CASES BIG 2025 Digital Booklet

UNIVERSITY OF

16 April2025 th

Biomechanics Interest Group Conference 2025

Chartering BIG Possibilities in Biomechanics

Welcome

It is my great pleasure to welcome you to the 2025 BiomechanicsInterestGroup(BIG)Conference,hostedatthe UniversityofGloucestershire BIGistheflagshipeventofthe Division of Biomechanics and Motor Behaviour, part of the Chartered Association of Sport and Exercise Sciences (CASES). For over 30 years, it has been the UK’s leading forumforsportandexercisebiomechanistsfromacademia, research,andappliedfields

We’re excited to present an outstanding programme, including a keynote from Professor Andrea Cereatti (Polytechnic University of Torino) on wearable inertial sensors and their role in biomechanics We also welcome TomCresswell,HeadofSportsScience&MedicineforGB Men’sBasketball,andworld-leadingpolevaultcoachScott Simpson. Their talks will offer fresh insight into the realworldapplicationofbiomechanicsinelitesport.

Alongsideourmainspeakers,we’reproudtohostadiverseline-upoforalandposterpresentationsspanning the discipline from students and early career researchers to seasoned professionals I encourage you to engagefully,askquestions,andbuildconnections

This event would not have been possible without the support of many. Thank you to the CASES Division of BiomechanicsandMotorBehaviouranditsChair,DrAndrewMitchell,fortrustingustohost.Imustexpress particular gratitude to Dr Theodoros Bampouras whose coordination, scientific oversight, and tireless dedicationhavebeencentraltoeveryaspectofthisevent’ssuccess Quitefrankly,withouthim,wemaynot havebeenabletobringthisconferencetogetherinthewaywehave SincerethanksalsogotoDrRomanda Dillonforshapingourdigitalpresencesoeffectively.

Our local organising committee has been brilliant throughout. I would like to give a very special mention to Ashish Balagopalan, one of our senior technicians, whose expertise, dedication, and problem-solving were instrumentaltothesuccessofthisevent Ialsothankourstudentvolunteers,whoseenergyensurestheday runssmoothly.

Finally, a heartfelt thank you to our sponsors and exhibitors. Biomechanics cannot exist without the technologies you provide Please make time to visit the exhibition stands your engagement is key to the futureofourfield

Warmregards, Prof Athanassios Bissas

Biomechanics and Motor Behaviour Division Deputy Chair

Biomechanics Interest Group Conference 2025

Chartering BIG Possibilities in Biomechanics

Announcements

A two-day Conference, combining the Annual Conference and the Student Conference.

3-4 June 2026 - a reimagined conference to the sector from the Manchester Metropolitan University Institute of Sport.

Celebrating the application of evidence-based science into practice.

The go-to learning and networking experience in 2026 for delegates across all career stages.

First Call for Hosting BIG 2026 or 2027

With #BASESBIG2025 firmly behind us, we are looking for a host to be running this event in the years 2026 and 2027

Anyone interested in hosting BIG 2026 or BIG 2027, or wants to have some more information about it, are encouraged to contact the Biomechanics and Motor Behaviour Division (CASES.biomech@gmail.com). The application form can be downloaded here.

Biomechanics Interest Group Conference 2025

SCHEDULE

08.45-09.15

09.15-09.30

Oralpresentations

MasonStolycia:In-vivoAchillesTendonDisplacementDuring HingedControlledAnkleMotionBootWear

GasparEpro:Similarmusclehypertrophyofthetricepssurae muscleinresponsetodifferentmechano-metabolicstress exercise

09.30-10.45

FenjaDeister:Stressimagingarthrometryforassessinganterior talofibularligamentstraininvivo

MateusAlbuquerquePlacido:Improvingtripresistancewith perturbation-basedgaittrainingusingamovementrestricting kneebraceinhealthyyoungadults

JoannaWootton:Interventionstoreducefallsandimprovesafety onstairs:asystematicreviewoftheevidence

QianQian:Effectsofa4-weektaichiinterventiononpostural controlinindividualswithchronicankleinstability

10.45-11.15

11.15-12.15

KeynoteLecture

ProfessorAndreaCereatti:Towearornottowear?everythingyou alwayswantedtoknowaboutinertialsensors butwereafraidtoask

Biomechanics Interest Group Conference 2025

SCHEDULE

12.15-13.00

Posterdefence

StephGrady:Theimpactofsedentarybehaviourandphysicalactivityon footmusclestrengthandfallriskinolderadults

PhillipHeritage:Analysisofisometricneckstrengthcharacteristicsin sportingandgeneralpopulations

DianaSoares:Theeffectoffootwearmidsolethicknessonhealthyolder adults’walkinggaitandfootwearperceptions

SimonBriley:Mood,gaitbiomechanics,andcognitiveload:investigating theinfluenceofcognitivedemandsonthemood-motorrelationshipin youngadults

NicholasRipley:Acutefatigueinpeakisometrichamstringforceinelite malesixeslacrosseplayers

13.00-13.30

RichCollins:Muscleactivationofthebicepsfemoris&semitendinosusin differenteccentrichamstringexercisesinfemalefootballplayers

GabriellaWilson:DobiomechanicalchangesexplainthedeclineinCPR chestcompressionperformanceovertime?

IvanJukić:Coachingtoolsandacuteperformanceenhancements:dothey comewithanytrade-offs?

HarryDavies:Agreementbetween‘Theia3D’andmarker-based performanceindicatorsoftheSnatch:acasestudy

HazelTucker:Validityandreliabilityofcommonwearabletechnologyto estimaterunningmetricsduringovergroundrunning

ChristinaCefai:Canwearablesbeusedtoestimatetheprobabilityoftibial stressfractures?asimulationstudy

MaxPinckney:Jointmechanicalworkvariabilityduringcontrolledankle motion(cam)bootwear

Biomechanics Interest Group Conference 2025

SCHEDULE

13.30-14.15

14.15-15.30

TomCresswell:BiomechanicsdominateseveryconversationI haveatwork,fromdirectortocoachtoathletetostafftoparent

Oralpresentations

RyleaHart:Thedevelopmentoftemplate-basedmodelsforanalysing resistance-trainingmovementperformance

LiamHoulton:Effectofalternativecomplex-contrasttrainingset strategiesonverticaljumppropulsiveforce

JackFahey:Forceplate-derivedisometricmidthighpullbenchmarksin elitefemaleyouthfootballers

GabrieleAzzolini:Theeffectofstuddesignongroundreactionforce andsubjectiveperceptioninfootball-specificmovements

XiYang:Wearabletechnologyintennis:playerwillingness,usage,and application

LoganWade:Themajorbarrierslimitingintegrationofmarkerless motioncapturewithinclinicalpracticeintheUnitedKingdom

Biomechanics

Chartering BIG Possibilities in Biomechanics

Biomechanics and Motor Behaviour Division

Dr Andrew Mitchell Division Chair

Andrew began studying sport back in the early 1990s at the University of Chichester and soon came to realise his specific area of interest was the biomechanics of sports injuries

Upon graduation, he studied Athletic Training and Sports Medicine at Campbell University in North Carolina (USA), and then completed an MSc in Sports Medicine and Kinesiology at the University of Tennessee in Knoxville (USA)

He returned to the University of Chichester to read for a PhD, focussing on the biomechanics of the lateral ankle sprain He taught at the University of Hertfordshire for 13 years before taking up the role as Head of School of Sport Science and Physical Activity in 2013

Andrew is now the Associate Dean within the Faculty of Education, English and Sport and led the submission of UoA 24 in the REF2021 at the University of Bedfordshire He is an Associated Professor in Biomechanics and his research focuses on lower limb biomechanics and the ankle sprain mechanism.

Prof Athanassios Bissas

Deputy Chair

Professor Athanassios Bissas – Professor of Sport and Exercise Technologies at University of Gloucestershire, UK.

Professor Bissas’ research interests lie in the area of biomechanics of locomotion with a focus on sprint running, neuromuscular adaptions and technologies of motion analysis Together with his team he has produced over 200 research outputs and he is actively involved in research projects with institutions across Europe and USA Amongst other research projects, he led the two largest biomechanics projects ever conducted for the London 2017 and Birmingham 2018 World Athletics Championships

Chartering BIG Possibilities in Biomechanics

chanics and Motor haviour Division

Lauren is a research associate in biomedical engineering at the University of Strathclyde. Her background is in sport and exercise science and she specialises in biomechanics and rehabilitation Currently she is assessing ankle instability through joint variability and developing interactive treatments. She also owns a strength and conditioning business

Dr Lauren Forsyth Co-opted Member

Dr Theodoros Bampouras

Dr Theodoros M Bampouras is currently a Senior Lecturer in Research Methods at Liverpool John Moores University. Theo’s research interests lie primarily in the areas of muscle performance, mechanics and function. He has published work in muscle function assessment methods and muscle conditioning for improved power, as well as in the areas of balance, gait and vision in healthy older adults He is the Membership Representative for the Division and always keen to hear members’ views on developing the Division further

Membership Representative

Chartering BIG Possibilities in Biomechanics

Biomechanics and Motor Behaviour Division

Rachel Mason

CPD Representative

Dr Diana Soares

Student Representative

Rachel Mason is a PhD student at University of Northumbria at Newcastle Her primary research interest is the use of wearable technology for objective running gait analysis. Within the university, Rachel is part of the Physiotherapy Innovation Laboratory, where the research involves a translational multidisciplinary approach to understand human movement and develop novel clinical assessment and rehabilitation tools. Rachel is the CPD advisor for the division and is keen to encourage a multi-disciplinary, holistic approach.

Diana holds a Licentiate in Dance, an MSc in Dance Science, and more recently, a PhD in Biomechanics At the University of Bedfordshire, she is a Visiting Lecturer in Dance Science and an HPL in Applied Biomechanics Additionally, she works as a research consultant and exercise referral specialist, leading dance and exercise sessions for individuals with long-term health conditions at the University Community Exercise Clinic

Chartering BIG Possibilities in Biomechanics

Biomechanics and Motor Behaviour Division

Julia is a third-year undergraduate student coming to the end of her Sport and Exercise Science degree at Liverpool John Moores University, the focus of her major project was on how lower-limb neuromuscular pre-activity is affected by the anticipation of a task and how this may link to ACL injuries in women athletes. Within BASES she is the undergraduate student representative for the division.

Julia Suchanecka Student Representative

Dr Romanda Dillon Co-opted Member

Romanda is currently an Impact and Evaluation Support Officer and the University of East London She graduated from the University of Mississippi with her bachelor's degree in Kinesiology. She went on to earn her Master's degree in Kinesiology from Stephen F. Austin State University, located in Nacogdoches, Texas Romanda moved to England to start her doctoral studies at Loughborough University, specialising in Sports Biomechanics, emphasising optimal performance in the tennis serve and badminton jump smash.

Her passion for promoting diversity in biomechanics has led to roles within both the International Women in Biomechanics and the Black Biomechanics Association groups

Biomechanics Interest Group Conference 2025

Chartering BIG Possibilities in Biomechanics

University of Gloucestershire Organising Committee

Professor Athanassios Bissas Professor of Sport and Exercise Technologies

Dr Nicola Theis Senior Lecturer in Sport and Exercise

Dr Martine Deighan Senior Lecturer in Sport and Exercise

Anna Ferguson Technician Demonstrator

Ashish Balagopalan Technician Demonstrator

Biomechanics Interest Group Conference 2025

Chartering BIG Possibilities in Biomechanics

Invited Speakers

Prof Andrea Cereatti

Andrea Cereatti is a Full Professor of Bioengineering at the Department of Electronics and Telecommunications, Polytechnic University of Torino. He currently serves as President of the Italian Society of Clinical Movement Analysis and has been a board member of the 3-D AHM Technical Group of the International Society of Biomechanics (ISB) He is also a founding member of the National Association of the Italian National Bioengineering Group

His research focuses on joint kinematics estimation and modeling, wearable sensors for assessing locomotor capacity and performance in clinical and sports applications, and innovative approaches for neuromuscular rehabilitation and motor function enhancement

Professor Cereatti has organized numerous courses and workshops on wearable sensor applications in human movement analysis at leading conferences, including ICNR, ISEK, EMBC, ISB, SIAMOC, BHI-BSN, and WCB He has co-authored over 150 publications, including eight book chapters, and holds three patents in the field.

To wear or not to wear? Everything You Always Wanted to Know About inertial sensors…but were afraid to ask

Low-costwearableinertialsensorsaretransforminghumanmovementanalysis,enablingdatacollectionbeyondlaboratory settings and providing a more realistic understanding of movement in real-world environments However, to bridge the gap between research and practical application in clinical, sports, and exercise settings, it is essential to ensure these technologiesmeettechnical,clinical,andusabilitystandards.

This lecture will present a conceptual framework for the application of inertial sensors in biomechanics, highlighting key technological and methodological challenges alongside potential solutions It will also provide recommendations to enhance datareproducibilityandcomparabilityacrossstudies,ensuringthereliableandeffectiveuseofthesetoolsinpractice.

Biomechanics Interest Group Conference 2025

Chartering BIG Possibilities in Biomechanics

Invited Speakers

Scott Simpson

Tom Cresswell

Scott Simpson is a World Leading pole vault coach from Great Britain. He is currently the coach to four of the World's top-20 female pole vaulters, including 2024 World Indoor Champion - Molly Caudery (GBR) and 2016 Olympic Bronze medallist - Eliza McCartney (NZL). He has coached at four Olympic Games and now coached six Olympians

He has a background in Biomechanics having completed his BSc in Sport and Exercise Science and then studied at PhD level in the biomechanics of triple jumping, with further publications in the area of biomechanics of sprinting

He works closely with integrated support teams from both the UK and New Zealand to best service the athletes he coaches. This includes the applied use of biomechanics in aiding athlete health and enhancing performance

The application of biomechanical data in performance coaching in the pole vault

Tom Cresswell is the Great Britain’s Basketball Men’s Head of Sports Science & Medicine. He is also a Physiotherapist and performance coach at Hintsa Performance

Tom is a multi-sport physio and performance coach having worked indoors and outdoors, at gyms, pools, courts, pitches, slopes and racetracks. The common theme throughout has been basketball and for Great Britain he has staffed every age group at major tournaments He is a specialist generalist practitioner as well as clinical leader. But biomechanics is where Tom learned he could do what he set his mind to and it underpins everything he does.

Previously Tom has had roles as Lead Academy Physio at Birmingham City FC, Women’s Team Head of Physiotherapy at Bristol City FC, Williams F1 Racing, Mercedes-AMG Petronas F1 and Head of Medical Services at Hartpury University.

Biomechanics dominates every conversation I have at work, from director to coach to athlete to staff to parent

Chartering BIG Possibilities in Biomechanics

Awards and Sponsers

The Special Interest Group Awards seek to reward outstanding research contributions to biomechanics.

Best Oral Presentation Award

This award is given to the best oral presentation, including content and delivery. This award is sponsored by Human Kinetics.

Best Poster Presentation Award

This award is given to the best poster presentation, including content and delivery This award is sponsored by Human Kinetics.

Diversity in Biomechanics Research Award

This award is given to work most focused on researching diverse populations in biomechanics. This award is sponsored by the Biomechanics and Motor Behaviour Division.

Beyond the Laboratory Award

This award is given to work with the greatest impact on everyday life outside of traditional experimental settings. This award is sponsored by Human Kinetics.

Thank you to al the sponsors who proudly supported today’s event. Your commitment to Biomechanics has been instrumental in making not only this event but our biomechanics community a success We appreciate your support!

Biomechanics Interest Group Conference 2025

Chartering BIG Possibilities in Biomechanics

Oral Presentation

Mason L. Stolycia , David E. Lunn , Richard A. Wilkins , Josh Walker

Carnegie School of Sport, Leeds Beckett University, Leeds, UK 1

NIHR Leeds Biomedical Research Centre, Leeds Teaching Hospitals NHS Trust, Leeds, UK 2

Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds, Leeds, UK 3

Podiatry Department, Leeds Teaching Hospitals NHS Trust, Leeds, UK 4

m.l.stolycia@leedsbeckett.ac.uk

IN-VIVO ACHILLES TENDON DISPLACEMENT DURING HINGED CONTROLLED ANKLE MOTION BOOT WEAR

INTRODUCTION

Achilles tendon rupture (ATR) incidence has increased over recent years [1], with 8 per 100,000 persons experiencing ATR per year [2] Achilles Tendon (AT) re-rupture rates for patients managed using a conservative treatment approach are significantly higher than those patients treated surgically [3]. Conservative treatment involves limiting the ankle motion to allow healing of the tendon, which is normally done through a hinged or fixed controlled ankle motion (CAM) boot. The hinged boot allows ankle range of motion (RoM) to be manipulated over the course of a patient’s recovery A non-surgical, accelerated functional rehabilitation using such early range of motion approaches reduces re-rupture rates to those similar to surgical management [3], which may be due to better structural remodeling, returning the healed tendon’s composition close to that of a healthy AT through loading [4]. However, it is not understood how these boots affect a patient’s function or the mechanical loading of AT. This study aims to understand the ankle function and underlying muscle-tendon interaction during walking with a hinged CAM boot.

METHODS

Eight participants (3 male, 5 female; age = 22 8 ± 2 3 years; height = 170 4 ± 9 1 cm; mass = 67 7 ± 13 7 kg) underwent 3D kinematic (Qualisys, Sweden) and kinetic analysis in four conditions whilst walking on a 3D instrumented treadmill (h/p/cosmos, Germany) at a preferred walking speed. The CAM boot (VACOped®, Oped GmbH, Germany) was tested in three different ankle RoMs (0°, 15°, and 30° = B , B , and B ,respectively), and compared to their own footwear (SHOD). These conditions were chosen to replicate the Leicester Achilles Management Protocol (LAMP) loading regime [5]. The CAM boot was worn on the right leg with the participant’s own footwear and an EVENup® (Oped GmbH, Germany) shoe leveler worn on the contralateral limb in B , B Dynamic ultrasound (Telemed, Italy) of the gastrocnemius medialis (GM) and AT myotendinous junction was collected during walking, measuring AT displacement, GM fascicle length and pennation angle Kinematic and kinetic analyses were conducted in Visual3D (HAS-Motion, Canada), where joint mechanics were estimated using inverse dynamics. AT stretch was calculated using ankle angle changes, ankle moment arm, and measured AT displacement. GM muscle-tendon unit length change (ΔL ) was computed using ankle and knee angle data and regression equations, which was then decomposed into contractile and series-elastic element (CE and SEE, respectively) length changes (ΔL and ΔL , respectively); CE referring to the interaction of the muscles, and SEE tendons and aponeuroses, of the MTU during each walking condition All statistical analysis was conducted for left and right legs independently; therefore, no between limb comparisons were made.

