PERFECT sprinters require one thing 鈥� perfect legs. Arms hardly matter at all.
鈥淚f they didn鈥檛 help with balance, you might as well rip them off and throw them away,鈥� says Ralph Mann, an exercise biomechanics specialist and president of the Las Vegas company CompuSport, which trains elite sprinters.
The ideal sprinter has legs jam-packed with 鈥渇ast twitch鈥� muscle fibres, which contract quickly without waiting for oxygen to diffuse into the tissue (see diagram).
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While only half of an average person鈥檚 muscle fibres are fast twitch, Olympic sprinters commonly have 80 per cent. The stars of the future are going to need even more to beat this year鈥檚 champions.
The oxygen-free, or anaerobic, metabolism of fast twitch muscles is rapid. It鈥檚 also inefficient and quickly causes lactic acid build-up, which leads to muscle fatigue. But since male sprinters blast through 100 metres in less than 10 seconds, that isn鈥檛 a concern.
Height also matters. Longer legs produce longer strides, so the historic trend towards taller sprinters is bound to continue. To make the most of what they have, top sprinters overdevelop the upper leg muscles, especially the gluteus and hamstrings so they can produce short explosive bursts of acceleration. They also run differently to most longer-distance runners. 鈥淭he idea is to be in the air and paw at the ground as quickly as possible,鈥� says Kathy Simpson, a biomechanics specialist at the University of Georgia in Athens.
A college level sprinter, for instance, pushes off the ground in about 0.12 seconds, while top Olympians do it in 0.08 seconds. Over the course of a race of 50 paces, maintaining that difference on each step shaves two seconds off their times. If future track stars could consistently slice away even another 0.001 seconds off their lift-off, they could chop world records by an impressive 0.05 seconds.
But that鈥檚 not easy. The best world-class sprinters sustain their best performance throughout a race, taking a breathtaking five steps per second, their upper legs torquing at an astounding 600 degrees per second. 鈥淭here鈥檚 no magic to why they run so fast,鈥� says Mann. 鈥淏ut if you find any, let me know.鈥�
