%Fat

Lean Mass (kg)

Male (n=24)

181.6 ± 8.1

79.7 ± 8.8

24.1 ± 1.0

14.8 ± 3.6

64.7 ± 8.1

Female (n=16)

168.1 ± 5.8

63.0 ± 4.4

22.3 ± 1.4

21.0 ± 2.9

47.3 ± 3.7

Data are presented as means±SD

Table 2. Skeletal Dimensions.

SKELETAL DIMENSIONS (cm) Trunk Length

Humerus Length

Shoulder Width

Radius Length

Male

44.2 ± 2.2

33.1 ± 2.1

42.1 ± 2.5

25.4 ± 1.5

Female

41.1 ± 1.5

30.6 ± 1.8

37.4 ± 1.8

22.8 ± 1.3

p-value ES d

p<0.001 1.6 (VL)

p<0.001 1.3 (VL)

p<0.001 2.2 (VL)

p<0.001 1.9 (VL)

Greatest Pelvic Width

Pelvic Width Below Femoral Head

Femur Length

Tibia Length

Male

27.2 ± 1.7

15.3 ± 1.4

46.6 ± 2.4

40.0 ± 2.2

Female

26.4 ± 1.6

16.8 ± 0.8

42.6 ± 1.6

35.9 ± 2.0

p-value ES d

NS

p<0.001 1.3 (VL)

p<0.001 2.0 (VL)

p<0.001 2.0 (VL)

Data are presented as means±SD for skeletal dimensions assessed using ImageJ software. Type I error set at α=0.05. Sig. = Significant differences between sexes denoted with p-values.

ES= Cohen’s d statistic for effect size calculated for significant pairwise comparisons: 0.0-0.1, Negligible (N); 0.1-0.3, Small (S); 0.3-0.5, Moderate (M); 0.5-0.7, Large (L); >0.7, Very Large (VL)

Table 3. Functional Movement Screen.

Functional Movement Screen Scoring Frequencies (1-3 Scale, % of Athletes Scored in Each Category)

Men

Women Sig. ES φ

FMS™ Score

Deep Squat

1

33%

2

67%

3

0%

1

0%

2 3

Hurdle Step

In-line Lunge

Shoulder Mobility

Straight Leg Raise

Stability Pushup

Rotary Stability

8%

0%

14%

6%

6%

6%

75%

100%

50%

47%

56%

94%

17%

0%

36%

47%

39%

0%

0%

0%

0%

0%

22%

11%

94%

63%

28%

44%

16%

44%

79%

6%

38%

72%

56%

84%

22%

0%

P=0.021 0.4 (M)

NS

P<0.001 0.8 (VL)

NS

P=0.043 0.4 (M)

NS

NS

Data are presented as frequencies of men and women scoring in FMS™ classifications 1, 2, or 3. ES= Phi statistic for effect size calculated for significant pairwise comparisons: 0.0-0.1, Negligible (N); 0.1-0.3, Small (S); 0.3-0.5, Moderate (M); 0.5-0.7, Large (L); >0.7, Very Large (VL).

and height (r = -0.40) (p<0.05). Moderate and strong negative correlations were observed between the in-line lunge score and height (r = -0.63), total lean mass (r = -0.77), trunk lean mass (r = -0.73), and leg lean mass (r = -0.70). A moderate positive correlation was observed between pelvic width and the deep squat (r = 0.40), in-line lunge (r = 0.60), and active straight leg raise (r = 0.45) scores (p<0.05). For each of the exercises mentioned (deep squat, in-line lunge,

and straight leg raise), the female athletes were observed to score higher than the males (p<0.05). (Table 3).

Y-BALANCE SCREEN

Results for the YBT are shown in Figure 3. YBT measurements were taken for reach in the anterior, posteromedial, and posterolateral directions. No differences in Y-balance measures were observed between sexes after normalizing

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Sex-related Anthropometrics in a Lower-Body Mobility Assessment Among Professional Soccer Athletes

to individuals’ limb-length as is common in clinical assessment. Weak negative correlations were found between anterior reach and height, total lean mass (r = -0.36), leg lean mass (r = -0.39), and trunk lean mass (r = -0.39) (all p<0.05).

Moderate positive correlations were found between posterolateral reach and pelvic width below the femoral head (r = 0.42), femur length (r = 0.44), and tibia length (r = 0.051) (all p<0.05).

DISCUSSION

Figure 3. Y-Balance Comparison.

The YBT and FMS™ are frequently used measures that have been suggested for use in predicting athletic injury risk often used in a one–size-fits-all manner. The primary aim of this investigation was to determine the relationship between demographic and anthropometric factors such as sex, body composition, and skeletal dimension and scoring on the YBT and FMS™ in male and female professional soccer athletes. Consistent with the hypothesis, several of these factors were observed to be significantly correlated with test performance. The findings of these study highlight possible sources of bias that may influence test scoring. Although further study remains needed, the findings from this investigation provide potential target variables that may be further explored and potentially incorporated into the development of future screening tools.

SEX, BODY COMPOSITION, SKELETAL DIMENSIONS, AND FMS™ SCORING

In this investigation, significant differences were found between male and female athletes for the FMS™ test with a greater percentage of female athletes scoring in a higher classification than male athletes for deep squat, in line lunge, and straight leg raise (Table 3). While female athletes may be scoring more favorably than their male counterparts in these screens of fundamental movements, the literature has several reports of higher rates of injury among female athletes in comparison to male athletes.4,17–20 Agel et. al21 reported that women sustain ACL injuries at higher rates than their male counterparts in soccer, basketball, and lacrosse. While the cause of such injuries seems to be multifactorial, the Q-angle, or the angle of the femur to the tibia, has been loosely described as a potential contributing factor to knee injuries. As observed in this study, females tend to have greater pelvic width, resulting in greater Q-angle. Although this metric may contribute to higher scores in lower body mobility tests, it may also contribute to risk of knee injury, though the causal aspect of this relationship has yet to be confirmed.22 This indicates that other factors likely impact scoring performance on these generalized assessments which in turn may explain the reduced utility of assessments such as FMS™ and YBT to reliably predict injury risk or compare injury risk among athletes with differing musculoskeletal builds. Based on the results of this investigation, the authors hypothesize that biomechanical features that contribute to a lower center of gravity with a wider base of support and lower mass represent a key source of FMS™ testing bias.20,23 Expectedly, differences were observed in body composition and musculoskeletal dimensions between sexes in this

Data are presented as means±95%CI for Y-balance measures taken from both the male and female professional soccer athlete groups with no between-group differences detected.

study. Overall, the female professional soccer athletes had reduced height, lower body mass, lower lean mass, wider pelvic width, shorter femur length, and shorter tibia length than the male professional soccer athletes. Based on the given results, these factors likely contributed to a potential anatomical advantage that resulted in greater FMS™ test performance for the lower body. However, female soccer athlete injury rates still remain different compared to male athletes with non-contact injuries being more likely to occur in females and contact based injuries being more frequent in males.3,21 Male athletes are also more likely to sustain quadriceps strains while female athletes are more likely to sustain hamstring strains.3,4,18,19 Lastly, sex-based differences in muscle activation patterns during activity have been previously observed.23 Padua et al.23 found that across two-legged-hopping conditions the women demonstrated 46% more quadriceps muscle activity than men. Increase in quadricep activation could lead to increasing levels of fatigue, therefore putting women at a greater risk for injury.

Therefore, regarding the present results, rather than being at reduced risk of injury, there may be a scoring bias in the FMS™ screen that benefits female athletes due to certain inherent anatomical features such as pelvic width, height, and lean mass.

ANATOMICAL FACTORS ASSOCIATED WITH Y-BALANCE PERFORMANCE

Similar to the FMS™, the YBT measures were correlated with anatomical factors (lean mass and skeletal dimensions) whereby less lean mass but greater pelvic widths produced higher measures (despite test measures being normalized to limb length). In contrast to the FMS™ screen, skeletal dimensions are somewhat incorporated into the YBT (limb length).24,25 The authors hypothesize that this likely accounts for the lack of difference in YBT measures between men and women (Figure 3). However, the results still indicate that generalizing measures between those with different musculoskeletal builds will likely result in testing bias that cannot be accounted for by sex alone. In a recent systematic review, Plisky et al.24 echo these findings when assessing anterior reach and composite scores among multiple studies.43 However, a large variability in each sex, sport, and age/competition level was present in their included studies, lending to the possibility in composite score variance depending on the sex, sport, and competition level

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Sex-related Anthropometrics in a Lower-Body Mobility Assessment Among Professional Soccer Athletes

when considered as a whole.24 These authors suggest normative data be established based on a multitude of these factors, and future research should be performed using a wide variety of populations.24 FUTURE DIRECTIONS

Cumulatively, the findings of the present investigation suggest that it may be of benefit for anatomical features not typically considered in the FMS™ or the YBT to be incorporated, or considered in tandem with the respective tools.

Such factors may also be considered when tailoring exercises to address mobility deficiencies as is common for FMS™ screening.5 Notably, data are currently conflicting on whether or not FMS™ scoring are predictive of future injury frequency.5,26–28 For example, Moran et al.27 recently performed a meta-analysis of 24 investigations and reported that present data suggest that the use of FMS™ for injury prevention in soccer athletes was ineffective and that its efficacy was conflicting among in the literature among other sports (American football, basketball, ice hockey, running, and first responders such as police and firefighters).

Therefore, it is possible that the anatomical scoring bias observed here may have contributed to some of the lack of predictive utility observed in other investigations. Future research will need to determine how any additional metrics may be best incorporated into algorithms to reduce scoring bias in these types of athletic populations and whether or not eliminating such bias will improve clinical utility for injury risk assessment.

LIMITATIONS

& CONCLUSIONS

This investigation is not without limitations. Data collection and access to professional athletes is often limited and, although powered appropriately for comparisons in this investigation, participants were included from only two individual clubs which may limit generalizability across the studied populations. Participants in this study ranged in age from 22 to 32 years of age. This is a limited age range, and the authors acknowledge that there may be developmental differences in younger and older athletes that may also be associated with performance in the measures observed here. Although several factors were identified to be associated with testing bias, it is not yet clear how or whether these metrics should be incorporated into current scoring systems for FMS™ and YBT and whether or not do-

ing so would significantly the value of these assessments for injury risk screening. Therefore, further study will be required to examine which factors identified here may best be incorporated into FMS™ and YBT to reduce scoring bias and better predict injury risk. For example, evaluating the collinearity between some of the measures (possibly due, in part, to differences between sexes) reported on here in a larger study cohort may help to reduce total number of additional factors needed to reduce scoring bias. Lastly, while data exists in previous literature regarding injury frequency norms in male and female soccer athletes, the investigators in this study were not able to access injury history information on this group of athletes. Such information may have assisted in determining whether FMS™ or YBT scores were correlated with injury history across sports seasons.

CONCLUSION In summary, the results of this study indicate that sexbased differences observed between sexes for lower body components of the FMS™ and YBT measures may be attributed to anatomical variables such as height, lean mass, and skeletal dimensions that impact both FMS™ and YBT scoring, respectively. While the YBT and FMS™ were designed to evaluate dynamic joint mobility and fundamental movement competency, their use for potential risk for injury based on a one-size-fits-all generalized criteria is questioned. These assessments are likely better suited for use on a more individualized basis rather than comparing across groups of athletes. Further research is needed to determine if, and to what degree, sex, body composition, skeletal dimensions, and dynamic motion analysis might be incorporated in to scoring criteria or predictive modeling to enhance the use of these clinical assessments for predicting risk of injury.

CONFLICTS OF INTEREST

The authors have no conflicts of interest to disclose and no funding support was provided for the work presented in this manuscript.

Submitted: August 30, 2021 CDT, Accepted: January 09, 2022 CDT

This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CCBY-NC-4.0). View this license’s legal deed at https://creativecommons.org/licenses/by-nc/4.0 and legal code at https://creativecommons.org/licenses/by-nc/4.0/legalcode for more information.

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Sex-related Anthropometrics in a Lower-Body Mobility Assessment Among Professional Soccer Athletes

REFERENCES 1. Chimera NJ, Warren M. Use of clinical movement screening tests to predict injury in sport. World J Orthop. 2016;7(4):202.

2. Fousekis K, Tsepis E, Poulmedis P, Athanasopoulos S, Vagenas G. Intrinsic risk factors of non-contact quadriceps and hamstring strains in soccer: a prospective study of 100 professional players. Br J Sports Med. 2011;45(9):709-714. doi:10.1136/bjsm.20 10.077560

11. Dorrel BS, Long T, Shaffer S, Myer GD. Evaluation of the functional movement screen as an injury prediction tool among active adult populations: a systematic review and meta-analysis. Sports health.

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13. Gnacinski SL, Cornell DJ, Meyer BB, ArvinenBarrow M, Earl-Boehm JE. Functional movement screen factorial validity and measurement invariance across sex among collegiate Student-Athletes. J Strength Cond Res. 2016;30(12):3388-3395.

4. Eckard TG, Kerr ZY, Padua DA, Djoko A, Dompier TP. Epidemiology of quadriceps strains in national collegiate athletic association athletes, 2009–2010 through 2014–2015. J Athl Train. 2017;52(5):474-481. doi:10.4085/1062-6050-52.2.17

14. Stanelle ST, Crouse SF, Heimdal TR, Riechman SE, Remy AL, Lambert BS. Predicting muscular strength using demographics, skeletal dimensions, and body composition measures. Sports Med Health Sci. Published online 2021.

5. Basar MJ, Stanek JM, Dodd DD, Begalle RL. The influence of corrective exercises on functional movement screen and physical fitness performance in army ROTC cadets. J Sport Rehabil.

2019;28(4):360-367.

15. Walker O. Y Balance Test [Internet]. Published online 2016. https://www.scienceforsport.com/y-bala nce-test/

6. Campa F, Piras A, Raffi M, Toselli S. Functional movement patterns and body composition of highlevel volleyball, soccer, and rugby players. J Sport Rehabil. 2019;28(7):740-745.

7. Myers H, Christopherson Z, Butler RJ. Relationship between the lower quarter Y-balance test scores and isokinetic strength testing in patients status post ACL reconstruction. Int J Sports Phys Ther. 2018;13(2):152.

8. Bond CW, Dorman JC, Odney TO, Roggenbuck SJ, Young SW, Munce TA. Evaluation of the functional movement screen and a novel basketball mobility test as an injury prediction tool for collegiate basketball players. J Strength Cond Res. 2019;33(6):1589-1600.

9. Cook G, Burton L, Hoogenboom BJ, Voight M. Functional movement screening: the use of fundamental movements as an assessment of function-part 1. Int J Sports Phys Ther. 2014;9(3).

10. Cook G, Burton L, Hoogenboom BJ, Voight M. Functional movement screening: the use of fundamental movements as an assessment of function-part 2. Int J Sports Phys Ther. 2014;9(4).

16. Sawilowsky SS. New effect size rules of thumb. J Mod Appl Stat Methods. 2009;8(2):26.

17. Bollars P, Claes S, Vanlommel L, Van Crombrugge K, Corten K, Bellemans J. The effectiveness of preventive programs in decreasing the risk of soccer injuries in Belgium: national trends over a decade.

Am J Sports Med. 2014;42(3):577-582.

18. Bradley PS, Portas MD. The relationship between preseason range of motion and muscle strain injury in elite soccer players. J Strength Cond Res. 2007;21(4):1155.

19. Cross KM, Gurka KK, Saliba S, Conaway M, Hertel J. Comparison of hamstring strain injury rates between male and female intercollegiate soccer athletes. Am J Sports Med. 2013;41(4):742-748.

20. Mufty S, Bollars P, Vanlommel L, Van Crombrugge K, Corten K, Bellemans J. Injuries in male versus female soccer players: epidemiology of a nationwide study. Acta Orthop Belg. 2015;81(2):289-295.

21. Agel J, Rockwood T, Klossner D. Collegiate ACL injury rates across 15 sports: national collegiate athletic association injury surveillance system data update (2004-2005 through 2012-2013). Clin J Sport Med. 2016;26(6):518-523.

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22. Nguyen AD, Boling MC, Levine B, Shultz SJ. Relationships between lower extremity alignment and the quadriceps angle. Clin J Sport Med. 2009;19(3):201.

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International Journal of Sports Physical Therapy

Kaur N, Bhanot K, Ferreira G. Lower Extremity and Trunk Electromyographic Muscle Activity During Performance of the Y-Balance Test on Stable and Unstable Surfaces.

IJSPT. 2022;17(3):483-492.

Original Research

Lower Extremity and Trunk Electromyographic Muscle Activity During Performance of the Y-Balance Test on Stable and Unstable Surfaces a

Navpreet Kaur 1 , Kunal Bhanot 2, Germaine Ferreira 1 1

Physical Therapy, University of St. Augustine for Health Sciences, Austin, TX, 2 Physical Therapy, Carlow University, Pittsburgh, PA

Keywords: y balance test, star excursion balance test, electromyography, dynamic balance https://doi.org/10.26603/001c.32593

International Journal of Sports Physical Therapy Vol. 17, Issue 3, 2022

Background The Star Excursion Balance Test (SEBT) has been used as a rehabilitation exercise. To improve its efficacy, efficiency, and method variations, the Y-Balance Test (YBT) with anterior (A), posterolateral (PL), and posteromedial (PM) directions of the SEBT has been recommended. Electromyographic activity has been reported to change when the same task is performed on various surfaces.

Hypothesis/Purpose To compare the EMG activity of trunk and LE muscles during the performance of the YBT on stable and unstable surfaces.

Study Design Cross-Sectional study.

Methods Healthy adults with no history of chronic ankle instability were recruited for the study.

Surface electromyography was collected for bilateral (ipsilateral [i] and contralateral [c]) rectus abdominis (RA), external oblique (EOB), erector spinae (ES). While, gluteus maximus (GMAX), gluteus medius (GMED), medial hamstrings (MH), biceps femoris (BF), vastus medialis (VM), rectus femoris (RF), vastus lateralis (VL), anterior tibialis (AT), and medial gastrocnemius (MG) on the stance leg (ipsilateral side), during the performance of the YBT. The unstable surface was introduced using a Thera-Band stability trainer.

Differences in electromyography were examined for each reach direction and muscle between the stable and unstable surfaces (p≤ 0.05).

Results Twenty (10 male, 10 female) subjects participated (age: 27.5 ± 4.0 years, height:167 ± 1.0 cm, weight: 66.5 ± 13.0 kg, body fat: 14.1 ± 6.2%). Significantly higher muscle activity for the unstable surface (p<0.05) with moderate to large effect sizes were observed for the following muscles in the A direction: GMED, GMAX, VM, RF, and MG; PL direction: iEOB, iES, cES, GMED, BF, VM, RF, and MG; and PM direction iEOB, iES, GMED, BF, VM, and RF. Significantly higher muscle activity for the stable surface (p = 0.007) was observed in MH muscle in the A direction. No significant differences (p>0.05) between the stable and

a

Corresponding author: Dr. Navpreet Kaur, PT, PhD Associate Professor, Doctor of Physical Therapy Program, University of St. Augustine for Health Sciences, 5401 LaCrosse Avenue, Austin, TX, 78739 Phone Number: 737-202-3338 Fax Number: 512-394-9764 Email: nkaur@usa.edu

Lower Extremity and Trunk Electromyographic Muscle Activity During Performance of the Y-Balance Test on Stable and...

unstable surfaces were observed in iRA, cRA, cEOB, VL, and AT for any of the directions of the YBT.

Conclusion An increase in muscle activity was observed during YBT on unstable versus stable surfaces for some muscles.

Level of Evidence 2B

INTRODUCTION The Y-Balance Test (YBT), derived from the Star Excursion Balance Test (SEBT), is an inexpensive and commonly used objective measure to assess lower extremity (LE) dynamic balance, functional symmetry, and stability.1–4 Due to the possibility of errors that may occur during the performance of the SEBT and the absence of a standardized protocol for the performance of the test, the YBT has been gaining popularity in clinical and research settings.3–5 The YBT was designed to standardize the SEBT test performance and to improve the reliability of the test. The YBT™ (Functional Movement Screen, Danville, VA) is an instrumented version of the modified SEBT that assesses an individual’s performance in the anterior (A), posterolateral (PL), and posteromedial (PM) directions. To perform the YBT, the individual stands on an elevated central plastic platform and pushes a rectangular reach block with the foot along a calibrated plastic tubing in each of the three directions.

The YBT has been documented as a reliable tool to assess balance in athletes.3,6 Smith et al.7 found that A reach direction asymmetry on the YBT was associated with an increased risk for injury across various sports. They concluded that the YBT could be a valuable tool when screening athletes across multiple sports. Similar results were found by Butler et al.8 who suggested that poor performance on the YBT is associated with an increased risk for LE injuries in college football players. Poor performance on the YBT has also been linked to an increased incidence of ankle injuries in collegiate athletes.9 Increased risk of injuries has also been documented in high school cross-country male runners who demonstrated greater asymmetries while performing the YBT.1 It seems reasonable that identifying the risk factors associated with sports-related injuries could help clinicians/ trainers/coaches in designing programs/interventions to address those factors and overall decrease the injury rates.

LE injuries have been attributed to poor neuromuscular (NM) control.5,7,10 Neuromuscular control is defined as the detection, perception, and utilization of relevant sensory information to perform specific tasks.11 To reduce injury risk, training programs should include diverse interventions to improve dynamic balance and control. The SEBT has been utilized as a training tool to improve trunk NM control and dynamic balance assessed by measuring trunk strength and endurance using a pressure biofeedback unit and with single leg stance time with eyes open and closed, respectively.12,13 Significant improvements in these outcomes were seen in the subjects who were trained using the SEBT. No such studies have been published utilizing the YBT tool kit as a training instrument.

Another way of improving dynamic balance is by introducing unstable surfaces to the training programs.14,15 Unstable surfaces cause a greater challenge to NM control in comparison to stable surfaces and hence are commonly used by clinicians and trainers in their protocols. While introducing instability to exercises may improve stability, the effect on muscle activation has not been completely described. Surface EMG has been extensively used to measure muscle activity (activation) during various activities. Muscle activation, as measured using surface electromyography (EMG), has been documented to vary significantly depending on the type of surface.14–16 Adding instability may be effective in increasing the muscle activation in stabilizing muscles.15 Rehabilitation professionals commonly use the intensity of exercise, defined as a given percentage of the maximal muscle contraction and measured by the EMG, to design protocols for strength and stability training.16–18 Previous researchers have documented parameters to determine sufficient EMG activation to achieve various training effects.17,19,20 Strength gains are expected from exercises that cause EMG activation levels greater than 40% however, activation levels below 40% are still beneficial in improving NM control.17,19,20 Authors have found EMG activation to be direction-specific when measured in subjects performing the SEBT.19,21,22 To the authors’ knowledge, no studies measuring the EMG activity while performing the YBT have been published. Knowing the muscle activation patterns while performing YBT on various surfaces may assist in utilizing this test as a training tool. Therefore, the purpose of this study was to compare the EMG activity of trunk and LE muscles during the YBT on stable and unstable surfaces.

METHODS PARTICIPANTS

Twenty healthy adults (10 males and 10 females) were recruited via email to the university community to participate in the study. The study was approved by the Institutional Review Board of the University of St. Augustine for Health Sciences, Austin, TX. PROTOCOL

The participants signed the informed consent before starting the test protocol. The participants were screened for the inclusion/exclusion criteria (Table 1).19 Lange® skinfold calipers (model # 68902, Fitness Mart®, division of Country Technology, Inc. Gays Mills, WI) and three site formula regression equations for men (chest, abdomen, and thigh) and women (triceps, supra-iliac, and abdomen) were used

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Table 1. Inclusion/exclusion criteria of the study.

