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Sprinting Science: Notes on Bolt and Pistorius

Fri, 2012-08-03 14:40 -- cgorski
Aug 3 2012 - 2:30pm
By: Chris Gorski
Stowe School: The David Donaldson Athletics Track, credit to Nigel Cox (http://bit.ly/OOcPbs) under the following license: http://bit.ly/2oQJN

Competition in Olympic track and field events begins today. It's timing for running, jumping, and throwing to grab the world's attention.

This weekend, Usain Bolt and Oscar Pistorius are both scheduled to race. Usain Bolt is the Jamaican sprinter and star of the Beijing Games, who will compete in the 100-meter race. Pistorius is a South African 400-meter runner. He was born without fibulas in each leg and as a baby, his legs were amputated below the knees. He runs with carbon-fiber prosthetics, and is widely recognized as the first amputee Olympic competitor.
 
Each will be the subject of extensive attention when he runs.
 
In a wide-ranging sports science interview that included the topics in the Inside Science News Service stories on legal, performance-enhancing supplements, and the reasons why athletes in endurance sports seem to have such different body types, exercise physiologist Keith Baar, from the University of California, Davis, had some interesting things to say about both runners. 
 
He said that Usain Bolt has added weight to his upper body, and for a good reason, but it might have hurt more than it helped:
 
"He's added body mass to his upper body. The idea was that it would help him with his start, but what it's actually done is it's taken away his key component, which is what they call his speed endurance, his ability to maintain his top speed. So that was always his key… [B]asically the first 40 meters are accelerating from stop, so you need big muscles to do that, or you need strong muscles. When you get to 40 meters, everything else from 40 meters on is the ability to maintain your speed. It's bad to have muscle mass at that point."
 
For viewers, this means that it would seem less likely that Bolt would separate himself from the field in the last half of the race, as he did in Beijing.
 
The same principle comes into play with Oscar Pistorius, said Baar: "[Pistorius'] efficiency is approximately 60 percent efficiency. That's how much return he gets from the energy he puts in, whereas an average able-bodied runner is about 30-40 percent efficient." 
 
This is significant because of what it means for Pistorius' speed endurance, Baar said: "When Oscar Pistorius is at the Paralympics, what you see in the 100-meters, because he's a double amputee, is all of the single amputees are way ahead of him by 40 meters, after 40 meters he catches and passes them because he's able to store the energy he's produced without actually costing him anything extra, because his prosthetics are storing the energy and returning it."
 
What Pistorius' prosthetics do better than human legs, Baar said, is store and return energy. There's a great New York Times Magazine story about Pistorius that touches on the debate about the issues as to whether or not the runner has an advantage and if he should be allowed to compete against able-bodied athletes.
 
Going back to Usain Bolt -- Brian Godsey, the mathematician I talked to for another recent Olympics story, said that he had doubts that the sprinter would be able to match his astonishing dominance from 2008 and 2009, when he won titles and set world records. 
 
Godsey added that the 100-meter and 200-meter races, expected to feature Bolt and his training partner Johan Blake, who beat Bolt at the Jamaican Olympic trials meet, would make for an exciting couple of races, and might even spur on the two to post some great times.
 
The mathematical model Godsey developed predicted that there was a 12-percent chance that someone would break the world record in the 100-meter race during this calendar year. Could that happen this weekend? 
 
Here's one more piece of bonus sports science: Did you know that the speed of sound is a factor in Olympic sprinter performance? Check out this article from The Atlantic. Here's an excerpt:
 
"… [A]thletes far away from the starting pistol were delayed by the time it took for the sound to travel to them, and differences so tiny can matter in races in which the margins are so small."
 
Enjoy the competition. We'll have at least one more news service story and one more blog entry on the Olympics before they wrap up on August 12.
 
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