Four years after Oscar Pistorius made history at the London Olympics, the question remains unanswered
Science writer Larry Greenemeier cited the research of SMU biomechanics expert Peter Weyand for an article in Scientific American that examines the pros and cons of carbon-fiber blade prosthetics used by athlete amputees.
Greenemeier cites Weyand’s research findings from a study of Olympic blade-runner Oscar Pistorius to determine whether the double-amputee had a competitive advantage from his carbon-fiber prosthetic legs. The article “Blade Runners: Do High-Tech Prostheses Give Runners an Unfair Advantage?” published Aug. 5, 2016.
Weyand, director of the SMU Locomotor Performance Laboratory, is one of the world’s leading scholars on the scientific basis of human performance. His research on runners, specifically world-class sprinters, looks at the importance of ground forces for running speed, and has established a contemporary understanding that spans the scientific and athletic communities.
In particular, Weyand’s finding that speed athletes are not able to reposition their legs more rapidly than non-athletes debunked a widespread belief. Rather, Weyand and his colleagues have demonstrated sprinting performance is largely set by the force with which one presses against the ground and how long one applies that force.
Weyand is Glenn Simmons Centennial Chair in Applied Physiology and professor of biomechanics in the Department of Applied Physiology and Wellness in SMU’s Annette Caldwell Simmons School of Education and Human Development.
By Larry Greenemeier
Paralympic long jump champ Markus Rehm’s bid to compete in the 2016 Rio de Janeiro Olympics fell short in July when he could not prove that his carbon-fiber “blade” prosthesis didn’t give him an advantage. His baffling case serves as a reminder that four years after South African sprinter Oscar Pistorius propelled himself into history as the first amputee Olympic athlete to compete using blade prostheses, the technology’s impact on performance remains unclear despite ongoing research.
Blade prostheses, like Rehm uses on his right leg and Pistorius used on both, share some characteristics with biological limbs. The blades store energy as they bear the runner’s weight and then release it as the runner pushes off the ground, much the way a leg’s calf muscles and Achilles’ tendons spring and recoil. But an important difference is the foot, which on a blade prosthetic does not pivot or generate its own energy. A biological foot has muscle fibers that help it push off the ground in a way that creates “metabolic efficiency so your muscles don’t have to put all of the work back in with every step as you’re running,” says David Morgenroth, an assistant professor in the University of Washington’s Department of Rehabilitation Medicine…
…Shortly after track and field’s governing body, the International Association of Athletics Federations (IAAF), banned Pistorius in 2008 from competing against so-called “able-bodied” competitors, he underwent a series of tests at Rice University’s Locomotion Laboratory in an attempt to be reinstated. The researchers concluded that Pistorius used 17 percent less energy than that of elite sprinters on intact limbs. The tests also revealed that it took the South African 21 percent less time to reposition, or swing, his legs between strides. Big disagreements arose over how to interpret the research.
Southern Methodist University’s Peter Weyand and Matt Bundle from the University of Montana saw a clear overall advantage in Pistorius’s faster leg swings and more energy-efficient stride, which they said could create up to a seven-second advantage in the 400-meter race. “The more mass you have closer to the axis—in this case, your hips—the easier it is to stop the rotation and then turn it around,” Bundle says. “Whereas if you had that same amount of mass located a long way away from the axis—in your lower legs and feet—it becomes much more difficult to stop it and get it going in the opposite direction.”