Tag: Peter Weyand

By Rose Eveleth
Scientific American
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 Össur. 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 Össur. 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. (…)

By Sheila Eldred
Discovery News
When the start gun goes off for the individual 400 and 4X400 relay at the 2012 London Olympics, double-amputee sprinter Oscar Pistorius, the man known as the Blade Runner, will spring out of the blocks with the world’s best able-bodied athletes. It marks the first time an amputee will compete in the Olympics.

Pistorius will be wearing carbon-fiber prosthetics designed for sprinting. While the debate over whether his flex-foot Cheetahs makes it harder or easier for him to sprint continues, there’s no doubt that the way his body covers 400 meters is different from his competitors.

As the athletes explode from their starting blocks, the South African born without fibulas will likely get a slower start. Because he can’t flex an ankle or stiffen a leg, it takes slightly longer for Pistorius to start. As the athletes gain an upright position, however, Pistorius will be able to reposition his legs much more quickly than his competitors. It’s that repositioning speed that’s been the point of contention of much of the debate.

In 2008, the International Association of Athletics Federations, track and field’s governing body, banned Pistorius from competing against able-bodied competitors, deeming his blades an advantage.

Pistorius went to Rice University in Houston for what he hoped would be definitive testing that would prove he had no advantage. And at first, that appeared to be the case: using some of the data from the research, published in the Journal of Applied Physiology, the Court of Arbitration for Sport overturned the ban.

But later, two of the scientists pointed to key findings — the repositioning data — that they believe make up at least a 7-second difference in the 400-meter dash. Researchers Peter Weyand, an exercise physiologist at Southern Methodist University, and Matt Bundle, an assistant professor at the University of Montana, presented their case in a point-counterpoint article in the Journal of Applied Physiology in 2009.

The reason the data is so telling, says Weyand, is not just that it shows an advantage; it’s that the comparison between Pistorius and able-bodied world class sprinters is off the charts. (Weyand and Bundle released a statement that explains their science, hoping to clear up misconceptions.)

“With the most generous assumptions, he still comes out seven seconds ahead in the 400,” Weyand said. “He’s a below-average high school runner without those limbs. A lot of people don’t want to hear that.” (…)

By Nicholas St. Fleur
Science
Every Olympic season brings new scientific innovations that help athletes earn the gold and break world records. This year’s London Games, for example, will see South African double-amputee runner Oscar Pistorius make his debut on the 400-meter-dash while donning cutting edge, lightweight prosthetics. At the same time, Olympic officials will be cracking down on another innovation: new drugs that help athletes outcompete their rivals. Do prosthetic limbs offer an unfair advantage? What is being done to keep steroids and blood doping out of the games? And has scientific innovation become as important a player in the Olympics as the athletes themselves?

Hello everyone and welcome to ScienceLive! As you know, the Olympics are just a week away, and today we’re discussing the role of science in the London Olympics from blood dopers to the ‘Blade Runner’ and whether scientific innovation has become as important a player in the games as the athletes themselves.

Fleur: With us today is Don Catlin, a sports drug expert and professor emeritus at UCLA who founded the UCLA Olympic sport testing laboratory which is a national testing site for performance enhancing drugs in athletes.

To comment on the use of prosthetics in this year’s games is Peter Weyand, an Associate Professor of Applied Physiology and Biomechanics at Southern Methodist University in Dallas, Texas, who has studied the mechanics, physiology and locomotor performance behind running for decades.

Also on the biomechanics scene is J.L. McNitt-Gray, a Professor in the Departments of Biological Sciences and Biomedical Engineering at the University of Southern California, who studies the dynamics of human movement.

Let’s begin with a question for Peter and J.L. South African 400-meter-dash runner Oscar Pistorius will become the first amputee to compete against able-bodied athletes. What allows his prosthetic to help him keep up with the other athletes?

Weyand: Modern lower limb prostheses, in many respects, mimic the mechanical function of a biological leg during running. Two properties of the prostheses are particularly important: weight and springiness.

Excellent data is available to show that for single leg amputees, these limbs almost restore normal function, for double lower limb amputees, they enhance it due to the proerties above.

Single leg amputees are limited by their biological legs. Double limb amputees can fully exploit the mechanical properties of the prostheses for sprint running performance.

Weyand was asked whether the competitive advantage might prompt athletes to voluntarily have their legs amputated in order to have prosthetics.

Weyand: How realistic a voluntary amputation scenario might be is difficult to project at this time. One limitedly recognized aspect of the Pistorius controversy is that reaping the competitve advantages of lower limb prostheses requires having and using two of them. The primary reason Oscar Pistorius is so much faster than other amputees who use the same blades is because double lower limb amputees are quite rare.

Weyand was asked about the need for standardized prosthetics for the Olympics:

Weyand: The standardization issue is a critical one that raises difficult questions for the governing bodies of sport that are not unlike the performance enhancing drug issues in some ways. As science and technology progress, more and more powerful the avenues of performance enhancement become available and the lines between “natural” and unenhanced vs. enhanced become increasingly blurred.

Reasonable guidelines might be possible for prostheses, but the task of evaluating competitive fairness would be resource-intensive and probably never perfect. (…)