ROM0 ROM15 ROM30

ROM0 ROM15 MTU

RESULTS & DISCUSSION

Biomechanics Interest Group Conference 2025

Chartering BIG Possibilities in Biomechanics

Oral Presentation

Total mechanical work of the CAM boot-wearing limb was lower than SHOD in B , B and B (p < 0 001, p = 0 002 and p = 0 038, respectively; Figure 1) Absolute and relative ankle mechanical work increased incrementally with an increase in ankle RoM with significant differences (p < 0.05) between all conditions except B and B (Figure 1). The absolute knee and hip work were similar to the SHOD, with no significant differences (Figure 1) Relative joint contribution at the hip was significantly increased in B and B when compared to SHOD (p < 0 001), but B was not (Figure 1) Muscle-tendon unit length change (ΔL ) incrementally increased as boot RoM was increased, with B , B and B significantly lower than SHOD (p <0.001, p < 0.001 and p = 0.002, respectively; Table 1). AT stretch observed a similar trend, with B and B both significantly lower than SHOD (p = 0 012), but B was not significantly different (Table 1)

These findings showed that as ankle RoM is increased in the CAM boot, the AT stretch increased, leading to increased incremental loading of the AT Although tendon strain was not directly measured, AT stretch serves as an appropriate surrogate, showing incremental increases in tendon energy storage when CAM boot RoM is increased In primary ATR patients this could lead to greater mechanically induced healing through increased collagen synthesis and improved linear collagen organisation [6]. Such remodeling of the AT could increase tendon tensile strength [7], thus improving functional outcomes in non-surgical patients whilst reducing rerupture rates [4] In addition to AT stretch, it could be suggested that the AT contributes to the incremental increase in ankle work as the CAM boot RoM is increased This is suggested by the incremental increase in MTU and SEE length changes, whilst no changes are observedinCE Theincreasedankleworkcontributestothetotalmechanicalwork,whichbecomesclosertoresemblingSHODasRoM increases.Relativecontributionofthehip,kneeandanklearesimilartoSHODwalkinginBROM30(Figure1),showingthemechanismof thehingedCAMbootallowspatientstograduallyreturnto“normal”walkingduringrehabilitation.However,furtherresearchisneeded inapathologicalgroupofATRpatientstoobserveifthesefindingstranslatetoapatientpopulation

CONCLUSION

This study has provided preliminary data on the mechanisms of hinged CAM boots and potential contribution to healing for patients with a primary ATR. As boot RoM is increased, so is ankle RoM, which subsequently increased joint work done, AT displacement, and therefore AT stretch This improves the ankle’s ability to contribute to total mechanical work, which could mechanically induce healing oftheATwiththepotentialtoimprovepatientoutcomesandreducere-rupturerates

REFERENCES

[1].Lantto,I.,etal.ScandJMedSciSports,25(1),e133-8,2015.[LINK]

[2].Seow,D.,etal.,TheAmericanJournalofSportsMedicine,49(13),3728-3748,2021.[LINK]

[3] Ochen,Y,etal,Bmj,364,k5120,2019 [LINK]

[4] Yang,X,etal,Bone&JointResearch,7(10),561-569,2018 [LINK]

[5] Aujla,RS,etal,Injury,50(4),995-999,2019 [LINK]

[6].Bring,DK-I.,etal.,JournalofOrthopaedicResearch,27(2),274-280,2009.[LINK]

[7].Puetzer,JL.,etal.,Biomaterials,369,120527,2021.[LINK]

Biomechanics Interest Group Conference 2025

Chartering BIG Possibilities in Biomechanics

Oral Presentation

Gaspar Epro , Yiannis Lambrianides , and Kiros Karamanidis 1 1 1,2

London South Bank University, College of Health and Life Sciences, School of Applied and Health Sciences, London, United Kingdom

University of Koblenz, Department of Sport Science, Faculty of Mathematics and Natural Sciences, Koblenz, Germany 2 gasparepro@gmail.com

SIMILAR MUSCLE HYPERTROPHY OF THE TRICEPS SURAE MUSCLE IN RESPONSE TO DIFFERENT MECHANO-METABOLIC STRESS EXERCISE

INTRODUCTION

Muscle power generation capacity is partly determined by its volume, which is hence often assessed to evaluate the effectiveness of various interventions intended to improve muscle function in different population groups It seems that some muscles (e g quadriceps) are able to adapt to exercise with a region-specific hypertrophy, i e alterations in its shape [1], which could potentially be related to different fiber type distribution but also to distinct innervation patterns within the muscle during exercise. It is widely recognised that muscles are able to hypertrophy to a variety of mechanical loads given a certain total volume is exceeded, hence implying their dependence on the metabolic stress and overall physiological demand rather than the experienced mechanical load [2]. Little is known whether mono- and biarticular ankle plantarflexors change its shape in response to high metabolic stress exercise and whether it is dependent on the trained muscle length The current study investigated whether a high metabolic stress exercise at distinct operating lengths of triceps surae (TS), accordingly either low or high muscle force potential, leads to different adaptive changes in its mechanical and morphological properties.

METHODS

12 young adults (27±5 yrs) voluntarily took part in a 12-week exercise intervention for 3x week using 3 sets of cyclic unilateral isometric plantarflexion contractions until failure at 80% of individual maximal voluntary contraction (high muscle metabolic stress) According to the TS muscle forcelength-relationship [3], low and high levels of mechanical stress were implemented using a short (PF; 115⁰) or a long (DF; 85⁰) muscle-tendon unit (MTU) length for either legs. Ultrasonography and dynamometry were used to asses TS MTU mechanical and morphological properties. All three compartments of the TS muscle (m. soleus, m. gastrocnemius medialis and lateralis) were reconstructed using magnetic resonance imaging sequences to calculate muscle volume and its specific shape factors [4]

RESULTS & DISCUSSION

Despite almost 2-fold difference in the generated joint moments in training, a similar exerciserelated increment (p<0.05) between DF and PF legs was detected in TS muscle strength (~20-25%), along with comparable morphological adaptations across the three TS compartments with increased pennation angle (~10%), maximal anatomical cross-sectional area (ACSAmax; ~5%) as well as muscle volume (~6%) Even though the muscle growth occurred mainly close to the belly region of each muscle, no clear region-specific adaptation could be identified and ACSAmax demonstrated no significant shift in its position in relation to the muscle length in either of the exercised legs or investigated compartments of the TS Hence, also no alterations in the individual muscle specific shape factors could be observed over the 12-week training period.

Biomechanics Interest Group Conference 2025

Chartering BIG Possibilities in Biomechanics

Oral Presentation

CONCLUSION

The outcomes of the current study demonstrate that skeletal muscles remain highly responsive to metabolic stimuli even at moderate mechanical tension and stress levels in increasing their force and power generation capacity Furthermore, exercising at different operating lengths of the contractile element based on the force length-relationship seems not to lead to inhomogeneous regional hypertrophy in ankle plantarflexors.

REFERENCES

[1]. Narici, M.V. et al. Acta Physiologica Scandinavica, 157, 175-186, 1996. [LINK] [2]. Lambrianides, Y. et al. Scandinavian Journal of Medicine & Science in Sports, 34, e14638. [LINK] [3]. Csapo, R. et al. Journal of Experimental Biology, 213, 2582–2588, 2010. [LINK] [4] Albracht, K et al Journal of Biomechanics, 41, 2211-2218, 2008 [LINK]

Biomechanics Interest Group Conference 2025

Chartering BIG Possibilities in Biomechanics

Oral Presentation

Fenja Deister , Sevan Harput , Kiros Karamanidis , 1 1 1,2

Wolfgang Potthast , and Darren James 3 1

London South Bank University, London. UK 1 University of Koblenz, Koblenz, Germany 2

German Sport University Cologne, Cologne, Germany 3

deisterf@lsbu.ac.uk

STRESS IMAGING ARTHROMETRY FOR ASSESSING ANTERIOR TALOFIBULAR LIGAMENT STRAIN IN VIVO

INTRODUCTION

Lateral ankle sprain (LAS) is one the most common musculoskeletal injuries. LAS typically involves trauma to the anterior talofibular ligament (ATFL) Ex vivo, ATFL has a relatively low yield and ultimate force response [1] so understanding its capacity to tolerate mechanical loading in vivo may be beneficial for injury prevention and rehabilitation Therefore, the aim of this study is to present a method for assessing ATFL strain and its elastic material property in response to passive ankle inversion loading and additionally to investigate bi-lateral and sex-related differences in healthy participants. The respective rationale is: i) the uninvolved limb is often used as an intra-subject control for clinical comparison, but the extent of bilateral asymmetry in response to loading is uncertain, and ii) current evidence for sex-related differences is limited by a lack of standardization in testing procedures [2]

METHODS

Bilateral ATFLs were imaged in 44 volunteers without a history of a lateral ankle injury (25f/19m; 27±6 years) using a custom-made arthrometer [3] designed to passively invert the ankle joint from 0° to 5°,10° and 20° and thereby elongating ATFL. ATFL length and strain were assessed via B-mode ultrasonography (15 MHz, 2cm depth) taking the curved path of the ligament into account, and strain referenced to 0° inversion Shear-wave velocity (SWV; 15MHz, 4cm depth) - as an index of the ligament’s elastic material property, was measured via a 25mm region-of-interest within the midpart of the ligament with the probe stabilised in a mechanical arm over a 2cm gel-pad Prior reliability measurements (n=11) showed that ATFL length (ICC: 0.987; SEM: 0.4mm) and SWV (ICC: 0.989; SEM: 0.3m/s) measurements are repeatable. Main and interaction effects for ATFL length, strain and SWV were assessed using a two factor (limb & angle) repeated measures ANOVA with sex as the between-subjects factor (P<0.05).

RESULTS & DISCUSSION

ATFL length, strain and SWV increased with increasing inversion angle (P<0 001; Figure 1 A-F), thereby demonstrating the feasibility of this stress imaging arthrometry method

A significant main effect for limb existed in ATFL length (P<0.05) and strain (P<0.001). In starting position (0°), ATFL was significantly shorter in the right vs left limb (18.9±2.5mm vs 19.9±3.6mm, P<0 01) and remained so until 20° of inversion where no difference was apparent (P=0 14) A sex vs limb interaction effect (P<0 05) revealed that the observed limb differences in ATFL length were significant in males (across all angles tested, P<0 01) but not in females (P=0 98; Figure 1A&B)

Ligament strain increased significantly more in the right vs left limb (limb vs angle interaction: P<0.05), reaching 10.0±7.0% of its starting length at 20° inversion vs 5.9±3.6% in the left limb. Again, the observed limb differences (in ATFL strain) were significant in males (across all angles tested, P<0.001) but not in females (P=0.08; Figure 1C&D; sex vs limb interaction effect: P=0.095). In contrast to ATFL-length based measures, there was no significant main effect for limb or sex vs limb interaction in SWV (Figure 1E&F)

Biomechanics Interest Group Conference 2025

Chartering BIG Possibilities in Biomechanics

Oral Presentation

When both limbs were pooled together, there was no overall effect of sex in ATFL length (P=0 059), strain (P=0 426) and SWV (P=0 261)

A potential sex difference in ATFL length is not surprising since measures of foot and ankle morphometry are greater in males [4]. Whilst the present findings did not show this to a level of significance (P=0 059), this study has shown that significant bilateral differences in ATFL length exist in males but not females, and the same phenomena is present in measurements of strain. Bilateral asymmetry has previously been shown in the unloaded dorsal Lisfranc ligament within the foot, with the right side significantly shorter than the left [5]; however, when the feet were further stressed, this bilateral effect disappeared This contrasts with the present findings which, with the addition of a sex vs limb interaction, cannot easily be explained Thus, our intention is to expose these differences, but we can only hypothesize their underlying cause Measurement error may be responsible; however, the results of our reliability study suggest a robust approach and methodology with the bilateral differences observed in length and strain being higher than the respective SEM In addition, the investigator was blinded to participant records during reliability analysis Secondly, ATFL anatomy is complex; it has various bands which ultrasound cannot detect and varies considerably between individuals, limbs, and indeed sex [6]. Alternatively, a sex-specific effect of limb dominance might be an explanation, but evidence to support this conjecture is lacking; though it is worth noting that the majority (n=17) of right dominant male participants possessed a shorter right ATFL

Figure 1: ATFL sex vs limb interaction differences within female (A,C,E) and male (B,D,F) participants; (A+B): length; (C+D): strain and (E+F): SWV; a, b and c represent significant differences to 0°, 5° and 10°, respectively; and * , ** and *** represent the significance level (p<0.05, p<0.01, p<0.001, respectively).

At 20° inversion, ATFL can elongate up to 10% of its ‘neutral’ length in healthy participants. This is below ex vivo mechanical testing measures of yield (~13%) and ultimate (~20%) strain [1,7]. Finally, our non-congruent findings between strain and SWV measurements might reflect the variation in ATFL length at our presumed starting reference position and as such the morphological properties do not correlate with the ligament’s material properties

CONCLUSION

Stress imaging arthrometry is a robust and reliable methodology to assess ATFL strain and can perhaps be developed into a cost-effective solution to predict and manage lateral ankle sprain injury The observed sex vs limb interaction requires further research.

REFERENCES

[1] Siegler, S et al , Foot and Ankle International, 8, 234-242, 1988 [LINK]

[2]. Mizrahi, D.J. et al., J Ultrasound Medicine, 8, 1957-1963, 2018. [LINK]

[3]. Best, R. et al., Knee Surg Sports Traumatol Arthrosc., 24, 963-970, 2016. [LINK]

[4] Tomassoni, D et al , Maturitas , 79, 421-427, 2014 [LINK]

[5] Marshall, J J et al , The Journal of Foot & Ankle Surgery, 52, 319-323, 2013 [LINK]

[6]. Khawaji, B. & Soames, R., The Foot, 25, 141-147, 2015. [LINK]

[7]. Colville, M.R. et al., The American Journal of Sports Medicine, 18, 196-200, 1990. [LINK]

Biomechanics Interest Group Conference 2025

Chartering BIG Possibilities in Biomechanics

Oral Presentation

London South Bank University, College of Health and Life Sciences, School of Applied and Health Sciences, 1 London, United Kingdom

University of Koblenz, Department of Sport Science, Faculty of Mathematics and Natural Sciences, 2 Koblenz, Germany

albuquem@lsbu.ac.uk

IMPROVING TRIP RESISTANCE WITH PERTURBATION-BASED GAIT TRAINING USING A MOVEMENT RESTRICTING KNEE BRACE IN HEALTHY YOUNG ADULTS

INTRODUCTION

Perturbation-based gait training has been shown to be effective in improving fall resistance abilities, with long-lasting effects [1] that can be partially applied to real world scenarios [2]. A crucial aspect for balance recovery after a trip-like perturbation is the ability to increase the base of support (BoS) by modulating the muscle activity of leg extensors, as the knee extensor output directly influences the step length during walking [3] Systems to improve trip-resisting skills via perturbation-based training are commonly costly, complex and immobile, making it inaccessible for the wider community In recent years, exoskeletons have found wider use in gait rehabilitation to not only aid but also resist movement [4], however their efficacy as a potential approach for perturbation-based training is not clear/known. The aim of this study was to develop a novel mobile mechatronic system capable of inducing unpredictable resistance in knee extensor muscle output during gait and to evaluate its effectiveness in improving trip-resisting skills in healthy young adults through repeated perturbations

METHODS

Ten healthy young adults participated in a functional treadmill gait training session using an electromagnetic resistive knee brace, which perturbed the neuromuscular control of the leg extensors during the swing phase of the gait cycle. Perturbations were performed through a combination of unpredictable and sustained perturbations during walking, all together lasting 25 min. Locomotor transfer to recovery actions in trip-like perturbation was assessed by using pulling forces on participants ankle mid swing phase (n=10) Ten control participants without performing any gait perturbation exercises on the treadmill conducted the trip-like perturbation transfer task after 25 min Whole-body 3D motion capture was used to calculate lower extremity joint kinematics, the base of support (BoS) and margin of stability (MoS). Plantar flexor and knee extensor muscle activity of both legs was assessed during walking using EMG (1000Hz) and was normalized to MVC.

RESULTS & DISCUSSION

Unpredictable gait perturbations via the knee brace resulted in a decreased BoS and MoS (more unstable body configuration) compared to normal gait and led to an increased EMG activity in the monoarticular knee extensors during the swing phase and in the plantar flexors during the push-off phase (p<.05). In the trip transfer task, the intervention group demonstrated greater MoS and BoS at touchdown of the perturbed leg compared to the control group (p<.05) and required fewer recovery steps to achieve positive MoS values after the perturbation. Statistical parametric mapping revealed differences in lower limb joint kinematics after the trip-like perturbation, with greater knee extension angles for the recovery leg in the intervention group compared to the control (p< 05) This partly explains the improved balance recovery in the intervention group as it allows to take longer recovery steps after the perturbation

Mateus A. Placido , Julian Werth , Gaspar Epro , Perry Xiao , Kiros Karamanidis

Oral Presentation Biomechanics Interest Group Conference 2025

Chartering BIG Possibilities in Biomechanics

CONCLUSION

Unpredictable and sustained knee joint perturbations during gait induce adaptive changes in balance recovery responses that are transferred to tripping situations, highlighting the importance of knee extensor neuromuscular function for fall resilience. The findings of the current study provide evidence and confidence that the developed mechatronic system could be a feasible alternative method for perturbation-based training in older adults in order to reduce the risk of falls and fallrelated injuries globally.

