The following story ran on the July 18, 2012, edition of the Discover magazine Not Rocket Science blog. Physiologist Peter Weyend provided expertise for this story.
July 30, 2012
In 2008, at the Beijing Olympic Games, Jamaican sprinter Usain Bolt ran the 100m in just 9.69 seconds, setting a new world record. A year later, Bolt surpassed his own feat with an astonishing 9.58-second run at the 2009 Berlin World Championships. With the 2012 Olympic Games set to begin in London, the sporting world hopes Bolt will overcome his recent hamstring problems and lead yet another victorious attack on the sprinting record. He is arguably the fastest man in history, but just how fast could be possibly go?
That’s a surprisingly difficult question to answer, and ploughing through the record books is of little help. “People have played with the statistical data so much and made so many predictions. I don’t think people who work on mechanics take them very seriously,” says John Hutchinson, who studies how animals move at the Royal Veterinary College in London, UK.
The problem is that the progression of sprinting records is characterised by tortoise-like lulls and hare-like… well… sprints. People are getting faster, but in an unpredictable way. From 1991 to 2007, eight athletes chipped 0.16 seconds off the record. Bolt did the same in just over one year. Before 2008, mathematician Reza Noubary calculated that “the ultimate time for [the] 100 meter dash is 9.44 seconds.” Following Bolt’s Beijing performance, he told Wired that the prediction “would probably go down a little bit”.
John Barrow from the University of Cambridge – another mathematician – has identified three ways in which Bolt could improve his speed: being quicker off the mark; running with a stronger tailwind; and running at higher altitudes where thinner air would exert less drag upon him. These tricks may work, but they’re also somewhat unsatisfying. We really want to know whether flexing muscles and bending joints could send a sprinter over the finish line in 9 seconds, without relying on environmental providence.
To answer that, we have to look at the physics of a sprinting leg. And that means running headfirst into a wall of ignorance. “It’s tougher to get a handle on sprinting mechanics than on feats of strength or endurance,” says Peter Weyand from Southern Methodist University
, who has been studying the science of running for decades. By comparison, Weyand says that we can tweak a cyclist’s weight, position and aerodynamic shape, and predict how that will affect their performance in the Tour de France. “We know down to 1%, or maybe even smaller, what sort of performance bumps you’ll get,” he says. “In sprinting, it’s a black hole. You don’t have those sorts of predictive relationships.”...