“Newton figured out the laws of motion centuries ago but when we apply them to the human body it gets really complex, really quickly.” — Peter Weyand
Journalist Simon Usborne tapped the human-speed expertise of SMU biomechanics expert Peter Weyand for an article in the London newspaper The Guardian. The article examines the potential for humans to continue improving strength and speed beyond what has already been achieved.
Usborne interviewed Weyand for his expertise on the mechanics of running and speed of world-class sprinters like Usain Bolt. The article “How fast can we go? The science of the 100m sprint” published Oct. 3, 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 Simon Usborne
The greatest race in the Olympics is the simplest. Eight runners, eight straight lines. A bang, an explosion of muscle and, less than ten seconds later, a winner. And all they do is run. No bikes, boats, vaults or horses — just one foot in front of the other. Yet, in those three dozen blinks of an eye, sprinters in the 100m perform physical feats so advanced that scientists are still trying to understand them.
“On one level you’d think we would have pieced it together a long time ago,” says Peter Weyand, one of the world’s leading students of running and professor of applied physiology and biomechanics at South Methodist University in Dallas, Texas. “Newton figured out the laws of motion centuries ago but when we when we apply them to the human body it gets really complex, really quickly.”
Simply analysing the extreme motion and exertions of a sprinter is challenging. Weyand and his team have a large treadmill in their lab capable of rolling at 90mph. In the punishing max test, athletes straddle the moving belt and hop on for a few seconds at a time. They start slow, with rests in between. “We increase the speed until the athlete can’t maintain it,” the professor says. “We need eight steps without moving backwards for a good trial.”
The tests are a safer version of jumping off the back of an old Routemaster bus and staying upright for eight paces – athletes wear harnesses in case they trip – but how fast is the bus going? “The unofficial record on our treadmill is 11.72 metres per second,” Weyand says. That’s 26.7mph, or not far off a city speed limit, or Bolt’s peak speed during his 2009 world record run of 27.8mph. “When we have elite athletes do the test, the whole office comes over to watch.”
High-speed treadmills, slow-motion imaging and pressure sensors have allowed scientists to study aspects of elite sprinting that were largely unknown as recently as 15 years ago. “If you asked a coach in the late 1990s what they were doing it was all very much based on form,” Weyand says. “But when we started this work back at that time, the first thing we figured out is that what makes these guys fast is how forcefully they can hit the ground in relation to their body weight.”
When Usain Bolt looks like he’s floating over the track, he’s really not. That extreme rippling in the face that slow motion footage reveals in some runners demonstrates the forces that transfer from foot to floor. “We know that Bolt will peak out with each step at about five times his weight, while non-sprinting athletes will peak at about 3.5 times,” Weyand explains. “The science is clear: the top athletes are specialised to deliver the most force to the ground and that’s what makes them fast. But even now I think we’re still in the formative phase — it hasn’t yet translated into broad practices in training.”
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