REFERENCES

1) Epro et al , Journal of Neurophysiology, 119, 2229–2240, 2018 [DOI]

2) Werth et al., Scientific Reports, 12, 21901, 2022. [DOI]

3) Schulz et al., Clinical Biomechanics, 22, 689-696, 2007. [DOI]

4) Abdikadirova et al., IEEE Transactions on Neural Systems and Rehabilitation Engineering 32, 791799, 2024. [DOI]

Biomechanics Interest Group Conference 2025

Chartering BIG Possibilities in Biomechanics

Oral Presentation

Joanna Wootton , Toni Hall , Constantinos Maganaris , Theodoros M. Bampouras , Richard Foster , Mark Hollands , Vasilios Baltzopoulos and Thomas O’Brien

Research Institute for Sports and Exercise Sciences, Faculty of Science, Liverpool John Moores University, UK 1 National Institute for Health and Care Research (NIHR) Applied Research Collaboration (ARC) Northwest Coast, University of Liverpool, UK 2

j.wootton@2023.ljmu.ac.uk

INTERVENTIONS TO REDUCE FALLS AND IMPROVE SAFETY ON STAIRS: A SYSTEMATIC REVIEW OF THE EVIDENCE

INTRODUCTION

Falls are the leading cause of injury-related deaths worldwide [1] One-third of people ≥65 and half of those ≥80 experience at least one fall annually [2] In the UK, stair falls account for 230,000 fallrelated injuries each year [3], and of all falls that occur, stairs cause the most deaths [4,5]. Safe stair negotiation requires proper foot progression, placement, and control of the centre of mass (COM) within the base of support (BOS). Failure in these areas leads to falls through tripping, slipping, and loss of balance, respectively. Previous research has established this mechanistic understanding of stair falls through mostly laboratory-based studies Efforts to improve safety on stairs have developing interventions to target one or more of these mechanisms, and a large body of evidence now exists Therefore, this wealth of research must be evaluated to determine the most effective interventions to direct and prioritise future translational research and implementation. The aims of this systematic review are to a) synthesise, evaluate and assess stair fall interventions, b) identify those which have been proven effective and have potential for implementation, and c) establish a pathway for implementation for the interventions identified.

METHODS

Five databases were searched (PubMed, Web of Science, CINAHL, Scopus and MEDLINE) in March 2023, retrieving 7357 unique papers. Of these, fifty-seven interventions from fifty-one papers were included. Quality was assessed using the Cochrane RoB-2 tool, chosen for its multi-domain mode of assessment, giving flexibility in bias assessment. Due to the nature of many papers being proof-ofprinciple by design, a modified RoB-2 tool was developed and used in addition to the standard RoB-2, results from both tools are reported Following risk of bias assessment, data were extracted and grouped according to their overarching variable Interventions were allocated into one of three categories for synthesis and interpretation: stair dimensions and visual properties, surrounding environment, or human behaviour Evaluation of these interventions was carried out by a team of researchers (co-authors) who met to interpret these findings based on two factors: to understand the synthesised evidence on their effectiveness, and to recommend and prioritise future research to progress interventions along a pathway to implementation (adapted from MRC Complex Intervention Framework [7], Figure 1)

RESULTS & DISCUSSION

Using the Cochrane RoB 2 tool, forty-nine papers were deemed a high risk of bias, however, after further quality assessment using our modified tool the majority of papers were classed low risk for proof-of-principle studies. These results show that the quality of evidence is mixed with there not being any strong evidence for these interventions supporting implementation.

Only one study, investigating step-edge highlighters [6], was investigated in a real-world environment, all other interventions have been tested in a laboratory as proof-of-principle investigations These proof-of-principle interventions have proven positive effects on the risk factors investigated. This demonstrates the necessity to begin translational research on interventions that have been found to be effective in this lab environment to assess the application in real-world settings.

Interventions varied in outcome measures, each focusing on different risk factors Notably, none of the fifty-seven interventions assessed fall rates directly, likely due to the logistical challenges of long-term evaluations However, given their aim to reduce falls, this omission is significant

Biomechanics Interest Group Conference 2025

Chartering BIG Possibilities in Biomechanics

Oral Presentation

Synthesis of these interventions and their results highlights that several interventions show potential to improve stair safety. However, due to the varied outcome measures and lack of real-world testing, these interventions require further translational research before implementation in the realworld can be supported. The pathway to implementation (Figure 1) provides a view of the current research landscape and acts as signposting for future intervention development.

There are several interventions investigated in this review that are already being implemented, despite a lack of strong evidence of improving stair safety These interventions are step-edge highlighters, step dimensions, and the use of handrails; these interventions warrant further evaluation in naturalistic and real-world settings. Priorities should therefore be put on the optimisation of their application and establish their effectiveness in a real-world environment to reduce falls and improve direct measures of fall risk.

Figure 1: Pathway to Implementation Flowchart This flowchart identifies the current progress in the development of each intervention and the required the next stage of research

CONCLUSION

The findings of this systematic review have shown that there are no included interventions which directly assessed stair fall rates. Instead, the included interventions have proven effectiveness on measures of stair fall risk in laboratory studies. These interventions require targeted translational research for implementation in real-world environments. These effective interventions should then be used to inform healthcare professionals and policies in order to improve safety and reduce falls on stairs

REFERENCES

[1]. James, S.L., et al. Injury Prevention: Journal of the International Society for Child and Adolescent Injury Prevention, 26, 3-11, 2020. [LINK]

[2]. GOV UK. Guidance: Falls Applying All Our Health, 2022. [LINK]

[3] Roys, M S Applied Ergonomics, 32, 135-139, 2001 [LINK]

[4] Startzell, J K , et al Journal of the American Geriatrics Society, 48, 567-580, 2000 [LINK]

[5] Jacobs, J V Gait & Posture, 49, 159-167, 2016 [LINK]

[6]. Brown, C.B., et al. Ergonomics, 66, 1219-1228, 2023. [LINK]

[7]. Skivington, K. et al. British Medical Journal, 374, n2061, 2021. [LINK]

Biomechanics Interest Group Conference 2025

Chartering BIG Possibilities in Biomechanics

Oral Presentation

Qian Qian , Hengshuo Zhang , Jingdan Zhang , Patrick C. Wheeler , and Daniel T.P. Fong

2 1 1,3 1

School of Sport, Exercise and Health Sciences, Loughborough University, UK.

Wolfson School of Mechanical, Electrical and Manufacturing Engineering, Loughborough University, UK. 2 Department of Sport & Exercise Medicine, University Hospitals of Leicester NHS Trust, UK. 3

q.qian@lboro.ac.uk

EFFECTS

OF A 4-WEEK TAI CHI INTERVENTION ON POSTURAL CONTROL IN INDIVIDUALS WITH CHRONIC ANKLE INSTABILITY

INTRODUCTION

Ankle sprain is very common in sports, with up to 70% progressing to chronic ankle instability (CAI), which is associated with alterations in muscle activation, deficits in proprioception, and muscle weakness [1] These impairments negatively impact postural balance, often resulting in difficulties with dynamic stability and an increased risk of recurrent injury [2].

Tai Chi, a traditional Chinese martial art characterized by slow, controlled movements, has been shown to enhance balance, proprioception, and muscle strength. Moreover, Tai Chi is low-cost, requires no equipment, large space, or specific attire, and can be practiced anywhere However, limited research has explored its effects on individuals with CAI

Given the crucial role of the peroneal and tibialis anterior muscles in ankle stability, a simplified 16form Tai Chi sequence was designed to engage these muscles while maintaining training efficacy with reduced complexity. The study aimed to investigate the effects of a four-week Tai Chi intervention on dynamic balance and self-reported instability in individuals with CAI.

METHODS

Participants were recruited from Loughborough University based on International Ankle Consortium guidelines Eligibility criteria included (i) aged from 18 to 40, (ii) a history of significant lateral ankle sprain 12 months before study enrolment, (iii) reports of feeling instable or “giving way”,(iv) the most recent injury occurred more than 3 months before study participation, and (v) a CAIT score ≤25. Exclusion criteria included (i) a history of fractures, (ii) a history of previous surgeries to the musculoskeletal structures, (iii) other muscle, joint or nerve disorders that affect the function of the lower limbs, and (iv) already being a Tai Chi practitioner This study is approved by the Loughborough University Ethics Committee

The independent variables used in this study were treatment (4 weeks of Tai Chi training) for the intervention group and no treatment for the control group.Participants allocated to the Tai Chi group underwent a 60-minute Tai Chi exercise session three times a week. The dependent variables analysed in this study were postural stability, measured by the Star Excursion Balance Test (SEBT) in three directions (anterior, posteromedial, and posterolateral) and self-reported feeling of instability, measured by the Cumberland Ankle Instability Tool (CAIT) SEBT distance in each direction was normalized to the percentage of leg length

The Shapiro-Wilk test was used to assess the normality of the data. The Mann–Whitney U test was applied to data that did not meet the normal distribution assumption. Demographic characteristics of the participants were compared by independent samples t-tests and chi-square tests. To assess differences in SEBT and CAIT between evaluation times within-groups, a 2 (group) by 2 (time) repeated measures analysis of variance was used

Biomechanics Interest Group Conference 2025

Chartering BIG Possibilities in Biomechanics

Oral Presentation

RESULTS & DISCUSSION

Thirty participants completed the trial, with 15 individuals per group At baseline, there were no significant differences between the two groups in terms of demographic characteristics or tests. After four weeks of training, the Tai Chi group showed significant improvements in postural and perceived stability compared to the control group. Specifically, the Tai Chi group exhibited significant increases in anterior and posteromedial reach distances on the SEBT (p < 0 01; see Table 1), indicating improved dynamic balance in these directions However, no significant improvement was observed in the posterolateral direction, possibly due to the biomechanical demands of this movement, requiring greater lateral stability and hip control Additionally, perceived stability as measured by the CAIT improved significantly in the Tai Chi group (p < 0.01; see Table 1).

CONCLUSION

A four-week Tai Chi intervention improved both postural and perceived stability in individuals with CAI The simplified Tai Chi sequence, focusing on key stabilizing muscles, holds potential as an effective rehabilitation strategy. Future research with larger sample sizes, extended follow-up periods, and additional functional assessments is needed to further explore the rehabilitative benefitsofTaiChiforindividualswithCAI

ACKNOWLEDGMENTS

ThisstudywassupportedbyChinaScholarshipCouncil(GrantNo 202308060108)

REFERENCES

[1].P.A.Gribbleetal.,BritishJournalofSportsMedicine,50,1496–1505,2016.[Link]

[2] C Doherty,etal BritishJournalofSportsMedicine,51,113–125,2017 [Link]

Biomechanics Interest Group Conference 2025

Chartering BIG Possibilities in Biomechanics

Poster Presentation

Steph Grady , Jessica Piasecki ,Paul Felton ,Daniele Magistro , and Charlotte Apps

Sport Health and Performance Enhancement (SHAPE) Research Centre, Nottingham Trent University 1

steph.grady@ntu.ac.uk

THE IMPACT OF SEDENTARY BEHAVIOUR AND PHYSICAL ACTIVITY ON FOOT MUSCLE STRENGTH AND FALL RISK IN OLDER ADULTS

INTRODUCTION

Falls are associated with older age and account for approximately 684,000 fatalities annually [1] The foot muscles contribute to balance and mobility and comprise of intrinsic (IFM) and extrinsic (EFM) muscles, which originate in the foot or lower leg, respectively The arches of the foot flatten as we age, and joint work distribution alters leading to a reduction in range of motion and strength [2]. To compensate, older adults increasingly rely on proximal muscles at the hip and knee as opposed to distal muscles at the foot and ankle, altering gait in order to maintain stability [3]. Older age often coincides with increased sedentary behaviour, reported to amount to around 60-70% of waking hours [4], but it is unknown how this affects strength of the foot muscles Understanding the implications of sedentary behaviour on muscle ageing becomes crucial in the context of fall prevention Therefore, this study aims to examine how physical activity levels and sedentary behaviour influence foot muscle strength (IFM and EFM) and mobility

METHODS

Thirty-nine adults (≥ 50 years; 13 males, 26 females) were recruited. All participants completed a short foot exercise familiarisation designed to activate the IFM and received an activity monitor to wear for the following 7-days During experimental visits, an isometric dynamometer recorded peak force (N) from the plantarflexors, dorsiflexors and IFM to assess strength A custom-built chair was used where the hips were flexed at 90° and the knee was extended at 180° for completion of plantarflexion and dorsiflexion movement, activating the EFM. For the short foot exercise targeting the IFM, the force transducer bar was positioned at a 28.9° angle. The foot for all movements was secured to a force transducer with a strap positioned across the metatarsal phalangeal joint (Research Solutions [Alsager] Ltd, Stoke-on-Trent, UK). A standardised warm-up included submaximal contractions at 25%, 50% and 75% of their perceived maximal voluntary contractions, followed by three trials for each muscle group with a 1-minute rest in between This was followed by the Timed Up and Go test to assess mobility Accelerometer data from the activity monitors was converted into 60 s epochs and classified into Physical Activity and Sedentary Behaviour levels using established cutpoints [5,6]. The highest of two consecutive isometric trials within 5% of each was used and normalised to body weight. Results were analysed using SPSS, employing correlations, linear regression and a parallel multiple mediator model, where sedentary behaviour (X) predicted mobility (Y), with plantarflexion and dorsiflexion force as mediators

RESULTS

Linear regression analysis examined the relationships between sedentary behaviour, physical activity, age and EFM and IFM strength. Sedentary behaviour significantly predicted plantarflexion strength, (p = .03, R² = .116), indicating an inverse relationship, while no significant associations were found with dorsiflexor and IFM strength. Age was a significant predictor of dorsiflexor strength, (p = 002, R² = 212) which decreased with age, but not for plantarflexor strength Physical activity significantly predicted increased plantarflexor strength in older adults aged above 70 years (p = 002, R² = 219) but not those aged between 50-59 years old

Biomechanics Interest Group Conference 2025

Chartering BIG Possibilities in Biomechanics

Poster Presentation

Figure 1. A statistical diagram of the parallel multiple mediator model for the influence of sedentary behaviour on mobility.

DISCUSSION

The findings highlight the impact of sedentary behaviour and physical activity on foot muscle strength and mobility in older adults Sedentary behaviour time was associated with reduced plantarflexion strength (Figure 1), which aligns with previous research suggesting prolonged inactivity accelerates muscle deterioration [7]. No significant differences were observed between sedentary behaviour and IFM strength suggesting the IFM and EFM play different roles in stability and mobility, where the extrinsic muscles maybe are more susceptible to age associated strength loss Mediation analysis also suggests that the relationship between sedentary and mobility is influenced by plantarflexor strength highlighting the importance of maintaining mobility in older adults

CONCLUSION

Overall, these findings reinforce the importance of reducing sedentary behaviour and promoting physical activity in ageing populations to preserve foot muscle strength and mobility. Further research could explore whether structured interventions, targeted at the extrinsic foot muscles, could effectively counteract the negative effect of prolonged inactivity of lower limb function and discern the underlying mechanisms of neuromuscular performance to provide a more targeted approach to fall prevention

CONCLUSION

The results of the present study demonstrate that relative net peak force measured by IMTP did not differ between youth players from different phases (i.e. FDP, YDP and PDP). Increases in body mass (and therefore momentum) during maturation increases the mechanical stress and can increase injury risk if relative strength is not developed Youth female football players should aim to develop relative strength to better cope with the match demands with increasing age and increasing competition level

REFERENCES

[1] World Health Organization. World Health Organization, 2022 [Link]

[2] James, B., et al. American journal of physical medicine & rehabilitation, 68, 162-167,1989.[Link]

[3] Drabarek, D., et al. International Journal Biomechanics and Movement Science, 1, 1989 [Link]

[4] Harvey, J A ,et al Journal of aging and physical activity, 23, 471-487, 2015 [Link]

[5] Anguilar-Farias, N , et al Journal of Science and Medicine in Sport, 17, 293-299, 2014 [Link]

[6] Bammann, K , et al PloS one, 16 e 0252615, 2021 [Link]

[7] Raffin, J , et al Ageing Research Reviews, 83, 101807, (2023) [Link]

Biomechanics Interest Group Conference 2025

Chartering BIG Possibilities in Biomechanics

Poster Presentation

Diana Soares , Iain Fletcher , Andrew Mitchell and Laura Charalambous 1 1 1 1

Institute of Sport and Physical Activity Research, University of Bedfordshire, Bedford, UK 1

diana.soares@beds.ac.uk

THE EFFECT OF FOOTWEAR MIDSOLE THICKNESS ON HEALTHY OLDER ADULTS’ WALKING GAIT AND FOOTWEAR PERCEPTIONS

INTRODUCTION

Excessive midsole cushioning may increase fall risk in older adults (OA) by negatively affecting postural [1] and walking stability, and by increasing gait variability [2] Thicker midsoles may act as an interface between the feet and floor, potentially reducing OA plantar sensation and foot position awareness in relation to the ground [3] By hindering sensory feedback from cutaneous mechanoreceptors of the feet, fall risk may increase [1] However, well-cushioned athletic footwear has been recommended to improve OA comfort and support during activities of daily living (ADLs) [4], which may explain the frequent wear of athletic footwear by OA for outdoor ADLs and physical activity. While current recommendations warn of potential instability with thick soled footwear [4], evidence indicating how much midsole cushioning may detriment OA walking gait is still limited For example, a reduction in both step frequency and step length could be indicative of a compensatory strategy to stabilise gait Older adults need to perceive footwear as comfortable and stable as agerelated morphological changes to the feet can lead to foot pain [5] Perceived comfort can influence physical mobility, performance, and foot-related complaints [6], whereas reduced perceived stability increases fall-related anxiety, impairing OA postural stability and gait, ultimately increasing fall risk [7]. Therefore, this study examined 1) if athletic footwear with different midsole thicknesses significantly affected OA step frequency, step length, and gait speed in comparison with the participants’ most frequently used outdoor footwear, and 2) if the participants’ footwear perception regarding overall comfort, cushioning, fit, ease of use and overall stability differed significantly in athletic footwear with different midsole thicknesses

METHODS

Twenty-six healthy and physically active community-dwelling OA, 21 females (71.1 ± 4.5 years; 164.5 ± 5.3 cm; 68.4 ± 11.4 kg) and five males (70.6 ± 2.3 years; 175.2 ± 7.8 cm; 72.8 ± 9.7 kg), walked back and forth at their normal comfortable speed on a 10 m track wearing four footwear conditions: 1) own (participants’ most frequently used outdoor footwear); 2) thick midsole (New Balance 890v6); 3) moderate midsole (New Balance 1400v5); and 4) thin midsole (New Balance Minimus 20v7) All participants wore new standard socks. Footwear fitting was performed using the palpation method. After one-minute familiarisation with the testing procedures, two trials of 200 steps with a fiveminute seated rest were conducted. Optojump (Optojump Next v1.5, Microgate, Perform Better Ltd) collected spatiotemporal gait data. During the five-minute seated rest between footwear conditions, participants completed the adapted Monitor Orthopedic Shoes questionnaire [8] to examine footwear perception Spatiotemporal gait data analysis can be found elsewhere [9] Monitor Orthopaedic Shoes questionnaire data were entered into Microsoft Excel for analysis The frequency function counted participants rating below 50 mm for each footwear characteristic A repeated measures one-way ANOVA (Bonferroni post-hoc; p ≤ 0.05) analysed the within-participant main effects of the four footwear conditions. To investigate the magnitude of the differences between each footwear condition, Cohen’s d effect size was calculated. For non-parametric variables, the Friedman Test (Dunn-Bonferroni post-hoc; p ≤ 0 05) was used, and Kendall’s W measured effect size

RESULTS&DISCUSSION

Biomechanics Interest Group Conference 2025

Chartering BIG Possibilities in Biomechanics

Poster Presentation

The results indicated significant differences between the participants’ own shoes and the three midsoles for step frequency and step length, but not for gait speed (Table 1). As shown in Table 1, step frequency significantly reduced with all midsoles, while step length significantly increased with moderate and thin midsoles These findings highlight the impact of midsole thickness on OA walking gait, consistent with previous research [2]. Moderate and thin midsoles likely increased step length by enhancing foot comfort and stability, encouraging longer steps. Indeed, athletic footwear may reduce impact forces in OA [10] and thinner midsoles may improve dynamic posture [11], potentially enhancing step length Additionally, there was a lack of significant differences in gait speed between footwear conditions, potentially due to participants altering their step frequency and step lengthtomaintainconsistentstridevelocity.

