Scientists debate whether prosthetic legs give Pistorius an unfair advantage in the 400-meter race
?| July 24, 2012?|
Image: Wikimedia Commons/Erik van Leeuwen
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Runners who've faced off against Oscar Pistorius say they know when the South African is closing in on them from behind. They hear a distinctive clicking noise growing louder, like a pair of scissors slicing through the air?the sound of Pistorius's Flex-Foot Cheetah prosthetic legs.
It's those long, J-shaped, carbon-fiber lower legs?and the world-class race times that come with them?that have some people asking an unpopular question: Does Pistorius, the man who has overcome so much to be the first double amputee to run at an Olympic level, have an unfair advantage? Scientists are becoming entwined in a debate over whether Pistorius should be allowed to compete in the 2012 London Games.
Pistorius was born without fibulas, one of the two long bones in the lower leg. He was unable to walk as a baby, and at 11 months old both of his legs were amputated below the knee. But the growing child didn't let his disability slow him down. At age 12 he was playing rugby with the other boys, and in 2005, at age 18, he ran the 400-meter race in 47.34 seconds at the South African Championships, sixth best. Now 25, the man nicknamed the ?Blade Runner? has qualified for the 2012 Summer Olympics in London, just three weeks before the games were to begin. But should he be allowed to compete?
The question seems preposterous. How could someone without lower legs possibly have an advantage over athletes with natural legs? The debate took a scientific turn in 2007 when a German team reported that Pistorius used 25 percent less energy than natural runners. The conclusion was tied to the unusual prosthetic made by an Icelandic company called ?ssur. The Flex-Foot Cheetah has become the go-to running prosthetic for Paralympic (and, potentially Olympic) athletes. "When the user is running, the prosthesis's J curve is compressed at impact, storing energy and absorbing high levels of stress that would otherwise be absorbed by a runner's ankle, knee, hip and lower back," explains Hilmar Janusson, executive vice president of research and development at ?ssur. The Cheetah's carbon-fiber layers then rebound off the ground in response to the runner's strides.
After the German report was released, the International Association of Athletics Federations (IAAF) banned Pistorius from competing. Pistorius hired Jeffrey Kessler, a high-powered lawyer who's represented athletes from the National Basketball Association and National Football League. It soon became clear that the IAAF's study was very poorly designed, so when Pistorius's team asked for a new study they got it. Soon scientists gathered at Rice University to figure out just what was going on with Pistorius's body.
The scientific team included Peter Weyand, a physiologist at Southern Methodist University who had the treadmills needed to measure the forces involved in sprinting. Rodger Kram, at the University of Colorado at Boulder, was a track and field fan who studied biomechanics. Hugh Herr, a double amputee himself, was a renowned biophysicist. The trio, and other experts, measured Pistorius's oxygen consumption, his leg movements, the forces he exerted on the ground and his endurance. They also looked at leg-repositioning time?the amount of time it takes Pistorius to swing his leg from the back to the front.
After several months the team concluded in a paper for The Journal of Applied Physiology that Pistorius was "physiologically similar but mechanically dissimilar" to someone running with intact legs. He uses oxygen the same way natural-legged sprinters do, but he moves his body differently.
Source: http://rss.sciam.com/click.phdo?i=ee11cf48006af4dd7b1177790ab07337
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