Something Strange in Usain Bolt’s Stride
Last month, researchers here at Southern Methodist University, among the leading experts on the biomechanics of sprinting, said they found something unexpected
during video examination of Bolt’s stride: His right leg appears to strike the track with about 13 percent more peak force than his left leg.
lab, calls that period “30 milliseconds to glory.”
In other words, Weyand said, “You win your medal or you’re out of the running based on that short duration.”
Unlike elite marathon runners, who strike the ground with a force equal to about three times their body weight
and who must repeat each step about 25,000 times over 26.2 miles, sprinters are not concerned with endurance and fuel efficiency over 100 meters.
“But that superficial logic doesn’t really flesh out.”
A natural adaptation for Bolt has been to keep his left leg on the ground for slightly more time with
each step — 97-hundredths of a second, compared with 85-hundredths of a second for the right leg.
On average, Bolt struck the ground with 1,080 pounds of peak force on his right leg and 955 pounds on his left leg.
And with each stride, his left leg remains on the ground about 14 percent longer than his right leg.
“The logical thing to think is, well, you want both legs to deliver as much force as possible
and if one is not delivering as much force, if it delivered more force, he’d go faster,” Weyand said.
This gives him slightly more time to generate force with the left leg, Weyand said, providing greater lift off the ground.
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