Significant differences were not found for overall comfort, cushioning, fit, ease of use and overall stability (Table 2), indicating that the different midsoles did not impact the participants’ footwear perception. The Monitor Orthopedic Shoes Questionnaire [8] was not sensitive enough to reflect walking gait differences between different types of footwear midsoles, possibly because comfort measures may vary between and within individuals due to the subjective nature of perceived comfort [6] The reliability of the questionnaire was not measured using this study’s participants, which is a limitation Future research should evaluate the reliability in their specific population [6]

CONCLUSION

Wearing athletic footwear with different midsole thickness can influence OA step frequency and step length, and a thinner midsole may enhance walking stability. While well-cushioned athletic footwear is generally recommended to improve foot comfort and support in OA, these findings highlight how athletic footwear may affect walking gait in this population Despite gait differences, footwear was perceived similarly across all midsoles Future research should explore the reliability of footwear perception questionnaires in their population of interest

REFERENCES

[1].Menz, H. & Lord, S. Journal of the American Podiatric Medical Association, 89, 346-357, 1999. [LINK] [2].Hollander, K. et al. Gait and Posture, 95, 284-291, 2022. [LINK]

[3] Hatton, A L et al Journal of Electromyography and Kinesiology,19, 957-964, 2009 [LINK] [4] AGE UK, 2024 [LINK]

[5] Jellema, A H et al Maturitas, 127, 64-81, 2019 [LINK]

[6] Matthias, E C et al Footwear Science, 13, 255-274, 2021 [LINK]

[7].Young, W.R. & Williams, A.M. Gait and Posture, 41,7-12, 2015.[LINK] [8].Van Netten, S. et al. Journal of Rehabilitation Medicine, 41 ,913-918, 2009. [LINK] [9]. Soares et al. Gerontology, 70, 1055-1062. [LINK] [10]. Baltich, J. et al. PloS One, 10, e0125196, 2015. [LINK] [11] Robbins, S et al Journal of the American Geriatrics Society, 40,1089-1094, 1992 [LINK]

Poster Presentation Biomechanics Interest Group Conference 2025

Chartering BIG Possibilities in Biomechanics

Simon Briley , Tom Outram , Callum Osler , Sian Reynolds , 1 1 1 1

Sean Lowton-Smith , Paul Briley 1 2

School of Sport and Exercise Science, University of Derby, Derby, UK 1

Faculty of Medicine and Health Sciences, University of Nottingham, Nottingham, UK 2

s.briley@derby.ac.uk

MOOD, GAIT BIOMECHANICS, AND COGNITIVE LOAD: INVESTIGATING THE INFLUENCE OF COGNITIVE DEMANDS ON THE MOOD-MOTOR RELATIONSHIP IN YOUNG

ADULTS

INTRODUCTION

Major depression affects approximately 13% of the global population and is a leading cause of disability [1]. Yet its impact extends beyond mood disturbances to include subtle motor impairments such as altered gait, slumped posture, and balance deficits [2]. Although these motor symptoms are often overlooked, emerging evidence suggests that affective processing and motor control are intricately linked, particularly under conditions of increased cognitive demand

This study aims to identify key biomechanical variables correlated with emotional processing and mood under both single-task and dual-task walking conditions in a non-clinical sample. This work is intended to inform future interventions that target both mood and motor function in individuals with major depression.

METHODS

Twenty-two young adults (age 19 6 ± 0 6 years) provided written informed consent and underwent baseline psychological assessments Depressive symptoms were measured using the Patient Health Questionnaire (PHQ-8), anxiety with the Generalized Anxiety Disorder-7 (GAD-7) scale, and affective processing was evaluated using the CANTAB emotional bias task (recording the mean and standard deviation of reaction times for selecting “Sad”). Biomechanical data were collected using a dualsystem approach. A Kistler force plate embedded in a 10-meter walkway recorded high-resolution (1000 Hz) force data to capture gait events such as initial contact and toe-off and extract variables including walking velocity, anterior-posterior and mediolateral forces, impulse, and force variability In parallel, six Vicon Blue Trident IMUs were attached to the participants to record kinematic data throughout the six 10-meter walks; although these data will be processed and analysed at a later date, they are expected to provide valuable insights into segmental kinematics, and overall gait kinematics.

Participants completed six continuous 10-meter walks at a self-selected pace under two distinct conditions (Figure 1) In the single-task condition, participants walked without any additional cognitive challenge, thereby providing a baseline measure of natural gait mechanics In the dual-task condition, participants performed the same walking task while simultaneously counting backwards by 3’s, thereby imposing an ecologically valid cognitive load. Key gait events were identified from the force plate's vertical force curve, and corresponding biomechanical variables were extracted. Subsequent correlation analyses were conducted to evaluate the relationships between the psychological measures and the biomechanical outputs across both walking conditions, allowing for a nuanced understanding of how affective processing interacts with motor control under varying cognitive demands

Biomechanics Interest Group Conference 2025

Chartering BIG Possibilities in Biomechanics

Poster Presentation

RESULTS & DISCUSSION

Under dual-task conditions, slower emotional processing of sad faces (longer reaction times) was significantly correlated with reduced mean walking velocity (r = –0 749, p < 0 001) and lower anterior-posterior force production (r = –0 516, p = 0 017), indicative of a cautious gait strategy when cognitive load increased Moreover, mediolateral force variability was significantly negatively correlated with reaction time variability for both sad (r = –0.621, p = 0.003) and happy faces (r = –0.576, p = 0.006), suggesting that more consistent affective responses were associated with greater lateral force modulation. In contrast, during single-task walking, slower reaction times to sad faces were positively correlated with higher anterior-posterior (r = 0.45, p = 0.035) and mediolateral forces (r = 0 48, p = 0 023), while stance time variability showed significant negative correlations with both reaction time (r = –0 55, p = 0 008) and its variability (r = –0 45, p = 0 038) Minimal depressive symptoms were observed (PHQ-8 scores), which likely accounts for the absence of significant correlations between depressive symptom severity and biomechanical measures. These findings underscore the complex interplay between affective processing and gait biomechanics, suggesting that dual-task conditions may amplify latent motor control deficits. The contrasting results between single-task and dual-task conditions also imply that compensatory mechanisms may be at play when cognitive demands are minimal These baseline findings provide valuable insights into the potential of gait measures as early indicators of mood disturbances, supporting further work to develop targeted biomechanical interventions for major depression

CONCLUSION

Our findings reveal that cognitive load profoundly alters the relationship between affective processing and gait biomechanics. Under dual-task conditions, slower processing of emotional cues is linked to a cautious gait manifested by reduced speed and force while single-task walking suggests a compensatory increase in force production These insights underscore the value of integrating cognitive and motor assessments to detect subtle mood disturbances Ultimately, this study lays a robust foundation for developing targeted biomechanical interventions that could not only serve as early markers of depression but also improve mood and quality of life in affected individuals.

References are to be formatted as illustrated below. Provide the author names and initials if there are one or two authors, otherwise provide the first author and use et al. for three or more authors. Omit the article title, but provide the journal or book title in italics, with the volume number in bold, followed by the page numbers and publication year If available, provide the DOI link as a hyperlink using [LINK] See [2] below as an example Journal name abbreviations may be used if required

ACKNOWLEDGMENTS

We are grateful to the University of Derby Vice Chancellor’s Partnership Award Scheme for supporting this work. Thank you to Dan Walton and Alex Brent for supporting the data collection.

REFERENCES

[1] Kessler, R C et al Annu Rev Public Health, 34, 119-138, 2013 [LINK] [2]. Murri, M.B. et al. Psychiatry Res, 284, 112687, 2020. [LINK] [3]. Yogev-Seligmann, G. et al. Mov Disord, 23, 329-342, 2008. [LINK]

Figure1:Experimentalsetup

Biomechanics Interest Group Conference 2025

Chartering BIG Possibilities in Biomechanics

Poster Presentation

Ripley , Matthew Collier and Jack Fahey

School of Health and Society, University of Salford, Salford, UK 1

British Lacrosse, Manchester, UK 2

Department of Physiotherapy, School of Healthcare, University of Leicester, Leicester, United Kingdom 3

n.j.ripley@salford.ac.uk

ACUTE FATIGUE IN PEAK ISOMETRIC HAMSTRING FORCE IN ELITE MALE SIXES LACROSSE PLAYERS

INTRODUCTION

Hamstring strain injuries continue to be the most prevalent injury within team sports, however, monitoring hamstring strength using eccentric modalities remains low despite their efficacy [1]. With the increased availability in wireless force plate technology, novel methods for assessing single joint isometric strength are becoming common place [2] Isometric hamstring assessments have consistently been shown to be reliable and sensitive to detect fatigue immediately following a fatiguing activity [2]. Reductions in peak isometric force have been shown to be present for up to 72 hours [2], highlighting the need for regular monitoring to ensure practitioners can apply appropriate strategies to offset fatigue, enhance recovery and minimize injury risk.

Sixes lacrosse (SL) is a small-sided variant of field lacrosse, played across 32 minutes (4 x 8 min quarters), with the resultant physical match demands being a series of repeated high intensity efforts at high movement velocities [3] SL is due to make its inaugural appearance at the 2028 Olympics in Los Angeles, highlighting the importance of athlete health leading up to this event especially when previous hamstring strain injuries are a leading risk factor on future injury [4]. Therefore, the purpose to the present study was to identify if SL match play in international male lacrosse players has a fatiguing effect leading to a reduction in peak force.

METHODS

Ten male outfielders from the British Lacrosse squad (24 6 ± 2 3 years, 1 80 ± 0 08 m, 86 3 ± 4 5 kg) participated within the present study Peak isometric force measurements were collected using force plates, pre- and post a single match play to observe if SL match play resulted in hamstring fatigue. Between 45 and 30 minutes prior to commencing the standardised match warm up, all players performed the 90:90 isometric hamstring assessment. Following the match play, within 30 minutes all players repeated the assessment to determine changes because of fatigue Dominant limb (DL) and non-dominant limb (NDL), was identified via the participants preferred kicking limb The 90:90 isometric assessment were measured using a dual sensor force plate (Hawkin Dynamics (HD), Westbrook, ME, USA), sampling at 1000 Hz and collected using HD proprietary software Force plates were zeroed between participants. Placed upon a wooden plyometric box at an appropriate height for each participant using a goniometer, this was determined by participants lying in a supine position with their knee and hip at 90° of flexion for 90:90 isometric assessment. Participants heel rested on the force plate with footwear removed. The test was applied unilaterally with the nontesting limb being placed fully extended next to the box and arms placed across the chest Three trials for each limb were executed by the participants driving their heel down into the force plate for 3–5 s following three submaximal trials Participants were instructed to ‘pull their heel into the force plate as fast and as hard as possible’, while the assessor secured the participants at the hips. Isometric peak force for each limb attained were extracted for further analysis providing the mean and standard deviation (SD). Bayesian paired sample’s t-test were used to determine the level of evidence indicating the effect of fatigue on match play on the DL and NDL, independently. The Bayes factor (BF) was interpreted as 1-3, anecdotal; 3-10, moderate; 10-30, strong The BF prior was set at default to 0 707 Hedge’s g effect sizes and 95% confidence intervals (CI) were also calculated to determine the magnitude of the difference, the effect size was interpreted as, <0 20, trivial; 0 200.59, small; 0.60-1.19, moderate; ³1.20, large.

Nicholas

Results & Discussion

Biomechanics Interest Group Conference 2025

Chartering BIG Possibilities in Biomechanics

Poster Presentation

Mean ± SD for peak force within the DL pre- and post-match were 450 13 ± 66 31 N and 405 36 ± 76.85 N, respectively. Mean ± SD for peak force within the NDL pre- and post-match were 398.62 ± 86.63 N and 370.07 ± 66.390 N, respectively. The Bayesian paired sample’s t-test revealed strong level evidence supporting the reductions in peak force from pre- to post-match in both the DL and NDL (Figure 1). Moderate reductions for both the DL (g [95% CI] = 1.09 [0.23-1.91]) and NDL (g [95% CI] = 1 13 [0 26-1 96]), highlighting the fatiguing effect of Sixes lacrosse match play

Figure1.Bayesianpairedsample’st-testsdensityandeffectsizeplotsforDL(A)andNDL(B)pre-andpost-match

Hamstring strain injuries are highly prevalent in team sports, including SL [5], with a high rate of non-contact hamstring strain injuries With a reduction in hamstring force generating capacity immediately post-match highlighting a period of elevated injury susceptibility.Incomparisontoothertraditionalteamsports(e.g.soccerandrugby),wherecompetitivematchesareseparated by at least 24 hours in international competition, international SL players can be exposed to up four matches in a single day with current tournament formats lasting between 3-4 days Further research is required to determine the duration that reductions in peakforcecanbeobservedforandifspecificrecoverymodalitiescanmitigatethediminishedpeakforcevalues.

CONCLUSION

CompetitiveSLmatchplay,withininternationalSLplayers,resultswithinacutefatigueofthehamstringswithareductioninpeak isometric force. Hamstring strength is a key modifiable risk factor for hamstring strain injuries and reductions in force elevate the risk of injury incidence As the current international SL tournament formats require players to play multiple matches in a singledayacrossseveraldays,SLplayerscouldbeatagreaterriskofhamstringstraininjuryincidence

REFERENCES

[1] Ekstrand,J;Bengtsson,H;Walden,M;Davison,M;Hagglund,M Stillpoorlyadoptedinmaleprofessionalfootball:butteams thatusedtheNordicHamstringExerciseinteamtraininghadfewerhamstringinjuries–aretrospectivesurveyof17teamsofthe UEFA Elite Club Injury Study during the 2020–2021 season. British Medical Journal Open Sport & Exercise Medicine 2022, 8, 1-8, [LINK]

[2] McCall,A;Nedelec,M;Carling,C;LeGall,F;Berthoin,S;Dupont,G Reliabilityandsensitivityofasimpleisometricposterior lowerlimbmuscletestinprofessionalfootballplayers.JournalofSportsSciences2015,[LINK}

[3] Ripley, N; Collier, M; Wenham, T; Quinn, M Match Demands of Male International Lacrosse Players Competing Under the World Lacrosse Sixes Format in International Competition: Brief Report Journal of Australian Strength and Conditioning 2024, Accepted,1-20.

[4]. Green, B.; Bourne, M.; van Dyk, N.; Pizzari, T. Recalibrating the risk of hamstring strain injury (HSI)-A 2020 systematic review and meta-analysis of risk factors for index and recurrent HSI in sport British Journal of Sports Medicine 2020, 54, 1081-1088, [LINK].

[5]. Collier, M.; Ripley, N.; Wenham, T.; O’Neill, S. Injuries in International Men’s Sixes Lacrosse: Injury Surveillance of the British Lacrosse Men’s National Team During a 9-Month Training Cycle Leading up to and Including The World Games 2022 Journal of OrthopaedicandSportsPhysicalTherapyOPEN2023,1,1-7,[LINK].