Inclusion Criteria • •

Exclusion Criteria

Age 18-40 years, Age-related body composition (% body fat) between fair to very lean, as reported in ACSM's Guidelines for Exercise Testing and Prescription ◦ Men: Age 20-29: 4.2 - 18.6 %body fat; Age 30-39: 7.3 - 21.6 %body fat. ◦ Women: Age 20-29: 11.4 - 23.5 %body fat; Age 30-39: 11.0 - 24.8 %body fat

• • • • • • • •

to assess body composition.23 Skinfold measurements were taken by the guidelines provided by the ACSM’s Guidelines for Exercise Testing and Prescription23 at the sites mentioned above for both the men and the women. The body composition of the participants was assessed to achieve the most accurate surface EMG (sEMG) signal by reducing the effects of body fat on the sEMG signal by excluding participants with body fat percentage above the “Fair” category by age (Men: Age 20-29: 18.6 %body fat; Age 30-39: 21.6 %body fat. Women: Age 20-29: 23.5 %body fat; Age 30-39: 24.8 %body fat).24 The Trigno wireless EMG system (Delsys Inc. Boston, MA, USA) was used to collect all the EMG data. The wireless electrodes used measured 37mm x 26mm x 15 mm and encompassed a hard-wired single differential amplifier and a four-bar (99.9% silver) contact area, with an inter-electrode distance of 10 mm (Delsys Inc. Boston, MA, USA). Surface EMG was collected from the erector spinae (ES), external oblique (EOB), and rectus abdominis (RA) bilaterally (ipsilateral and contralateral side of the stance leg). While, gluteus medius (GMED), gluteus maximus (GMAX), medial hamstrings (MH), biceps femoris (BF), vastus medialis (VM), rectus femoris (RF), vastus lateralis (VL), anterior tibialis (AT), and medial gastrocnemius (MG) on the stance leg during the YBT. The skin was cleaned with a skin prep pad, and the area was shaved if body hair was present. The electrodes were placed according to the procedure described

by Cram et al.25 The participants performed light jumping jacks for 30 seconds for warm-up after the electrodes were placed.26 For normalization of the EMG data, maximum voluntary isometric contractions (MVIC) were performed for each muscle. The MVIC test positions were consistent with those demonstrated by Kendall27 and previous research.17,19 Proper electrode placements were also confirmed by observing the EMG amplitudes during the manual muscle tests before testing the MVIC. The participants were asked to perform primary muscle action of the neighboring muscles to assess for crosstalk. Manual pressure was gradually increased until maximum resistance was applied and then held for five seconds using a metronome. Each muscle test was repeated three times with the thirty-second rest between contractions. For all subjects, MVIC was averaged across the three intermediate seconds for each muscle to calculate the mean of the peak RMS value of the three trials.

History of chronic ankle instability (CAI) of the stance leg (the leg participants would stand on to kick a ball) Upper or lower extremity injury within prior 6 months History of upper extremity surgery within prior 6 months Any history of neck, back, or lower extremity surgery.

Currently experiencing pain anywhere in the body Difficulty maintaining single leg stance for 10 seconds on either leg Visible contra-lateral pelvic drop during single-leg stance History of head injury or any other disorder affecting their balance.

Two minutes of rest was provided between the MVIC testing of different muscles.

Y-BALANCE PERFORMANCE

A YBT kit™ was placed on the floor. This requires participants to stand on one limb and to perform a reaching task in three directions with the other lower limb while maintaining balance on the stance leg (Figure 1).3,4,6,10 The preferred stance leg was defined as the leg participant would stand on to kick a ball because it would simulate unilateral weight-bearing activities of the participants and also to make comparisons with previous EMG studies performed during the SEBT.19 Participants were asked to place the foot of their stance leg behind the designated line on the central platform on the tool kit. Participants completed the test barefoot. Participants were instructed to keep their arms by the side so their shoulder flexion and abduction did not exceed 45° while performing the YBT. No specific instructions were provided for trunk motion. An unstable surface was introduced by placing a Theraband™ stability trainer on top of the central platform (Figure 2). The order of the reach directions and surface conditions were randomized using computerized random sequence generator.

Participants were instructed to toe touch on the central platform before beginning to reach, marking the beginning of the single-leg stance phase. The toe touch event was recognized on the EMG data using a toe sensor that showed a signal spike on the computer screen. Participants were instructed to push the rectangular reach block as far as possible along the calibrated plastic tubing in one of the predetermined directions of the YBT with the opposite leg and return to the double-leg stance. They were asked to toe touch on the central platform before putting any weight on the reaching leg marking the end of the single-leg stance phase. A metronome was used at a rate of 30 beats/min (equates to two seconds) to ensure consistent timing and speed of each of the YBT trials where each reaching phase (from initial stance to maximum reach; two seconds) and the recovery phase (from maximum reach to bilateral stance; two seconds) was performed during one beat, a total of four seconds.19 Verbal cueing was provided to the participants during the YBT to synchronize their toe touch with the metronome beat.

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Maximum reach distances were recorded at the touchdown point. The reach distance was normalized by participants’ leg length measured from the anterior superior iliac spine (ASIS) to the distal end of the medial malleolus.28 Participants completed six practice trials with the metronome in each of the three (A, PL, PM) reach directions of the YBT. A five-minute break was provided between the practice trials and the data collection. Fifteen seconds of recovery time was given between test trials to reduce the risk of fatigue. A 60 second recovery time was utilized between reach directions, and the order of the reach directions was randomized. The trial was discarded if the heel of the stance leg lifted off the ground, or if the participant put weight on the reaching leg during maximal reach, lost balance even if the heel remained on the ground, could not return to the starting position, or did not match the metronome speed.

If the trial was discarded, additional trials were performed until the participant completed three good trials in each direction.

DATA PROCESSING

The data were collected at a sampling frequency of 1926 Hz, common-mode reduction ratio> 80 dB@60 Hz; signal to noise ratio of > 750 nv, and no gain was applied to the signal. All collected signals were subsequently bandpass filtered (between 20 and 450 Hz) with a 2nd order filter on the high-pass and a 4th order filter on the low-pass, then rectified and finally smoothed by using a root-mean-square (RMS) calculation. RMS was calculated using a default window length of 0.125 s with a 0.0625s window overlap. MVIC was used to calculate the percentage MVIC. The mean RMS value of the EMG signal of each muscle for each direction during the YBT was calculated during the two seconds reaching (eccentric) phase of each YBT trial. The reaching phase was measured from the beginning of the unilateral stance to the maximal reach identified by the toe sensor.

The EMG of the reaching phase was calculated to be consistent with the methods described in the prior literature.19,22 The RMS value of the reaching phase of the three trials was averaged for each muscle to be normalized to its respective MVIC value and represented as a percentage of the MVIC (%MVIC).

Figure 1. Participant demonstrating the Y-Balance Test in the posterolateral direction on the stable surface.

STATISTICAL ANALYSIS

Paired t-tests were used to determine differences in %MVIC of the three reach directions A (stable vs. unstable), PL (stable vs. unstable), and PM (stable vs. unstable) for each muscle. The level of significance was pre-set at p≤ 0.05, and SPSS version 23.0 was used for all the statistical analyses.

The Cohens d effect size was also calculated for each comparison.29

Figure 2. Participant demonstrating the Y-Balance Test in the posterolateral direction on the unstable surface.

RESULTS Twenty (10 male, 10 female) subjects participated (age: 27.5 ± 4.0 years, height:167 ± 1.0 cm, weight: 66.5 ± 13.0 kg, body fat: 14.1 ± 6.2%). Significant differences with moder-

ate to large effect sizes between stable and unstable surfaces (greater EMG values in the unstable condition) were observed for the following muscles in the A direction:

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Table 2. EMG activity of each muscle presented as %MVIC (maximal voluntary isometric contraction).

Directions

A

PL

PM

Stable (Mean ± SD)

Unstable (Mean ± SD)

Effect Size

Stable (Mean ± SD)

Unstable (Mean ± SD)

Effect Size

Stable (Mean ± SD)

Unstable (Mean ± SD)

Effect Size

iRA

13.1 ± 11.0

14.2 ± 12.4

0.14

7.1 ± 6.2

8.5 ± 9.0

0.43

6.1 ± 4.6

7.2 ± 6.9

0.35

cRA

9.0 ± 6.1

8.9 ± 5.3

0.04

5.1 ± 3.7

5.8 ± 5.0

0.4

5.2 ± 3.8

5.9 ± 4.9

0.43

iEOB

18.6 ± 15.1

22.1 ± 20.5

0.4

12.7 ± 9.3*

20.6 ± 20.6*

0.6

10.8 ± 9.9*

14.0 ± 14.1*

0.6

cEOB

32.4 ± 37.7

40.7 ± 53.5

0.5

25.0 ± 36.8

29.3 ± 35.3

0.4

36.8 ± 44.7

42.0 ± 46.8

0.4

iES

19.7 ± 17.1

22.3 ± 18.1

0.25

63.2 ± 27.5*

69.7 ± 31.6*

0.6

27.4 ± 13.9*

33.1 ± 15.5*

0.5

cES

21.2 ± 17.7

23.9 ± 16.7

0.33

27.6 ± 12.2*

32.4 ± 15.6*

0.6

36.1 ± 14.1

39.0 ± 16.5

0.45

GMED

35.5 ± 25.7*

42.2 ± 23.0*

0.96

23.4 ± 15.1*

27.5 ± 18.0*

0.6

36.5 ± 19.2*

42.7 ± 21.6*

0.9

GMAX

10.5 ± 6.4*

12.5 ± 9.3*

0.5

12.9 ± 7.6

13.0 ± 7.2

0.03

11.8 ± 6.0

12.8 ± 6.6

0.2

MH

30.8 ± 17.5*

22.8 ± 13.3*

0.7

18.1 ± 10.4

19.8 ± 12.0

0.2

19.3 ± 10.3

19.2 ± 11.2

0.02

BF

19.3 ± 10.9

20.5 ± 14.0

0.2

23.6 ± 12.9*

27.7 ± 12.8*

0.6

15.3 ± 8.8*

19.2 ± 13.2*

0.7

VM

97.1 ± 57.8*

127.8 ± 56.7*

1.2

63.2 ± 27.2*

73.8 ± 30.8*

0.9

89.5 ± 39.7*

100.5 ± 46.6*

0.7

RF

32.0 ± 22.8*

55.5 ± 32.0*

1.6

33.2 ± 27.1*

40.8 ± 29.6*

1.0

42.4 ± 32.8*

51.4 ± 30.4*

1.1

VL

88.5 ± 38.6*

116.1 ± 46.6*

1.6

65.9 ± 32.8*

77.4 ± 37.8*

1.2

87.4 ± 44.4*

96.1 ± 48.4*

0.7

AT

41.6 ± 18.5

43.9 ± 12.5

0.2

52.1 ± 17.0

55.3 ± 19.2

0.3

47.5 ± 19.2

46.6 ± 18.3

0.08

MG

38.8 ± 20.5*

48.9 ± 24.3*

0.7

47.9 ± 27.8*

58.3 ± 32.7*

0.9

41.2 ± 27.6

44.8 ± 26.1

0.3

Muscles

SD, Standard Deviation; A, Anterior; PM, Posteromedial; PL, Posterolateral; iRA, Ipsilateral rectus abdominis; cRA, Contralateral rectus abdominis; iEOB, Ipsilateral external oblique; cEOB, Contralateral external oblique; iES, Ipsilateral erector spinae; cES, Contralateral erector spinae; GMAX, Gluteus maximus; GMED, Gluteus medius; MH, Medial Hamstrings; BF, Bicepts Femoris; VM, Vastus Medialis; RF, Rectus Femoris; VL, Vastus Lateralis; AT, Anterior Tibialis; MG, Medial Gastrocnemius.

Bold text indicates statistically significant difference between the stable and unstable conditions.

GMED (p < 0.001), GMAX (p = 0.04), MH (p = 0.001), VM (p < 0.001), RF (p < 0.001), VL (p < 0.001), and MG (p = 0.004), in the PL direction: iEOB (p = 0.02), iES (p = 0.003), cES (p = 0.015), GMED (p = 0.01), BF (p = 0.019), VM (p = 0.001), RF (p = 0.001), VL (p < 0.001), and MG (p = 0.001), and in the PM direction iEOB (p = 0.03), iES (p = 0.02), GMED (p = 0.001), BF (p = 0.007), VM (p = 0.006), RF (p < 0.001), and VL (p = 0.005). No significant differences between the stable and unstable surfaces were observed in iRA (A: p = 0.5, PL: p = 0.06, PM: p = 0.12 ), cRA (A: p = 0.88, PL: p = 0.13, PM: p = 0.053), cEOB (A: p = 0.052, PL: p = 0.11, PM: p = 0.09), and AT (A: p = 0.47, PL: p = 0.14, PM: p = 0.7) for any of the directions of the YBT (Table 2). The reach distance between the two conditions for all the three directions were higher for the stable versus the unstable condition (Table 3).

Table 3. Normalized reach distance during the YBT. Condition →

Unstable Mean ± SD (% leg length)

% Difference

Directions ↓

Stable Mean ± SD (% leg length)

A

63±7

60±7

4.87

PL

82±10

78±9

5.0

PM

89±8

87±9

2.3

SD, Standard Deviation; A, Anterior; PL, Posterolateral; PM, Posteromedial

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DISCUSSION The present study compared the muscle activation of the various trunk (iRA, cRA, iEOB, cEOB, iES, cES) and LE muscles (GMED, GMAX, MH, BF, VM, RF, VL, AT, MG) while performing the YBT on stable and unstable surfaces. Significant differences in muscle activation were noted for eleven out of fifteen muscles due to the change in the surface. The findings of the current study may provide evidence regarding utilizing the YBT as a training tool in stable and unstable conditions. To the authors’ knowledge, no previous studies have measured muscle activation during this test. In general, the addition of unstable surfaces while performing lower extremities weight-bearing exercises have been documented to either increase, decrease or cause no change in the muscle activation patterns.14–16,18,30–35 Adding an unstable surface during the performance of the YBT resulted in significantly increased muscle activation in nine (iEOB, iES, cES, GMED, GMAX, BF, VM, RF, VL, MG) out of fifteen muscles in the current study. This is similar to the results found by other authors18,31 who investigated the effect of various surfaces while performing bridging exercises. To overcome the effects of instability, the body tends to attempt to offer stability by increasing the muscle activation of certain muscles. Alfuth et al.30 and Ridder et al.36 reported that adding unstable surfaces while having subjects perform a single leg stance activity caused an increase in the activation of the selected LE muscles.

Increased level of external perturbations while maintaining balance on the unstable surfaces requiring more co-contraction of the muscles has been hypothesized as one of the possible reasons for increased stabilizing muscle activation.32,34 Krause et al.33 also reported the variations in the selected LE muscle recruitment in the subjects performing a standard lunge compared to the lunge performed in suspension equipment. The suspension lunge condition resulted in increased muscle activation requiring more stability due to the unstable environment created by the suspension equipment. Unstable surfaces have also been reported to cause increased muscle recruitment in the selected LE muscles while performing upper extremity exercises. Shin et al.16 found that when subjects were asked to perform upper extremity exercises while standing on an unstable surface, there was an increase in the activation of the selected muscles near the ankle joint in an attempt to maintain balance on the unstable surface using secondary to use of an ankle strategy by the subjects.

A large effect size was observed for RF in all the directions, for GMED, VM, and VL in two out of the three directions, and for MG, one out of two directions. A moderate effect size was observed for these muscles in the other directions. The moderate effect size was also observed for the iEOB, iES, and BF for two out of the three directions and cES, GMAX, and MH for one out of the three directions.

Moderate to large effect size shows that the higher muscle activity during the unstable surface is due to the difference in condition, and is likely clinically meaningful. In most directions, a large effect size was observed for the quadriceps and GMED muscles because they are key to maintaining balance during a single-leg squat task.37 Compared to a stable surface, performing the YBT on an

unstable surface resulted in no significant difference in five muscles (iRA, cRA, cEOB, VL, AT) and a decrease in muscle activity for the MH muscle. These findings are also in agreement with the conclusions from previous researchers investigating the effects of various surfaces on muscle recruitment.15,35 Some of the proposed reasons for no change in muscle activation under unstable conditions included variability in the subjects’ training/activity levels, the type of the unstable surfaces used, the distance of the muscle from the unstable surface, the muscle role (prime movers versus stabilizers) in performing the exercise, and biomechanical movement compensations due to added demand on the neuromuscular system.15,35,38,39 The use of unstable surfaces has been proposed to place more demands on the neuromuscular system, which in turn may help to improve postural stability and endurance through neural adaptations.15,40–44 Basketball players, when trained on unstable surfaces, have shown improvement in balance and stability in contrast to their controls who trained on a stable surface.44 Performing stabilization exercises on unstable surfaces have been reported to be more effective than stable surfaces at improving pain, stability, and disability measured using visual analog scale, Stork Balance Stand test, and Oswestry Disability Index, respectively, in patients with lumbar pain.41 Performing exercises on unstable surfaces demonstrated greater therapeutic effects in comparison to stable surfaces to improve balance in healthy individuals. The authors suggested that it may be because the unstable surfaces are more effective in influencing the somatosensory system.43 Exercising on unstable surfaces has been shown to be more effective in improving balance and walking abilities among stroke patients than stable surfaces.40,42 Authors have also shown the utility of introducing unstable load during strengthening exercises to stress the neuromuscular system.45–47 The results of their studies showed a decrease in muscle activity for the prime movers but an increase in muscle activity for the stabilizer muscles. They hypothesized that an unstable load places extra demand on the body for stabilization, challenging balance and neuromuscular control.

Ganesh et al.12 and Chaiwanichsiri et al.13 utilized the SEBT as an intervention to improve balance and proprioception in their study subjects. Although the YBT is commonly used to measure balance and NM control, based upon the current results, having individuals perform the YBT on the unstable surface may increase muscle activity in key stabilizing muscles and may be considered for use as a training tool for improving balance and stability. However, if clinicians choose to use YBT to improve balance and NM control in their clients, another test and measure should be utilized for pre-post assessment to avoid a threat to construct validity of the YBT via a learning effect.

LIMITATIONS AND FUTURE SUGGESTIONS

The use of surface EMG to describe muscular activity during a dynamic activity has limitations such as skin displacement, movement artifact, motor unit recruitment variations, a sub-maximal effort by participants, and the possibility of cross-talk from surrounding muscles in spite of using methodology that is commonly cited in previous re-

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search.17,19,25,27 This study was conducted using healthy adults; therefore, generalizability to a population that is not similar to the subjects in the current study should be avoided. Confirmation of the findings from the present study is necessary for larger and more diverse populations.

Future research should include three-dimensional analysis to learn more about the relationship between joint kinematics and neuromuscular parameters. It would be interesting to investigate if any gender differences exist while performing the YBT. It would also be interesting to see the effect of various types of unstable surfaces on YBT performance.

tivation of many of the trunk and LE muscles, with the unstable surface inducing increased activation for most of the studied muscles. Clinically, the results from the current study may guide the use of the YBT with an unstable surface as an exercise intervention for training balance and NM control.

CONCLUSION

Submitted: April 12, 2021 CDT, Accepted: January 09, 2022 CDT

CONFLICTS OF INTEREST

The authors have no conflicts of interest to declare.

The results of this study indicate that the performance of the YBT on different surfaces produced a change in the ac-

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14. Behm DG, Colado Sanchez JC. Instability resistance training across the exercise continuum.

Sports Health. 2013;5(6):500-503.

15. Andersen LL, Andersen JL, Magnusson SP, Aagaard P. Neuromuscular adaptations to detraining following resistance training in previously untrained subjects. Eur J Appl Physiol. 2005;93(5-6):511-518.

16. Shin D, Cha J, Song C. Electromyographic analysis of trunk and lower extremity muscle activities during pulley-based shoulder exercises performed on stable and unstable surfaces. J Phys Ther Sci. 2015;27(1):71-74.

17. Vezina MJ, Hubley-Kozey CL. Muscle activation in therapeutic exercises to improve trunk stability. Arch Phys Med Rehabil. 2000;81(10):1370-1379.

18. Czaprowski D, Afeltowicz A, Gebicka A, et al.

Abdominal muscle EMG-activity during bridge exercises on stable and unstable surfaces. Phys Ther Sport. 2014;15(3):162-168.

19. Norris B, Trudelle-Jackson E. Hip- and thighmuscle activation during the star excursion balance test. J Sport Rehabil. 2011;20(4):428-441.

20. Andersen LL, Magnusson SP, Nielsen M, Haleem J, Poulsen K, Aagaard P. Neuromuscular activation in conventional therapeutic exercises and heavy resistance exercises: Implications for rehabilitation.

Phys Ther. 2006;86(5):683-697.

21. Bhanot K, Kaur N, Brody LT, Bridges J, Berry DC, Ode JJ. Hip and trunk muscle activity during the Star Excursion Balance Test in healthy adults. J Sport Rehabil. 2019;28(7):682-691.

22. Earl JE, Hertel J. Lower-extremity muscle activation during the star excursion balance tests. J Sport Rehabil. 2001;10(2):93-104.

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Lower Extremity and Trunk Electromyographic Muscle Activity During Performance of the Y-Balance Test on Stable and...

23. Thompson WR, Gordon NF, Pescatello LS. ACSM’s Guidelines for Exercise Testing and Prescription. 8th ed.

Lippincott Williams & Wilkins; 2009.

24. Escamilla RF, Babb E, DeWitt R, et al.

Electromyographic analysis of traditional and nontraditional abdominal exercises: implications for rehabilitation and training. Phys Ther.

2006;86(5):656-671.

25. Cram JR, Criswell E. Cram’s Introduction to Surface Electromyography. 2nd ed. Jones & Bartlett Publishers; 2010.

26. Fradkin AJ, Gabbe BJ, Cameron PA. Does warming up prevent injury in sport? the evidence from randomised controlled trials. J Sci Med Sport.

2006;9(3):214-220. doi:10.1016/j.jsams.2006.03.026 27. Kendall FP, McCreary EK, Provance PG, Rodgers MM, Romani WA. Muscles: Testing and Function, with Posture and Pain. 5th ed. Lippincott Williams & Wilkins; 2005.

28. Gribble PA, Hertel J. Considerations for normalizing measures of the Star Excursion Balance Test. Meas Phys Educ Exerc Sci. 2003;7(2):89-100.

29. Cohen J. Statistical Power Analysis for the Behavioral Sciences. Academic Press; 2013.

30. Alfuth M, Gomoll M. Electromyographic analysis of balance exercises in single-leg stance using different instability modalities of the forefoot and rearfoot. Phys Ther Sport. 2018;31:75-82.

31. Choi K, Bak J, Cho M, Chung Y. The effects of performing a one-legged bridge with hip abduction and use of a sling on trunk and lower extremity muscle activation in healthy adults. J Phys Ther Sci. 2016;28(9):2625-2628.

32. Ferreira LAB, Pereira WM, Rossi LP, Kerpers II, de Paula Jr AR, Oliveira CS. Analysis of electromyographic activity of ankle muscles on stable and unstable surfaces with eyes open and closed. J Bodyw Mov Ther. 2011;15(4):496-501.

33. Krause DA, Elliott JJ, Fraboni DF, McWilliams TJ, Rebhan RL, Hollman JH. Electromyography of the hip and thigh muscles during two variations of the lunge exercise: a cross-sectional study. Int J Sports Phys Ther. 2018;13(2):137.

