13 July 2012

The science behind Bolt's speed

Colchester Campus

Usain Bolt

The secrets of Usain Bolt’s phenomenal speed are uncovered in new research from the Essex.

Despite Bolt not having the physique of a typical sprinter, sports scientist Dr Matthew Taylor believes he can explain Usain Bolt’s phenomenal speed. His research, published in the International Journal of Sports Medicine, suggests that Bolt’s height gives him an advantage.

Dr Taylor explained: “Over 100m, sprinters Bolt has run against, such as Tyson Gay and Asafa Powell, take about 45 steps. Bolt takes 41. This allows him to cover a greater distance with each step, which in turn means he spends more time on the ground – only around one-hundredth of a second more with each step. We think that allows him to generate force over a longer time frame – and as he lands his leg is less stiff, which possibly allows him to store and then release some energy as he leaves the ground again.”

The findings suggest that Bolt’s height and build are an advantage for him, despite the fact that, in Dr Taylor’s words, “sprinters are usually quite bulky, but Bolt is tall and slender. The prevailing wisdom is that you can accelerate easier if you’re shorter. When you come out of the blocks, you take a high number of steps to accelerate. Elite sprinters are getting taller and slimmer – but at 6’5” Bolt is the tallest – and he can quite clearly accelerate very well.”

Dr Taylor and a colleague used statistics from Bolt’s record-breaking 100m in Berlin in 2009 to create a mathematical model. He and Professor Ralph Beneke, formerly at Essex, and now at the University of Marburg have written three papers, which together form the first hypothesis for how Bolt runs.

They believe that Bolt could actually be running faster. “He says he can do around 9.4 seconds,” Dr Taylor said. “Partly, that is to freak out his opponents, but in the Beijing 100m final, he relaxed at the end, because he was celebrating for the last 20 or 30 metres. Looking at Berlin, it actually took him 0.14 seconds to react to the starting gun. There were five other sprinters faster than Bolt at that point, but it was the only time in the entire race when he was behind. If the conditions were optimal – the maximum legal wind behind him, the fastest possible legal reaction time out of the blocks and if he’d been in Mexico City, at altitude – he could have run under 9.5, a mid 9.4.”

Dr Taylor would like to test his theory in the lab. “No-one really knows the biomechanics of someone running at that speed,” Dr Taylor said. “We need to strap some kit to Usain Bolt. The fastest speed someone does in a lab setting is around nine metres per second. Bolt’s fastest speed over 100m is about 12.5m per second. We need someone to develop some miniaturised kit which you can strap onto someone’s spikes – and then we need to put Bolt in the spikes.”

Picture: courtesy of Pete Niesen/Shutterstock.com

Ends

Notes to editors

For further information, please contact the University of Essex Communications Office on 01206 872400, e-mail: comms@essex.ac.uk

Together, Dr Taylor and Professor Beneke have published three papers on Usain Bolt:
• Spring mass characteristics of the fastest men on earth, International Journal of Sports Medicine, 2012
• The Fastest Men's 100m Sprint Final – Stature and Step Rate were Cues for Success (written with Renate Leithäuser), Medicine & Science in Sports & Exercise, 2011.
• What gives Bolt the edge – A.V. Hill knew it already! Journal of Biomechanics, 2010.

Existing statistics show that, during the fastest part of the Beijing 100m final, Bolt’s steps were 2.77 metres long, compared to 2.51m for Asafa Powell and 2.48m for Tyson Gay. Taylor and Beneke’s model estimates that Bolt was in contact with the ground for 0.091 seconds with each step during the fastest part of the race, compared to 0.080s for Asafa Powell and 0.070s for Tyson Gay.

Professor Ralph Beneke is now Director of the Institute for Sports Science and Motology.

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