Biomechanics Interest Group Conference 2025

Chartering BIG Possibilities in Biomechanics

Poster Presentation

Tia Steadman and Rich Collins 1 1

Buckinghamshire New University 1

rich.collins@bnu.ac.uk

MUSCLE ACTIVATION OF THE BICEPS FEMORIS & SEMITENDINOSUS IN DIFFERENT ECCENTRIC HAMSTRING EXERCISES IN FEMALE FOOTBALL PLAYERS

INTRODUCTION

In women's football, injuries are a major concern, with lower extremity muscle/tendon and ligament injuries resulting in 4 8 injuries per 1000 hours of sporting exposure [1] Of them, hamstring strains were the most common and are prevalent in running and kicking movements, causing prolonged injury resulting in long-term hindrances to performance and overall strength [2]. Strengthening the hamstrings is vital for injury prevention as strong hamstring muscles lower the chance of strains, improve overall performance, preserve appropriate muscle balance, and help reduce the risk of lower limb injury. Specific training plans which aim to include exercises that lengthen the hamstrings (eccentric contractions) are seen to improve both athlete's short and long-term health, improving stability and defining power Eccentric hamstring muscle contractions also improve performance during the concentric phase of stretch-shortening cycles, which is important in football tasks including sprinting, jumping, and running. During these activities, the hamstrings also function as shock absorbers, to decelerate during landing tasks or to precisely deal with high external loading [3]. Eccentric training programmes, which include exercises such as Nordic hamstrings curls and deadlifts, are proven to reduce the risk of hamstring strain by over 80% as well as improve participant sprint time in female football players when compared to traditional training programmes [4] However, limited research has delved into how eccentric exercises impact each hamstring, thus addressing this would provide a more informed basis on exercise prescription for specific injuries/demands. The aim of this study is to understand the differences in hamstring muscle activation patterns found in four different eccentric exercises commonly adopted in football training and rehabilitation plans.

METHODS

The study included twelve Buckinghamshire New University (BNU) women's football players (height = 164 5 ± 5 1cm, mass = 63 4 ± 12 2kg, age = 20 9 ± 1 4 years) using a single group repeated measures design, where four exercises: double stiff leg deadlift (DSLDL), unilateral stiff-leg deadlift (USLDL), Nordic hamstring curl (NHC) & ball leg curl (BLC) were examined for 3 reps. A metronome set at 60bpm was used to standardise movement velocity. To enhance validity, exercise order was randomised, while weighted deadlifts were completed at 70% of the participants 3 rep-max. A Delsys Trigno EMG system was used to collect the average and peak muscle activation of the bicep femoris (BF) and semitendinosus (ST) during the eccentric phase of each exercise via the Delsys Tringo Discover App All electrodes were placed in accordance with recommendations from the Surface Electromyography for the Non-Invasive Assessment of Muscles (SENIAM) working group To normalise data, a 5-second maximal voluntary isometric contraction (MVIC) was conducted prior to testing in a prone position with the knee stabilised at 45 flexion and hips 0 extension relative to the anatomical position. Surface Electromyography (EMG) recordings were obtained from the dominant extremity during each exercise Data was acquired at a sampling frequency of 2148Hz and filtered at a bandwidth of 20-450Hz Following acquisition, amplitude analysis of the data was performed in EMGWorks analysis to calculate the root mean square (RMS) of each recording, normalise the data to the recorded MVIC, and determine the “onset” of muscle activation based on a deviation from the baseline RMS signal of ±3SD. Statistical analysis of the calculated peak and mean EMG amplitudes was performed using Jeffrey’s Amazing Statistics Programme (JASP) (version 0.19.3). Four Friedman’s tests were conducted to compare either the peak or average activation of each muscle across different exercise conditions, following data distribution examination via Shapiro-Wilk testing Where necessary, post-hoc Conover tests were subsequently conducted to assess pairwise comparisons Additionally, paired t-tests or Wilcoxon tests were carried out to compare the mean activation between BF and ST muscles for each exercise condition

RESULTS & DISCUSSION

Biomechanics Interest Group Conference 2025

Chartering BIG Possibilities in Biomechanics

Poster Presentation

For BF, significant differences were found in both peak (p < 0 001, Kendall’s W = 0 50) and mean activation (p < 0 001, Kendall’s W = 0 57), with NHC showing the highest values and DSLDL the lowest Post-hoc analysis identified significant differences in mean activation between BLC & DSLDL; DSLDL & NHC; DSLDL & USLDL; NHC & USLDL (p < 0.001), and BLC & NHC (p = 0.002). For ST, significant differences were found in peak (p = 0.006, Kendall’s W = 0.12) and mean activation (p = 0.005, Kendall’s W = 0.12), with NHC again showing the highest values. Post-hoc analysis revealed significant differences in peak activation between DSLDL & NHC (p = 0.03) and NHC & USLDL (p < 0.001), while for mean activation, significant differences were found between NHC and all other exercises; BLC (p = 0 04), DSLDL (p = 0 02); and USLDL (p < 0 001) When comparing the relative muscle activation of BF and ST in each exercise, significant differences were noted for average activation in three of the four exercises. BF showed significantly greater mean activation in NHC (p = <0.001) and USLDL (p = 0.007), while ST mean muscle activation was significantly greater in DSLDL (p = <0.001). Increased BF mean activation noted in BLC was not deemed statistically significant (p = 0.08).

Figure1:Comparisonoftheeffectsofexercisetypeineachmusclegroup(%MVIC)

Since NHC demonstrate the highest activation across both hamstring muscles, it should be an integral exercise in injury prevention programmes, especially for female footballers who are at higher risk for ACL and hamstring injuries Their incorporation has the potential to decrease anterior tibial translation and shear force, lessening the force applied to the ACL by the hamstrings reacting with a greater resistive tensile force to improve overall joint stability [5]. BF is also the most injured hamstringmuscle,furtherembeddingtheimportanceofincludingNHC’instrengtheningtoreduceinjuryriskduetoitshighpeak and average activation ST shows lower activation overall across three exercises, which may be problematic if only highactivationBFexerciseslikeNHCareusedinisolation.TobettertargetSTandlessenimpactontheBF,USLDL’sandDSLDL’sshould also be included in training programmes to ensure balanced hamstring growth DSLDL’s will also be a better fit for early-stage rehabilitation and neuromuscular control training on the hamstring muscle as they elicit less overall activation allowing for less stresstobeplacedontheinjuredtissues,prioritisingprogressionwithoutoverloading.

CONCLUSION

Exercises like USLDL and DSLDL should be integrated into injury prevention plans for female football players in addition to Nordic Hamstring Curls. This will balance the activation of the BF and ST, lowering the risk of injury and enhancing performance. More research into the muscle activation between males and females in hip and knee-dominant exercise is required to gather further informationonthemosteffectiveexerciseprescriptionforfemalestocombattheiranatomicaldifferences

REFERENCES

[1] López-Valenciano,A,etal SportsMedicine,51(3),423–442,2021 [LINK]

[2].Aiello,F.,etal.SportsMedicine,53(1),151–176,2022.[LINK]

[3].Vogt,M.&Hoppeler,H.H.JournalofAppliedPhysiology,116(11),1446–1454,2014.[LINK]

[4] Espinosa,GDA,etal BiomedicalHumanKinetics,7(1),125–134,2015 [LINK]

[5].Chumanov,E.S.,etal.ClinicalBiomechanics,23(7),857–865,2007.[LINK]

Biomechanics Interest Group Conference 2025

Chartering BIG Possibilities in Biomechanics

Poster Presentation

Gabriella M. Wilson , Sean Lowton-Smith , Simon J. Briley , Rebekkah North , 1 1 1 1

Mark A. Faghy , and Alan R. Williams 1 2

University of Derby, School of Sport and Exercise Science 1 .University of Derby, School of Nursing and Midwifery 2

100618196@unimail.derby.ac.uk

DO BIOMECHANICAL CHANGES EXPLAIN THE DECLINE IN CPR CHEST COMPRESSION PERFORMANCE OVER TIME?

INTRODUCTION

Sudden cardiac death (SCD) is the most common medical cause of death in athletes, with incidences estimated to be around 1 in 40,000 to 1 in 80,000 athletes per year [1] Initiation of cardiopulmonary resuscitation (CPR) prior to the arrival of emergency services can double the survival rate after an out-of hospital cardiac arrest [2] The depth of chest compressions during CPR is significantly associated with return of spontaneous circulation and survival to hospital discharge, making it an essential component of effective CPR delivery [3]. Previous research has observed a decline in chest compression depth (CCD) prior to the recommended 2-minute changeover [4].

The study purpose was to investigate spatio-temporal and kinetic alterations during CPR performance, to elucidate how rescuers performance declines over time

METHODS

In this observational cross-sectional time trial, thirty-eight Sport Therapy and Rehabilitation students at the University of Derby performed CPR until volitional exhaustion or cut off at 10 minutes. This study will compare the performance of rescuers who perform CPR in line with current CCD guidelines beyond the recommended 2-minute changeover time, with those who decline in CCD performance prior to this point

All participants were independently certified in CPR. Mean age (21.8 years ± 5.7); height (1.76 m ± 0.09); weight (74.3 kg ± 13.2); body fat percentage (19.3% ± 8.1); time since CPR certification (7.9 months ± 6.9); female (N= 14, 36.8%); male (N= 24, 63.2%). Participants completed a familiarization session at least 1 week prior to the time trial. Participants wore six Blue Trident inertial measurement units (IMU) [Vicon] during the trial: on both wrists, above both elbows, and placed approximately on the C7 spinous process and L5/S1 lumbosacral joint (see figure 1) The use of IMU devices may identify differences between heavier and lightweight rescuers, monitor biomechanical changes in relation to fatigue, and potentially create a biomechanical model for CPR performance (data yet to be analysed).

HR and RPE were recorded at 1-minute intervals. Blood lactate was measured pre- and post-test. Ground reaction force was measured via a Bertec force plate [FP4060-15-TM] with Provec software [V 6 034 0] to identify the cut-off time for rescuer decline in chest compression depth performance (see figure 2) Two-way mixed ANOVAs were used to determine main effects for time (T1, T2), group (> 2-minute group, < 2-minute group), and a time*group interaction for each outcome variable

Biomechanics Interest Group Conference 2025

Chartering BIG Possibilities in Biomechanics

Poster Presentation

Figure 2: Laerdal Skillmeter Resusci-Anne manikin on top of Bertec Force Platform TM ®

RESULTS & DISCUSSION

23 (60.5%) participants were able to complete effective CPR for beyond the recommended 2-minute changeover (> 2-minute group) in line with current CCD guidelines. 15 (39.5%) declined in CCD performance prior to the recommended 2 minutes (< 2-minute group). Two-way mixed ANOVAs indicated significant interaction between group and time for rate of force development (RFD) p= .012 and peak FY force (medial-lateral in the orientation of the force plate) p = 028 Mean blood lactate was 1 42 mmol/L ± 0 67 at rest and 2 56 mmol/L ± 1 07 post completion of CPR Mean HR was 117 b min-1 in minute 1 peaking in minute 5 at 127 b min-1 indicating that cardiovascular fatigue did not explain the decline in performance. Independent t-tests highlighted no significant differences in weight, hand grip strength and press up performance between each group (p> .05).

CONCLUSION

Those who maintain CCD performance during CPR the recommended 2-minute changeover time increase their rate of forcedevelopment and peak medial-lateral force,in comparison to those who are unable to maintain compression depth beyond 2 minutes This may indicate a change in technique in those able to maintain CPR CCD performance, which may be explained by theIMUdata(tobeanalysed).

REFERENCES

[1] Harmon,KG,etal Heart(BritishCardiacSociety),100,1227–1234,2014[LINK]

[2].Hasselqvist-Ax,I.etal.,NewEnglandJournalofMedicine,372,2307–2315,2015.[LINK].

[3] Talikowska,M,etal Resuscitation,96,66–77,2015 [LINK]

[4] Pechaksorn,N &Vattanavanit,V EmergencyMedicineInternational,2020,2020 [LINK]

Poster Presentation Biomechanics Interest Group Conference 2025

Chartering BIG Possibilities in Biomechanics

Harry Davies , Steffi Colyer 1 1

Centre for the Analysis of Motion, Entertainment Research and Applications, University of Bath, UK

hjd58@bath.ac.uk

AGREEMENT BETWEEN ‘THEIA3D’ AND MARKER-BASED PERFORMANCE INDICATORS OF THE SNATCH: A CASE STUDY

INTRODUCTION

The Snatch, the first of the two lifts performed in Olympic Weightlifting, has shown some of the highest recorded ground reaction forces seen in sporting activity (1). The Snatch commences with the barbell being displaced from the floor, a transition around the knee then contact at the hip crease where the arms continue to pull on the barbell as the athlete dives under. The pulling phases require athletes to generate large amounts of vertical ground reaction force (GRF) to break the inertia of the barbell whilst minimising horizontal displacement Peak force generated at the first and second pull phases of the Snatch has shown high correlation to performance and as such the pulling phase is of interest to researchers and coaches (2). During the pull, lower-limb kinematics remain consistent across lifts due to task constraints, yet kinetics are load-dependent, as larger GRF must be generated to displace and accelerate heavier external loads (3). Knowledge of individual segment contributions such as net joint moments (NJM) could provide valuable insight to lower limb neuromuscular control strategies of athletes, understand the effect of training cycles and deterioration of technique with load, and lower limb synergies (2,3,4) Training and competition analysis has shown a strong correlation between increased hip and knee NJMs to total system mass (4,5), but robust recording of athlete kinematics in competition is not always feasible (3,5)

Current understanding of Snatch NJM is limited to laboratory-based testing as competition and training testing is not feasible. Theia3D, a deep learning-based pose estimator, has shown very good system agreement for kinematic analysis during simple gait and jumping tasks (6) but has yet to be fully tested on dynamic and ballistic tasks in non-laboratory conditions If sufficiently robust, the kinematics derived by Theia3D could be utilised in inverse dynamics calculations to provide markerless-derived NJM This study therefore evaluates the agreement between Theia3D and marker-derived joint angles and NJM at the lower limb in the Snatch at near maximal load.

METHODS

Three healthy male competitive weightlifters (25 ± 2 years, 174 ± 9 cm, 82 ± 7 kg, 103 ± 15kg 1-RM) were recruited to perform one repetition at 80 and 85% of 1-repetition maximum in the Snatch A 200-Hz synchronized Qualisys motion capture system was used, consisting of sixteen infrared cameras and eight video cameras Four Kistler 9260A force plates were used, sampling at 1000 Hz Data was synchronised and triggered through Qualisys Track Manager (QTM) using a Miqus Sync Unit. A full body marker set was applied by the same researcher. Marker data was labelled in QTM before being exported as C3D with the force data into Visual 3D v2025.03.1. Video data were processed through Theia 3D v2024.1.17, with an 8-Hz smoothing frequency, and was then exported and merged with the synchronised force data Joint angles and NJM was calculated in Visual 3D , where hip (Thigh to Pelvis) knee (Shank to Thigh) and ankle (Foot to Shank) angles were calculated

NJMs were calculated for the following phases from the barbell position, first pull (initial displacement to initiation of transition), second pull (end of the transition to the beginning of turnover) and entire pulling phase. Both systems derived NJM were filtered with a 6-Hz Butterworth filter. Joint angle RMSE was calculated between the marker and Theia3D-derived joint angles across the duration of the Snatch NJM RMSE was calculated for the first and second pull and total pull duration

Biomechanics Interest Group Conference 2025

Chartering BIG Possibilities in Biomechanics

Poster Presentation

Figure 1: Theia3D and marker-based left hip & knee NJM during a single 85% Snatch

Table 1: RMSE Mean ± SD of the Normalized NJM (Nm•kg-1) of Hip, Knee & Ankle Moment during 80 & 85% Snatch

RESULTS & DISCUSSION

Joint angle patterns appear similar across systems (Figure 1), with similar waveform and magnitudes The knee exhibited 2 1° difference between systems at peak flexion, the left hip had 2 1° whilst the ankle had 9.5°. Large RMSE values were present across all three joints for joint angles. Larger RMSEs for joint angles were observed at the ankle compared with the hip and knee joint. NJM derived from Theia3D inputs demonstrated relatively low RMSE values (~0.2-0.3 Nm•kg-1) for the NJM of the hip and knee during the Snatch pulling phases (Table 1). As a percentage of the peak NJMs averaged between systems, the knee joint RMSE for the entire pull is 11 3% and 9 6% for the knee and hip, respectively

CONCLUSION

Within the population used in this preliminary case study, joint angles and NJM for the lower limb calculated with Theia3D were comparable to traditional marker-based methods. NJM showed close agreement at both the knee and hip for both pulling phases and the entire pull, while larger differences were seen in the joint angle RMSEs. This study gives reason to believe that Theia3D could be a tool used to test and monitor weightlifting biomechanics in the Snatch more readily, in both training and competition setting when assessing joint kinematics and NJM This has the potential to provide opportunities to capture truly externally valid data and thus provide unique insights into the weightlifting biomechanics literature. Further work should assess if the same system agreement is observed with a diverse subject sample including larger differences in weight classes as well as the second competition lift, the Clean and Jerk.

ACKNOWLEDGMENTS

This work was funded by the EPSRC [EP/M023281/1 and EP/T014865/1] The authors thank Dr Sharma, Molly Eden, Rebecca Guy, Cameron Bell & Resilience Weightlifting Bath for the help and support

REFERENCES

[1]. Haff, G., et al. JSCR 23(3), 13. 2001. [LINK]

[2]. Shaun, J., et al. Sport Biomech, 1-17, 2024. [LINK]

[3] Kipp, K , Sports Biomech, 21(9), 1008–1020, 2020 [LINK]

[4] Kipp, K , et al JSCR 25(5), 1229-1234, 2011 [LINK]

[5] Baumann W et al JAB 4(1), 68-69, 1988 [LINK]

[6] Kanko R et al (2021) J Biomech 121, 110422 [LINK]

Biomechanics Interest Group Conference 2025

Chartering BIG Possibilities in Biomechanics

Poster Presentation

Hazel Tucker , Hans Von Lieres Und Wilkau , Tjerk Moll , Richard Willy , 1 1 1 2

Kelly J. Ashford and Isabel S. Moore 3 1

1 Cardiff Metropolitan University, Cardiff, United Kingdom

2University of Montana, Missoula, United States

3 The University of British Columbia, Kelowna, Canada

st20188133@outlook.cardiffmet.ac.uk

VALIDITY AND RELIABILITY OF COMMON WEARABLE TECHNOLOGY TO ESTIMATE RUNNING METRICS DURING OVERGROUND RUNNING

INTRODUCTION

Wearable technologies such as smart phones and watches are now commonly used to track running metrics by recreational runners [1,2,3] The wide use of wearable technologies allows researchers to prospectively monitor running metrics over a long period in large cohorts. This could be used in longitudinal monitoring of injury [e.g., 2] or for intervention studies such as gait retraining [e.g., 4]. The aim of this study was to establish the validity and reliability of commonly used wearable technologies to measure running metrics.