34. Lee S, Choi YH, Kim J. The effects of changes in support and inclined boards on lower-extremity muscle activity. J Phys Ther Sci. 2017;29(6):1045-1047.

35. Wahl MJ, Behm DG. Not all instability training devices enhance muscle activation in highly resistance-trained individuals. J Strength Cond Res. 2008;22(4):1360-1370.

36. De Ridder R, Willems T, Vanrenterghem J, Roosen P. Influence of balance surface on ankle stabilizing muscle activity in subjects with chronic ankle instability. J Rehabil Med. 2015;47(7):632-638.

37. Claiborne TL, Armstrong CW, Gandhi V, Pincivero DM. Relationship between hip and knee strength and knee valgus during a single leg squat. Journal of applied biomechanics. 2006;22(1):41-50.

38. De Mey K, Danneels L, Cagnie B, et al. Shoulder muscle activation levels during four closed kinetic chain exercises with and without Redcord slings. J Strength Cond Res. 2014;28(6):1626-1635.

39. Lehman GJ, Gilas D, Patel U. An unstable support surface does not increase scapulothoracic stabilizing muscle activity during push up and push up plus exercises. Man Ther. 2008;13(6):500-506.

40. Bang DH, Shin WS, Noh HJ, Song MS. Effect of unstable surface training on walking ability in stroke patients. J Phys Ther Sci. 2014;26(11):1689-1691.

41. Kang TW, Lee J hyun, Park DH, Cynn HS. Effect of 6-week lumbar stabilization exercise performed on stable versus unstable surfaces in automobile assembly workers with mechanical chronic low back pain. Work. 2018;60(3):445-454.

42. Kim BS. Effects of pressure sense perception training on unstable surface on somatosensory, balance and gait function in patients with stroke. J Korean Soc Phys Med. 2015;10(3):237-245.

43. Nam HC, Cha HG, Kim MK. The effects of exercising on an unstable surface on the gait and balance ability of normal adults. J Phys Ther Sci. 2016;28(7):2102-2104.

44. Sedaghati P. The effect of selective plyometric exercises using an unstable surface on the movement performance of basketball players. Ann Appl Sport Sci. 2018;6(3):15-22.

45. Kohler JM, Flanagan SP, Whiting WC. Muscle activation patterns while lifting stable and unstable loads on stable and unstable surfaces. J Strength Cond Res. 2010;24(2):313-321.

46. Saeterbakken AH, Solstad TEJ, Stien N, Shaw MP, Pedersen H, Andersen V. Muscle activation with swinging loads in bench press. PLOS One. 2020;15(9):e0239202.

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Lower Extremity and Trunk Electromyographic Muscle Activity During Performance of the Y-Balance Test on Stable and...

47. Solstad TE, Andersen V, Shaw M, Hoel EM, Vonheim A, Saeterbakken AH. A Comparison of Muscle Activation between Barbell Bench Press and Dumbbell Flyes in Resistance-Trained Males. J Sports Sci Med. 2020;19(4):645.

International Journal of Sports Physical Therapy

Measson MV, Ithurburn MP, Rambaud AJM. Intra-rater Reliability of a Qualitative Landing Scale for the Single-Hop Test: A Pilot Study. IJSPT. 2022;17(3):493-500.

Original Research

Intra-rater Reliability of a Qualitative Landing Scale for the SingleHop Test: A Pilot Study Maxime V. Measson 1, Matthew P. Ithurburn 2, Alexandre JM. Rambaud 3

a

1

Externat Saint Michel, Institut de Formation en Masso-Kinésithérapie de Saint Etienne, Saint Etienne, France, 2 Department of Physical Therapy and Center for Exercise Medicine, University of Alabama at Birmingham, Birmingham, AL, USA, 3 Externat Saint Michel, Institut de Formation en MassoKinésithérapie de Saint Etienne; Department of Clinical and Exercise Physiology, Sports Medicine Unity, University Hospital of Saint Etienne, Faculty of Medicine; SFMKS Lab, Société Française des Masseurs-kinésithérapeutes du Sport Keywords: movement quality, landing error scoring system, hop tests, return to sport https://doi.org/10.26603/001c.33066

International Journal of Sports Physical Therapy Vol. 17, Issue 3, 2022

Background The test battery classically used for return-to-sport (RTS) decision-making after anterior cruciate ligament (ACL) reconstruction (ACLR) may not be sufficient, as it does not include a qualitative analysis of movement. Therefore, the Landing Error Scoring System (LESS) scale was adapted to a primary functional test in the typical RTS test battery: the single leg hop for distance (SHD).

Hypothesis/ Purpose The aim of this study was to determine the intra-rater reliability of the LESS scale adapted to the SHD (SHD-LESS scale) in healthy young athletes.

Study Design Reliability analysis

Methods Nineteen healthy individuals (14 men, 5 women; mean age: 22.4 years) participated in the study. Participants performed the SHD tasks on both limbs (dominant and non-dominant) using a standardized protocol in two sessions that were one week apart (single reviewer; 2-dimensional video). Intra-class correlation coefficients (ICC2,1) were used to measure the reproducibility of the scale in the dominant (dom) and non-dominant (nondom) limbs. Additionally, limb data (dom and nondom) were pooled and evaluated collectively with intra-class correlation coefficients. The Kappa coefficient was used to assess the reproducibility of each individual item of SHD-LESS scale.

Results The intra-rater reliability was good (ICCdom = 0.77; ICCnondom = 0.87; ICCpooled = 0.87) for the overall SHD-LESS scale scores. Agreement of SHD-LESS individual items ranged from 62% to 100%. Dorsiflexion at initial contact (97% agreement; kappa value=0.79) and knee valgus after landing (88% agreement; kappa value=0.65) had excellent agreement and kappa values.

Conclusion The newly-adapted SHD-LESS scale showed good intra-rater reliability overall. Further studies should evaluate the impact of using the SHD-LESS scale within the RTS test battery on outcomes in patients after ACLR.

a

Corresponding author: Alexandre J.M. Rambaud Department of Clinical and Exercise Physiology, Sports Medicine Unity, University Hospital of Saint Etienne, Faculty of Medicine, Saint-Etienne, France alexandre.rambaud@chu-st-etienne.fr

Intra-rater Reliability of a Qualitative Landing Scale for the Single-Hop Test: A Pilot Study

Level of Evidence 3

INTRODUCTION After an anterior cruciate ligament (ACL) injury, the aim of ACL reconstruction is to restore functional stability of the knee. Following surgery, a primary end goal of rehabilitation is to prepare the patient to resume sports-related activities, defined in a recent consensus statement on return-to-sport (RTS) as being a part of a continuum: returnto-participation, return-to-sport, and return-to-performance.1 During late-stage rehabilitation, sport-specific tasks such as pivoting and rapid change of directions are typically resumed. To start the transition toward RTS at the completion of rehabilitation, clinical practice guidelines recommend that athletes complete a RTS testing battery in order to evaluate readiness for the return to the field without restriction and with the lowest possible risk of reinjury.2 However, recent meta-analysis data demonstrated that the ACL reinjury rate (ipsilateral and contralateral) in athletes under 25 years of age following RTS was 23%,3 suggesting that currently-used RTS testing may not be comprehensive and may be insufficient to identify those at risk of poor outcomes or reinjury. While RTS testing batteries often include measures of muscle strength and knee-related functional performance, such as one-leg hop for distance tests,2 a key measure missing from most testing batteries used in RTS decision-making is the assessment of movement patterns or movement quality.4 One-leg hop for distance tests, such as the single leg hop for distance (SHD), are the most commonly-used lower limb functional tests after ACLR.5 The SHD remains the most used test because it is simple and does not require any equipment. In addition, the SHD allows for the evaluation of the ability of the knee to absorb load during landing.6 The Limb symmetry Index of SHD, a ratio of the performance of the operated limb to the healthy limb, is widely used in return to sport test batteries.2 But SHD performance/distance symmetry analysis (LSI of SHD) has previously been questioned due to the potential risk of masking information about poor or altered movement strategies to achieve symmetric distance.7,8 For this reason, we sought to combine the objective measurement of distance with a qualitative analysis of landing.

The Landing Error Scoring System (LESS) was originally developed for a double-leg landing task by Padua and colleagues,9 and has a good interrater and intra-rater reliability (.95 and .96 respectively).10 Recent work by O’Connor11 has adapted this scale for a single-leg drop-landing task. However, in the scientific literature, no previous work has utilized a quality of movement scoring system with the most commonly performed functional performance task in the RTS test battery: the SHD.12 Additionally, because the SHD assesses unilateral characteristics of the lower limb, its use as the functional task of interest may be better suited for an assessment of movement quality in those with unilateral injuries compared to a bilateral jump-landing-rebound task (such as the original LESS).11 The aim of this study was to evaluate the intra-rater reliability of the LESS adapted

to the SHD (SHD-LESS) in healthy young athletes. The hypothesis of this study was that the reproducibility of the SHD-LESS would be good or excellent (ICC > 0.75).

METHODS STUDY DESIGN

This study was an intra-rater reliability study and followed the “Guidelines for Reporting Reliability and Agreement Studies” (GRRAS) and “Quality Appraisal of Reliability Studies” (QAREL)13,14 during the planning and implementation of this study. Prior to the study, a declaration of conformity for the protection of data has been made (MR4 2214186v0) to CNIL (Commission Nationale de l’Informatique et des Libertés). All subjects signed written informed consent prior to participating in any study-related procedures.

PARTICIPANTS

Nineteen healthy young individuals (14 men and 5 women; age: 22.4 ± 0.25 years; height: 175.0 ± 1.5 cm; weight: 68.2 ± 2.0 kg) were recruited between February and May 2019 and participated in the study. The inclusion criteria specified that participants were non-professional athletes, participated in a cutting/pivoting sport (soccer, basketball, handball, rugby, budo…) with a minimum frequency of two training sessions/week and one match or game/week, and were between 18 and 25 years old. All participants were enrolled and tested during their sports season. Exclusion criteria were a history of knee injury (ACL or other ligaments of the knee joint) or a history of lower limb musculoskeletal injury less than three months prior to enrollment and testing.

TESTING PROCEDURES

Participants completed the SHD task (Figure 1) in two sessions separated by six to 10 days. The general protocol consisted of four consistent steps: 1) introduction to the testing session and tasks, 2) warm-up, 3) test set-up, and 4) task performance and data collection. Following a standardized warm-up program,15 study participants were shown a video demonstration of the correct SHD technique with the following instructions: 1) begin standing on a lower limb behind the start line with arms crossed over the chest; 2) attempt to jump as far forward as possible; and 3) land on the same lower limb while keeping the arms crossed to avoid upper extremity momentum assisting in jump performance (described previously16). Participants were informed that the test would be invalidated if they lost balance (inability to maintain balance upon jump landing for at least 3 seconds) or could not control the landing. Participants were then allowed to ask questions to clarify their understanding of what was required in order to correctly perform the SHD and were provided three practice trials. Following practice trials, participants performed three trials on both the dominant limb and the non-dominant limb, as described by Reid

International Journal of Sports Physical Therapy

Intra-rater Reliability of a Qualitative Landing Scale for the Single-Hop Test: A Pilot Study

Table 1. Single leg hop for distance – landing error scoring system (SHD-LESS) scale.

Score

Sagittal View

Frontal View

Others

1. Forward Trunk Flexion at IC Error: flexion < 5°.

Yes = 0 No = 1

2. Knee Flexion at IC Error: flexion <5°.

Yes = 0 No = 1

3. Ankle Dorsiflexion at IC Error: the landing is not done with the heel.

Yes = 0 No = 1

4. Forward Trunk Flexion Displacement Error: Trunk DOES NOT flex more than at IC

Yes = 0 No = 1

5. Knee Flexion Displacement Error: <30° more flexion after IC; F(IC)-F(displacement).

Yes = 0 No = 1

6. Ankle Dorsiflexion Displacement Error: Heel DOES NOT touch the ground

Yes = 0 No = 1

7. Knee Valgus at IC Error: the vertical line passing through the center of the patella is medial to or passes through the big toe.

Yes = 2 No = 0

8. Lateral Trunk Flexion at IC Error: the trunk is tilted by more than 10°.

Yes = 1 No = 0

9. Knee Valgus Displacement A. Error: the vertical line through the big toe is outside/lateral or on the axis of the patella on the key frame.

If not, B. Error: the vertical line through the big toe is outside or on the axis of the patella among all images between the IC and after displacement.

Yes = 2 No = 0 if not, Yes = 1 No = 0

10. Contralateral Pelvic Drop Displacement Error: Contralateral pelvic drops below ipsilateral pelvic.

Yes = 1 No = 0

11. Tibial Rotation Displacement Error: there is tibial rotation (more than 2°, included).

Yes = 1 No = 0

12. Distance covered > 64% height Error: the distance is less than 64% of the subject size.

Yes = 0 No = 1

13. Overall impression Error if the movement performed by the subject is "rigid/poor" at the hip, knee and ipsilateral ankle.

Excellent=0 Average=1 Poor=2

OVERALL SCORE (0-16) IC: initial contact; Displacement: Maximal flexion knee

et al.17 The dominant limb was defined as “the primary foot used to kick a ball”.

SHD-LESS SCALE

An adapted LESS scale was created to evaluate the SHD landing: the SHD-LESS scale (Table 1). The adapted SHDLESS scale was developed using the same procedures as the single-leg drop-landing LESS scale recently described

by O’Connor.11 All items on the O’Connor LESS scale for falling and landing on one leg were analyzed for their applicability to the SHD assessment. As a result of this analysis, the items (items 1, 2, 3, 8 and 9) were modified to be relevant to the SHD task (Table 1).

In addition, two items have been added to the SHD-LESS. The first item added (item 12; Table 1) included an evaluation of the jump performance (distance, cm). In completing the SHD, participants were instructed to jump as far as possible, and this external focus allowed participants to concentrate on the jumping performance and not the explicit execution of the movement/landing. Because it was

Figure 1. Single leg hop for distance (SHD) task and 2D camera configuration.

possible that participants could purposefully jump a shorter distance to improve the overall landing movement quality which might affect the results,18 the jump distance criterion

International Journal of Sports Physical Therapy

Intra-rater Reliability of a Qualitative Landing Scale for the Single-Hop Test: A Pilot Study

Table 2. Intra-rater reliability of qualitative (Landing Error Scoring System scale adapted to the single leg hop for distance (SHD): SHD-LESS score) and quantitative (jump distance) measures between sessions 1 and 2. Data are shown as ICC value (95% confidence interval); ICC: intraclass correlation coefficient; dom: dominant lower limb; nondom: non-dominant lower limb.

Qualitative: Quality of landing score Test: SHD (SHD-LESS score)

Quantitative: Jump Performance Test: SHD (jump distance)

ICCdom

0.77 (0.46 - 0.91)

0.90 (0.73 - 0.96)

ICCnondom

0.87 (0.67 - 0.95)

0.94 (0.83 - 0.98)

ICCpooled

0.87 (0.75 - 0.93)

0.92 (0.85 - 0.96)

was defined as a minimum distance equal to 64% of the participant’s height.19 If the participant was unable to achieve this distance, a penalty of one point was imposed (Table 1). The second item added (item 13; Table 1) included an overall impression of movement quality during the SHD landing. This item is the same as that of item 16 of the original double-leg landing LESS described by Padua and colleagues.9 Overall landing quality were evaluated as excellent (0 points), average (1 point), or poor (2 points).

TWO-DIMENSIONAL VIDEO ANALYSIS

As described by Everard et al., two cameras were used to film the jumps from the front and the side.10 Prior to completing the video evaluation and scoring, each SHD test video was verified to include the necessary scoring information (angles, distances, and key images). The cameras were placed on a tripod perpendicular to the frontal and sagittal plane, at a height of 60 cm and a distance of 3m (Figure 1). The video recordings were analyzed using Kinovea (Kinovea, www.kinovea.org, version 0.8.15).

Markers were placed on the great trochanter, the lateral epicondyle of the knee, the lateral malleolus, the center of the patella (estimation of the center of the knee; equidistant from the epicondyles of the femur), and the center of the line passing through the two malleoli (estimation of the center of the ankle joint).

The video evaluations were scored by a single rater (AR; physiotherapist with 20 years of experience). After collecting all data, analyses were performed first for Session 1 and then Session 2, consecutively. The video evaluation to score the SHD-LESS was completed in two parts. First, the evaluation of the jumping performance (item 12; distance) was performed, and this defined the trial that would be evaluated for qualitative performance (the trial with the furthest distance among the 3 trials). Using this trial, the remaining items from the SHD-LESS were scored (items 1-11; 13).

Session 1 and Session 2. ICC2,1 values were interpreted as poor (<0.50), moderate (0.50-0.74), good (0.75-0.89), or excellent (0.90-1.00), according to Portney and Watkins.21 SHD distance was compared between Sessions 1 and 2 with statistical adapted tests to the distribution of variables (paired simple t test or Wilcoxon test). Statistical significance was set at p < 0.05. To determine intra-rater reliability of each individual item of the SHD-LESS scale, kappa coefficients were calculated. The kappa-values were interpreted as follows values ≤ 0 as indicating no agreement and 0.01–0.20 as very poor agreement, 0.21–0.40 as poor agreement, 0.41– 0.60 as moderate agreement, 0.61–0.80 as strong agreement, and 0.81–1.00 as near perfect agreement and =1, perfect agreement.22 Statistical analyses were performed using JASP (JASP Team [2018] Version 0.9.2.0) and R software (version 3.4.4 [2018–03–15]).

RESULTS The final sample included 17 participants that completed the SHD. Two outliers were excluded from analyses for the SHD test (SHD performance/distance difference between Sessions 1 and 2 >2.5 SD). For the overall SHD-LESS scale scores, intra-rater reliability ICC values were between 0.77 and 0.87 (Table 2).

For individual items within the SHD-LESS scale, kappa coefficients ranged from very low to almost perfect, depending on the individual item evaluated (Table 3). For jumping performance (quantitative measure), intra-rater reliability of jumping performance ranged from 0.90 to 0.94, depending on the lower limb (dominant vs. non-dominant vs. pooled) (Table 3). No statistical differences were found between Sessions 1 and 2 for the of quality of landing scores (pdom=0.41 ; pnondom=0.07 ; ppooled=0.05) or for SHD jump distance (pdom=0.55 ; pnondom=0.53 ; ppooled=0.73).

DISCUSSION

STATISTICAL ANALYSIS

MAIN RESULTS (OVERALL SHD-LESS SCORES)

In order to determine intra-rater reliability of the scale, the overall score of the SHD-LESS was compared between Session 1 and Session 2 individually for each lower limb (dominant and non-dominant) using intraclass correlation coefficients (ICC2,1) with statistical adapted tests to the distribution of variables (Pearson test or Spearman test). Following research by Van Melick and al.,20 the dominant and non-dominant limbs were pooled and evaluated between

The aim of this study was to determine the intra-rater reliability of using an adapted version of the LESS scale for a new task, the SHD. For the overall scores on the SHD-LESS scale, we found good intra-rater reliability (ICC=0.77 and ICC=0.87 for the dominant and non-dominant limb, respectively).21 Regarding the reproducibility of this newly-developed SHD-LESS scale, there are no previous studies with

International Journal of Sports Physical Therapy

Intra-rater Reliability of a Qualitative Landing Scale for the Single-Hop Test: A Pilot Study

Table 3. Percent agreement and Kappa coefficients for SHD-LESS (Landing Error Scoring System scale adapted to the single leg hop for distance) individual items.

SHD-LESS Items

Item description

% Agreement

Kappa value

Interpretation

1

Forward Trunk Flexion at IC (degrees)

94%

NC

NC

2

Knee Flexion at IC (degrees)

100%

NC

NC

3

Dorsiflexion at IC (position)

97%

0.79

Strong

4

Forward Trunk Flexion Displacement (degrees)

79%

0.34

Poor

5

Knee Flexion after Landing (degrees)

97%

0.00

Very poor

6

Ankle Dorsiflexion after Landing (position)

71%

0.12

Very poor

7

Knee Valgus at IC (position)

88%

- 0.06

Disagreement

8

Lateral Trunk Flexion at IC (degrees)

71%

0.30

Poor

9

Knee Valgus after Landing (position)

88%

0.65

Strong

10

Contralateral Pelvic Drop after Landing (position)

65%

0.02

Very poor

11

Tibial Rotation Displacement (degrees)

62%

0.24

Poor

12

Distance Covered > 64% Height (Distance)

97%

0.84

Almost perfect

13

General observation

76%

0.42

Moderate

IC: Initial Contact.

which to compare our results. In addition, we observed differences in ICC values between the dominant and non-dominant lower limbs. The dominant limb was defined as the primary foot used to kick a ball. However, unilateral tasks were evaluated in the current study, and it may have not been necessary to differentiate dominant and non-dominant limbs. The data could have been pooled initially.20 When analyzing the pooled data, good intra-rater reliability was found (ICCpooled = 0.87), utilizing a larger sample size (17 subjects with 2 legs; n=34).

SECONDARY OUTCOMES (INDIVIDUAL ITEM ANALYSES)

In this study, percentage of agreement for individual SHDLESS items ranged from 62% to 100%. For tibial rotation (item 11), the rater (AR) of the study achieved only 62% agreement. Because tibial rotation is a transverse plane variable, it is likely that evaluating this item may be particularly difficult with cameras only in the sagittal and frontal planes, and may be inappropriate for a 2D assessment of movement. In calculating percent agreement values, Cohen suggests the possibility that there is the potential for false agreement when raters make random guesses, and Cohen’s kappa was developed to account for this concern.23 For individual item assessment of the SHD-LESS, the Kappa coefficients ranged from very poor to almost perfect for both

scales. While overall scores for the SHD-LESS demonstrated good reliability, only three items (dorsiflexion of the ankle, knee flexion displacement, and knee valgus displacement) showed Kappa values interpreted as strong on the 13 items for this scale. Interpretation of the Kappa scores for some items does not seem possible, because no errors were found in the video analyses for some items (not allowing for calculation of the Kappa score). These items may have less relevance for a healthy population, but could be of great relevance for individuals following ACL reconstruction.24,25 Thus, future studies should evaluate the reliability (overall and individual item assessment) of the SHD-LESS in patients following ACL reconstruction.

To ensure that subjects performed a reasonably similar task between the two sessions, jumping performance on the SHD (quantified as hop distance) has been investigated and an excellent agreement for jump performance (distance; item 12; Table 2) on the SHD task has been obtained. These findings are consistent with previous work examining the reliability of the SHD for jump performance (distance), which found excellent reliability (ICC=0.92).17 While the jump distances between the two sessions were highly correlated, recent research has shown that individuals following ACL reconstruction with similar distance performance on the SHD and other dynamic tasks use varying movement strategies to accomplish the tasks.26,27 Thus, the landing

International Journal of Sports Physical Therapy

Intra-rater Reliability of a Qualitative Landing Scale for the Single-Hop Test: A Pilot Study

movement strategies used with similar distance jumps between the 2 trials could not be really identical, which may affect the reliability of the qualitative landing assessment.26,27

recovering from ACLR or how ready for return to sport they are.

FURTHER APPLICATIONS

The current study, although pilot in nature, is not without important limitations. First, the 2D video analysis time was particularly long to complete the scale scoring for each task (30 minutes for one limb). This may limit the clinical application of these scales in a real-time setting. Secondly, the current study included only a young population (20-25 years old), with more males than females, which does not reflect or apply to the general population. Finally, items of this newly-developed SHD-LESS scale were not previously validated, due to the pilot nature of this study. Future research should refine and validate these individual items for eventual applications in patient populations (such as those post-ACL reconstruction) for which movement quality assessment may be a critical part of a multifactorial functional assessment.

