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How Stuff Works: Scientists Discover Something Mind-blowing About How Usain Bolt Runs

How Stuff Works covered the research of Peter Weyand and his colleagues on the asymmetrical running gait of the world’s fastest man.

Journalist Patrick J. Kiger with the news site How Stuff Works covered the research of SMU biomechanics expert Peter Weyand and his colleagues Andrew Udofa and Laurence Ryan for a story about Usain Bolt’s asymmetrical running gait.

The article, “Scientists Discover Something Mind-blowing About How Usain Bolt Runs,” published Aug. 2, 2017.

The researchers in the SMU Locomotor Performance Laboratory reported in June that world champion sprinter Usain Bolt may have an asymmetrical running gait. While not noticeable to the naked eye, Bolt’s potential asymmetry emerged after the researchers dissected race video to assess his pattern of ground-force application — literally how hard and fast each foot hits the ground. To do so they measured the “impulse” for each foot.

Biomechanics researcher Udofa presented the findings at the 35th International Conference on Biomechanics in Sport in Cologne, Germany. His presentation, “Ground Reaction Forces During Competitive Track Events: A Motion Based Assessment Method,” was delivered June 18.

The analysis thus far suggests that Bolt’s mechanics may vary between his left leg to his right. The existence of an unexpected and potentially significant asymmetry in the fastest human runner ever would help scientists better understand the basis of maximal running speeds. Running experts generally assume asymmetry impairs performance and slows runners down.

Udofa has said the observations raise the immediate scientific question of whether a lack of symmetry represents a personal mechanical optimization that makes Bolt the fastest sprinter ever or exists for reasons yet to be identified.

Weyand, who leads the lab and its researchers, he is an expert on human locomotion and the mechanics of running. He is Glenn Simmons Professor of Applied Physiology and professor of biomechanics in the Department of Applied Physiology & Wellness in SMU’s Annette Caldwell Simmons School of Education & Human Development, is director of the Locomotor Lab.

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By Patrick J. Kiger
How Stuff Works

Jamaican sprinter Usain Bolt is the world record-holder in both the 100- and 200-meter, and winner of those events in the last three Summer Olympics. Bolt can hit a top speed of around 27 mph (43.5 kph), and has clearly established himself as the greatest sprinter of all time. But there’s something curious about his legs, and the way he uses them.

As the athlete prepares to run in his final world championship meet in London’s 2017 World Athletics Championships, taking place Aug. 4-13 and less than three weeks before Bolt’s 31st birthday, scientists are still trying to figure out just how the fastest human on the planet manages to achieve such incredible speed. Researchers at the Southern Methodist University (SMU) Locomotor Performance Laboratory don’t quite have the answer yet — but they’ve made a surprising discovery.

The researchers analyzed video footage of Bolt and other sprinters from the 2011 Diamond League race at the World Athletics Championships in Monaco. They also used a “two mass model” analysis tool they developed, which allows them to study the physical forces that a runner creates — without actually bringing Bolt into a lab and putting him on a treadmill. They found that Bolt had an uneven, assymetrical stride, which is something that scientists might have expected to slow him down.

When he runs, Bolt’s right leg strikes the ground with 13 percent more peak force than does his left leg, and with each stride, his left leg stays in contact with the track about 14 percent longer than the right. The researchers findings have been published in a new study in the Journal of Experimental Biology.

Bolt’s asymmetrical stride is probably due to his anatomy. As he recounted in his autobiography “The Fastest Man Alive: The True Story of Usain Bolt,” Bolt discovered as an adult that he has scoliosis, a condition in which his spine curves slightly to the left, which has forced his hips out of alignment so that his right leg is a half-inch (1.2 centimeters) shorter than the left. Bolt has written that he feels awkward standing still, and leans to the right because it feels uncomfortable to stand and place pressure on his left leg. Sitting in the same position for too long gives him backaches.

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