METHODS

Twenty-two participants (height: 1 73±0 11m; body mass: 73 2±13 5kg; age: 26 3±4 2 years; 9 females/13 males) were recruited Having provided written informed consent, all participants were asked to complete two testing sessions. Time between sessions was 7±3 days. Both testing sessions were completed on an outdoor 400m athletics track. During each visit participants completed two 400m runs (normal running and running to a metronome at +5% baseline stride rate). Only the normal running results are presented here During each run participants wore 5 wearable technologies (Apple watch series 10, Coros Pace 3, Garmin Forerunner 955, Polar Ignite, and iPhone 15 pro using Cadence App) recording running metrics Two watches were worn on the left forearm and two on the right forearm The phone was worn in an armband around the upper arm Stride rate and running velocity estimates from these wearable technologies were compared to that of 2-D video and timing gates to establish validity for each device. Test-retest reliability intraclass correlation coefficients for each device were calculated along with standard error of measurement (SEM) and minimum detectable changes (MDC)

RESULTS & DISCUSSION

Bland-Altman plots are displayed in Figure 1 showing estimated stride rate for each device compared to 2-D video and in Figure 2 for estimated running velocity. Additionally, root mean square deviation scores of estimated stride rate for each device compared to video during normal running ranged from 0.99 (Apple) to 9.17 (Polar). Root mean square deviation scores for estimates of running velocity for each device compared to timing gates during normal running ranged from 0.25 (Apple) and 0 51 (Polar) Intraclass correlation coefficients, SEM and MDC scores for stride rate and velocity are presented in Table 1 For test-retest reliability all devices displayed excellent ICC The MDC ranged from 1 81 strides per minute (Apple) to 3 79 (Polar) strides per minute The MDC of velocity ranged from 0.28 m/s (Coros) to 0.46 m/s (Polar) during normal running.

RESULTS & DISCUSSION

Biomechanics Interest Group Conference 2025

Chartering BIG Possibilities in Biomechanics

Poster Presentation

Total mechanical work of the CAM boot-wearing limb was lower than SHOD in B , B and B (p < 0 001, p = 0 002 and p = 0 038, respectively; Figure 1) Absolute and relative ankle mechanical work increased incrementally with an increase in ankle RoM with significant differences (p < 0 05) between all conditions except B and B (Figure 1). The absolute knee and hip work were similar to the SHOD, with no significant differences (Figure 1). Relative joint contribution at the hip was significantly increased in B and B when compared to SHOD (p < 0.001), but B was not (Figure 1). Muscle-tendon unit length change (ΔL ) incrementally increased as boot RoM was increased, with B , B and B significantly lower than SHOD (p <0 001, p < 0 001 and p = 0 002, respectively; Table 1) AT stretch observed a similar trend, with B and B both significantly lower than SHOD (p = 0 012), but B was not significantly different (Table 1)

CONCLUSION

Wearabletechnologiesshowedgoodvalidityformeasuringstriderateandrunningvelocity.Thepolarwatchtestedappearedto overestimate stride rate compared to that measured with 2-D video. Test-retest reliability was excellent for all devices for estimates of stride rate and velocity Validity and reliability of the phone-based application was comparable to those of running watches

ACKNOWLEDGMENTS

Theauthorswouldliketoacknowledgetheparticipantsforgivinguptheirtimetotakepartinthisstudy

REFERENCES

[1] Chowdhary,K,etal Healthcare,12,642-654,2024 [LINK]

[2].Neal,B.,etal.PhysicalTherapyinSport,65,130-136,2024.[LINK]

[3].Pobiruchin,M.,etal.JMIRmHealthanduHealth,5,24-36,2017.[LINK]

[4] Willy,R,etal,JournalofSportSciences,34,1602-1611,2016 [LINK]

Biomechanics Interest Group Conference 2025

Chartering BIG Possibilities in Biomechanics

Poster Presentation

Ms Christina M. Cefai , Dr Joseph W. Shaw , Dr Daniel J. Cleather

Faculty of Sport, Technology and Health Sciences, St Mary s University, Twickenham, UK 1 Ballet Healthcare, The Royal Ballet, Royal Opera House, London, UK 2 Institute for Globally Distributed Open Research and Education 3 christinacefai@gmail.com

CAN WEARABLES BE USED TO ESTIMATE THE PROBABILITY OF TIBIAL STRESS FRACTURES? A SIMULATION STUDY

INTRODUCTION

With repetitive loading, bone experiences repetitive stress and strain cycles. This makes it susceptible to mechanical fatigue where microdamage is created and accumulated, resulting in the deterioration of bone’s material properties and capacity to withstand loading. As a biological material, bone also has the ability to remove and replace damaged bone over time. However, if the rate of damage formation and accumulation is higher than the rate of damage removal, bone stress injuries can occur The mechanical-load response pathway starting from loading to bone stress injury occurrence is highly complex and dependent on several factors Quick transitions in training load have been identified as a risk factor together with movement patterns and impaired bone health and ability to remodel [1]. While periodic magnetic resonance imaging may help early identification of a bone stress injury, this might not be very practical. Computational multi-scaled models and mechanobiology models have been developed to estimate damage propagation, strain on bone cells and remodelling, however these are based on simulations rather than patient-specific models [2] A tissue-level mechanical-load response pathway in bone has been modelled to estimate the probability of bone stress injury occurrence [3] While measurement variabilities for each step of the model have been investigated [4-7], their cumulative effect on a probabilistic model has not been investigated The aim of this study was to assess the impact of four measurement variabilities (MV) within the pathway on a probabilistic model of stress fractures during running using wearables.

METHODS

Previously published running musculoskeletal data [8] and patient-specific finite element model of the right tibia and fibula [9] were used to estimate the cumulative probability of tibial stress fracture occurrence (P ) in the first 40 days of running 5 km a day at 5 m s Two simulations were run, the first assuming theoretically perfect measurements (zero-error model) and the second including randomised MVs. In the zero-error model, the average ankle joint reaction and muscle forces were applied to the finite element model. The strain distribution was discretised into eight groups and used to estimate P , taking into account mechanical fatigue and remodelling. The same procedure was used in the second simulation, consisting of six pathways, with the inclusion of 1500 randomised values for each MV as defined in Table 1 fr -1

RESULTS & DISCUSSION

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The zero-variability model resulted in a P on day 40 of 21%, compared with an interquartile range (IQR) of 26% (median offset -1%) for the patient-specific pathway and 36% (median offset -4%) for the generic model pathway (Figure 1). The single MV pathways also resulted in a large range of possible outcomes for P , with IQRs (median offsets) of 17% (0%) for MV1, 10% (-1%) for MV2, 17% (-1%) for MV3 and 27% (-3%) for MV4 This is due to several assumptions taken in the musculoskeletal modelling and finite element analysis and variability inherent within measurement systems In addition, a simplistic probabilistic model was also used when compared with the multifactorial nature of bone stress injuries.

CONCLUSION

Currently, the probability of bone stress injuries cannot be accurately predicted due to the large impact of the measurement variabilities on the probability of stress fracture occurrence Improvements need to be made in the estimation of each variable to reduce measurement variability and its cumulative effect In addition, wearables can be developed to directly estimate the strain in bone, reducing the cumulative effect of the measurement variability. This can be helpful to monitor quick transitions in tissue-specific loading in an applied setting and bone stress injury risk from a mechanical load perspective.

Figure1The sensitivity results for the patient-specific and generic model pathways on P , defined as the cumulative probability of stress fracture occurrence on or before 40 days of running 5km a day at 5 m·s . All 1500 simulation results (circles) for each model are the cumulative result of the measurement variabilities. All simulations originated from a single measurement of ankle joint reaction forces from an inertial measurement unit The solid black lines are the zero-variability model of the mechanicalloadresponsepathway fr

ACKNOWLEDGEMENTS

The research work disclosed in this publication is partially funded by the Endeavour II Scholarships Scheme The project is co-funded by the ESF+ 2021-2027

REFERENCES

[1]. Hoenig, T. et al., Nature Reviews Disease Primers, 8, 26, 2022. [LINK] [2]. Meslier, Q. A. & Shefelbine, S. J. Current Osteoporosis Reports, 21, 2, 2023. [LINK] [3]. Edwards, W.B. et al. Medicine & Science in Sports & Exercise, 41, 12, 2009. [LINK] [4]. Xiang., L. et al., Computers in Biology and Medicine, 170, 108016, 2024. [LINK] [5] Pelegrinelli, A R M et al , Medical Engineering & Physics, 122, 104074, 2024 [LINK] [6] Gray, H A , et al , Journal of Biomechanical Engineering, 130, 031016, 2008 [LINK] [7] Bruce, O L , et al , Journal of Biomechanical Engineering, 146, 091005, 2024 [LINK] [8] Hamner, S R & Delp, SL Journal of Biomechanics, 46, 780-787, 2013 [LINK] [9]. Keast, M. et al., Royal Society Open Science, 10, 230262, 2023. [LINK]

Poster Presentation Biomechanics Interest Group Conference 2025

Chartering BIG Possibilities in Biomechanics

Max Pinckney , David E. Lunn , Aaron Thomas , Mason L. Stolycia , and Josh Walker

Carnegie School of Sport, Leeds Beckett University, Leeds, UK 1

NIHR Leeds Biomedical Research Centre, Leeds Teaching Hospitals NHS Trust, Leeds, UK 2

m.pinckney@student.leedsbeckett.ac.uk

JOINT MECHANICAL WORK VARIABILITY DURING CONTROLLED ANKLED MOTION (CAM) BOOT WEAR

INTRODUCTION

Controlled ankle motion (CAM) boots are orthotic devices used to treat lower-limb pathologies such as foot ulcerations caused by diabetes mellitus, Achilles tendon ruptures, and metatarsal fractures, and are often worn for extended periods of time The boot restricts ankle range of motion and offloads the ankle and foot, allowing for continued ambulation during treatment [1]. After prescription of the CAM boot, patients have reported developing or having a worsening of secondary site pain in the lower back, hips, and knees [2]. CAM boots alter walking gait by creating leg length discrepancies and adding mass to the boot-wearing limb, as well as restricting ankle motion [3]. This leads to an increased relative contribution of the knee and hip to total mechanical work in the boot wearing limb during walking compared to walking with normal footwear, which can be partially mitigated by the addition of a shoe leveller on the contralateral limb [3] However, understanding the between-stride variability in joint work requirements would help understand the possible association between compensatory mechanisms and secondary site pain. High and low variability have both been associated with injury risk. For example, too little can lead to repeated loading to the same tissue, causing greater tissue breakdown, whereas too much variability demonstrates poor movement control, increasing injury risk, loss of postural stability, and fall risk [4,5] Given the lack of understanding of movement variability during CAM boot wear, the aim of this study was to compare gait variability of lower-limb mechanical work during CAM boot walking (with and without a shoe leveller) with normal walking

METHODS

Eight male and four female (age: 29 ± 8 y; stature: 1.81 ± 0.86 m; body mass: 81.6 ± 13.7 kg) healthy subjects took part in this study Three experimental conditions were included: (1) walking while wearing a rigid CAM boot (Rebound® Air Walker, Össur, Iceland) on their right leg (BOOT); (2) the addition of a 28-mm shoe leveller (EVENup®, Oped GmbH, Germany) on the left leg (EVEN); and (3) walking in their own trainers bilaterally (NORM) After two minutes of familiarisation, 20 seconds of continuous kinetic and kinematic data were collected for each condition using three-dimensional motion capture and an instrumented, motorised treadmill (see Walker et al. [3]) at a self-selected walking speed, providing at least 15 gait cycles per condition. Data were exported to Visual3D for kinematic and kinetic modelling. Joint moments and joint mechanical work were calculated through inverse dynamics Total mechanical work of ipsilateral (right) and contralateral (left) legs were calculated from the sum of the mechanical work of the ankle, knee, and hip for each leg Relative contribution of each joint to the total mechanical work was calculated by dividing joint mechanical work by the total mechanical work. Variability was measured by calculating the coefficient of variation (CV) and median absolute deviation (MAD) expressed as percentages. CV and MAD were compared between conditions using a one-way repeated measures analysis of variances (ANOVA) with Bonferroni adjustment for post-hoc tests. Alpha level was set at 0.05.

RESULTS & DISCUSSION

When presented as MAD (%), variability was significantly higher in BOOT compared to NORM for left total mechanical work and left ankle work (p = 0.048 and p = 0.043, respectively; Figure 1A), and BOOT was also higher than EVEN for ankle work only (p = 0.043; Figure 1A). When variability was presented using CV (%), BOOT and EVEN both showed more variability than NORM for right total mechanical work (p = 0.005 and p = 0.042, respectively; Figure 1B), and BOOT was higher than NORM for right hip mechanical work (p = 0 039; Figure 1B) Descriptive statistics for total and joint mechanical work and relative joint contribution to total mechanical work are presented in Table 1

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Chartering BIG Possibilities in Biomechanics

Poster Presentation

1: Variability scores for mechanical work measurements in the three footwear conditions.

BOOT displayed a higher MAD in the left (non-boot-wearing) limb, which appeared to be mitigated by the implementation of a shoe leveller (EVEN), which was more similar to NORM This implies that the leg length discrepancy caused by CAM boot wear led to an increased work variability across the limb, possibly caused by an unfamiliar gait pattern and a lack of neuromuscular control, which could lead to an elevated risk of injury, trips, or falls. These differences in MAD for the left leg were not present in CV, which tended to show more differences between conditions in the right (boot-wearing) leg It should be noted that there were high levels of between-subject variation in both MAD and CV scores (see large standard deviations in Figure 1) This suggests that subjects adopt an individualised compensatory strategy during CAM boot wear, which could be unequally influenced by the leg length discrepancy, the mass of the CAM boot, or the restricted ankle function. This could be explored further by adopting an individualised approach to analysis to further understand compensatory mechanisms, possibly then stratifying individuals by their compensatory strategies in future explorations (e.g., “hip abduction” and “knee flexion” groups).

CONCLUSION

Variability of mechanical work is increased when wearing a CAM boot This might increase the risk of falls and contribute to secondary sight pain because of a lack of movement control [4,5]. The addition of the shoe leveller is beneficial as it mitigates for the leg length discrepancy and reduces some of the increased mechanical work variability caused by the CAM boot-induced leg length discrepancy. As such, the implementation of shoe levellers might reduce risk of trips or falls and should be considered alongside CAM boot prescription The current findings demonstrate large individual differences in variability, particularly in the contralateral limb This should be taken into consideration when prescribing CAM boots and understanding the causes of secondary site pain, and this should be explored with further research into compensatory strategies, particularly during prolonged bouts of CAM boot wear.

REFERENCES

[1] Stolycia, M L et al Journal of Foot and Ankle Research, 17, e12044, 2024 [LINK]

[2] Ready, L V et al JAAOS Glob Res Rev, 2, e044, 2018 [LINK]

[3] Walker, J et al Gait and Posture, 108, 208-214, 2024 [LINK]

[4] Stergiou, N. & Decker, L.M. Human Movement Science, 30, 869-888, 2011. [LINK]

[5] Baida, S.R. et al. Scandinavian journal of medicine & science in sports, 28, 1320-1338, 2018. [LINK]

Figure

Biomechanics Interest Group Conference 2025

Chartering BIG Possibilities in Biomechanics

Oral Presentation

Dr Rylea Hart , Dr Heather Smith , Dr Yanxin Zhang 1 1 1

Department of Exercise Sciences, Faculty of Science, The University of Auckland, New Zealand 1

ryleahartnz@gmail.com

THE DEVELOPMENT OF TEMPLATE-BASED MODELS FOR ANALYSING RESISTANCE-TRAINING MOVEMENT PERFORMANCE

INTRODUCTION

Artificial intelligence (AI) has been used to autonomously analyse resistance training (RT) movements, primarily through machine learning (ML) models that classify performance and detect technical errors. While ML is the dominant approach, template-based (TB) modelling has been applied in related fields (e.g., rehabilitation) but remains underexplored in RT.

TB models compare observed movements to a predefined “correct” template using distance-based (e g , dynamic time warping) or probabilistic (e g , hidden Markov models) methods [1-3] Unlike ML, they require only a subset of correct movements, making them less data-intensive Therefore, they could be a more viable alternative where large datasets are impractical an issue common in exercise science.

Despite their success, TB models primarily identify deviations from “normal” movement patterns [13] without capturing the directionality of errors They have also been limited to simple classification tasks, such as monitoring range of motion [1-3], reducing their practical utility

This study investigates a novel TB model for classifying RT movements (barbell back squat and deadlift) and aims to enhance feedback by assessing more complex movement characteristics. The TB model’s performance will be compared to a traditional ML approach to evaluate its practical utility.

Methods

Sixty-one RT participants (male: 37, female: 24; age: 26.2 ± 3.1 years; mass: 78 2 ± 13 2 kg; >6 months RT experience) completed maximal and submaximal RT protocols for the barbell back squat and deadlift A strength and conditioning expert reviewed video footage and labelled predefined technical deviations, including early hip rise, spinal flexion (deadlift only), and dynamic right knee valgus and varus.

Movement data was captured using two Azure Kinect cameras positioned behind participants Depth imaging was processed via iPi MoCap to generate 3D avatars, from which joint centres were extracted Positional data was smoothed using a fourth-order low-pass Butterworth filter (4 Hz cutoff)

Joint and segment angles were computed using previous biomechanical methods [4], with analysis restricted to the concentric phase. Continuous relative phase analysis quantified hip-knee and shanktrunk coordination for early hip rise detection

TB classifiers were developed to detect predefined technical deviations for each exercise. Data from a subset of “correct” movement performances, as judged by the expert labeller, was used to quantify the “correct” movement template The mean kinematic waveform ± 2 standard deviations was computed from the subset for several variables related to each technical deviation (e g , shank, thigh, and hip adduction for dynamic right knee valgus) The TB model would then classify observed movement performances as “correct” if they remained within the waveform boundaries and vice versa for “incorrect” (see Figure 1 for an example).