Finally, it would be interesting to evaluate inter-rater reproducibility as well as to establish a cut-off score to reduce the risk of (re)injury, especially after ACL reconstruction.

The overall scores for the SHD-LESS scale demonstrated good reliability and may be an important component in future ACL reconstruction RTS testing batteries. The SHDLESS scale contributes to an objective RTS evaluation, with an analysis of the quality of landing during the test most frequently used in the decision to RTS (i.e., the SHD).12 The SHD may also be the most relevant sport-related task to evaluate for quality of movement in individuals following ACLR. Specifically, unilateral tasks may be more relevant than bilateral tasks for qualitative assessment, because of the possibility of compensation on the healthy lower limb during a bilateral landing task like the drop vertical jump (DVJ).28 Additionally, the single-leg hop tests described originally by Noyes et al.29 have been used extensively and previously evaluated for intra- and inter-rater reproducibility.17,30 These functional tests therefore provide clinicians with important information in the follow-up and serial testing of their ACLR patients.

The single-leg drop landing task is also incorporated in RTS testing batteries following ACL reconstruction,31 and is associated with other important elements such as psychological factors and social-contextual factors.32 Also, a single-leg drop landing task may be more biomechanicallydemanding26 compared to SHD and only appropriate in late-stage rehabilitation. The SHD is often performed earlier in rehabilitation following ACL reconstruction (approximately 3 months) to assist with return to running, and thus may have greater utility during early-to-mid rehabilitation progression.33,34 Single-leg distance jump tests appear to have low sensitivity in predicting injury-free return to sport, but high specificity,35 and providing an objective assessment of the patient’s functional abilities after ACLR. It should be noted that functional tests, although providing valuable information, do not, on their own, indicate how well the patient is

STUDY LIMITATIONS

CONCLUSION The newly-adapted SHD-LESS scale showed good intrarater reliability, and could be used alongside the evaluation of SHD performance in RTS testing following ACL reconstruction. Further studies should evaluate the inter and intra-rater reliability of the SHD-LESS in individuals following ACL reconstruction as well as the impact of using the SHD-LESS scale within the RTS test battery on outcomes.

CONFLICTS OF INTEREST

The authors declare that they have no conflicts of interest.

Submitted: April 27, 2021 CDT, Accepted: January 23, 2022 CDT

This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CCBY-NC-4.0). View this license’s legal deed at https://creativecommons.org/licenses/by-nc/4.0 and legal code at https://creativecommons.org/licenses/by-nc/4.0/legalcode for more information.

International Journal of Sports Physical Therapy

Intra-rater Reliability of a Qualitative Landing Scale for the Single-Hop Test: A Pilot Study

REFERENCES 1. Ardern CL, Glasgow P, Schneiders A, et al. 2016 Consensus statement on return to sport from the First World Congress in Sports Physical Therapy, Bern. Br J Sports Med. 2016;50(14):853-864. doi:10.11 36/bjsports-2016-096278 2. van Melick N, van Cingel REH, Brooijmans F, et al.

Evidence-based clinical practice update: practice guidelines for anterior cruciate ligament rehabilitation based on a systematic review and multidisciplinary consensus. Br J Sports Med. 2016;50(24):1506-1515. doi:10.1136/bjsports-2015-09 5898 3. Wiggins AJ, Grandhi RK, Schneider DK, Stanfield D, Webster KE, Myer GD. Risk of secondary injury in younger athletes after anterior cruciate ligament reconstruction: a systematic review and metaanalysis. Am J Sports Med. 2016;44(7):1861-1876. do i:10.1177/0363546515621554 4. Johnston PT, McClelland JA, Webster KE. Lower limb biomechanics during single-leg landings following anterior cruciate ligament reconstruction: a systematic review and meta-analysis. Sports Med. 2018;48(9):2103-2126. doi:10.1007/s40279-018-094 2-0 5. Abrams GD, Harris JD, Gupta AK, et al. Functional performance testing after anterior cruciate ligament reconstruction: a systematic review. Orthop J Sports Med. 2014;2(1):2325967113518305. doi:10.1177/2325 967113518305 6. Kotsifaki A, Korakakis V, Graham-Smith P, Sideris V, Whiteley R. Vertical and horizontal hop performance: contributions of the hip, knee, and ankle. Sports Health. 2021;13(2):128-135. doi:10.117 7/1941738120976363 7. Gokeler A, Welling W, Benjaminse A, Lemmink K, Seil R, Zaffagnini S. A critical analysis of limb symmetry indices of hop tests in athletes after anterior cruciate ligament reconstruction: A case control study. Orthop Traumatol Surg Res. 2017;103(6):947-951. doi:10.1016/j.otsr.2017.02.015 8. Thomeé R, Neeter C, Gustavsson A, et al.

Variability in leg muscle power and hop performance after anterior cruciate ligament reconstruction. Knee Surg Sports Traumatol Arthrosc.

2012;20(6):1143-1151. doi:10.1007/s00167-012-191 2-y

9. Padua DA, Marshall SW, Boling MC, Thigpen CA, Garrett WEJ, Beutler AI. The Landing Error Scoring System (LESS) is a valid and reliable clinical assessment tool of jump-landing biomechanics: The JUMP-ACL study. Am J Sports Med. 2009;37(10):1996-2002. doi:10.1177/03635465093432 00 10. Everard E, Lyons M, Harrison AJ. Examining the reliability of the Landing Error Scoring System with raters using the standardized instructions and scoring sheet. J Sport Rehabil. 2020;29(4):519-525. doi:10.112 3/jsr.2018-0387 11. O’Connor ML. The development of the Single-Leg Landing Error Scoring System (SL-LESS) for lower extremity movement screening. Theses and Dissertations. 2015;1069. https://dc.uwm.edu/etd/106 9 12. Burgi CR, Peters S, Ardern CL, et al. Which criteria are used to clear patients to return to sport after primary ACL reconstruction? A scoping review. Br J Sports Med. 2019;53(18):1154-1161. doi:10.1136/bjsp orts-2018-099982 13. Lucas NP, Macaskill P, Irwig L, Bogduk N. The development of a quality appraisal tool for studies of diagnostic reliability (QAREL). J Clin Epidemiol.

2010;63(8):854-861. doi:10.1016/j.jclinepi.2009.10.00 2 14. Kottner J, Audigé L, Brorson S, et al. Guidelines for Reporting Reliability and Agreement Studies (GRRAS) were proposed. J Clin Epidemiol.

2011;64(1):96-106. doi:10.1016/j.jclinepi.2010.03.002 15. Dingenen B, Malfait B, Nijs S, et al. Can twodimensional video analysis during single-leg drop vertical jumps help identify non-contact knee injury risk? a one-year prospective study. Clin Biomech.

2015;30(8):781-787. doi:10.1016/j.clinbiomech.2015.0 6.013 16. Rambaud AJM, Semay B, Samozino P, et al.

Criteria for Return to Sport after Anterior Cruciate Ligament reconstruction with lower reinjury risk (CR’STAL study): protocol for a prospective observational study in France. BMJ Open.

2017;7(6):e015087. doi:10.1136/bmjopen-2016-01508 7 17. Reid A, Birmingham TB, Stratford PW, Alcock GK, Giffin JR. Hop testing provides a reliable and valid outcome measure during rehabilitation after anterior cruciate ligament reconstruction. Phys Ther.

2007;87(3):337-349. doi:10.2522/ptj.20060143

International Journal of Sports Physical Therapy

Intra-rater Reliability of a Qualitative Landing Scale for the Single-Hop Test: A Pilot Study

18. Hanzlíková I, Hébert-Losier K. Landing Error Scoring System scores change with knowledge of scoring criteria and prior performance. Phys Ther Sport. 2020;46:155-161. doi:10.1016/j.ptsp.2020.09.00 4 19. Brumitt J, Heiderscheit BC, Manske RC, Niemuth PE, Mattocks A, Rauh MJ. Preseason functional test scores are associated with future sports injury in female collegiate athletes. J Strength Cond Res. 2018;32(6):1692-1701. doi:10.1519/jsc.000000000000 2243 20. van Melick N, Meddeler BM, Hoogeboom TJ, Nijhuis-van der Sanden MWG, van Cingel REH. How to determine leg dominance: the agreement between self-reported and observed performance in healthy adults. Macaluso A, ed. PLoS ONE. 2017;12(12):e0189876. doi:10.1371/journal.pone.018 9876 21. Portney LG, Watkins MP. Validity of Measurements. Foundations of Clinical Research: Applications to Practice. 2000;2.

22. Landis JR, Koch GG. The measurement of observer agreement for categorical data. Biometrics.

1977;33(1):159. doi:10.2307/2529310 23. McHugh ML. Interrater reliability: the kappa statistic. Biochem Med. 2012;22(3):276-282. doi:10.11 613/bm.2012.031 24. Boden BP, Torg JS, Knowles SB, Hewett TE. Video analysis of anterior cruciate ligament injury: abnormalities in hip and ankle kinematics. Am J Sports Med. 2009;37(2):252-259. doi:10.1177/0363546 508328107 25. Hayes CW, Brigido MK, Jamadar DA, Propeck T. Mechanism-based pattern approach to classification of complex injuries of the knee depicted at MR imaging. Radiographics. 2000;20 Spec No:S121-S134. doi:10.1148/radiographics.20.suppl_1.g00oc21s121 26. King E, Richter C, Franklyn-Miller A, Wadey R, Moran R, Strike S. Back to normal symmetry?

Biomechanical variables remain more asymmetrical than normal during jump and change-of-direction testing 9 months after anterior cruciate ligament reconstruction. Am J Sports Med. 2019;47(5):1175-1185. doi:10.1177/036354651983065 6

27. King E, Richter C, Franklyn-Miller A, et al.

Biomechanical but not timed performance asymmetries persist between limbs 9 months after ACL reconstruction during planned and unplanned change of direction. J Biomech. 2018;81:93-103. doi:1 0.1016/j.jbiomech.2018.09.021 28. Taylor JB, Nguyen AD, Shultz SJ, Ford KR. Hip biomechanics differ in responders and nonresponders to an ACL injury prevention program.

Knee Surg Sports Traumatol Arthrosc.

2018;28(4):00167-00018. doi:10.1007/s00167-018-515 8-1 29. Noyes FR, Barber SD, Mangine RE. Abnormal lower limb symmetry determined by function hop tests after anterior cruciate ligament rupture. Am J Sports Med. 1991;19(5):513-518. doi:10.1177/0363546 59101900518 30. Haitz K, Shultz R, Hodgins M, Matheson GO. Testretest and interrater reliability of the functional lower extremity evaluation. J Orthop Sports Phys Ther.

2014;44(12):947-954. doi:10.2519/jospt.2014.4809 31. Blakeney WG, Ouanezar H, Rogowski I, et al.

Validation of a composite test for assessment of readiness for return to sports after anterior cruciate ligament reconstruction: The K-STARTS Test. Sports Health. 2018;10(6):515-522. doi:10.1177/1941738118 786454 32. Rambaud AJM, Neri T, Dingenen B, et al. What modifying factors can help improve anterior cruciate ligament reconstruction rehabilitation? A narrative review. Ann Phys Rehabil Med. 33. Rambaud AJM, Ardern CL, Thoreux P, Regnaux JP, Edouard P. Criteria for return to running after anterior cruciate ligament reconstruction: a scoping review. Br J Sports Med. 2018;52(22):1437-1444. doi:1 0.1136/bjsports-2017-098602 34. Rambaud AJM, Rossi J, Neri T, Samozino P, Edouard P. Evolution of functional recovery using hop test assessment after ACL reconstruction. Int J Sports Med. 2020;41(10):696-704. doi:10.1055/a-1122-8995 35. Kyritsis P, Bahr R, Landreau P, Miladi R, Witvrouw E. Likelihood of ACL graft rupture: not meeting six clinical discharge criteria before return to sport is associated with a four times greater risk of rupture. Br J Sports Med. 2016;50(15):946-U84. doi:10.1136/bjspo rts-2015-095908

International Journal of Sports Physical Therapy

Loudon J, Parkerson-Mitchell A. Training Habits and Injury Rate in Masters Female Runners. IJSPT. 2022;17(3):501-507.

Original Research

Training Habits and Injury Rate in Masters Female Runners Janice Loudon, PT, PhD, ATC 1 1

a

, Amy Parkerson-Mitchell, MSPT 2

Creighton University, Omaha, NE, USA, 2 @CoachAmyPT, Overland Park, KS, USA

Keywords: running, aging athlete, running injuries, training https://doi.org/10.26603/001c.32374

International Journal of Sports Physical Therapy Vol. 17, Issue 3, 2022

Background The number of masters females that choose long-distance running as a form of exercise is growing exponentially. As clinicians working with these athletes, it is important to understand their training habits and how these habits relate to running related injuries (RRI).

Purpose The primary aim of this study was to identify the training behaviors and cross training engagement in masters female runners. A secondary aim was to determine RRI rates and their relationship to training behaviors.

Methods A 31-question online survey was completed by 68 masters females aged 45 and older.

Answers from 18 of the 31 questions were used to address the specific aims of the study.

Descriptive variables and Chi Square analyses were used to synthesize the data.

Results The majority of the cohort ran less than 30 miles week distributed over three days/week.

Most participated in cross-training activity that included strength training, cycling, and swimming. Injury was prevalent in this group of runners with many experiencing more than one RRI over their running history. The area of the hip and gluteal region was the most common site of injury.

Conclusion This cohort of runners trained in a relatively smart manner, with a moderate volume of running mileage, and utilization of cross-training. Many had experienced some form of injury that halted their running for a period of time.

Level of Evidence Level 3 – Case Controlled, retrospective survey

INTRODUCTION Running is one of the most popular types of physical activity and is becoming more common in the older athlete.1,2 The benefits attributed to recreational running in the older individual include improvements in physical and mental health, all-cause mortality reduction, and social participation.3–6 After starting to run on a regular basis, runners report changes in their lifestyles, including more energy,

a

Corresponding author: Janice Loudon 10121 Delmar Lane, Overland Park, KS 66207 Janice.loudon@gmail.com

less stress, better eating habits, and better sleep.7 Of the two sexes, participation by females has increased more than males in long distance running events and triathlons over the last decade.8 A masters female is operationally defined as one that is aged 40 years and older and therefore, this category spans several decades. Key research has demonstrated that as the female ages there is a tendency for a decline in aerobic capacity,5 muscle mass,3 bone density,9 flexibility10 and power.11 Additionally, post-menopausal females may have

Training Habits and Injury Rate in Masters Female Runners

more drastic physiological changes due to the loss of key hormones, such as estrogen.12,13 Based on these findings, it can be speculated that masters females should train differently than their younger counterparts.10,14,15 Additionally, injury due to running is common in longdistance runners. It is estimated that up to 70% of endurance athletes sustain an injury which prevents them from continuing their running routine.16 Research on RRI most commonly involves participants that are younger runners or male runners.10,17 Modifiable risk factors associated with RRI may include reduced flexibility and muscular weakness.2 It is currently unknown whether masters female runners that participate in cross-training activities to improve strength and flexibility have a reduction in RRI. Little has been published on the training habits of endurance masters female athletes and the running related injuries (RRI) that may accompany their habits. The primary aim of this study was to identify the training behaviors and cross training engagement in masters female runners. A secondary aim was to determine RRI rates and their relationship to training behaviors.

study, she received the link to the survey designed in MailChimp (Atlanta, GA). If the participant did not complete the survey within a two-week period, a reminder email was sent. Once the survey was completed the data was housed in MailChimp and copied to a Microsoft Excel spreadsheet for analysis.

DATA AND STATISTICAL ANALYSES

Descriptive analyses of the subject characteristics, running habits, cross-training participation and injury history were presented as mean and frequencies (%). Running years, age, strength training, and running volume were individually cross-tabulated with injury using chi-square (X2) tests of independence. Alpha level was p ≤ 0.05. For running years dichotomy was set at < 15 years and ≥ 15 years. For age, dichotomy was set at < 50 years and ≥ 50 years. For running volume, dichotomy was set at < 30 miles/wk and ≥ 30 miles/ wk. These dichotomies were set by the authors based on their experience with running athletes.

RESULTS

METHODS PARTICIPANTS

Females over the age of 45 years that participate in a consistent (> 2 x weekly) running program for the prior two years were solicited to complete a retrospective survey. Exclusion criteria included runners that: 1. could not read or interpret the survey; 2. stopped running for more than four weeks in the prior two years; and 3. had sustained an injury/disease that significantly altered their training program. The participants were recruited from area running clubs in a Midwest city through social media and word of mouth.

SURVEY

A 31-question Web-based survey was administered to a convenience sample of female distance runners in order to identify their typical running behavior, cross-training activity, and injury history. The readability of the survey was assessed before use and deemed appropriate for individuals at an 8th grade reading level by a sample of older female runners. The response options for each question were set as categorical in order to improve speed of survey completion and the survey took approximately 20 minutes to complete. The survey was available online for a period of six months (November, 2020 – April, 2021). To answer the specific aims of this study, 18 of the 31 question answers were used for data analysis. Of the 18 questions, two dealt with demographics, nine dealt with running habits, three dealt with cross-training habits, and four dealt with injury history. The remaining questions not used for this study were designed to assess more specifics about treatment for the runners RRI’s.

PROCEDURE

Before the launch of the survey, institutional level ethical approval was granted by the IRB at Creighton University, Omaha, NE. Once the subject agreed to participate in the

A total of 68 surveys were completed. For the questions posed for this study, there was no missing data. Most of the participants were between the ages of 45 – 60 years (80.8%). With the remaining 8.8% between 61 – 65 and 10.3% 66 years or greater. Eighty-six percent of participants were white, 4.4% were African American, 1.5% Latino, 1.5% Asian, 1.5% American Indian and the remaining 5.9% in another category.

RUNNING HABITS

Most participants had been running for over 15 years (47.8%). This cohort of runners trained at a pace of a 9-minute mile pace or slower (96.5%) with the remainder training between 8:00 – 8:59 pace. Most ran at least partially on the road or pavement (94.1%). Close to half also incorporated treadmill running (48.5%) and off-road training (45.6%).

The weekly mileage was distributed from under 10 miles to over 40 miles per week. Figure 1 displays the range of mileage for the participants. Almost half the participants ran three times per week. Sixty-three of the 68 participants competed in some sort of racing from a 5k to IronMan triathlon distance.

When asked why they run, the majority (30.9%) picked mental health as a reason to run closely followed by personal challenge and competing. Figure 2 shows the distribution of reasons. Most of those surveyed did not train with a group or follow a training plan. Further, the majority incorporated one or more different running workouts such as hill repeats (61.8%), speed work (73.5%), long runs (79.4%), and tempo runs (70.6%).

Close to 80% of the runners participated in a warm-up routine. The majority (52.9%) used walking as at least one component followed by stretching (23.8%) and dynamic drills (16.2%).

International Journal of Sports Physical Therapy

Training Habits and Injury Rate in Masters Female Runners

CROSS TRAINING

In this cohort, 97.1% cross-trained and many participated in more than one mode of cross training. Strength training (77.9%) was the most common followed by cycling (64.7%), swimming (47.1%), and yoga (30.9%). The frequency of the cross-training averaged 2.6 days/week.

RUNNING INJURY

In this group of master females, only 11.8% had never sustained a running related injury, the majority (70.6%) had sustained more than one injury over their running history.

Seventy-two percent had sustained an injury that was severe enough to modify training (decrease intensity, distance or frequency) or stop running. The location of the injuries was distributed as follows: hip/gluteal region (48.5%) followed by the foot (42.6%) then the knee (41.2%). All injury locations are shown in Figure 3.

Figure 1. Mileage distribution for female runners

INJURY VERSUS RUNNING HABITS

Years running and injury were not significant (X2 = 1.65, p = 0.199). Age and injury were not significant (X2 = .286, p = 0.592). Running volume and injury were significantly related (X2 = 7.41, p = 0.007). Strength training and injury were not significant (X2 = .659, p = 0.416).

DISCUSSION This is the first published study to document the running habits and cross-training practices of recreational female master distance runners. The aims of the study were to document the training patterns and injury history of this cohort. The runners included in this study are classified as devoted recreational runners most of whom had been running for numerous years.18

Figure 2. Reasons why runners run

RUNNING HABITS

The volume of running for the participants varied from less than 10 miles per week to over 40 miles. The majority ran between 10 and 20 miles a week. These miles were commonly dispersed between three days per week. Although this type of mileage may seem low to a younger runner, it is consistent with what is seen in male masters athletes19 as well as what is recommended for good health. Further, the volume and consistency found in the runners is acceptable for significant mortality benefits as discovered by Lee et al.20 The female subjects exercised well above the World Health Organization’s recommendation of 75 minutes of vigorous intensity exercise per week.21 Their running speed is relatively slow with the majority running at a 10 – 11 minute/mile pace, but this pace is not unusual for recreational women. A study by Thuany et al. found that pace slowed almost linearly after the age of 19 up to age 65 in Brazilian female runners.22 Although classified as recreational, most of the group participated in races and found that racing was a motivating factor for continuing to be active. Participation in mass running events fosters a sense of social togetherness and promotes social-psycho-

Figure 3. Injury location

logical well-being.23,24 Interestingly, in the present study most of the runners did not follow a formal training plan or run with a running group. This result is similar to what Krouse et al. found in female ultrarunners who chose not to use coaches due to cost or their ability to rely on past experience in the sport.25 The runners in this study utilized a variety of running terrains, but most preferred to train at least some of the time on the road. The treadmill was also a common mode for at least half the runners for some portion of their train-

International Journal of Sports Physical Therapy

Training Habits and Injury Rate in Masters Female Runners

ing. Being that the survey was given to runners in the Midwest, it may have been impossible to run year-round on the roads due to the weather.

CROSS-TRAINING

The survey question that asked about cross-training included the following answer choices with the participant able to pick all that applied: resistance/strength training, cycling, swimming, yoga, other, and I don’t cross-train. Almost all participants (97.1%) engaged in some form of cross-training activities besides their weekly running. Many participated in more than one form of cross-training. The most popular activity was strength training followed by cycling and swimming. Although it is questionable if the addition of cross-training improves performance,26 it is still advised for this cohort of runners.2 These cross-training activities are important in this population to diminish stress to joints, improve neuromuscular coordination, and to help prevent burn-out and staleness.2 Resistance or strength training was used in 77.9% of the participants. Study results are similar to a study by Blagrove et al. who found 76.9% of their surveyed competitive runners utilized resistance training.17 Evidence suggests strength training or explosive training sessions twice a week is beneficial for improving running economy.27,28 In older marathon runners, resistive training improved running economy.29 The strength training performed by participants in the present study seems to be in line with this recommendation because most runners reported that they typically performed the training on average three times per week. Besides performance enhancement, resistance training in the older female will help with minimizing sarcopenia and improve bone mineral density.30–32 Another area of cross-training that is recommended by authorities is flexibility training.2,19 Loss of tissue extensibility is inevitable in this group and may be associated with injury. Yoga, a form of flexibility exercise was utilized by close to 31% of the participants. Additionally, 23.5% of the participants used stretching as part of their warm-up. The authors recommend that a dedicated flexibility program be used five to seven times per week to maintain range of motion of critical joints such as the ankle, hip and low back.

