The human body is capable of creating great forces – this is what propels the runner down the track. The brain stimulates the muscles, which then contract. The muscles are connected to the bones by fibres known as tendons – so the contraction of the muscles causes the bones to move, and can make you run.
Now, I have never been a very fast runner, and you may know people who are very fast, or are very good at running long distances.
Some of this is down to genetics – what you got from your parents. If you are trying to run fast you want you muscles to have a lot of ‘fast twitch’ fibres. This contract very rapidly, but get tired quickly. So very good for 100m, but not for marathons (for those you want slow twitch fibres). The shape of your body also makes a difference – if you are tall (like Usain Bolt – but he is unusually tall for a 100m runner), if you put on muscle easily etc
The majority is probably down to training – no matter what potential your body might have. The training will condition your muscles, so you can create the explosive starts and power needed. You will also learn the technique to get the most out of your body
Finally, you need the mental attitude, and at high level running this can really make the difference between wining and losing
So… a mixture of all is needed at the top level to achieve those kind of times
It is amazing that the human body can travel this fast. As Tess said some of it is down to genetics but you can also train your muscles to create more Type I fibres which contract quicker to help us sprint faster 🙂