Biomechanics Interest Group Conference 2025

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Oral Presentation

To evaluate TB model performance, computed kinematic data and expert annotations were used to train and test the classifiers via cross-validation. This involved selecting a subset of “correct” movement performances, and then assessing the developed TB models on the held out data. Additionally, ML classifiers were developed for the same technical deviations using a LASSO logistic regression approach [4] and used as a comparison for the TB model performance Classification performance was quantified using weighted accuracy

RESULTS & DISCUSSION

Classification results for the TB and ML models are presented in Table 1. TB model performance ranged from poor to good (weighted accuracy: 54.1%–78.1%), with higher accuracy observed for sagittal plane deviations (e.g., early hip rise and spinal flexion) compared to frontal plane deviations (e g , right knee dynamic valgus and varus) This discrepancy may be due to the greater magnitude of movement in the sagittal plane, making deviations more distinguishable While TB models produced comparable results to ML models, ML models consistently outperformed them in classification accuracy. Additionally, classification performance was consistently lower in the deadlift than in the squat for both model types.

hese findings suggest that the TB model can serve as a viable alternative to ML models for some classification tasks, offering an interpretable and data-efficient approach Unlike ML methods, which require large labelled datasets, TB models can be developed using a subset of “correct” movement performances, making them more practical for real-world applications However, improvements in classification accuracy are needed to enhance their utility A key limitation of TB models is their reliance on high-quality input data and some level of expert knowledge to identify useful input data, whereas ML models can adapt to abnormalities and identify useful variables through optimising their decision-making process. Nonetheless, advancements in accessible motion capture technologies (e.g., computer vision-based tracking) may help mitigate some of these limitations, further improving TB model applicability

Conclusion

The TB model demonstrated comparable performance to ML methods, highlighting its potential as a data-efficient alternative for autonomous RT movement assessment. However, improvements particularly monitoring frontal plane deviations are necessary for practical use. While ML models consistently outperformed TB models, advancements in motion capture technologies may help address TB model limitations, improving their practical applicability Future research should focus on enhancing TB model accuracy and expanding its capabilities to provide more detailed movement insights

REFERENCES

[1]. LIAO, Y., ET AL. COMPUTERS IN BIOLOGY AND MEDICINE, 119, P.103687, 2020. [DOI LINK] [2]. MANGAL, N.K. & TIWARI, A.K., COMPUTERS IN BIOLOGY AND MEDICINE, 132, P.104316, 2021. [DOI LINK] [3]. SARDARI, S., ET AL. COMPUTERS IN BIOLOGY AND MEDICINE, 158, P.106835, 2023. [DOI LINK] [4] HART, R K , ET AL SPORTS BIOMECHANICS, VOLUME NUMBER, 1-33, 2023. [DOI LINK]

Oral Presentation Biomechanics Interest Group Conference 2025

Chartering BIG Possibilities in Biomechanics

Liam J,

Houlton , Jeremy A. Moody , Theodoros M. Bampouras and Joseph I. Esformes

1 1, 3 2 1

School of Sport and Health Sciences, Cardiff Metropolitan University 1 School of Sport and Exercise Sciences, Liverpool John Moores University 2

School of Physical Education and Sports, Nişantaşı University 3

st20090559@outlook.cardiffmet.ac.uk

EFFECT OF ALTERNATIVE COMPLEX-CONTRAST TRAINING SET STRATEGIES ON VERTICAL JUMP PROPULSIVE FORCE

INTRODUCTION

Muscular performance following repeated contractions is the net product of the temporal interaction between fatigue, which reduces neuromuscular force generation, and post-activation performance enhancement (PAPE), which enhances force generation and improves strength and power performance, with fatigue dissipating faster than PAPE [3] Complex-contrast training (CCT) alternates high-load conditioning activities (CAs) and high-velocity explosive activities [1] to enhance explosive force application through PAPE, particularly the rate of force development (RFD) [10]. Intra-contrast rest periods (ICRP) are prescribed between CAs and explosive activities to minimise fatigue [4]. To achieve this, ICRPs of 5-12 minutes have been suggested [2,7,9], which may make CCT impractical in many athletic training scenarios where training time is limited. Conversely, shorter intervals may not manifest PAPE sufficiently [4] In addition to fatigue, movement pattern interference from slower CA contraction speeds may also negatively affect subsequent explosive movements, possibly limiting CCT efficacy [10] Rest redistribution (RR) is an alternative set structure that minimises fatigue accumulation by redistributing pre-prescribed rest periods between repetitions [11]. Several studies have shown that RR can assist in maintaining kinetic and kinematic performance for more repetitions than traditional sets [5, 6]. Intra-contrast rest redistribution may enhance CCT application by reducing acute fatigue, maintaining movement velocity, and potentially decreasing the total contrast rest period (TCRP) required for PAPE to be observed, but research is limited [8] This study examined the effects of redistributing 30-second rest periods between 3RM back squat repetitions on subsequent countermovement jump (CMJ) and squat jump (SJ) performance, with varying TCRPs.

METHODS

With Institutional ethical approval, fifteen participants (age = 26.00±2.59 years, stature = 1.76±0.07 m, body mass = 82 49±5 32 kg, back squat 3RM = 141 33±13 64 kg, 3RM relative strength = 1 72±0 15) attended the facility on seven occasions The first session was used for familiarisation The second session was a maximal strength assessment of participants’ 3RM back squat The remaining five sessions were used for data collection Five TCRPs (60, 120, 180, 240 and 300 s; TCRP60, TCRP120, TCRP180, TCRP240 and TCRP300, respectively) and two vertical jump variants (CMJ and SJ) were assigned evenly in a counterbalanced, repeated measures design. Each visit consisted of a control condition (CON) and an experimental condition (EXP). For CON, participants performed five jumps (CON PRE), an ICRP (the difference between the prescribed TCRP and total RR), and another five jumps (CON POST) Following ten minutes of rest to minimise fatigue accumulation, participants performed EXP by executing a 3RM back squat with 30 s rest between repetitions, followed by the same ICRP as CON, and another set of five jumps (EXP POST), with CON PRE also operating as EXP PRE. All jumps were performed on two force platforms (PS-2141, Pasco, Roseville, CA, USA). Dependent variables (propulsive impulse (J ), peak force, mean force, various RFD measures, and propulsion time (t )) were calculated from the force-time data. The best repetition was chosen for analysis based on J from CON PRE, CON POST and EXP POST. A 5 (TCRP60, TCRP120, TCRP180, TCRP240 and TCRP300) x 2 (CON and EXP) x 2 (PRE and POST) repeated measures ANOVA was used to assess differences

RESULTS & DISCUSSION

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Chartering BIG Possibilities in Biomechanics

Oral Presentation

Descriptive statistics for CMJ are provided in Table 1. Repeated measures ANOVA showed no significant change in J , suggesting overall jump height was not affected by RR within any TCRP. No effect or interaction of peak force or mean force was observed Significant TCRP*CONDITION*TIME interactions were observed for RFD (F = 4 052, p = 0 006, η = 0 224), RFD (F = 3 671, p = 0 010, η = 0 208) and t (F = 12 950, p < 0 001, η = 0 481) Post hoc analysis of RFD showed EXP POST was significantly higher than EXP PRE and CON POST for TCRP180 (g of 1 145 and 1 107, respectively), TCRP240 (g of 0.836 and 1.107, respectively) and TCRP300 (g of 1.107 and 0.641, respectively). Post hoc analysis of RFD showed EXP POST was significantly higher than EXP PRE for TCRP180 (g = 0.727), TCRP240 g = 0.793) and TCRP300 (g = 0.973). Post hoc analysis of t showed EXP POST was significantly lower than EXP PRE and CON POST for TCRP240 (g = 1.530) and TCRP300 (g = 0 923) No significant interactions or effects were observed for SJ variables

When rest was redistributed between CA repetitions, TCRP180 provided enough total rest to observe enhanced CMJ RFD, consistent with the notion that PAPE will enhance rapid submaximal force application rather than peak forces [10] Furthermore, the lack of significant results observed for SJ variables suggests RFD may be augmented via the stretch-shortening cycle rather than enhanced motor unit recruitment. Changes in tPROP may explain the limited change in CMJ JPROP. Shorter tPROP and greater RFD may mean that the area under the force-time curve remains constant. Thus, while JPROP and jump height were unaffected, the strategy to achieve similar overall performance changed. The current results suggest that RR may reduce the time required to achieve improved performance due to diminished acute CA fatigue and minimised interference in movement patterns while maintaining the same total amount of work accomplished

CONCLUSION

RR may reduce the TCRP required to observe PAPE. TCRP180 may limit CA fatigue and movement pattern interference enough to observe enhanced RFD. While no change in JPROP was observed, results suggest that RR may affect jumping strategy. RR within CCT sets may be useful to practitioners for enhancing explosive force application and RFD and for maximising training density and time

REFERENCES

[1] Cormier, P , et al Sports Med, 52, 2371-2389, 2022 [LINK] [2] Crewther, B T , et al J Strength Cond Res, 25, 3319-3325, 2011 [LINK] [3].Esformes, J. I., et al. J Strength Cond Res, 25, 143-148 [LINK] [4].Houlton, L. J., et al. J Strength Cond Res, 38, e645-e655 [LINK] [5].Janicijevic, D., et al. J Strength Cond Res, 37, 980-986, 2023. [LINK] [6] Merrigan, J J , et al Int J Sport Phys Perf, 15, 255-261, 2020 [LINK] [7] Seitz, L B & Haff, G G Sports Med, 46, 231-240, 2016 [LINK] [8] Sirieiro, P , et al Int J Ex Sci, 14, 902-911, 2021 [LINK] [9] Thomas, K , et al Scand J Sci Med Sport, 27, 35-44, 2017 [LINK] [10]. Tillin, N. & Bishop, D. Sports Med, 39, 147-166, 2009. [LINK] [11]. Tufano, J. J., et al. J Strength Cond Res, 31, 848-867, 2017. [LINK]

Biomechanics Interest Group Conference 2025

Chartering BIG Possibilities in Biomechanics

Oral Presentation

Jack Fahey , Paul Comfort , Nicholas, Ripley

Directorate of Psychology and Sport, School of Health and Society, University of Salford, Salford, M5 4BR

1 Department of Football Medicine and Science, Manchester United Football Club, Carrington Training Complex, Manchester, UK

2 Strength and Power Research Group, School of Medical and Health Sciences, Edith Cowan University, Joondalup, Western Australia

3 j.t.fahey@salford.ac.uk

FORCE PLATE DERRIVED ISOMETRIC MID THIGH PULL BENCHMARKS IN ELITE FEMALE YOUTH FOOTBALLERS

INTRODUCTION

Female football continues to grow in participation and competition at youth and senior levels [1]. Unfortunately, females exhibit greater injury risk than male counterparts [2] with relative strength being a strongly associated modifiable risk factor [3] Previous findings in elite female youth footballers demonstrate an increase in body mass, linear and change of direction speed and gross peak force, but relative strength remained unchanged [4] This presents a problem for youth players relating to injury risk and those seeking progression into higher levels and competition (i.e., senior and international football). The isometric mid-thigh pull (IMTP) enables safe and reliable assessment of peak force; however, no benchmarks currently exist for IMTP relative peak force in elite female youth footballers. Such information would enable practitioners to monitor relative strength during adolescence as a proxy to whether youth players are being physically prepared for the increasing demands of football with increasing competition and increasing age Therefore, the purpose of this study was to provide relative peak force benchmarks for elite youth footballers

METHODS

An observational cross-sectional design was used to assess relative net peak force during the IMTP in elite female youth footballers. Ninety-four highly trained to elite female footballers registered with a Tier 1 Plus Football Association Academy volunteered for the study and were categorised into three distinct phases: Foundation Development Phase (FDP) (U11-U12, n = 21, 10 9 ± 0 6 years, 42 8 ± 7 6 kg, 148 6 ± 7 6 cm), Youth Development Phase (YDP) (U13-U15, n = 35, 13 6 ± 1 0 years, 54 8 ± 7 9 kg, 160.6 ± 6.5 cm) and Professional Development Phase (PDP) (U16-U21, n = 38, 16.2 ± 1.1 years, 63.4 ± 6.8 kg, 167.3 ± 5.8 cm). An a priori sample size estimation calculation based on between age group effect size of 3.2 [4], statistical power of 0.80, three groups, and alpha level of 0.05 using G*Power (version 3.1.9.2). provided a minimum 9 participants per group.

Three IMTP trials were conducted using force plates (Hawkin Dynamics, ME, USA) All participants were set up to ensure that the posture reflected the start of the second pull phase of a clean and used weightlifting straps to eliminate grip strength as a limiting factor Participants were required to remain as still as possible for at least 1-second and instructed to “push as hard and as fast as possible for 3-5 seconds”. An additional trial was included if a countermovement was performed or difference in peak force of >250 N was achieved between trials. Net peak force was calculated as the peak force achieved during the IMTP trial (i e , gross peak force) minus the system weight taken during a 1-second weighting period of a countermovement jump measured prior to the IMTP Net peak force was subsequently ratio scaled using body mass

Normality was assessed using skewness and kurtosis (i.e., z-test) and calculated by dividing the skewness value and excess kurtosis by their respective standard errors. For samples under 50 participants per group, a z-test value less than 1.96 confirms normal distribution of data to support the creation of benchmarks.

Biomechanics Interest Group Conference 2025

Chartering BIG Possibilities in Biomechanics

Oral Presentation

Relative within-session reliability was calculated using a two-way mixed model intraclass correlation coefficient (ICC, 3,1) interpreted from the lower bound 95% confidence interval (95CI) as: ≤0.49 = poor, 0.5 – 0.74 = moderate, 0.75 – 0.89 = good and ≥0.90 = excellent. Absolute within-session reliability was calculated using the coefficient of variation (CV%) interpreted from the upper bound 95CI as: ≥15 1% = poor, 10 1 - 15% = moderate, 5 1 – 10% = good and ≤5% = excellent To establish whether relative net peak force could be used as for benchmarks, a one-way analysis of variance with partial eta squared was conducted Pairwise comparisons were calculated with Bonferroni post-hoc analysis and Hedges g effect sizes and 95CI, interpreted as 0.00–0.19 = trivial, 0.20–0.59 = small, 0.60-1.19 = moderate, 1.20-1.99 = large and ≥2.00 = very large. Benchmarks were calculated by converting z-scores (individual score – between-subject mean / between subject standard deviation) into T-scores (z-score x 10 (+50)) using Microsoft Excel (Microsoft Corp., Redmond, WA, USA).A traffic light system was created for T-Score performance bands with descriptors for ease of interpretation for end users

RESULTS & DISCUSSION

Z-test scores confirmed normal distribution for pooled samples (range = -1.45 - 1.30). Absolute and relative reliability was good to excellent for relative net peak force (ICC = 0.95 (95CI = 0.93 - 0.97), CV = 5.24 (95CI = 4.50 – 5.99)). Large differences in body mass were observed between phases (FDP = 42.8 ± 7 8kg, YDP = 54 83 ± 8 0kg, PDP = 63 4 ± 6 8kg, g = 1 76 – 3 60) Small differences were observed in relative net peak force (p = 0 07, ηp = 0 05), with small to moderate pairwise comparisons between phases (g = 0 24 – 0 60) This permitted the creation of relative net peak force benchmarks and are displayed in Figure 1. 2

Our findings are similar to Emmonds et al [4] and highlight a problem for youth female players because force relative to body mass determines acceleration, and impulse (∆force x ∆time) relative to mass determines movement velocity. Greater relative peak force has been reported in elite senior male footballer plyers compared to junior, and international players compared to regional players [5]. Youth footballers should aim to develop relative strength to better cope with the increased mechanical stress observed during adolescence and those seeking progression into higher levels and competition (i e , senior and international football)

CONCLUSION

The results of the present study demonstrate that relative net peak force measured by IMTP did not differ between youth players from different phases (i.e. FDP, YDP and PDP). Increases in body mass (and therefore momentum) during maturation increases the mechanical stress and can increase injury risk if relative strength is not developed. Youth female football players should aim to develop relative strength to better cope with the match demands with increasing age and increasing competition level

REFERENCES

[1] FIFA Women’s Football Member Association Survey Report, 1, 1-144, 2023 [LINK]

[2]. Robles-Palazón, F.J. et al. Journal of sport and health science, 11, 681-695, 2022. [LINK]

[3]. Comfort, P, et al. PloS one, 19, e0296877, 2024. [LINK]

[4] Emmonds, S et al International Journal of Sports Science and Coaching, 13, 779-786, 2018 [LINK]

[5] Soriano, M et al International Journal of Sports Physiology and Performance, 19, 629–636, 2024 [LINK]

Figure 1. Relative net peak force benchmarks measured by IMTP for elite female youth footballers

Oral Presentation Biomechanics Interest Group Conference 2025

Chartering BIG Possibilities in Biomechanics

Gabriele Azzolini , Silvia Fantozzi , and Ezio Preatoni 1 1 2

Department of Electrical, Electronic, and Information Engineering "Guglielmo Marconi", 1 University of Bologna, Italy

Department for Health, University of Bath, Bath, UK 2

ga720@bath.ac.uk

THE EFFECT OF STUD DESIGN ON GROUND REACTION FORCE AND SUBJECTIVE PERCEPTION IN FOOTBALL-SPECIFIC MOVEMENTS

INTRODUCTION

Most anterior cruciate ligament (ACL) injuries in football are non-contact and typically occur in movements involving accelerations, change of direction, landing, and pivoting [1]. ACL lesions are problematic because they often require surgery, lead to lengthy recovery, can cause long-term knee instability, are associated with early insurgence of osteo-arthritis, and hinder returning to the same playing standard The role of football boot design in affecting lower limb loading and hence ACL injury factors has been investigated by some authors [2], but evidence upon the effects of stud features on biomechanical factors related to injury is limited. We assessed the effect of stud mechanical features (flexibility) on lower limb loading, and player reported perception during labbased football-specific movements.