INJURIES

It has been estimated that 89% of master athletes experience one sports-related injury since turning 50 years; of these injuries, 68% are due to repetitive overuse.13,33 Similarly, in the present study, close to 88% reported a RRI that made them modify their training or stop running at some point in their running career. Many of the runners (70.8%) reported more than one injury and 45% reported a recurring injury. Injury rates tend to be higher in the masters runner compared to the younger runner.1 Probable explanations include less resilient connective tissue, lack of joint flexibility and loss of stabilizing strength.19 Within the masters cohort, there was no statistically significant association (p = 0.592) between age and injury. For the Chi square analysis the subjects were divided by age , those younger than 50 (N = 20) compared to those over 50 (N = 48). It can be con-

cluded that within the masters runner category, an increase in age does not equate to increased injury risk. Ganse et al. suggest that experienced master athletes lesson their risk of injury by practicing injury prevention.16 From survey results, the most common location for injury was the hip/gluteal region (48.5%) followed by the foot (42.6%) and the knee (41.2%). Other authors have found somewhat different results, Matheson et al. found the knee as the most common injury site for both older and younger runners.34 Knobloch et al. found Achilles tendinopathy to be the most common injury, but this was in elite runners and the majority of subjects were males.35 Within the studied runners, running training volume (> 30 miles/week) was statistically related (p = 0.007) to an increased number of injuries experienced by the runners. This result is similar to other studies.36,37 McKean et al. found that of the masters runners that they surveyed, the runners who ran more volume experienced more injuries.1 This result is a key finding and a recommendation for the master female would be to limit weekly mileage to less than 30 miles/week. We would also recommend that females over 50 focus on the quality and variety of their runs, getting away from runs greater than 8 miles, run at a slow distance. The overall weekly volume and number of run days per week may be less, but mixing running sessions up with hill repeats, intervals, and fartleks, as well as mixing strength with run segments helps boost performance, neuromuscular patterns, and efficiency while at the same time giving the body adequate recovery time. Also, not running two days in a row gives the body a better chance to recover from repetitive loading forces and possibly help prevent injury.2,13 Participation in cross-training does not seem to be associated with lower self-reported injury rates. In this study, most runners reported a RRI and the majority participated in cross training and strength training, so there appears to be no protective effect. However, the time between injury and cross training were not specified so conceivably the runner could have been injured prior to starting a cross training program. Further, although the survey asked about RRI, it cannot be ruled-out that an injury was a result of the additional cross-training activity. For example, activities such as intense cycling or cross fit could cause or compound an injury.

LIMITATIONS

A number of limitations are important to acknowledge.

First, the survey was developed by the researchers and has not undergone validity or reliability testing. Some questions may have been misinterpreted, thus producing inaccurate data. Secondly, the survey was limited by participant’s self-report (recall bias) of their training program and injury rates. Third, selection bias may be present, as those participants who chose to complete the survey may have different training programs than those who did not complete the survey. Fourth, the survey group was geographically from the Midwest USA, and generalizability of the results to other geographical regions must be performed with caution. A final limitation of the study was the categorical nature of the question responses which potentially lim-

International Journal of Sports Physical Therapy

Training Habits and Injury Rate in Masters Female Runners

ited specificity of the answers. Future research that includes longitudinal studies would be informative on determining cause and effect relationships between training habits and injury.

CONCLUSIONS

In this original research, female endurance athletes were surveyed about their training habits, cross-training activity, and injury history. The results indicate that this cohort of runners trained with a moderate volume of running mileage, and many utilized various methods of cross-training. Many had experienced some form of injury that halted their running for a period of time.

DISCLOSURES

No financial support was used in this investigation and the disclosure form is completed. There is no Conflict of Interest by the authors.

Submitted: July 27, 2021 CDT, Accepted: November 22, 2021 CDT

This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CCBY-NC-4.0). View this license’s legal deed at https://creativecommons.org/licenses/by-nc/4.0 and legal code at https://creativecommons.org/licenses/by-nc/4.0/legalcode for more information.

International Journal of Sports Physical Therapy

Training Habits and Injury Rate in Masters Female Runners

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11. Orr R, de Vos NJ, Singh NA, Ross DA, Stavrinos TM, Fiatarone-Singh MA. Power training improves balance in healthy older adults. J Gerontol A Biol Sci Med Sci. 2006;61(1):78-85.

22. Thuany M, Knechtle B, Hill L, Rosemann T, Gomes TN. Running pace percentile values for Brazilian nonprofessional road runners. Healthcare. 2021;9(7):829. doi:10.3390/healthcare9070829

12. O’Toole ML, Hiller DB, Crosby LO, Douglas PS. The ultraendurance triathlete: a physiological profile.

Med Sci Sports Exerc. 1987;19(1):45-50.

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Training Habits and Injury Rate in Masters Female Runners

23. Lampinen P, Heikkinen E. Reduced mobility and physical activity as predictors of depressive symptoms among community-dwelling older adults: An eight-year follow-up study. Aging Clin Exp Res. 2003;15(3):205-211. doi:10.1007/BF03324501 24. Malchrowicz-Mośko E, Poczta J. Running as a form of therapy socio-psychological functions of mass running events for men and women. Int J Environ Res Public Health. 2018;15(10):2262. doi:10.33 90/ijerph15102262 25. Krouse RZ, Ransdell LB, Lucas SM, Pritchard ME. Motivation, goal orientation, coaching, and training habits of women ultrarunners. J Strength Cond Res. 2011;25(10):2835-2842. doi:10.1519/JSC.0b013e3182 04caa0 26. Flynn M, Carroll K, Hall H, Bushman B, Brolinson P. Cross training: indices of training stress and performance. Med Sci Sports Exerc.

1998;30(2):294-300.

27. Borde R, Hortobágyi T, Granacher U. Dose–response relationships of resistance training in healthy old adults: A Systematic Review and MetaAnalysis. Sports Med. 2015;45(12):1693-1720. doi:1 0.1007/s40279-015-0385-9 28. Denadai BS, de Aguiar RA, de Lima LCR, Greco CC, Caputo F. Explosive training and heavy weight training are effective for improving running economy in endurance athletes: A Systematic Review and Meta-Analysis. Sports Med. 2017;47(3):545-554. doi:1 0.1007/s40279-016-0604-z 29. Piacentini MF, De Ioannon G, Comotto S, Spedicato A, Vernillo G, La Torre A. Concurrent strength and endurance training effects on running economy in master endurance runners. J Strength Cond Res. 2013;27(8):2295-2303. doi:10.1519/JSC.0b0 13e3182794485

30. Baechle T, Earle R. Essentials of Strength Training and Conditioning. 3rd ed. Human Kinetics; 2008.

31. Balsalobre-Fernández C, Santos-Concejero J, Grivas GV. Effects of strength training on running economy in highly trained runners: A Systematic Review with Meta-Analysis of controlled trials. J Strength Cond Res. 2016;30(8):2361-2368. doi:10.151 9/JSC.0000000000001316 32. Kohrt WM, Spina RJ, Holloszy JO, Ehsani AA. Prescribing exercise intensity for older women. J Am Geriatr Soc. 1998;46(2):129-133.

33. Burns J, Keenan AM, Redmond AC. Factors associated with triathlon-related overuse injuries. J Orthop Sports Phys Ther. 2003;33(4):177-184. doi:10.2 519/jospt.2003.33.4.177 34. Matheson GO, Macintyre JG, Taunton JE, Clement DB, Lloyd-Smith R. Musculoskeletal injuries associated with physical activity in older adults. Med Sci Sports Exerc. 1989;21(4):379-385.

35. Knobloch K, Yoon U, Vogt PM. Acute and overuse injuries correlated to hours of training in master running athletes. Foot Ankle Int. 2008;29(7):671-676.

36. van Gent RN, Siem D, van Middelkoop M, et al.

Incidence and determinants of lower extremity running injuries in long distance runners: a systematic review. Br J Sports Med. 2007;41(8):469-480. doi:10.1136/bjsm.2006.033548 37. Voight AM, Roberts WO, Lunos S, Chow LS. Preand postmarathon training habits of nonelite runners. Open Access J Sports Med. 2011;2:13-18. do i:10.2147/OAJSM.S16665

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Classification Based Treatment of Greater Trochanteric Pain Syndrome (GTPS) with Integration of the Movement System

42. Allison K, Bennell KL, Grimaldi A, Vicenzino B, Wrigley TV, Hodges PW. Single leg stance control in individuals with symptomatic gluteal tendinopathy.

Gait Posture. 2016;49:108-113. doi:10.1016/j.gaitpos t.2016.06.020

48. Birnbaum K, Pandorf T. Finite element model of the proximal femur under consideration of the hip centralizing forces of the iliotibial tract. Clin Biomech.

2011;26(1):58-64. doi:10.1016/j.clinbiomech.2010.0 9.005

43. Hardcastle P, Nade S. The significance of the Trendelenburg test. J Bone Joint Surg Br. 1985;67(5):741-746. doi:10.1302/0301-620X.67B5.405 5873

49. Birnbaum K, Siebert CH, Pandorf T, Schopphoff E, Prescher A, Niethard FU. Anatomical and biomechanical investigations of the iliotibial tract.

Surg Radiol Anat. 2004;26(6):433-446. doi:10.1007/s0 0276-004-0265-8

44. Youdas JW, Mraz ST, Norstad BJ, Schinke JJ, Hollman JH. Determining meaningful changes in pelvic-on-femoral position during the Trendelenburg test. J Sport Rehabil. 2007;16(4):326-335. doi:10.1123/ jsr.16.4.326 45. Nadeau S, McFadyen BJ, Malouin F. Frontal and sagittal plane analyses of the stair climbing task in healthy adults aged over 40 years: what are the challenges compared to level walking? Clin Biomech.

2003;18(10):950-959. doi:10.1016/s0268-0033(03)001 79-7 46. Protopapadaki A, Drechsler WI, Cramp MC, Coutts FJ, Scott OM. Hip, knee, ankle kinematics and kinetics during stair ascent and descent in healthy young individuals. Clin Biomech (Bristol, Avon).

2007;22(2):203-210. doi:10.1016/j.clinbiomech.200 6.09.010 47. McFadyen BJ, Winter DA. An integrated biomechanical analysis of normal stair ascent and descent. J Biomech. 1988;21(9):733-744. doi:10.1016/0 021-9290(88)90282-5

50. Dwek J, Pfirrmann C, Stanley A, Pathria M, Chung CB. MR imaging of the hip abductors: normal anatomy and commonly encountered pathology at the greater trochanter. Magn Reson Imaging Clin N Am. 2005;13(4):691-704, vii. doi:10.1016/j.mric.200 5.08.004 51. Allison K, Vicenzino B, Bennell KL, Wrigley TV, Grimaldi A, Hodges PW. Kinematics and kinetics during stair ascent in individuals with Gluteal Tendinopathy. Clin Biomech. 2016;40:37-44. doi:10.10 16/j.clinbiomech.2016.10.003 52. Allison K, Wrigley TV, Vicenzino B, Bennell KL, Grimaldi A, Hodges PW. Kinematics and kinetics during walking in individuals with gluteal tendinopathy. Clin Biomech. 2016;32:56-63. doi:10.10 16/j.clinbiomech.2016.01.003 53. Gandbhir VN, Lam JC, Rayi A. Trendelenburg Gait.

In: StatPearls. StatPearls Publishing; 2021.

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Disantis AE, Martin RL. Classification Based Treatment of Greater Trochanteric Pain Syndrome (GTPS) with Integration of the Movement System. IJSPT. 2022;17(3):508-518.

Clinical Commentary/Current Concept Review

Classification Based Treatment of Greater Trochanteric Pain Syndrome (GTPS) with Integration of the Movement System a

Ashley E. Disantis 1 , RobRoy L. Martin 1 1

Department of Physical Therapy, Duquesne University

Keywords: GTPS, classification, treatment, rehabilitaiton, exercise https://doi.org/10.26603/001c.32981

International Journal of Sports Physical Therapy Vol. 17, Issue 3, 2022

Greater trochanteric pain syndrome (GTPS) refers to pain in the lateral hip and thigh and can encompass multiple diagnoses including external snapping hip (coxa saltans), also known as proximal iliotibial band syndrome, trochanteric bursitis, and gluteus medius (GMed) or gluteus minimus (GMin) tendinopathy or tearing. GTPS presents clinicians with a similar diagnostic challenge as non-specific low back pain with special tests being unable to identify the specific pathoanatomical structure involved and do little to guide the clinician in prescription of treatment interventions. Like the low back, the development of GTPS has been linked to faulty mechanics during functional activities, mainly the loss of pelvic control in the frontal place secondary to hip abductor weakness or pain with hip abductor activation. Therefore, an impairment-based treatment classification system. is recommended in the setting of GTPS in order to better tailor conservative treatment interventions and improve functional outcomes.

Level of Evidence Level V, clinical commentary

INTRODUCTION Greater trochanteric pain syndrome (GTPS) refers to pain in the lateral hip and thigh and can encompass multiple diagnoses including external snapping hip (coxa saltans), also known as proximal iliotibial band syndrome, trochanteric bursitis, and gluteus medius (GMed) or gluteus minimus (GMin) tendinopathy or tearing.1,2 Although the symptoms associated with GTPS were previously thought to be primarily the result of trochanteric bursitis, multiple histologic and imaging studies have identified gluteal tendinopathy with or without bursitis as the primary source of pain and dysfunction.3–5 GTPS presents clinicians with a diagnostic challenge as no cluster of special test exists to identify the specific pathoanatomical structure involved or the severity of its involvement. Therefore, there is a need for an impairment-based classification system for GTPS to allow for tailored conservative treatment interventions and improved patient outcomes.

The use of the term GTPS is non-specific to pathology and refers to the many sources of pain in the lateral hip.

a

Corresponding author: Ashley Disantis, PT, OCS UPMC Children’s Hospital of Pittsburgh Pittsburgh, PA 15224 disantisa@duq.edu 412-396-1811

This is similar to the use of the term “non-specific low back pain”, which encompasses many different pathologies including but not limited to muscular strains, spinal stenosis, and intervertebral disc degeneration.2 Instead of using special tests to identify the specific anatomical structure involved, which is common practice for many peripheral joints, examination procedures for the low back focus on the identification of impairments that lead to the development of pain.6 It has been suggested that identifying the specific anatomical structure involved in the onset of low back pain is not necessary to achieve successful resolution of pain.7–9 As a result, an impairment-based treatment classification approach is recommended in an attempt to tailor treatments to a particular subgroup depending on subjective and objective findings. GTPS presents clinicians with a similar diagnostic challenge as non-specific low back pain with special tests being unable to identify the specific pathoanatomical structure involved and do little to guide the clinician in prescription of treatment interventions.

Like the low back, the development of GTPS has been linked to movement systems abnormalities during functional activities. The primary movements system finding is the loss

Classification Based Treatment of Greater Trochanteric Pain Syndrome (GTPS) with Integration of the Movement System

of pelvic control in the frontal plane secondary to hip abductor weakness and/or pain.10,11 Therefore, conservative interventions should focus on the correction of these impairments to reduce pain and improve movement control in individuals with GTPS. The purpose of this clinical commentary is to present an impairment-based classification system for GTPS to allow for tailored treatment interventions. Grimaldi & Fearon12 presented a graded exercise program for the treatment of GTPS. Because the focus of their work was based solely on gluteal tendinopathy, further classification based on tissue irritability is warranted.12 We propose a classification system based on findings identified during a standard physical examination coupled with findings from a movement system assessment. By addressing identified impairments, treatment will focus on correcting the faulty mechanics that lead to the development of GTPS rather than treatment being aimed towards a single anatomical structure.

GREATER TROCHANTERIC PAIN SYNDROME GTPS has an incidence of 1.8 out of 1000 patients in the primary care setting, mainly affecting females in the 4th-6th decades of life.13–17 Multiple studies have demonstrated a higher incidence of GTPS with concomitant low back pain, hip osteoarthritis (OA), iliotibial band tenderness, and knee pain.18,19 While the majority of GTPS is observed in middle aged females, at a much lower rate runners, football players, and dancers have also shown to be affected due to high hip adduction moments during performance of their respective sport.s17,20–22 In general, abnormal forces across the hip secondary to faulty biomechanics are hypothesized to lead to GTPS. Specifically, weakness or pain in the hip abductors results in a loss of pelvic control in the frontal plane, presenting as a Trendelenburg or compensated Trendelenburg position during tasks performed on a single leg. Pelvic obliquity increases the compressive forces through the lateral hip leading to degeneration of the GMed and GMin tendons and/or inflammation of the trochanteric bursae and proximal iliotibial band.23 Individuals suffering from GTPS complain of pain at the lateral hip, with symptoms potentially radiating distally to the level of the buttock and lateral thigh. Pain generally worsens with single limb weight bearing activities and laying on the affected side. The greatest degree of tenderness should specifically be located on the lateral or posterior aspect of the greater trochanter.3,15,24,25 Activities that exacerbate symptoms include walking and ascending stairs, as well as other single leg activities, such as putting on pants or getting in/out of the bathtub. Due to the high likelihood of overlapping pathologies, particularly hip joint osteoarthritis and low back pain, it is important to first assess for the presence of intra-articular hip and/or lumbar spine pathology. It is also important to rule out the presence of a femoral stress fracture or avascular necrosis of the hip which would require a physician referral.19 Individuals complaining of radiating pain below the knee, pain in the low back that increases with sitting or walking, and pain specifically associated with movement of the lumbar spine should undergo a comprehensive lower quarter screen. This examination should assess for myotome related weakness,

decreased sensation in dermatomal pattern, abnormal findings during lower extremity reflex testing, and lumbar range of motion.

For those with groin pain and morning stiffness hip osteoarthritis should be considered.26 Intra-articular hip joint pathology should be considered with the reproduction of groin pain during a Flexion-Abduction-External Rotation (FABER) test and/or Scour test, decreased range of motion in a capsular pattern, and demonstration of an antalgic gait pattern.27 With subjective findings including a rapid increase in weightbearing activities or excessive steroid or alcohol use, a femoral stress fracture or avascular necrosis of the hip, respectively, should be considered. If the objective examination is consistent with either of these diagnoses and an immediate referral to a physician is warranted.

A summary of differential diagnoses can be found in Table 1.

While special tests are frequently utilized in the clinical setting to identify GTPS, there is currently no test or cluster of tests utilized to identify which specific pathoanatomical structures are involved or the severity to which they are involved. Some frequently utilized special tests include resisted hip abduction and external rotation, FABER, the resisted external de-rotational, and Trendelenburg tests.

Ganderton et al.28 found the FABER, resisted hip abduction, and the resisted external de-rotational tests to have the highest diagnostic test accuracy in confirming GTPS. Previous research on the Trendelenburg test and the resisted external rotation test has reported sensitivity and specificity values in individuals with GTPS of 73% and 77% and 88% and 97.3%, respectively.4,29 Multiple authors have also identified palpation of the greater trochanter and trochanteric bursae to be a useful tool in confirming the presence of GTPS.5,17,28 It should be noted, however, that no studies report sensitivity and specificity values for these palpatory tests in identifying the specific pathoanatomical structure involved. Therefore, it should be emphasized that these tests have minimal utility beyond confirming the presence or absence of GTPS and offer little to the clinician in prescribing appropriate treatment interventions.

Given the limited clinical utility of special tests, clinicians should focus on examination procedures that identify the impairments responsible for the development and persistence of GTPS. Previous research has established hip abductor weakness, loss of pelvic control in the frontal plane, and iliotibial band tightness and thickening as factors increasing compressive forces through the bursae and GMed and GMin tendons.10,11 Identifying impairments in hip flexibility and strength will assist with identifying individuals who will benefit from stretching and strengthening exercises and/or manual interventions. Along with standard range of motion, strength, and flexibility screens, a thorough analysis of the movement system should be performed. Movement system assessments are evaluations of biomechanics during functional activities providing insight into faulty movement patterns allowing clinicians to tailor treatment interventions to address identified impairments.30

International Journal of Sports Physical Therapy

Classification Based Treatment of Greater Trochanteric Pain Syndrome (GTPS) with Integration of the Movement System

Table 1. Differential Diagnoses: Key Subjective and Objective Findings Key Subjective Findings • •

Lumbar Spine Pathology

Hip Joint Osteoarthritis

Femoral Stress Fracture

Avascular Necrosis of the Hip

Key Objective Findings

Pain that radiates below the knee Low back pain that increases with sitting or walking Pain that increases with movement of the lumbar spine

•

• • •

Pain located in the anterior hip Morning stiffness that resolves in <1 hour Increased pain and difficulty with weight bearing activities

• • •

Reproduction of pain during a FABER and/or Scour test Decreased range of motion in a capsular pattern Antalgic gait pattern

•

Pain located in the anterolateral hip that worsens with weight bearing Recent rapid increase in weight bearing activities

• •

Painful and limited hip range of motion Antalgic gait pattern

Pain located in the anterolateral hip that worsens with weight bearing History of excessive alcohol or steroid use

• •

Painful and limited hip range of motion Antalgic gait pattern

•

• • •

IMPAIRMENT BASED TREATMENT CLASSIFICATION Since the mechanism for developing GTPS has been identified as strength and biomechanical deficits of and around the hip, an impairment-based treatment classification, similar to those described for the low back, may be useful to help appropriately tailor treatment interventions.10,11 We recommend classifying patients presenting with GTPS into two categories, contractile and/or non-contractile, and then further sub-classifying based on irritability.

CONTRACTILE

A patient with a contractile presentation would report a reproduction of pain with resisted hip abduction, lengthening or stretching of the hip abductors, palpation of the gluteal muscles and/or tendons, and would demonstrate faulty mechanics during functional activities. Any of these findings would suggest the gluteal muscles, proximal iliotibial band, and/or tensor fascia latae are involved. However, it does not indicate which specific structure or the severity of involvement. Therefore, we recommend identifying the irritability of muscular involvement as high or low before prescribing interventions. Treatment for a contractile presentation should focus on muscle and tendon healing through soft tissue mobilization (STM) and graded loading exercises. In patients demonstrating severe pain, profound weakness, and a significant limited ability to walk without an assistive device, a physician referral is warranted to rule out a compete tear of the hip abductors.

HIGH IRRITABILITY

Highly irritable individuals in the contractile classification will be unable to abduct their hip against gravity and report moderate to severe reproduction of pain. The patient may also report severe difficulty with functional tasks involving single leg stance (SLS) and exhibit an antalgic gait. During

• •

Pain, weakness, or altered sensation in dermatomal or myotomal pattern Abnormal findings during lower extremity reflex testing Pain reproduced with motion testing of the lumbar spine

this phase, STM to the gluteal muscle bellies, tensor fascia lata (TFL), and/or iliotibial band (ITB) are recommended to facilitate healing. STM of the gluteal tendons and trochanteric bursae should be avoided to limit further tissue irritation. GMed and GMin strengthening should be initiated through isometric contractions in gravity eliminated positions progressing to against gravity positions as tolerated. Low intensity isometrics have been shown to induce analgesic effects in individuals with patellar tendinopathy, however, these results are variable across populations.31 We therefore recommend a graded exercise program progressing from isometric contractions in the high irritability phase progressing to isotonic contractions in the low irritability phase. Core exercise should be initiated in supine and quadruped with a focus on proper activation of the lower abdominals. During this phase, all activities should be pain-free. Examples of gluteal and core exercise progressions for the high irritability phase can be found in Figures 1 and 2.

Along with a tailored exercise program, extensive education should be provided regarding activity and postural modifications with the goal of reducing load and compression through the lateral hip. Strategies should be given to help minimize time spent on a single leg during activities of daily living, such as sitting rather than standing to put on pants thereby reducing tensile load through the gluteal muscles. The importance of avoiding hip adduction should be stressed for sitting, standing, and sleeping to limit excessive compression through the lateral hip.12 For example, education should be provided to avoid crossing legs in both sitting and standing and to sleep in supine with a pillow under their knees or in sidelying with a pillow between their legs (Figure 3).

