PRINCIPAL INVESTIGATOR

Competitive Spirit

Colorado researcher’s findings influence the world of organized sports

O&P Almanac introduces individuals who have undertaken O&P-focused research projects. Here, you will get to know colleagues and healthcare professionals who have carried out studies and gathered quantitative and/or qualitative data related to orthotics and prosthetics, and find out what it takes to become an O&P researcher.

THE CONTROVERSY surrounding the use of running prostheses by Oscar Pistorius, a South African sprinter with bilateral leg amputations, served a positive purpose for Alena M. Grabowski, PhD: “It captivated me and got me involved in prosthetic research,” she says.

Ten years ago, Pistorius achieved a time for the 400-meter sprint that qualified him to compete in the Olympics; however, he was initially denied the opportunity to compete by the International Association of Athletics Federations (IAAF, now

Alena Grabowski, PhD, works in the Applied Biomechanics Lab at University of Colorado Boulder. World Athletics), which claimed that prostheses provided an advantage to their user. At the time, Grabowski was part of a research team that concluded the opposite: that the use of prosthetic legs does not provide amputees with an advantage compared with elite nonamputee sprinters. “Our team’s research was used in the Court of Arbitration in Sport (CAS) to successfully appeal the IAAF’s decision,” and Pistorius was allowed to compete in the 2012 Olympic Games.

Over the past decade, Grabowski—a runner herself—has been captivated by how devices such as prostheses and orthoses affect the physiology and biomechanics of people with physical disabilities and has pursued several groundbreaking research projects to better understand the use of these devices.

Studying Human Movement

The Pistorius prosthetic controversy ignited a career rich in movement research. Grabowski earned a bachelor’s degree in kinesiology from University of Colorado Boulder (UC Boulder) in 1998, followed by a doctorate degree from the same university in 2007. Grabowski completed postdoctorate work at the Massachusetts Institute of Technology’s Media Lab and at the Providence VA Center for Restorative and Regenerative Medicine in 2011.

Grabowski observes as a lower-limb amputee runs on the treadmill.

Left, Grabowski works with a study participant.

Today, Grabowski serves dual roles, as an associate professor at UC Boulder and as a research healthcare scientist with the Department of Veterans Affairs Eastern Colorado Healthcare System in Denver. At UC Boulder, Grabowski’s appointment is focused on research, but she also teaches biomechanics and is the director of the Applied Biomechanics Lab. She aims to improve the function and enhance the performance of people with and without physical disabilities, such as leg amputation, as they walk, run, cycle, sprint, and jump.

To accomplish those goals, Grabowski and her team investigate how mechanical and robotic devices such as prostheses, exoskeletons, and sports equipment affect people’s ability to move. “We utilize different types of biomechanical equipment in the lab, such as force-measuring treadmills, motion capture, force platforms, electromyography to measure muscle activity, a materials testing machine to determine stiffness of prostheses and orthoses, and indirect calorimetry to measure metabolic rates,” she explains.

Impactful Studies

In recent years, Grabowski has studied the motion of competitive and even elite athletes. Her team conducted a systematic series of studies to establish how the use of runningspecific prostheses by athletes with unilateral and bilateral leg amputations affect performance. “First, we found that sprinters with leg amputations using running-specific prostheses have slower acceleration out of the starting blocks, slower curve-running speed, and slower maximum speed compared to nonamputees,” she says.

However, the prosthetic configuration used by athletes with a leg amputation may affect their running and sprinting performance. “We determined the biomechanics, metabolic demands, and maximum speeds of athletes with unilateral and bilateral leg amputations each using 15 different prosthetic configurations: three models with three stiffness categories at one height, and two additional heights with the optimal stiffness category.” The optimal distance-running prosthetic configuration elicited the lowest metabolic cost, and the optimal sprinting prosthetic configuration maximized speed, according to Grabowski. “Athletes with unilateral leg amputations optimized distancerunning performance when they used a J-shaped model, and athletes with bilateral leg amputations optimized distance-running performance when they used J- or C-shaped models with lower-than-recommended stiffness,” she says. Sprinting speed was maximized when these athletes used J-shaped models but was not affected by prosthetic stiffness or height. “We used the results from the most economical prosthetic configurations to hypothesize that, despite biomechanical differences between athletes with and without leg amputations, metabolic cost is within the same range,” she says. Thus, use of an optimal runningspecific prosthetic configuration can enhance the performance of athletes with leg amputations when compared to other configurations, but it does not normalize biomechanics or performance when compared to nonamputees.

