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Scientists say they can explain Usain Bolt's extraordinary speed with a mathematical model.
His 100m time of 9.58 seconds during the 2009 World Championships in Berlin is the current world record.
They say their model explains the power and energy he had to expend to overcome drag caused by air resistance, made stronger by his frame of 6ft 5in.
The team calculated that Bolt's maximum power occurred when he was less than one second into the race and was only at half his maximum speed. This demonstrates the near immediate effect of drag, which is where air resistance slows moving objects.
They also discovered less than 8% of the energy his muscles produced was used for motion, with the rest absorbed by drag.
It's no secret why running is fun. Speed, the wind in your face, that adrenaline rush -- as soon as toddlers learn to run, it's hard to keep them still. They will choose running over walking as the preferred mode of transport. It's too bad that as people get older, as we become more circumspect in our movements, we also cease to run. In some cultures running is even considered a big no-no for grownups to do.
There's no great secret to running, and the benefits are great. Would you like to recapture the joy of running? Here are some ideas on how to start running for beginners.