LOW IRRITABILITY

Those with low irritability of the lateral hip musculature will be able to abduct their hip against gravity, but continue to complain of mild to moderate reproduction of pain.

International Journal of Sports Physical Therapy

Classification Based Treatment of Greater Trochanteric Pain Syndrome (GTPS) with Integration of the Movement System

Treatment recommendations for this phase include initiation of pain-free stretching of the hip abductors, concentric and eccentric hip abductor strengthening, functional training focusing on single leg activities, and progression of core strengthening. STM should continue to be utilized in conjunction with pain-free stretching if tightness was identified through muscle length testing, such as an Ober’s test.

It should be noted that soft-tissue mobilization should be directed at the gluteal muscle bellies, TFL, and/or ITB, not at the trochanteric bursae or gluteal tendon insertions, to avoid further tissue irritation.19 GMed and GMin strengthening should be progressed to include isotonic contractions in the low irritability phase as the focus shifts from pain control and healing to restoration of function. Heavy slow resistance exercise has been shown to improve tendon quality and compared to eccentric exercise, heavy slow resistance exercise yielded similar clinical outcomes.32–34 We therefore recommend a combination of concentric and eccentric exercise as per pain tolerance. A large focus should be given to weight bearing hip abductor strengthening as weight bearing abductor exercises demonstrate significantly greater EMG activity than all non-weight bearing exercise, except sidelying hip abduction.35 If tolerated, a resistance band should be incorporated to increase hip abductor activation and challenge lower extremity neuromuscular control. A GMed and GMin strengthening progression for the low irritability phase can be found in Figure 4. Core exercises should be progressed to incorporate a plank progression as well as weight bearing functional tasks. Careful attention should be paid to frontal plane control of the pelvis during all weight bearing strengthening exercises.

The main goal of this phase is to restore appropriate pelvic control during functional tasks. Similar to the strengthening progression, functional training should begin in double leg stance progressing to the transition from double to SLS and finally to training on a single leg. In order to challenge neuromuscular control, dynamic functional training should be incorporated once the patient demonstrates mastery of static tasks. We recommend beginning the return to activity and sport progression with a walking program to incorporate progressive loading of the gluteal muscles as well as to improve cardiovascular endurance. Once the patient can ambulate 15-minutes with minimal pain and appropriate pelvic control, progression to sport-specific activities including running, jumping, hopping, and cutting should be initiated, if necessary. Progression should be dictated by pain and frontal plane control of the pelvis.

NON-CONTRACTILE

Individuals exhibiting pain during palpation of or around the greater trochanter, decreased strength of the hip abductors without reproduction of pain during resisted testing, and/or faulty mechanics during movement system evaluations would suggest a non-contractile source of GTPS. It should be emphasized that while these individuals may demonstrate weakness and functional deficiency of the hip abductors, these activities will not elicit pain. Clinicians should also evaluate for any cardinal signs of inflammation, including rubor, erthythema, edema, and tenderness, which

Figure 1. Hip abductor isometric exercise (with or without resistance band) in a) short lever arm, gravity eliminated position and b) long lever arm, gravity eliminated position, c) short lever arm against gravity with towel roll to avoid hip abduction, and d) long lever arm against gravity with heel against the wall to avoid compensation.

indicate involvement of the trochanteric bursae.36,37 Different from a contractile presentation, which focuses muscle and tendon healing through loading exercise, primary interventions for a non-contractile presentation are aimed at reducing compressive forces over the greater trochanter and alleviating bursal irritation and overload of the lateral structures of the hip. Treatment should focus on decreasing inflammation, restoring flexibility of the lateral hip, particularly of the iliotibial band, improving strength of the hip abductors, and improving of functional movement patterns. We again recommend classifying the patient into either high or low irritability to better tailor treatment interventions.

HIGH IRRITABILITY

A patient with a highly irritable, non-contractile source of GTPS will exhibit severe signs inflammation. Modalities to decrease inflammation, including heat, ice, ultrasound, low-level laser therapy, shockwave therapy, and electrical stimulation can be utilized.38,39 Gentle soft-tissue mobilization of the structures surrounding the greater trochanter is useful in improving flexibility of the lateral hip. Clinicians should avoid any STM of or in close proximity to the trochanteric bursae as this would increase bursal irritation. Much like the highly irritable contractile presentation, hip abductor strengthening should begin with isometric exercise progressing to concentric exercise only as tolerated by pain. To progressively load the hip abductors and endure proper control of the pelvis, we recommend beginning abductor strengthening, core strengthening, and functional training in a non-weight bearing position and progressing to weight bearing as strength and movement patterns improve.

International Journal of Sports Physical Therapy

Classification Based Treatment of Greater Trochanteric Pain Syndrome (GTPS) with Integration of the Movement System

Figure 2. Transverse abdominis activation exercise with a) alternating upper extremity movement, b) bilateral upper extremity movement, and c) isometric lower extremity hold with alternating upper extremity movement.

LOW IRRITABILITY

A patient with low-irritability and a non-contractile presentation will exhibit mild signs of inflammation, however, they may continue to report reproduction of pain with palpation of the greater trochanter and trochanteric bursae.

Treatment principles should mirror those described for the low irritability, contractile presentation. Eccentric strengthening of the abductors, high-level core strengthening, and functional training including sport-specific tasks should be prescribed with the goal of returning the patient to their previous level of functioning.

Figure 3. Sleeping modifications in a) supine and b) sidelying

ABNORMAL FRONTAL PLANE MOVEMENT SYSTEM DYSFUCNTION DURING SINGLE LEG TASKS Development of GTPS is thought to result from faulty mechanics during functional activities, mainly the loss of pelvic control in the frontal place secondary to hip abductor weakness or pain with hip abductor activation.10,11 The GMed and GMin are responsible for maintaining pelvic control in the frontal plane during single leg weight bearing activities and are the tendons most implicated in GTPS.40 From the bottom up, these hip abductors also control the hip adduction moment resulting from the external ground reaction force medial to the hip.41 Any deviation in frontal plane control, due to either pain or weakness, increases the compressive forces of the GMed and GMin tendons on the greater trochanter and trochanteric bursae as well as increases the tension through the iliotibial band. Individuals with GTPS frequently complain of pain and difficulty while completing tasks requiring single leg support as these tasks stress the hip abductors. Given the large role faulty biomechanics plays in the development of GTPS, clinicians must thoroughly evaluate movement patterns through movement system dysfunction assessments. Movement system dysfunction assessments allow for identification of biomechanical deviations during functional activities. In the setting of GTPS, clinicians should evaluate pelvic control during a 30-second SLS, stair ascent, and the stance phase of the gait cycle.

Figure 4. GMed and GMin strengthening progression (with or without resistance band) for the low irritability phase including a) bridge, b) single leg bridge, c) standing hip abduction, and d) side stepping.

SINGLE LEG STANCE

Assessing pelvic control during a 30-second SLS provides information on the function of the GMed and GMin as they are responsible for maintaining a level pelvis during single leg activities.28,40,41 The SLS task should be broken down into the transition phase, going from double to SLS, and

International Journal of Sports Physical Therapy

Classification Based Treatment of Greater Trochanteric Pain Syndrome (GTPS) with Integration of the Movement System

the stance phase, when only one foot is on the ground. The transition phase requires hip abductor activation to assist with the lateral translation of the pelvic girdle while stance phase requires the hip abductors to control pelvic tilt.42 In the setting of hip abductor weakness or pain with activation of the hip abductors, an individual may exhibit a Trendelenburg sign, meaning the contralateral hip will drop towards the floor, or a compensated Trendelenburg, meaning the patients trunk leans ipsilaterally to the stance leg (Figure 7).43,44 Allison et al.42 found individuals with gluteal tendinopathy exhibit greater hip adduction and ipsilateral pelvic shift in preparation for leg lift and greater hip adduction and less control over the pelvis during the stance phase. Other signs of hip abductor dysfunction include the need for upper or lower extremity support during the SLS task. To get a complete picture of SLS performance, a contralateral SLS should be assessed to highlight side-to-side differences in pelvic control.

STAIR ASCENT

The ability to negotiate stairs is critical for maintaining independence and is required to complete many activities of daily living. Compared to walking on level ground, the strength required to negotiate stairs is significantly higher.45–47 Individuals with GTPS frequently complain of pain during stair ascent or the inability to complete the stair task, greatly reducing their quality of life. During stair ascent, the hip abductors are responsible for maintaining a level pelvis as the body moves vertically to reach the next stair.45 When compared to level ground walking, stair ascent requires greater hip flexion, hip adduction, and knee internal rotation moments which in turn increases the tension through the iliotibial band. Additionally, stair ascent requires activation of the tensor fascia lata, gluteus maximus, and the vastus lateralis, all which have attachments to the iliotibial band.48–50 This increase in tension on the iliotibial band leads to even greater compression over the greater trochanter.45,46 Allison et al.51 reported individuals with gluteal tendinopathy were 4.5 times more likely to exhibit a large hip adduction moment and greater pelvic translation at heel strike during stair ascent than healthy controls.51 Additionally, the presence of a contralateral trunk lean was observed in those with gluteal tendinopathy.51 When assessing the movement system during stair assent, clinicians should evaluate the frontal plane mechanics during the stance phase, meaning when the lower extremity being assessed is on the ground. Poor performance of the hip abductors during stair ascent can manifest through a pelvic drop, pelvic translation, and/or trunk lean.

The individual may also exhibit a step to gait pattern or excessive use of upper extremity support on a handrail.

GAIT

SLS comprises 40% of the gait cycle, potentially aggravating the symptoms of GTPS as there is a higher load through the hip abductor tendons compared to the swing phase.19,30 Compared to healthy controls, those with gluteal tendinopathy were found to have a greater hip adduction moment during the stance phase.52 A Trendelenburg gait

Figure 5. Core progression for the low irritability including a) bird dog, b) transverse abdominis activation on physioball with alternating upper and lower extremity movement modified plank, c) modified plank, and d) modified side plank.

Figure 6. Functional squat progression (with or without resistance band from a) bilateral stance, b) staggered stance, and c) unilateral stance to improve lower extremity neuromuscular control and hip abductor strength.

Figure 7. Single leg stance with a) normal frontal plane mechanics, (b) a Trendelenburg, and (c) a compensated Trendelenburg.

pattern, with or without the complaint of pain, may be an indication of gluteal dysfunction. In the case of a mild gait deviation, a 30-second SLS test should also be performed in

International Journal of Sports Physical Therapy

Classification Based Treatment of Greater Trochanteric Pain Syndrome (GTPS) with Integration of the Movement System

Table 2. Impairment-Based Treatment Classification for GTPS CLASSIFICATION Contractile • • • • •

Non-Contractile

Pain with palpation of the muscle belly or tendon of the GMed or GMin Pain with palpation of the proximal iliotibial band Pain and weakness during strength testing of the hip abductors Decreased flexibility of the iliotibial band Poor frontal plane control and reproduction of pain during single leg activities

•

Signs of inflammation including rubor, erthythema, oedema, and tenderness Pain with palpation of the greater trochanter or trochanteric bursae Weakness of the hip abductors without reproduction of pain Decreased flexibility of the iliotibial band Poor frontal plane control during single leg activities without reproduction of pain

• • • •

↓

↓

High Irritability • •

•

Unable to abduct hip against gravity with moderate to severe pain Poor frontal plane control and difficulty completing single leg tasks due to moderate to severe pain Antalgic gait secondary to pain

Low Irritability •

•

High Irritability

Able to abduct hip against gravity with mild to moderate pain Poor frontal plane control and difficulty completing single leg tasks due to mild pain

•

•

•

↓

Severe rubor, erthythema, oedema, and tenderness Unable to abduct hip against gravity with no reproduction of pain Poor frontal plane control during single leg tasks

↓

Low Irritability •

•

•

↓

Mild rubor, erthythema, oedema, and tenderness Able to abduct hip against gravity with no reproduction of pain Poor frontal plane control during single leg tasks

↓

TREATMENT Goal: Muscle and tendon healing •

• •

STM of the hip abductors and iliotibial band to facilitate tendon healing Submaximal isometric hip abductor exercises Initiation of core strengthening

•

• •

Goal: Reducing inflammation

Heavy loading and eccentric strengthening of the hip abductors Progression of core strengthening Functional training and return to sport

order to better assess the functional performance and endurance of the abductors. With severe gluteal dysfunction, a compensatory trunk lean to balance out the center of gravity may be observed.53 In order to appropriately tailor treatment interventions, findings of the physical examination and movement assessments should be utilized to appropriately categorize the patient into a contractile or non-contractile presentation. Impairment-based treatment can then be utilized based on irritability to address muscle strength, flexibility deficits, and motor control impairments during functional activities.

The goal of treatment is to improve motor patterns to reduce the compression of the gluteal tendons on the trochanteric bursae and greater trochanter and ultimately reduce pain and improve function. A summary of the recommended treatment algorithm for GTPS can be found in Table 2.

CONCLUSION GTPS is a term utilized to describe pain in the lateral hip

• •

•

Modalities to reduce inflammation STM of the hip abductors and iliotibial band to improve flexibility Stretching of the lateral hip

• •

• •

Pain free stretching of the lateral hip Concentric and eccentric strengthening of the hip abductors Core strengthening Functional training and return to sport

and can include external snapping hip (coxa saltans), trochanteric bursitis, and gluteal tearing and tendinopathy.1,2 Individuals suffering from GTPS complain of lateral hip, thigh or buttock pain that worsens with single leg activities and lying on the affected side. Currently, there are no tests or cluster of tests to identify the involved pathoanatomical structure or the severity of dysfunction.

Therefore, an impairment-based treatment classification system is recommended, delineating patients into two categories: contractile or non-contractile. Once the patient is categorized into contractile or non-contractile based on physical examination findings and assessments of the movement system, impairment-based treatments can be utilized to appropriately tailor interventions to improve functional outcomes. Treatment of contractile sources of GTPS should focus on muscle and tendon healing through STM and loading exercises whereas treatment of non-contractile sources of GTPS should focus on reducing compressive forces over the greater trochanter and alleviating bursal irritation and overload of the lateral structures of the hip.

Submitted: October 19, 2021 CDT, Accepted: January 09, 2022

International Journal of Sports Physical Therapy

Classification Based Treatment of Greater Trochanteric Pain Syndrome (GTPS) with Integration of the Movement System

CDT

This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CCBY-NC-4.0). View this license’s legal deed at https://creativecommons.org/licenses/by-nc/4.0 and legal code at https://creativecommons.org/licenses/by-nc/4.0/legalcode for more information.

International Journal of Sports Physical Therapy

Classification Based Treatment of Greater Trochanteric Pain Syndrome (GTPS) with Integration of the Movement System

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In: StatPearls. StatPearls Publishing; 2021.

International Journal of Sports Physical Therapy

Sciascia A, Bois AJ, Kibler WB. Nonoperative Management of Traumatic Acromioclavicular Joint Injury: A Clinical Commentary with Clinical Practice Considerations. IJSPT. 2022;17(3):519-540.

Clinical Commentary/Current Concept Review

Nonoperative Management of Traumatic Acromioclavicular Joint Injury: A Clinical Commentary with Clinical Practice Considerations Aaron Sciascia, PhD, ATC, PES, SMTC, FNAP 1

a

, Aaron J. Bois, MD, MSc, FRCSC 2, W. Ben Kibler, MD 3

1

Institute Clinical Outcomes and Research, Lexington Clinic, 2 Sport Medicine Centre, University of Calgary; McCaig Institute for Bone and Joint Health, Cumming School of Medicine, University of Calgary, 3 Shoulder Center of Kentucky, Lexington Clinic Keywords: scapula, acromioclavicular joint, traumatic, evaluation, classification, nonoperative management https://doi.org/10.26603/001c.32545

International Journal of Sports Physical Therapy Vol. 17, Issue 3, 2022

Traumatic injuries of the acromioclavicular joint result in pain and potentially long-term alterations in scapulohumeral rhythm that occurs due to disruption of the clavicular strut function which is integral to scapular kinematics. Nonoperative treatment remains a valid option in most acromioclavicular joint injuries with the potential of minimizing pain and restoring scapulohumeral rhythm. However, few studies have provided nonoperative treatment details. Therefore, the purpose of this clinical commentary is to discuss the rationale, indications, and techniques of nonoperative treatment and present an organized approach for evaluating and managing such patients based on the best available evidence. Attention will be focused on identifying the treatment methods employed and the results/outcomes of such treatments.

Level of Evidence 5

INTRODUCTION Nonoperative treatment of acromioclavicular (AC) joint injuries has been reported in numerous cohorts with varying results based on the severity of injury.1–5 Nonoperative treatment of AC joint injuries has proven benefits based on the similar outcomes identified in comparative studies of nonoperative and operative treatment.3,4,6–39 The consistent summation of findings has identified that operative treatment is better suited for reducing the separated joint per 2-dimensional radiographic assessments while nonoperative approaches typically result in quicker return to activities of daily living, work, and/or sport activities. However, although a reduction of symptoms can be achieved through nonoperative treatment methods for low-grade injuries,40 residual deficits in function can remain from six months to five years following injury.41 Similarly, others have revealed that patients undergoing nonoperative care for low-grade injuries could expect symptoms to resolve by 12 months; however, patients with lingering symptoms at six months correlated with those who were symptomatic beyond one year.42 Conversely, other investigators have identified a higher

a

incidence of unfavorable outcomes with nonoperative treatment, which led them to suggest that adverse outcomes were likely underestimated.43 A long-term follow-up study found that more than half of patients treated nonoperatively experienced symptoms and obtained noticeably lower functional scores when compared with the uninjured shoulder approximately 10 years after sustaining Rockwood Type I or II injuries (Table 1).44 While differences in joint dimensions were detected by ultrasonography, radiographic degenerative changes were not observed.44 This suggests that although joint health appeared relatively unaffected from a 2-dimensional radiographic assessment, 3-dimensional function remained negatively affected. Deficiencies in 3-dimensional function would have consequences for rehabilitation protocol design as exercise selection would need to be re-evaluated. The use of 2-dimensional alignment as an outcome overlooks the complexities of 3-dimensional shoulder function including: 1) possible alterations of scapulohumeral rhythm (SHR) defined as the coupled sequenced motion of the scapula and humerus in all phases of arm motion and 2) the re-establishment of AC and coracoclavicular (CC) load transfer.

Despite the existence of numerous case series comparing

Corresponding author: Aaron Sciascia PhD, ATC, PES, SMTC, FNAP Institute Clinical Outcomes and Research, Lexington Clinic, 1221 South Broadway, Lexington, KY 40504 ascia@lexclin.com

Nonoperative Management of Traumatic Acromioclavicular Joint Injury: A Clinical Commentary with Clinical Practice...

Table 1. Rockwood Classification of Acromioclavicular Joint Injuries Injury Type

Acromioclavicular Ligament

Coracoclavicular Ligament

Trapezoid and Deltoid Muscles

I

Partial tear

No tear

No tear

II

Complete tear

Partial tear

No tear

III

Complete tear

Complete tear

No tear

IV

Complete tear

Complete tear

Distal end of the clavicle is displaced posteriorly into or through the trapezius muscle

V

Complete tear

Complete tear

Detachment from distal part of clavicle

VI

Complete tear

Complete tear

Inferior displacement of the clavicle beneath the coracoid process

operative to nonoperative interventions,3,4,6–39 no study has identified the frequency and type of nonoperative treatment methods utilized in each study. Considering evidencebased rehabilitation would likely be based on the efficacy of the interventions examined in the literature, it would be helpful for clinicians to know which nonoperative treatments have in fact been compared against operative treatments. Therefore, as part of this clinical commentary, the authors systematically reviewed the literature to identify which nonoperative interventions for AC joint injuries have been utilized in empirical studies as well as the parameters of application. This information could serve as the foundation for developing evidence-based recommendations for clinical practice.

ACROMIOCLAVICULAR JOINT FUNCTION AND INJURY Efficient upper limb mechanics requires coupled motions of the clavicle and acromion, with the AC joint acting as a stable articulation. The S-shaped clavicle acts as a 1) strut, maintaining length and stiffness,45,46 2) crank handle, allowing large amounts of distal rotational arcs of motion for small amounts of proximal rotation,47–49 and 3) the only bony attachment of the upper extremity to the axial skeleton. The clavicle has minimal muscular attachments with most of the clavicular long axis rotation, anterior/posterior motion, and elevation/depression occurring through the influence of scapular motion.

The AC joint is a relatively stiff structure, with strong posterior, superior, and anterior ligament components that are thicker on their acromial insertions than their clavicular insertions.50 Individual AC joint motions average 5° of acromial elevation and 8° of acromial rotation.51,52 A 3-dimensional kinematic analysis of the AC joint, demonstrated that the scapula rotated 35° on an axis (termed the ‘screw axis’) that passed through the insertions of the AC and CC ligaments, and that with abduction, the lateral clavicle translated 3.5mm in the anterior/posterior direction and 1mm in the superior direction.53 This stiffness creates a strong link that allows rotational and elevation motions produced by the scapula or clavicle to be efficiently transmitted to the other bone of the articulation.54,55 Interruptions of the normal integrity of the AC and CC ligaments change the normal linkage between the scapula and the

clavicle and can result in dyskinetic motion patterns during limb movement. In addition, indirect AC joint stability and stiffness is maintained by the CC ligaments. An uncompromised clavicle and AC joint are imperative components to maintaining scapular integrity. Injury to any of the static restraints can cause the scapula to become unstable which in turn will negatively affect arm function. Thus, intact AC joint anatomy is the basis for optimal arm and shoulder mechanics as it creates the most efficient screw axis and allows efficient SHR.

INJURY MECHANISMS, PATHOMECHANICS AND INCIDENCE The mechanism of traumatic AC injury is a progression of loading due to imposed trauma, such as a fall onto the shoulder. Studies have demonstrated the progression of the initial anatomic disruption from the posterior and superior AC ligaments to the anterior AC ligaments.49,56–58 These ligaments are avulsed off their clavicular attachments and create horizontal and rotational laxity,57,58 and the loss of the lateral tension band. Progression of the disruption can occur through the inferior capsule into the substance of the trapezoid and conoid ligaments.59 This creates the vertical instability and the loss of the optimal force and motion transfer between the scapula and clavicle.

The deformity that occurs because of AC joint subluxation or dislocation results from the dissociation of the scapula from the supporting strut of the clavicle.46,49,60 Gravity displaces the scapula downward and there is a concomitant scapular protraction and internal rotation such that the scapula is displaced medial to the AC joint.60 With displacement of the scapula there are significant functional consequences in the biomechanics of the shoulder. There is an uncoupling of the scapulohumeral complex such that the scapular stabilizing muscles are not able to maintain appropriate positioning of the glenohumeral and acromiohumeral joints.61 This uncoupling creates an alteration in SHR. There is also a subsequent loss of rotator cuff strength and function that can only be restored by retraction of the scapula and restoration of the pivot point of the AC joint.62,63 The malposition of the scapula may also lead to impingement of the rotator cuff.64,65 As the arm is elevated the orientation of the acromion remains in an anteriorly tilted position relative to the humerus. In the acute injury

International Journal of Sports Physical Therapy

Nonoperative Management of Traumatic Acromioclavicular Joint Injury: A Clinical Commentary with Clinical Practice...

there may be inhibition of shoulder function due to pain initially; however, as the acute symptoms resolve there can be chronic dysfunction of the shoulder that occurs due to the anatomical disruption.50 This is due to the loss of the strut function of the clavicle and loss of appropriate scapulohumeral orientation. This results in pain at the AC joint, external impingement, and loss of function during work and recreational activities that require forward elevation. The inability to adequately retract the scapula leads to an apparent loss of rotator cuff strength and loss of cocking or the ability to appropriately position the arm for overhead athletic and work activities.