Grabowski also has led investigations focusing on jumping. “The long jump performances of Markus Rehm, a German athlete with a leg amputation, have generated speculation that use of a running-specific prosthesis and affected leg as the takeoff leg for the long jump provides an advantage compared to nonamputees,” she explains. Grabowski worked as part of an international research team to measure the biomechanics and performance of elite athletes with and without a leg amputation during maximum distance long jumps. “All of the athletes with a leg amputation used their affected leg, including their prosthesis, as their takeoff leg,” says Grabowski. The athletes had a slower run-up speed but an enhanced takeoff step technique for the long jump compared to performance-matched nonamputees.

Grabowski’s team is studying how use of running-specific prostheses affects the performance of Blake Leeper, a U.S. athlete with bilateral amputations.

“Our results imply that use of a running-specific prosthesis has a neutral effect on long jump performance for athletes with a leg amputation compared to nonamputee athletes,” she says. However, the rule made by the IAAF regarding the use of running-specific prostheses states that athletes must prove that the use of a prosthesis does not provide them with an advantage compared to nonamputees. “Based on the neutral effect of athletes with a leg amputation using a prosthesis for the long jump, the IAAF did not allow Rehm to compete in sanctioned track and field events, including the Olympics,” she says.

“The effects of using a runningspecific prosthesis on the performance of athletes with a leg amputation remains controversial,” Grabowski adds. Her team is currently involved in research to determine how use of running-specific prostheses affects the performance of Blake Leeper, a U.S. athlete with bilateral leg amputations who has attained a 400-meter time of 44.36 seconds, which is faster than the Olympic-qualifying time and Oscar Pistorius. “We have analyzed and compared Leeper’s performance metrics over 400 meters to those of nonamputees to address the IAAF rule that put the burden of proof on an athlete to show that the use of prostheses does not provide an advantage compared to nonamputees,” she explains. “The IAAF did not allow Leeper to compete, and I served as an expert witness in the appeal of the IAAF decision in the CAS.” CAS ruled that the IAAF must have the burden of proof, but that Leeper is not allowed to compete because he did not abide by the International Paralympic Committee’s rule on the maximum allowable standing height (MASH).

“The MASH rule is very controversial because it is based on people of Caucasian and Asian descent, but not on people of African descent,” Grabowski explains. “Moreover, MASH has not been used by the IAAF to regulate height of nonamputee athletes. Thus, the controversy surrounding the use of running prostheses remains, and we are conducting additional studies to determine how use of running-specific prostheses affect performance.”

Investigations Into Walking

While many of her studies have implications for elite athletes, Grabowski also devotes resources to walking-related investigations. “Over time, the design of leg prostheses has improved, but until recently, leg prostheses have been incapable of actively adapting to different walking speeds in a manner comparable to biological limbs,” she explains. “People with a leg amputation using passive-elastic prostheses require greater energy to move, walk at slower preferred speeds, and have asymmetric movements and forces during walking compared to nonamputees.”

Grabowski conducted a series of studies analyzing the use of a bionic battery-powered ankle-foot prosthesis (BiOM) that emulates the function of a biological ankle during level-ground walking. People using the BiOM realized normative metabolic costs and biomechanics during level-ground walking over a range of speeds and dramatically improved their performance compared to using a passive-elastic prosthesis.

She also has worked with her team on a series of studies analyzing and comparing the use of the BiOM to use of a passive prosthesis and to nonamputees during walking on uphill and downhill slopes. One study determined that, in nonamputees, the ankle’s contribution to the mechanics of the leg changes with speed and slope during walking, suggesting that a bionic powered prosthesis may need sophisticated control to normalize metabolic costs and biomechanics. Another study concluded that when people with a leg amputation used the BiOM, they reduced their metabolic cost and improved their biomechanics when walking uphill compared to using a passive-elastic prosthesis, but their metabolic costs and biomechanics did not change when walking downhill. “Use of a bionic battery-powered ankle-foot prosthesis has the potential to dramatically improve the physical function of people with a leg amputation during level-ground and uphill walking,” Grabowski concludes.