METHODS

Using a single-session, cross-sectional design, we assessed the effects of three different stud features on 3D ground reaction forces (GRF) and subjective scoring of comfort, stability, grip and overall appreciation. Eleven male recreational football players (27.2 ± 6.8 y.o.; height 1.79 ± 0.06 m; weight 76.1 ± 6.2 kg) partook in the study, which included 90° and 180° change of direction manoeuvres. Participants wore standard 8-stud boots (Mizuno Morelia Neo IV β Elite), sprinted from ~5 m landing with their dominant foot on a force plate (Kistler 9287CA, 2000 Hz), and after cutting on their dominant limb, they pushed off the force plate and continued sprinting for ~2 m The lab floor and the force plate were covered in artificial turf, fixed with double side carpet tape Three different stud conditions were presented in random order for each movement task: STD, rigid commercial standard; OPT, flexible; and FLX, very flexible studs. SASpik (saspik.it) provided OPT and FLX. Repeated measure non-parametric ANOVA (Friedman test) and statistical parametric mapping (www.spm1d.org), followed by pairwise comparison with Bonferroni correction, were used to compare scalar quantities and timeseries over the first 40 ms from foot strike. Scalar measures included subjective feedback via Visual Analog Scales – VAS, and GRF loading rates, calculated as the ratio between force peak and time to peak All the GRF were normalized to bodyweight and α was set at 0 05

RESULTS & DISCUSSION

Participants demonstrated to have a better overall appreciation (+35.7%, P=0.006) and feeling of comfort (+27.9%, P=0.011) for boots fitted with the OPT rather than STD studs (Figure 1). In the 90° cutting task, the OPT studs generated higher GRF than both FLX (+28 2% on average, p=0 010) and STD (+30 15% on average, p=0 010) between 20 and 23 ms from foot strike (Figure 2a) In the 180° cutting task, the difference was reported between 3 and 5 ms, with STD showing higher GRF than FLX (+48 27% p=0 010) Overall, FLX appears to induce lower vertical GRF in the initial contact phase than the less flexible stud alternatives. This also happens when looking at the medio–lateral loading rates in both tasks (Figure 3), where FLX showed lower magnitudes than STD (-30.94%, Cohen’s d = 0.47 in 90° cutting; -41.36%, Cohen’s d = 1.03, in 180° cutting), suggesting that more rigid studs may generate a steeper rise of GRF in the direction of cut, and at times higher values of vertical GRF, which altogether may increase the loading on lower limb structures These outcomes should be considered preliminary, given the relatively small sample size tested and the variability in individual behaviour

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Chartering BIG Possibilities in Biomechanics

Figure1:Subjectivefeedbackinfourcategories:OverallAppreciation,Comfort,StabilityandGrip.

Figure 2: Average vertical GRF in 90° (a) and 180° cutting task Results from different stud conditions are reported as population mean (solid lines) and standard deviation (cloud). Periods of significant differences from SPM analysis are highlighted through coloured bands along the timeline (left colour vs right colour(s))

3: Medio – Lateral loading rates in 90° (left) and 180° (right) task

CONCLUSION

Our findings suggest that studs featuring a degree of flexibility compared to current commercial standards may reduce or at least delay the rise of ground reaction forces during the initial foot-strike phase in cutting maneuvres, thus potentially mitigating lower limb mechanical demands during rapid directional changes.

ACKNOWLEDGMENTS

Materials for testing (boots and studs) were provided in-kind by SASpik srl, which signed a research agreement with Dr Fantozzi SASpik did not have any input in the experimental choices, data analysis, and dissemination of findings

REFERENCES

[1]. Alentorn-Geli E et al. Knee Surg Sports Traumatol Arthrosc., 17, 705–729, 2009. [LINK] [2]. Bennett HJ, et al. J Appl Biomech., 31(5), 309-17, 2015. [LINK]

Figure

Biomechanics Interest Group Conference 2025

Oral Presentation

Xi Yang , Anna Fitzpatrick , Mark King , and Stuart A. McErlain-Naylor

1 1 1 1

Chartering BIG Possibilities in Biomechanics School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK 1

x.yang@lboro.ac.uk

WEARABLE TECHNOLOGY IN TENNIS: PLAYER WILLINGNESS, USAGE, AND APPLICATION

Introduction

The rise of wearable technology in recent years has contributed to an increasing popularity of data analytics in tennis These devices have been applied for various purposes, including joint function analysis [1], running load estimation [2] and swing mechanics [3], offering valuable insights for enhancing technical and physical performance. Despite the widespread adoption of wearable technologies and substantial research supporting their potential benefits [4-5], little attention has been given to players’ perceptions of wearable technologies, particularly their willingness to adopt such technologies in training and matches Previous research has investigated the perceptions of racket-sport coaches regarding the placement of IMUs in both contexts [6], highlighting the importance of strategic sensor placement for regular training monitoring However, players may hold different perceptions and preferences, as they directly experience the physical impact on the body of the sensors during hitting In contrast, coaches are more likely to prioritize sensor placement based on technical considerations and training objectives This study therefore aims to investigate tennis players’ willingness to adopt wearable technology, their current usage, and its potential applications

Methods

Participants were recruited through personal networks, including clubs, universities, and sports academies in the United Kingdom, China and Australia, targeting tennis players of various levels They were contacted via email or messages and invited to complete the survey Participants were encouraged to share the survey with other players All responses were collected using the online platform Qualtrics (Qualtrics TX online software, Utah, USA; https://www.qualtrics.com). The survey questions included: Demographic information: participants’ training years, training country, match experience and playing level were collected using dropdown based multiple-choice questions Sensor number acceptance and placement preference: the sensor’s size and appearance were described, followed by questions regarding the maximum number of sensors participants would be willing to wear and their preferred body locations during training and matches, using three multiple-choice questions (i.e., yes/maybe/no). Current sensor usage: participants were asked about whether they currently use wearable devices to monitor training or matches, using two multiple-choice questions (i e , yes/no) Sensor application: participants rate the importance of various factors influencing their willingness to wear a particular sensor, as well as their interest in different sensor applications, using a five-point Likert scale ranging from “Extremely important/interesting” to “Not important/interesting at all ” Ethical approval was obtained from the Loughborough University Ethics Committee Informed consent was obtained within the first section of the survey. Responses were excluded if the survey was less than 50% complete, and if the participants had not participated in any formal match during the previous 12 months. Validated responses were analysed using descriptive statistics, with results presented as absolute values and percentages of the total responses

Results & Discussion

Ninety-six participants were included in this study, consisting of 46 males and 50 females, with 16 1 ± 4 8 years of training experience Most participants were aged 18-25 years (n = 74), followed by 14 participants aged 26-30 years and 8 participants over 30 years. Participants currently train in the United Kingdom (n = 81), Australia (n = 9), and China (n = 6). The playing levels of the participants were classified according to the World Tennis Number (WTN) levels The distribution was as follows: elite professional players (WTN 0-5, n = 12), semi-professional players (WTN 6-10, n = 27), senior amateurs and college varsity players (WTN 11-20, n = 40), and intermediate amateurs or club players with competitive experience (WTN > 20, n = 17).

Biomechanics Interest Group Conference 2025

Chartering BIG Possibilities in Biomechanics

Oral Presentation

Participants’ willingness to wear different numbers of sensors was determined by selecting “yes”, most participants (27.4%, n = 25) were willing to wear 2-3 sensors, followed by 4-5 sensors (20.8%, n = 19) and 6-7 sensors (16 4%, n = 15) during training In match scenarios, the largest proportion of participants (45 1%, n = 37) accepted 2-3 sensors, while 23 1% (n = 19) were willing to wear 4-5 sensors 19 5% (n = 16) were willing to wear 0-1 sensors, and the percentage further declined for greater sensor numbers. Participants were most willing to wear sensors on the upper back (91.2%), shoes (81.0%), lower back (76 0%), and upper arms (racket side: 69 6%, non-racket side: 73 4%) during training Similar results were observed among racket sports coaches [6]; however, unlike players, they were not willing to wear sensors on both sides wrists, non-racket side lower arm and lower limbs. This difference indicate that players prioritize comfort and freedom of movement, particularly in areas that are frequently involved in dynamic movements such as footwork and hitting The willingness to wear sensors decreased across all body segments in match settings; the upper back (69 6%) and shoes (62 0%) remained the most acceptable locations. These preferred body locations could serve as a foundation for developing artificial intelligence in stroke activity recognition, offering a practical balance between data accuracy and player comfort In terms of current usage, 53 8% of participants use a heart rate monitor during training, while only 18 2% use GPS devices, 13 8% use racket sensors and/or smartwatch, and 8 8% use inertial measurement sensors. In match scenarios, 18.5% of participants use a heart rate monitor, with even less adoption of racket sensors and/or smartwatch (9.9%), GPS devices (8.6%), and inertial measurement sensors (6 3%) The primary factors influencing players’ willingness to wear sensors were identified as feel and comfort (63 4%), regulatory approval (i e , permitted by the International Tennis Federation) (53 6%), and sensor weight (46 3%), with these aspects being rated as “extremely important ” In contrast, 46.3% of participants considered the appearance of the sensor to be “not important at all” (Figure 1) Stroke load monitoring was the most highly rated application, with 90 2% of participants considering it “extremely interesting” or “very interesting” Tactical feedback and injury prevention also received strong support, with 80 4% and 81 7% of participants, respectively

Figure1:FactorsInfluencingSensorAcceptance.

CONCLUSION

This is the first survey to investigate the current acceptance, preference and adoption of wearable technology by tennis players Players exhibit a receptive attitude towards wearable technology, which plays an important role in bridging scientific research and its practical application in tennis The findings highlight that tennis players are generally open to using multiple sensors. The preferred locations for wearing 2-3 sensors are the upper back, shoes, and lower back. However, sensor acceptance in match scenarios was noticeably lower than in training Furthermore, the results highlight key areas where wearable sensor applications could have the greatest impact, particularly in stroke load monitoring, injury prevention and tactical analysis. Future research should focus on developing wearable technology applications that better respond to players’ needs while also considering their willingness to adopt these technologies, ensuring that scientific findings translate into real benefits in practice

REFERENCES

[1]. Brocherie, F., & Dinu, D. Frontiers in Sports and Active Living, 4, 2022. [LINK]

[2] Hoppe, M W , et al Pediatric Exercise Science, 26, 281-290, 2014 [DOI LINK]

[3] Keaney, E M , & Reid, M Sports Biomechanics, 19, 831-839, 2020 [DOI LINK]

[4]. Brich, Q., et al. Int. J. Sports Physiol. Perform., 19, 519-532, 2024. [DOI LINK]

[5]. Seçkin, A. Ç., et al. Applied Sciences, 13 (18), 10399, 2023. [DOI LINK]

[6] Wylde, M J , et al Int J Racket Sports Sci , 3, 45–55, 2021 [DOI LINK]

Biomechanics Interest Group Conference 2025

Chartering BIG Possibilities in Biomechanics

Oral Presentation

Logan Wade , James Bilzon , M Polly McGuigan 1 1 1

lw2175@bath.ac.uk

Department for Health, University of Bath, Bath, United Kingdom 1

THE MAJOR BARRIERS LIMITING INTEGRATION OF MARKERLESS MOTION CAPTURE WITHIN CLINICAL PRACTICE IN THE UNITED KINGDOM

INTRODUCTION

Compared to marker-based motion capture, markerless motion capture brings biomechanics into the real world, enabling data collection by untrained users with minimal preparation, participant time and cost, along with automated data processing capabilities Previous research has identified that open-source markerless methods perform well at calculating temporospatial [1, 2] and sagittal plane kinematic results [3, 4], with further research demonstrating how markerless systems could integrate in clinical applications [5, 6]. However, within the National Health Service (NHS), there are currently no known markerless motion capture systems in use that automatically process data and provide gait results to inform patient care or monitoring

This project aims to identify the major barriers limiting biomechanical application of AI based markerless motion capture in clinical practice This project will help future biomechanical researchers understand areas for future development and potential barriers that may arise during integration of this technology.

METHODS

Workshops and discussions with clinicians (physiotherapists, rheumatologist, nurses, etc), ethical bodies and medical device regulators were conducted to identify key requirements and barriers for markerless motion capture integration within UK clinical practice These requirements have informed the development of a markerless motion capture pipeline designed in collaboration with clinicians for use in an active clinic. This markerless pipeline runs entirely offline, recording video data from three cameras positioned around the front of a treadmill. Recorded video is processed using the opensource OpenCap offline processing pipeline [4] which calculates kinematic results. Walking gait parameters are then computed and displayed to the clinician and participant, facilitating comparison of walking gait between trials and sessions in the same participant This markerless system is currently being evaluated in a feasibility research study at a private neuro-rehabilitation clinic in the UK. Key requirements and barriers identified during workshops, discussions and during the development of this system are discussed to provide insight to future biomechanics researchers.

RESULTS & DISCUSSION

This project has identified a number of key requirements and barriers which fall within the themes of: integration into current clinical practice, data security and medical software device classification

Integration into current clinical practice: Workshops with clinicians highlighted the need to minimise costs, ideally keeping them below £1000-2000 or less, especially for small private practice and NHS sites. Development of the local markerless pipeline in collaboration with an active clinic identified two critical requirements: minimising time to provide feedback for the participant, and ensuring the system can handle multiple people moving around in the background The open-source offline OpenCap processing pipeline includes built-in support for OpenPose [7] and HRNET [8] pose estimation algorithms While OpenPose is highly effective at handling multiple people in the background, the performance of HRNET is potentially better [9], although HRNETs processing speed is significantly decreases when multiple individuals are in view. Additionally, software licensing constraints must be considered, as HRNETs license may facilitate clinical integration, while OpenPose is restricted to research only applications. To achieve clinical integration, further development would involve optimising performance to handle multiple people in the view while ensuring a more flexible and open licensing model suitable for clinical use

DATA SECURITY:

Biomechanics Interest Group Conference 2025

Chartering BIG Possibilities in Biomechanics

Oral Presentation

Workshops with clinicians and ethical bodies, including the University of Bath and NHS Health Research Authority, highlighted the importance of data security, particularly regarding the storage and retention of patient-identifiable images. It is feasible to use the web-based OpenCap version for university level research studies as long as users are explicitly informed that identifiable video data will be transferred for processing overseas (Stanford, USA), and video data will be retained by the developers for software development purposes. However, within the NHS, such data cannot leave the UK and off-site transfer of identifiable information may not be possible. As a result, NHS research and clinical systems will generally need to be self-contained, operating without reliance on cloud-based storage or processing to ensure compliance with NHS data security regulations

Medical Software:

Discussions with ethical bodies, including the University of Bath and NHS Health Research Authority, as well as the NHS medical software device regulatory body, have clarified that any software that would influence patient treatment in any way must be classified as a medical software device. Until this classification is achieved, the software cannot be deployed within the NHS for clinical use. If the system solely records and processes patient movement, without providing the results to the clinician or patient, then it likely would not fall under the category of a medical software device as it would not influence patient treatment or outcomes. This distinction often applies to research settings, which may make it possible to use markerless systems within NHS sites, provided identifiable patient data is securely managed However, integration into NHS clinical practice that influences patient care or treatment (within or outside of research), will likely need to first be apply to be a medical software device and comply with all associated regulatory requirements.

As part of the medical software approval process, evidence must be provided to demonstrate that any errors in the system’s results can be identified and overridden by the clinician In AI-based systems, this can be achieved in two ways: 1) Access to raw data: clinicians should be able to review the original video recordings of the patient, as well as intermediate AI-generated outputs such as 2D pose detection, 3D joint centre locations and inverse kinematic analysis 2) Transparent AI decision-making: As AI models advance and incorporate larger datasets, particularly those that may generate clinical reports (e g using Large Language Models), they will need provide clear explanations of how conclusions were reached alongside the raw data. Such systems could outline key supporting and contradiction measures, present confidence scores, and ensure clinicians can interpret the data independently before making clinical decisions

CONCLUSION

Markerless motion capture has now reached the capability of recording, processing and providing results to clinicians without any intervention of biomechanically trained personnel To convert this research into clinical practice while also ensuring protection of the patient, markerless applications may require listing as medical software devices, alongside other barriers to implementation in clinical practice.

ACKNOWLEDGMENTS

This research was funded by the Centre for Analysis of Motion, Entertainment Research and Applications (EP/T022523/1).

REFERENCES

[1] Wade, L , et al , PeerJ,10, p e12995, 2022, [LINK] [2].Kanko, R.M., et al., Journal of Biomechanics, 122, p. 110414, 2021, [LINK] [3] Needham, L , et al , Journal of Biomechanics, 144, p 111338, 2022, [LINK] [4] Uhlrich, S D , et al , PLOS Computational Biology, 19, p e1011462, 2023, [LINK] [5] Furtado, S , et al , PLOS ONE, 19, p e0300351, 2024, [LINK] [6].Calderone, J., et al., Gait & Posture, 2025, [LINK] [7].Cao, Z., et al., IEEE Trans Pattern Anal Mach Intell, 43, p. 172-186, 2019, [LINK] [8] Contributors, M OpenMMLab Pose Estimation Toolbox and Benchmark 2020; Available from: [LINK] [9] Sun, K , et al , Journal,p 5686-5696, Year, [LINK]

Thank You Biomechanics Interest Group Conference 2025

DearFriendsandBIGcolleagues,

Chartering BIG Possibilities in Biomechanics

We want to thank all our speakers, CASES communications team and attendees for making BIG 2025 'Charting BIG Possibilities in Biomechanics' conference a success. We hope that everyone found the conferenceinformativeaswellasenjoyable.

The primary goal of this conference was to bring together colleagues in Biomechanics from both within the UK and beyond to push the field forward with our research . We believe that our dynamic group of speakers gave an in-depth insight into the progressive research and application within biomechanics, provided'foodforthought'forfurtherresearchandcollaborations.

Yourpresencehelpedmakethiseventagreatsuccess,andyourenthusiasmandpositivespirithelped makeourtimetogetherproductiveandfun.Wewishyouallthebestandhopethatyoucontinuetobe engagedwiththeCASESBiomechanicsandMotorBehaviourDivisioninthefuture.

YoursSincerely, TheBiomechanicsandMotorBehaviourDivisionCommittee

All Biomechanics and Motor Behaviour Division Committee Members 2020 - present