The incidence of AC joint separations or dislocations ranges from 1.7 to 9.2 per 10,000 individuals.66–69 In athletes such as collegiate and professional football players as well as military cadets, the incidence increases to 3.3 to 26 per 10,000 exposures.70–73 The literature demonstrates that males sustain anywhere from 2.2 to 8.5 more AC joint separations than females.66,72,73 Low-grade separation (Rockwood Types I and II) occur more often compared to high-grade separations (Rockwood Types III and higher), ranging from 4-11%.70–72

LITERATURE ASSESSMENT (NONOPERATIVE TREATMENT) To provide nonoperative treatment recommendations, the literature was systematically searched for articles based on the following inclusion criteria: English language only; cohort studies that compared nonoperative to operative treatment methods or cohort studies/case series with exclusive description of nonoperative treatment only. The focus was on identifying the treatment methods employed and the results or outcomes of the treatments. Articles were excluded if the treatment methods were not described or able to be discerned based on the provided descriptions. Articles determined to be literature reviews (nonsystematic reviews), current concepts/opinion papers, or single patient case studies were also excluded due to the level of evidence being below Level 4. Additionally, abstracts published in peer-reviewed journals as special editions or supplements or any non-published data were not included.

The results of the review were compiled and tabulated through a standard frequency analysis to identify the commonly used nonoperative treatment components. Reported outcome measures and outcome results were summarized and reviewed for commonalities between reports. The Joanna Briggs Institute Critical Appraisal Checklist for Case Series was utilized to assess the quality of each article retained for the review.74 The assessment sheet was comprised of 10 questions where each question could receive an answer ranging from yes, no, unclear, or not applicable.

This scoring sheet was modified to a binary (“yes” = 1 or “no/unclear/not applicable” = 0) scoring system yielding a possible 10 points, to better illustrate commonalities between retained studies. One of the authors (ADS) with over 20 years clinical and research-related experience individually reviewed and appraised each retained article.

Figure 1. Flow chart for selecting articles to be included in the commentary

LITERATURE RESULTS A total of 61 articles were identified via the search strategy for possible retention (Figure 1). After applying the inclusion criteria, 33 articles were excluded, and 28 articles were retained for review. All details specific to the nonoperative treatment components of retained studies are summarized in Appendix A. Twenty-three articles (82%) compared operative to nonoperative treatment while five articles (18%) exclusively employed nonoperative treatment. The most utilized nonoperative interventions across all 28 studies were immobilization (i.e., sling) (100%), shoulder motion (61%), and general shoulder strengthening (50%). Medication was prescribed in 29% of studies. Ice and scapular strengthening were mentioned in 18% and 14% of studies, respectively.

Few studies (18%) reported on rehabilitation parameters (i.e., frequency, intensity, sets/repetitions).

All outcome measures and results are summarized in Appendix B. Of the 23 studies that compared operative to nonoperative treatments, review of the outcomes revealed three commonalities: 1) nonoperative treatment permitted earlier improvements in subjective outcomes, but no differences occurred at long-term follow-up after six months,9,13,26–29,31–35 2) operative treatment resulted in better joint reduction,9,27,30,31,34,38 and 3) nonoperative treatments resulted in faster return to activities, but residual symptoms such as pain and joint instability may persist.7,25,36,37 Of the five studies that exclusively utilized nonoperative treatments, the nonoperative treatment components (Appendix A) and outcomes (Appendix B) varied between the studies. The nonoperative treatment components included: immobilization,24,42–44,75 medication,42–44 ice,43 motion,24 scapular strengthening,24,44 and shoulder strengthening.24,43,44 Exercise details were provided for one study only.24 Carbone et al.,24 reported 78% of patients had no scapular dyskinesis and improved subjective functional outcomes (Constant and Subjective Shoulder Value) at oneyear follow-up. Similarly, Mouhsine et al.,43 reported 52% of patients were asymptomatic at six-year follow-up. Verstift et al.,75 reported a significant reduction in Constant

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Nonoperative Management of Traumatic Acromioclavicular Joint Injury: A Clinical Commentary with Clinical Practice...

score in the involved arm compared to the contralateral arm as well as substantial radiographic changes such as an increase in AC joint space, osteolysis, ligament ossification, and distal clavicle deformity at an average follow-up of seven years. However, this same group reported Simple Shoulder Test (SST) and Disabilities of the Arm, Shoulder, and Hand scores for the involved arm that were “acceptable” compared to the contralateral arm.75 Conversely, Mikek44 reported decreased Constant, SST, and University of California Los Angeles scores at long-term follow-up (average 10.3 years) while Shaw et al.,42 found significant correlation between high levels of pain/restricted movement and high levels of disability as well as significant correlation between symptoms at six months and symptoms one month prior to one-year follow-up.

Critical appraisal of the retained studies revealed an average score of 6/10 (Appendix C). While all articles reported follow-up outcomes and utilized appropriate statistical analyses, two articles did not report patient demographic information.21,22 Eight articles (30%) did not have clear inclusion criteria,12,14,24,25,28,32,35,38 nine articles (33%) did not clearly report if AC injuries were identified in a standardized way or if the methods used for identification were valid, 7,14,31,32,35,37,38,43,44 and nine articles (33%) did not provide clear reporting of the presenting site/clinical demographic information.9,14,21–26,30 The three items with the lowest reporting were consecutive inclusion of participants (30%),7,12,21,25,35,42–44 complete inclusion of participants (14%),7,13,25,42,75 and clear reporting of clinical information (39%).22,24,26,30–32,34,36,38,39,44,75

INTERPRETATION OF THE LITERATURE Following further review of the included studies, concerns were raised regarding a large number of methodological inconsistencies between studies. First, the surgical techniques were highly variable with fixation methods including hook plates26,27,30,33; screws or pins7,12,14,29,37–39; wire, graft, tape, or suture9,13,21–23,25,28,31,32,34,36,39; and biologic allograft.35 Second, a variety of outcome measures were used in isolation or in combination such as subjective patient ratings, subjective physician ratings, radiographic assessments, and impairment measures. Finally, a lack of robust details regarding nonoperative interventions such as specific exercises, frequency, duration, intensity of exercise, number of visits, or when to progress a patient through the program were not reported by most studies.

The variation in surgical and rehabilitation technique is likely rooted in clinical philosophies and views about how the AC joint functions as part of arm function as described above. Traditional views of injury to the AC or CC ligaments was based on restoring the disrupted anatomy from a cosmetic perspective as evidenced by the seminal injury classifications systems76,77 and the variation in surgical techniques that aimed to reduce or eliminate the disarticulated joint with various materials.7,9,12–14,21–23,25–34,36–39,39 However, more recent work has identified that AC joint injury can have profound 3-dimensional functional consequences such as alterations in SHR also known as scapular dyskinesis.24,78 Scapular dyskinesis can occur as part of high-grade AC

joint injuries due to the disruption of both the AC and CC ligaments and subsequent vertical and horizontal instability and loss of optimal force and motion transfer between the scapula and clavicle.79 The disrupted scapular function is a primary component of the residual impairment reported in most studies and can be clinically observed as scapular dyskinesis.

The identification of 3-dimensional scapular dysfunction as part of AC injury led to the development of an alternative AC joint injury classification system that expands and modifies the traditional 2-dimensional Rockwood system76 by allowing clinicians to consider 3-dimensional functional consequences as part of the injury.60,80 The International Society of Arthroscopy, Knee Surgery, and Orthopaedic Sports Medicine (ISAKOS) created an algorithmic classification system that discerns the type of AC joint injury by whether or not scapular dyskinesis is present.60 This was done due to the ongoing debate that has existed regarding whether or not to operatively or nonoperatively manage Rockwood Type III injuries.1,81,82 The debate has existed because many AC joint injuries that have been classified as Rockwood Type III due to visual prominence of the distal clavicle, have complete tears of the trapezoid ligament but intact conoid ligaments. Since the Type III classification encompasses both incomplete and complete CC ligament injuries, both altered or normal scapular kinematics can exist under the same injury classification.78,83 This may be why minimal correlation of imaging and symptoms with the traditional classification systems or with published outcomes occurs.2,60,84–86 As such, injuries where partial CC ligament injury exists have been re-classified in the ISAKOS system as Type IIIA, which accounts for CC ligament involvement but without functional consequence to scapulohumeral rhythm. Those injuries with complete disruption of both CC ligaments have a greater frequency of associated scapular dyskinesis.24,78 Thus, higher grades of AC joint injury (Rockwood/ISAKOS IIIB-V) create more alterations in normal scapulohumeral rhythm, with potential for larger amounts of dysfunction due to a greater disruption of the anatomy. Considering that many articles retained in this review included Rockwood Type III injuries and that surgical techniques that simply aim to realign the clavicle with the acromion do not fully account for the 3-dimensional mechanics of the upper limb, the variation in surgical technique selection and the reported outcomes found in this review is not completely unexpected.

The most concerning finding of this review is that several of the comparative studies provided a wealth of information regarding surgical treatment yet did not provide the important details that are pertinent for analyzing the effectiveness of conservative management. In most cases, the comparison to surgical stabilization was the use of a sling with no other use or standardization of rehabilitation.7,9,12–14,21–39,42–44 Occasionally, administration of “mild” analgesics9,23,25,26,30,42–44 and application of ice9,23,25,35,43 was permitted, but dosage information was not provided. As noted earlier, when additional rehabilitation interventions that could be classified as therapeutic exercise were included such as progressive motion,9,13,21,23–31,34–38 scapular strengthening,24,26,35,44 and/or shoulder strengthening9,21,24,27–29,33–36,38,43,44 de-

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Nonoperative Management of Traumatic Acromioclavicular Joint Injury: A Clinical Commentary with Clinical Practice...

tails related to the exercise parameters were insufficient or not described at all. For example, when details were provided for motion, a wide range of methods including passive, active-assisted, and active shoulder range of motion were employed yet no sets and repetitions or criteria to progress were described. In some cases, time of initiation of motion or formal rehabilitation9,13,21,23,24,26,28,31,32,34–38,44 was mentioned but rarely were all necessary program details included. This included four of the five articles that exclusively utilized nonoperative treatments.42–44,75 Furthermore, quality of evidence surrounding this topic has been described as low-quality by previous authors3 as well as the current study, and as a result, it is understandable why clinical decision-making has been difficult as to how to best manage AC joint injuries conservatively.

Using the current literature as a guide, there are two nonoperative treatment case series that provide some guidance regarding therapeutic intervention programming.

First, Carbone et al.,24 described a program based on the combination of mobility, scapular strengthening, shoulder strengthening, and kinetic chain-based exercises. The program was supervised and administered by a physiotherapist a minimum of three hours per week for the first six weeks, then 1.5 hours per week until the final follow-up. Second, Petri et al.,35 described a program with similar components as Carbone et al.,24 except the program was performed two to three times per week for six weeks and it was separated into three progressive phases. Although neither program provided sets and repetitions, intensity, or criteria to progress the patient, both provide specific exercises that could be attempted, thus providing some assistance to rehabilitation practitioners. An additional resource for AC joint injury treatment program development would be the guidelines developed by Reid et al.,87 which were compiled from common interventions identified in the literature. The guidelines divide treatment into categories (acute phase, recovery phase, and return-to-sport), which follow established philosophies and reports that incorporate mobility, scapular strengthening and control, and the kinetic chain into shoulder rehabilitation.88–90

CLINICAL RECOMMENDATIONS FOR NONOPERATIVE TREATMENT Combining the above mentioned studies24,35 as well as the authors’ clinical experience, it is believed that if the focus of treatment were to shift from cosmetic reduction of the separated acromion and clavicle to strategies that restore dynamic shoulder function via the re-establishment of scapular control, post-treatment outcomes for all types of AC joint injuries may become optimized. Rehabilitation measures may not fully realign the dissociated acromion and clavicle, depending on the amount of combined ligament disruption. Although the deformity may persist, scapular control (or lack thereof) and patient feedback can serve as useful benchmarks for determining if the outcome is acceptable. Therefore, a rehabilitation program that uses scapular control as the primary metric should be employed (Table 2).91

A focused AC joint rehabilitation program should differ from traditional general glenohumeral joint strengthening programs in several key areas. First, while seminal studies have identified exercise maneuvers that can activate high amounts of electrical activity in shoulder and scapular muscles (arm elevation to shoulder height and above, prone horizontal abduction, internal/external rotation at shoulder height, etc.) the foundational work was performed on asymptomatic individuals.92–96 It is possible that the dissociated AC articulation in both low- and high-grade injuries may not tolerate such high demand maneuvers. Second, the identified maneuvers were often performed in a uniplanar manner with the body in vertical or horizontal (prone or supine) stationary positions. Considering the scapula as a ‘link’ within the kinetic chain, these isolated maneuvers may not re-establish scapular mobility and control in the necessary motor patterns that require integrated use of the majority of the kinetic chain segments (i.e., using the legs and trunk to facilitate scapular and shoulder movement and muscle activation). Failure to incorporate the kinetic chain throughout the rehabilitation process, (i.e., both early and late phases), could lead to a less than optimal rehabilitation outcome likely due to the encouragement of inefficient or improper motor patterns.65,97–101 In some instances, the scapula and arm can be overtly dysfunctional. In these instances, minimizing the degrees of freedom via the elimination of gravity dependent positions may be necessary, such as placing the patient in a seated position.91,102 However, the authors contend that most AC joint injuries with concomitant scapular dysfunction should benefit from the incorporation of sitting or standing positions in the early phases of rehabilitation as these positions most closely mimic kinetic chain function.

After rest and activity modification recommendations have been initiated and symptoms have been reduced (and possibly eliminated), an attempt at rehabilitation can be initiated. Physiological deficits and/or impairments (strength, flexibility, endurance, etc.) identified on physical examination may be addressed; however, a progressive program should be employed. This often begins with increasing mobility to assure the scapula and humerus move fluidly throughout arm motion (Figures 2-Figures 6). Next, avoiding maneuvers that will excessively load, stress, or move the compromised AC joint is recommended. This can be achieved using short-lever exercises that can be performed with the arms in an adducted position (i.e., the arms positioned against the thorax) (Figures 7-Figures 9) rather than positions that require the arms to be in the forward elevated or abducted positions (i.e., long-lever exercises). Examples of exercises and the rationale for their use have been provided in Table 3. Although short lever by design, maneuvers such as scapular shrugging or elevation and scapular proprioceptive neuromuscular facilitation should be avoided in the first two phases of rehabilitation (approximately the first 3-6 weeks) because of the excessive movement and stress that occurs at the AC joint during their performance.

Once the patient has demonstrated that the initial exercises can be performed without exacerbating the previous symptoms, progression into more dynamic motions that require some degree of arm elevation or abduction (approximately 30-45°) may be added to the treatment progression (see

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Nonoperative Management of Traumatic Acromioclavicular Joint Injury: A Clinical Commentary with Clinical Practice...

Table 2. Sample Rehabilitation Progression for Acromioclavicular Joint Injury Stages

Estimated Weeks Acute Phase

Recovery Phase

1

2

3

4

5

Step-up/step-down

X

X

X

4-way hip

X

X

X

X

X

Squat

X

Lunge

X

X

X

X

X

X

X

Anterior and posterior muscle stretching (Figures 2a-f)

X

X

X

X

X

Exercise ball motion/mobility (Figure 3a-d and 4a-f)

X

X

X

X

X

X

X

X

Conscious correction (Figure 7ab)

X

X

X

Sternal lift (Figure 8a-b)

X

X

X

Robbery (Figure 8c)

X

X

X

Low Row (Figure 9a-b)

X

X

X

Lawnmower: arm close (Figure 9c-d)

X

X

Functional Phase

6

7

8

9

10

11

12

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

Lawnmower: arm away (Figure 10a-b)

X

X

X

X

X

Fencing (Figure 10c-d)

X

X

X

X

X

X

Wall washes (Figure 10e-h)

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

Proximal segment control

Mobility interventions

Weight shifting (Figure 5a-c) Closed chain pendulums (Figure 6a-e) Short lever interventions

Long lever interventions

Standing rotator cuff exercises (Figure 11a-d) Rotator cuff exercises with trunk rotation (Figure 11e-h) Weight training Note: Weeks for individual patient progressions may vary

short-lever and long-lever intervention examples in Table 2) (Figures 10-Figures 11). The authors suggest patients be provided an exercise regimen that begins with 1-2 sets of 5-10 repetitions with no external resistance. Additional sets and repetitions can be added based on symptoms and exercise tolerance, with a goal of 5-6 sets of 10 repetitions being able to be performed without an increase in symptoms.

Resistance may be added next beginning with light free weights (2-3 pounds maximum) and then progressing to elastic resistance. Although effective at increasing scapular muscle activity103, elastic resistance has high variability when used by patients, especially when arm position is progressed throughout a treatment program.104 Elastic resistance can be monitored and progressed when using perceived exertion scales105; however, the authors recommend beginning with free weights as those devices allow for more stability and fulfillment of isotonic contractions. Longer

lever maneuvers can then be incorporated into the treatment program in the later phases of rehabilitation but only when the previous maneuvers have been mastered by the patient and have demonstrated little to no symptom exacerbation (Figures 11a-11h).

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Nonoperative Management of Traumatic Acromioclavicular Joint Injury: A Clinical Commentary with Clinical Practice...

Figure 2a-f. Anterior muscle stretching is performed utilizing a bolster (a) and the patient in a supine position with the bolster aligned with the vertebral column (b). The patient places the arms into external rotation at the side of the body (c). Manual overpressure can be applied by the clinician for a more intense stretch (d).

Latissimus dorsi stretch can be performed with the patient side-lying and the arm in maximal abduction while the clinician stabilizes the scapula and applies overpressure to the humerus (e). The posterior muscle stretch is performed with the patient supine. The lateral border and body of the scapula is manually stabilized against the table while the arm is passively moved across the body (f).

Figure 3a-d. Exercise ball mobility can be performed seated (a) with the trunk being actively flexed and extended to move the arm through the sagittal plane (b), the scapular plane (c), and the frontal plane (d).

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Nonoperative Management of Traumatic Acromioclavicular Joint Injury: A Clinical Commentary with Clinical Practice...

Figure 4a-f . The exercise ball exercises can be advanced to a standing position (a) with both arms moving in the sagittal plane (b). Additional advancements can include single arm sagittal plane movement (c-d) and frontal plane movement (e-f).

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Nonoperative Management of Traumatic Acromioclavicular Joint Injury: A Clinical Commentary with Clinical Practice...

Figure 5a-c. Weight shifting begins with the patient placing both hands on a firm surface (a). Body weight is then shifted laterally to the right (b) and left (c). This can be performed rhythmically or with brief pauses in each terminal position.

Figure 6a-e. Closed chain pendulums are performed standing (a) and hip lateral movements to allow the arm to gain abduction (b), adduction (c), flexion (d), and extension (e).

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Nonoperative Management of Traumatic Acromioclavicular Joint Injury: A Clinical Commentary with Clinical Practice...

Figure 7a-b. Conscious correction of scapula begins with the patient standing (a) and being instructed to actively “squeeze your shoulder blades together” (b). Utilization of mirrors or mobile devices can assist patients with visualizing correct scapular positioning.

Figure 8a-c. Sternal lift begins with the knees and trunk flexed and the arms held away from the body (a) and the patient is instructed to lift the chest using extension of the hips and trunk (b). The Robbery maneuver is the advancement of the Sternal Lift where the patient is instructed to “place the elbows in the back pockets” (c).

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Nonoperative Management of Traumatic Acromioclavicular Joint Injury: A Clinical Commentary with Clinical Practice...

Figure 9a-d. The low row in the starting position (a) and with extension of the hips and trunk to facilitate scapular retraction (b). Lawnmower with arm close to body begins with the patient standing and the arm close to the body as if supported by a sling (c). The patient is instructed to extend the hips and trunk followed by rotation of the trunk to facilitate scapular medial translation and retraction (d).

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Nonoperative Management of Traumatic Acromioclavicular Joint Injury: A Clinical Commentary with Clinical Practice...

Table 3. Exercise Examples and Rationale for Employment* Guidelines

Goal(s)

Examples

Rationale

Establish proper postural alignment and proper motion.

Eliminate postural deficiencies: rounded shoulders, forward head, thoracic kyphosis, and lumbar lordosis.

Improve motion deficiencies in glenohumeral, scapular, spinal, and lower extremity segments.

Programs designed to target all kinetic chain segments using manual therapy such as joint mobilization, passive stretching, active stretching using an exercise ball, and/or massage as well as home-based patient programs.

Following immobilization, do not immediately mobilize the AC joint.

Malalignment and limitation of fluid motion throughout the kinetic chain can place loads and stresses in areas where excessive or repetitious loading is not tolerated.

Facilitation of scapular motion via exaggeration of lower extremity/trunk movement.

Use of the legs and trunk to perform trunk rotation or move from flexion to extension to gain scapular retraction.

Lawnmower with arm close to body Low row (seated or standing) Sternal lift Robbery

Using larger muscles and motions to facilitate smaller muscles and motions aim to decrease loads and stresses at smaller joints. Also, these movements mimic kinetic chain functioning.

Exaggeration of scapular retraction in controlling excessive protraction.

Assure the scapula is retracted or able to be easily retracted when performing arm movements.

Limit the amount of protraction that occurs early which can decrease the function of the rotator cuff muscles.

Low row standing Wall washes

Assists with realigning the acromion and clavicle and establishes a firm foundation for rotator cuff muscle activation.

Utilize closed chain exercise before advancing to open chain exercise.

Decrease the forces acting on the arm and increase sensory feedback by utilizing closed chain exercise

Lawnmower with arm away from the body Fencing

Decreases traction on the arm and lessens the risk of ‘anterior-inferior-medial’ motion of the acromion in relation to the clavicle.

Work in multiple planes.

Utilize the previously established motion and strength to work on advanced motor control using open chain exercise(s) in multiple planes of motion.

Standing abduction Internal rotation and external rotation at 0°and 90°of abduction Standing forward elevation Standing elevation in plane of the scapula

Permits the introduction of longer levers and open chain movements in a controlled manner.

Incorporate long lever maneuvers.

Build muscle endurance and higher levels of strength utilizing maneuvers that require the arm to be further away from the body.

Perform challenging yet functional exercises that simulate activities of daily living and work/sport maneuvers.

Incorporate trunk rotation with arm motion to increase shoulder and scapular muscle activation.

*Adapted from Sciascia and Cromwell Rehabil Res Pract 201291

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Nonoperative Management of Traumatic Acromioclavicular Joint Injury: A Clinical Commentary with Clinical Practice...

Figure 10a-h. Lawnmower with arm away from body is the advancement of the previous lawnmower exercise with the arm in a slightly flexed position to begin (a) but the same hip extension and trunk rotation components (b). The Fencing exercise begins with the arm elevated to 90° in the frontal plane (c) and performed by side stepping and simultaneously retracting the scapula and adducting the arm (d). Wall washes are performed with the patient standing with the scapulae in a retracted position and the arm placed on the wall holding a towel or similar soft object (e). The patient is instructed to step forward while simultaneously sliding the hand across the wall (f). This maneuver can be performed vertically moving from a squat position (g) to an erect position (h).

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Nonoperative Management of Traumatic Acromioclavicular Joint Injury: A Clinical Commentary with Clinical Practice...