More To Come

Grabowski plans to continue studying topics that are relevant to individuals with limb loss. For example, she and her team are determining how visual feedback of peak propulsive force affects the biomechanics and metabolic costs of people with a leg amputation using the BiOM. “We also are comparing how the interaction of prosthetic foot stiffness and ankle power affect

the biomechanics and metabolic costs of people with a leg amputation,” she says.

Additional future projects include a study to optimize prosthetic configuration; bicycle fit in people with a leg amputation; and optimizing running-specific O&P components for military women with lower-limb salvage or amputation. “In future research, I hope to use results from all of my previous studies to design and develop lower-limb orthoses and prostheses that can improve the function of people with a disability during walking, running, jumping, bicycling, and sprinting,” she says.

“I think it’s really important for researchers and clinicians to be able to understand each other and address the challenges in our field,” Grabowski adds. “I hope that my research contributes to better understanding how prostheses and orthoses affect the way that people with a disability move, be it walking or sprinting. I also hope that clinicians and O&P business owners are open to contributing to research and to adopting new and proven technology to support their patients’ mobility.”

Notable Works

Alena M. Grabowski, PhD, is the author or co-author of dozens of peer-reviewed articles and conference presentations. Some of her most impactful contributions include the following: • Herr, H.M., Grabowski, A.M. “Bionic Ankle-Foot

Prosthesis Normalizes Walking Gait for Persons With

Leg Amputation.” Proceedings of the Royal Society B, 2012, 279: 457-464. http://royalsocietypublishing.org/ content/royprsb/early/2011/07/07/rspb.2011.1194.full.pdf • Weyand, P.G., Bundle, M.W., McGowan, C.P.,

Grabowski, A.M., Brown, M.B., Kram, R., Herr, H.

“The Fastest Runner on Artificial Legs: Different

Limbs, Similar Function?” Journal of Applied

Physiology, 2009, 107: 903-911. http://jap.physiology. org/content/107/3/903 • Grabowski, A.M., McGowan, C.P., McDermott, W.J.,

Beale, M.T., Kram, R., Herr, H. “Running-Specific

Prostheses Limit Ground Force During Sprinting.”

Biology Letters, 2010, 6: 201-204. http://rsbl.royalsocietypublishing.org/content/6/2/201 Grabowski holds a lower-limb prosthesis.

Ferrier Coupler Options! Interchange or Disconnect

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Enables a complete disconnect immediately below the socket in seconds without the removal of garments. Can be used where only the upper (above the Coupler) or lower (below the Coupler) portion of limb needs to be changed. Also allows for temporary limb replacement. All aluminum couplers are hard coated for enhanced durability. All models are interchangeable.

Model A5

The A5 Standard Coupler is for use in all lower limb prostheses. The male and female portions of the coupler bolt to any standard 4-bolt pattern component.

The F5 Coupler with female pyramid receiver is for use in all lower limb prostheses. Male portion of the coupler features a built-in female pyramid receiver. Female portion bolts to any standard 4-bolt pattern component.

The Ferrier Coupler with an inverted pyramid built in. The male portion of the pyramid is built into the male portion of the coupler. Female portion bolts to any 4-bolt pattern component. NEW! The FA5 coupler with 4-bolt and female pyramid is for use in all lower limb prostheses. Male portion of coupler is standard 4-bolt pattern. Female portion of coupler accepts a pyramid.

NEW! The FF5 has a female pyramid receiver on both male and female portions of the coupler for easy connection to male pyramids.

NEW! The FP5 Coupler is for use in all lower limb prostheses. Male portion of coupler has a pyramid. The Female portion of coupler accepts a pyramid. The Trowbridge Terra-Round foot mounts directly inside a standard 30mm pylon. The center stem exes in any direction allowing the unit to conform to uneven terrain. It is also useful in the lab when tting the prototype limb. TheThe unitunit isis waterproof and has a traction base pad.

Model FA5

Model F5 Model FF5

Model P5 Model FP5 Model T5