Figure 11a-h. Standing rotator cuff exercises begin with the patient in an upright position (a) with the arms transitioning through forward elevation (b), elevation in the plane of the scapula (c), and abduction (d). Standing rotator cuff exercises with trunk rotation begin with the patient upright (e) then performing synchronous glenohumeral external rotation and trunk rotation (f) followed by other maneuvers such as forward elevation with trunk rotation (g=beginning position, h=terminal position).

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Nonoperative Management of Traumatic Acromioclavicular Joint Injury: A Clinical Commentary with Clinical Practice...

It is important to appreciate that the moderate to high degree of AC joint instability that is often associated with traumatic high-grade injuries may not achieve complete symptom resolution with rehabilitation. Muscle optimization has a ceiling effect, as the loss of skeletal stability of the scapula and clavicle and the resulting alteration of optimal SHR can be an obstacle too difficult to overcome with conservative measures. The likelihood of regaining higher degrees of function is greater in cases where only one set of ligaments has been compromised (Rockwood/ISAKOS Types I-IIIA) rather than both sets of ligaments (Rockwood/ ISAKOS Types IIIB-V),1 yet it is still possible to have lingering symptoms with all types of low-grade and high-grade injuries. This confounding concern should be discussed with patients prior to initiating a conservative treatment program.

To summarize the kinetic chain-based treatment approach, the authors suggest the following as guidelines to be followed for managing AC joint injuries nonoperatively: 1) prescribe rest and activity modification as needed to decrease acute symptoms (approximately 1-2 weeks); 2) begin incorporating therapeutic exercise for addressing proximal segment control (exercises designed for leg and trunk/core strengthening); 3) employ exercises for scapular and shoulder mobility and/or lower extremity mobility as needed (mobility can be addressed simultaenously with proximal segment control interventions); 4) progress to short-lever interventions beginning with maneuvers that utilize trunk and leg motion to facilitate more optimal scapular positioning and mobility; and 5) phase out short-lever interventions and phase in long-lever maneuvers (begin with maneuvers requiring the arm to be slightly flexed or abducted then transition to maneuvers with the arm at or above shoulder height).

RETURN-TO-ACTIVITY One of the challenges with rehabilitating the upper extremity following injury is selecting interventions that optimally prepare the patient for return-to-activity. Progression of the treatment plan for AC joint injury to higher-level/demanding exercises can be difficult due to: 1) the anatomical disruption has not been restored following supervised treatment, 2) AC joint injuries primarily occur via traumatic mechanisms and despite best efforts to prepare individuals for the risks of physical activity, traumatic events cannot be completely prevented, and 3) the literature being void of empirical studies that provide a detailed therapeutic approach and a summation of the results of that approach for its effectiveness for returning patients to activity following AC joint injury. The existing return-to-activity literature

has mostly focused on the rate of return following surgical intervention with a recent meta-analysis on the topic identifying a 94% return for a variety of sports for patients who sustained a Rockwood Type III or higher injury.106 However, the authors noted that methodological heterogeneity resulted in low quality evidence for the studies retained in their review. Two recent reports centered on nonoperatively managed AC joint injury noted return-to-activity time frames ranging from three to four weeks (professional hockey players)107 and five to seven weeks (professional soccer players).108 However, the treatment details were not reported in either study and the classification of the AC injuries sustained in the soccer players was not reported.108 Due to the lack of key information surrounding treatment of the AC injuries from those works, there is a need for research aimed at identifying higher intensity sport-specific movements and exercises in athletic populations who have sustained AC joint injury.

CONCLUSIONS AND RECOMMENDATIONS Although a number of comparative treatment studies exist for the management of AC joint injuries, the large amount of methodological differences that exist between these reports do not permit definitive nonoperative treatment recommendations to be made. Using the evidence-based medicine approach which combines the best available evidence with clinician experience and patient values, the following conclusions can be offered: 1) variation in outcomes are possibly due to using 2-dimensional AC joint alignment rather than 3-dimensional shoulder function; and 2) a treatment program that is functionally-based rather than cosmetically-based could provide nonoperative treatment guidance as it allows for dynamic scapular and shoulder motion to be addressed to optimize arm function due to the demonstrated relationship between scapular position and motion and varying amounts of AC injury. The strength of these recommendations are level B as per the Strength-ofRecommendation Taxonomy as the evidence is inconsistent in methodological design and limited in regards to treatment methods and details reported.109

CONFLICTS OF INTEREST

The authors declare no conflicts of interest.

Submitted: August 24, 2021 CDT, Accepted: December 01, 2021 CDT

This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CCBY-NC-4.0). View this license’s legal deed at https://creativecommons.org/licenses/by-nc/4.0 and legal code at https://creativecommons.org/licenses/by-nc/4.0/legalcode for more information.

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Nonoperative Management of Traumatic Acromioclavicular Joint Injury: A Clinical Commentary with Clinical Practice...

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Nonoperative Management of Traumatic Acromioclavicular Joint Injury: A Clinical Commentary with Clinical Practice...

62. Kibler WB, Sciascia AD, Dome DC. Evaluation of apparent and absolute supraspinatus strength in patients with shoulder injury using the scapular retraction test. Am J Sports Med. 2006;34(10):1643-1647. doi:10.1177/03635465062887 28 63. Tate AR, McClure P, Kareha S, Irwin D. Effect of the scapula reposition test on shoulder impingement symptoms and elevation strength in overhead athletes. J Orthop Sports Phys Ther. 2008;38(1):4-11. d oi:10.2519/jospt.2008.2616 64. Reuther KE, Thomas SJ, Tucker JJ, et al. Scapular dyskinesis is detrimental to shoulder tendon properties and joint mechanics in a rat model. J Orthop Res. 2014;32(11):1436-1443. doi:10.1002/jor.2 2693 65. Kibler WB, Ludewig PM, McClure PW, Michener LA, Bak K, Sciascia AD. Clinical implications of scapular dyskinesis in shoulder injury: the 2013 consensus statement from the “scapula summit.” Br J Sports Med. 2013;47:877-885. doi:10.1136/bjsports-20 13-092425 66. Chillemi C, Franceschini V, Dei Giudici L, et al.

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Nonoperative Management of Traumatic Acromioclavicular Joint Injury: A Clinical Commentary with Clinical Practice...

SUPPLEMENTARY MATERIALS Appendix A Download: https://ijspt.scholasticahq.com/article/32545-nonoperative-management-of-traumatic-acromioclavicularjoint-injury-a-clinical-commentary-with-clinical-practice-considerations/attachment/ 82515.docx?auth_token=FCEhsAOIMSHv7OwUplr4

Appendix B Download: https://ijspt.scholasticahq.com/article/32545-nonoperative-management-of-traumatic-acromioclavicularjoint-injury-a-clinical-commentary-with-clinical-practice-considerations/attachment/ 82516.docx?auth_token=FCEhsAOIMSHv7OwUplr4

Appendix C Download: https://ijspt.scholasticahq.com/article/32545-nonoperative-management-of-traumatic-acromioclavicularjoint-injury-a-clinical-commentary-with-clinical-practice-considerations/attachment/ 82517.docx?auth_token=FCEhsAOIMSHv7OwUplr4

International Journal of Sports Physical Therapy

Shah N, Grunberg C, Hussain Z. Can a Patient use an App at Home to Measure Knee Range of Motion? Utilizing a Mobile App, Curovate, to Improve Access and Adherence to Knee Range of Motion Measurements. IJSPT. 2022;17(3):541-547.

Technical Note/Tips from the Field

Can a Patient use an App at Home to Measure Knee Range of Motion? Utilizing a Mobile App, Curovate, to Improve Access and Adherence to Knee Range of Motion Measurements Nirtal Shah 1

a

, Corey Grunberg 2, Zahra Hussain 3

1

Faculty of Kinesiology and Physical Education, University of Toronto, 2 Physical Therapy, University of Toronto, 3 Dalla Lana School of Public Health, University of Toronto Keywords: Mobile health, mobile app, knee, range of motion, Curovate https://doi.org/10.26603/001c.33043

International Journal of Sports Physical Therapy Vol. 17, Issue 3, 2022

Introduction Knee range of motion is a critical measure of progress after knee injury and knee surgery.

However, many patients do not understand the importance of knee range of motion and most do not have a way to self-monitor their knee range of motion at home. The patient being able to measure their own range of motion can provide improved access to this critical health metric, and could improve adherence with their daily knee range of motion exercises. The purpose of this technical report is to determine if a mobile app, Curovate, can provide reliable measures of knee range of motion compared to standard goniometric measurements.

Procedures There were four positions of knee flexion and four positions of knee extension each measured twice with a standard goniometer and four different mobile devices with the app Curovate. The reliability and validity of the Curovate app was tested across mobile devices and operating systems and compare to goniometric knee range of motion measurements. A total of 80 measurements were taken. All testing was completed on a healthy 23-year-old male with no knee pathology.

Results A strong positive correlation, Pearson’s r > = 0.9985, for all positions of knee flexion and extension across all four mobile devices as well as each mobile device compared to standard goniometric measurements.

Conclusions This article presents a unique method for patients to measure their knee range of motion using the mobile app Curovate. Overall, the mobile app, Curovate, was found to have a strong positive correlation across four mobile devices with varying operating systems and compared to goniometric measurements.

Level of evidence 4

a

Corresponding author: Nirtal Shah DPT, MScPT, MPH, FCAMPT Faculty of Kinesiology and Physical Education 55 Harbord Street, Toronto, ON, M5S 2W6 University of Toronto Canada nirtal.shah@utoronto.ca

Can a Patient use an App at Home to Measure Knee Range of Motion? Utilizing a Mobile App, Curovate, to Improve Access and...

INTRODUCTION The ability of clinicians and patients to obtain accurate joint angle measurements of the knee joint is key to monitoring progress following surgical repair or arthroplasty.1 Adequate knee range of motion is a necessary component of many activities of daily living, including walking, climbing stairs and entering a bathtub.2 However, patients rarely have access to their own knee range of motion measurements. Typically, the physical therapist measures the patient’s knee extension and flexion at a healthcare facility with a standard goniometer and explains this measurement to the patient. The physical therapist utilizes these measures to monitor patient progress, documents the measurements, and reports these values back to the patient.3 The patient may not always understand these measures, do not remember the actual numbers, and most do not have a reliable way to measure this on their own. Previous researchers have reported that patients who are disengaged with their home rehabilitation have lower rates of rehabilitation adherence.4,5 Digital methods exist for measuring knee range of motion. Hancock et al. demonstrated that goniometric measurements using digital inclinometer technology are more accurate than both manual goniometry and clinician estimation for full knee flexion, full knee extension and three other angles of knee flexion on six knees for a total of 300 measurements.6 However, many physical therapists and most patients do not have access to digital inclinometers. This disconnect between an important clinical measure that is inaccessible by the patient may contribute to poor patient adherence and lower levels of patient engagement and participation in rehabilitation exercises aimed at restoring knee range of motion.

The explosion of mobile health technology has made it possible for health metrics to be accessed by patients in their home. In addition, various forms of mobile health are aimed at improving patient adherence with health behaviours such as smoking cessation, taking prescription medications and improving adherence to exercise all while being patient-centric and at a lower cost than conventional healthcare.7 There are various apps that are capable of measuring knee range of motion. One such smartphone mobile app, Curovate, can be used by both the patient and the physical therapist is capable of measuring knee flexion and extension. Curovate is available for download in the Apple App Store and the Google Play Store.

Curovate is a subscription-based mobile application intended for patients following anterior cruciate ligament (ACL) reconstruction or injury, total knee replacement and total hip replacement. In addition to providing daily video guided exercises specific for each surgery or injury stage, progress tracking, and in-app chat with a licensed physical therapist it also functions as a digital knee range of motion measurement tool. Curovate is free for a five-day trial and then requires either a monthly ($8.99 USD) or an annual ($45.99 USD) subscription paid through either the App Store or Play Store.

The purpose of this technical report was to determine if a mobile app, Curovate, can provide reliable measures of knee range of motion compared to standard goniometric mea-

Figure 1. Demonstrating how one angle of knee flexion (F1) was measured and sustained. In this case, the participant’s foot is resting on a wedge on a non-slip mat on top of a plinth. A permanent marker was used to delineate bony landmarks for standard goniometric measurements. Two pieces of athletic tape were used to stay consistent when placing the various mobile devices on the leg.

surements.

PROCEDURES The participant used during data collection for this technical report was a 23-year old individual with no previous or current pathologies of the knee joint. A healthy subject was chosen for this technical report in order to test the reliability of the mobile app measurement. In future studies subjects with knee injury and pathology will be tested utilizing the mobile app. Data collection presented no identifiable risk to the participant. Additionally, no confidential information was collected about the participant during data collection. The participant signed a photograph release form and consented to all testing and images taken for the purpose of this submission.

All goniometric measurements were completed by a licensed physical therapist, with 21 years of clinical experience in orthopaedics and sports medicine with extensive experience measuring knee range of motion in clinical practice. The primary author first manually located the bony landmarks for knee range of motion. Specifically, the midpoint of the lateral malleolus, the lateral aspect of the lateral femoral condyle and the midpoint of the greater trochanter. The bony landmarks were marked with a permanent marker on the participants body for consistency. In addition, the primary author placed two strips of athletic tape above and below the participant’s knee with a line on each to consistently place each mobile device on the same spot for all measurements (See Figures 1 & 2).

To test range of motion, four angles of knee flexion (F1-F4) and four angles of knee extension (E1-E4) were measured on the same subject and then repeated (Appendix). Images of all eight angles of knee flexion and exten-

International Journal of Sports Physical Therapy

Can a Patient use an App at Home to Measure Knee Range of Motion? Utilizing a Mobile App, Curovate, to Improve Access and...

Table 1. Correlation between goniometric measurements and Curovate mobile app knee range of motion measurements on four mobile devices.

Goniometer Goniometer

Samsung S7 Android

iPhone 11 iOS

iPhone XR iOS

iPad Pro iOS

1

Samsung S7 Android

0.9991

1

iPhone 11

0.9985

0.9997

1

iPhone XR

0.9991

0.9998

0.9996

1

iPad Pro

0.9989

0.9997

0.9998

0.9998

sion can be found in the Appendix.

In all measurements the participant was supine on a plinth with a non-slip exercise mat placed under his torso and leg. Each position of knee flexion or extension was sustained with the use of a foam roll, a hard-plastic wedge or the participants foot being in contact with the non-slip mat.

During pilot testing it was determined that this allowed the participant to be able to sustain the position consistently without changing the joint angle between measurements.

All knee range of motion measurements were first completed using a standard, long arm, goniometer produced

by CME Corporation (Warwich, RI), according to Clarkson, 2020 clinical guidelines.8 The mobile app Curovate allows the individual to measure, store and track their knee flexion and extension measurements (Figures 3 & 4).

Once the patient has completed the self-measurement they are presented with their current range of motion and they can also view their previous measures within the app (See Figure 4). Previous authors have noted that smartphone-based knee range of motion measures lack reliability on various devices and operating systems.9 To test this limitation this technical report tested using an iPad Pro (operating system 14.8), iPhone 11 (operating system 14.8), iPhone XR (operating system 14.4.2) and a Samsung S7 Android mobile device (operating system 8.0.0). Goniometric measurements were taken first followed by each mobile device and then repeated the measures again at the same knee angle with the goniometer and then with all four mobile devices.

Pearson’s correlation coefficient was used to determine the correlation between all of the measures. Microsoft Excel (2018, v 16.16.27, Microsoft Corporation) was utilized to calculate Pearson’s r.

RESULTS The correlational results of the 80 measurements taken with a standard goniometer and the four different operating systems/devices are presented in Table 1. Strong positive correlations are demonstrated across all mobile devices as well as mobile device measurements compared to standard goniometric measurements. Please refer to the Appendix to see the table of raw measurements for each measurement method (Appendix).

1

Figure 2. In this case a hard-plastic wedge was used to simulate a patient who is lacking terminal knee extension. This was one of the positions used to measure knee extension (E2) with all four mobile devices and standard goniometric measurement.

DISCUSSION Patients who have had an anterior cruciate ligament injury or surgery, total knee replacement, or various other knee injuries and surgeries are always advised by their physical therapist to perform daily knee range of motion exercises.

The loss of knee range of motion can have detrimental effects on a patient’s functional abilities.2 Daily life activities such as walking, using the stairs and getting in and out of a seated position all require an adequate amount of knee range of motion.2 In most cases clinicians have various methods to measure knee range of motion in the clinical environment but patients have no way to measure their own range of motion. This lack of independence and poor understanding of range of motion may be possible to address through mobile health technology. This would provide the

International Journal of Sports Physical Therapy

Can a Patient use an App at Home to Measure Knee Range of Motion? Utilizing a Mobile App, Curovate, to Improve Access and...

patient with access to information regarding range of motion measures at home and could motivate them to adhere to their range of motion exercises.

This technical report provides preliminary information regarding the reliability of a mobile app, Curovate, for measurement of knee range of motion. This preliminary testing demonstrated a high degree of positive correlation using Pearson’s r to compare across all mobile devices and operating systems for all angles of knee flexion and extension measured when compared to standard goniometric measurement in a single subject. Based on these preliminary findings the authors suggest that a patient can effectively measure their knee flexion and extension at home independently. This would provide the patient with critical range of motion measures at home which could motivate them to adhere to their home range of motion program.

The limitation of this technique of measurement includes the need for a smartphone and the mobile app Curovate. This limitation is becoming less relevant as smartphone ownership increases globally. Current estimates suggest that 4.92 billion people or 66% of the world population own a mobile device.10 Another potential limitation is that a patient may not place the smartphone on the same area of their lower leg for subsequent measures which would reduce the reliability of the measure. In this report a piece of athletic tape was used to reproduce the placement of the mobile devices for each measurement. A patient at home would be less consistent and therefore this may reduce the overall reliability and validity of the measure taken by the patient. To address this limitation, a YouTube video guide can be used by a patient to measure their range of motion at home (YouTube link: https://youtu.be/kzYKnLlxEFA Supplementary Video #1). Another potential solution would be for the patient to be carefully instructed by their physical therapist on how to place the mobile device to obtain reliable measures of knee range of motion. The additional time spent by the physical therapist would benefit both the patient as well as the physical therapist who could review the patient’s range of motion measures at subsequent appointments. As this is a single subject technical report these results are not generalizable to patient with knee injury and surgery. Future research will be focused on testing the reliability and validity of this measure taken independently by patients with knee pathology in their home setting as this is the intended use of the mobile app and comparing these measurements to those obtained by physical therapists in a clinical setting. Further research is required with a large sample size to test the reliability, validity and clinical applicability of this smartphone-based measurement.

This preliminary study for a technical note could have been strengthened by making the range of motion measurements blinded, as well as testing inter-rater reliability with a novice physical therapist and a patient conducting the app measurement. As physical therapists continue to improve patients’ independence with range of motion measurements, a future direction of research could be how selfmeasurement contributes to patient adherence to range of motion home exercises. Another area of future research is how this home measurement can be integrated with telehealth visits, video check-ins, and remote patient monitoring. There is a possibility for cost savings and improving

Figure 3. This image shows how a patient would independently measure their knee extension (E4) and knee flexion (F3) range of motion along with the app screen that is presented in each case.

timeliness of care if such measures could automatically trigger clinician alerts while the patient utilizes the app for home rehabilitation.

To provide data transparency, the authors have provided raw values for each measurement in the supplementary table and as much detail as possible to allow other clinicians and researchers to test and evaluate these findings.

CONCLUSIONS The results of these preliminary tests demonstrate strong

International Journal of Sports Physical Therapy

Can a Patient use an App at Home to Measure Knee Range of Motion? Utilizing a Mobile App, Curovate, to Improve Access and...

positive correlations across mobile devices and compared to standard goniometric measurements. This simple and unique mobile app can provide patients with an effective method to measure of their knee range of motion at home.

Further study using larger sample sizes is warranted.

CONFLICTS OF INTEREST

The primary author (NS) has a conflict of interest as he is the CEO of Curovate. The second and third authors have no conflicts of interest to declare.

Submitted: November 12, 2021 CDT, Accepted: January 09, 2022 CDT

Figure 4. This image shows the results and measurements as they are presented to the patient once they have completed the process of measuring their range of motion as depicted in Figure 3.

This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CCBY-NC-4.0). View this license’s legal deed at https://creativecommons.org/licenses/by-nc/4.0 and legal code at https://creativecommons.org/licenses/by-nc/4.0/legalcode for more information.

International Journal of Sports Physical Therapy

Can a Patient use an App at Home to Measure Knee Range of Motion? Utilizing a Mobile App, Curovate, to Improve Access and...

REFERENCES 1. Holzgreve F, Maurer-Grubinger C, Isaak J, et al. The acute effect in performing common range of motion tests in healthy young adults: a prospective study. Sci Rep. 2020;10(1). doi:10.1038/s41598-020-78846-6 2. Rowe PJ, Myles CM, Walker C, Nutton R. Knee joint kinematics in gait and other functional activities measured using flexible electrogoniometry: how much knee motion is sufficient for normal daily life?

Gait Posture. 2000;12(2):143-155. doi:10.1016/s096 6-6362(00)00060-6

6. Hancock GE, Hepworth T, Wembridge K. Accuracy and reliability of knee goniometry methods. J Exp Orthop. 2018;5(1):46. doi:10.1186/s40634-018-0161-5 7. Malvey D, Slovensky DJ. MHealth: Transforming Healthcare. New York, NY: Springer Science+Business Media; 2014.

8. Clarkson H. Musculoskeletal Assessment: Joint Range of Motion, Muscle Testing, and Function. Philadelphia, PA: Lippincott Williams & Wilkins; 2020.

3. Collins JE, Rome BN, Daigle ME, Lerner V, Katz JN, Losina E. A comparison of patient-reported and measured range of motion in a cohort of total knee replacement patients. J Arthroplasty.

2014;29(7):1378-1382.e1. doi:10.1016/j.arth.2014.0 2.023

9. Keogh JWL, Cox A, Anderson S, et al. Reliability and validity of clinically accessible smartphone applications to measure joint range of motion: a systematic review. PLoS ONE. 2019;14(5):e0215806. d oi:10.1371/journal.pone.0215806

4. Nicolson PJA, Hinman RS, Kasza J, Bennell KL. Trajectories of adherence to home-based exercise programs among people with knee osteoarthritis.

Osteoarthr Cartil. 2018;26(4):513-521. doi:10.1016/j.j oca.2018.01.009

10. DeGusta M. MIT technology review. Are smartphones spreading faster than any technology in human history? Published May 9, 2012. Accessed November 11, 2021. https://www.technologyreview.co m/2012/05/09/186160/are-smart-phones-spreading-f aster-than-any-technology-in-human-history/

5. Campbell R, Evans M, Tucker M, Quilty P, Dieppe P, Donovan JL. Why don’t patients do their exercises?

Understanding non-compliance with physiotherapy in patients with osteoarthritis of the knee. J Epidemiol Community Health. 2001;55(2):132-138. doi:10.1136/j ech.55.2.132

International Journal of Sports Physical Therapy

Can a Patient use an App at Home to Measure Knee Range of Motion? Utilizing a Mobile App, Curovate, to Improve Access and...

SUPPLEMENTARY MATERIALS Appendix Download: https://ijspt.scholasticahq.com/article/33043-can-a-patient-use-an-app-at-home-to-measure-knee-rangeof-motion-utilizing-a-mobile-app-curovate-to-improve-access-and-adherence-to-knee-range-of-m/attachment/ 83453.pdf?auth_token=xwNfnYdmB1fd8e--Qulp

International Journal of Sports Physical Therapy

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