The science behind Usain Bolt’s ‘superhuman’ legs

He’s a nine Gold medal-winning Olympic Champion, who has been known as the ‘fastest man on Earth’ and set to be the fastest player on FIFA 19, but what is the reason for Bolt’s ‘superhuman’ speed?

Speed is influenced by a range of factors, one of the key factors being muscle composition. There are two types of muscle fibres: slow-twitch and fast-twitch. Fast-twitch muscle fibres are associated with a fast contraction rate (40-45mm per second), whereas slow-twitch contract at a rate of approximately 15mm per second. Fast-twitch muscle fibres are therefore required for rapid movements including sprinting. Most muscles in the body tend to have a mixture of both types of muscle fibre.

Speed is influenced by a range of factors, one of the key factors being muscle composition

Usain Bolt’s legs, however, have a higher proportion of fast-twitch to slow-twitch fibres than the average man at 80% compared with 50%, respectively. This composition gives an edge enabling remarkable power and force and a speed 99.9% higher than the general population.

This ‘superhuman feature’ is due to a combination of genetics alongside intense training. Combined strength and endurance training results in (altered) muscle fibre type recruitment. Training can help shape undifferentiated fibres into either slow- or fast-twitch; however, the best runners were born with an imbalance of one or the other. This means that our genetics predispose whether we can develop into elite marathoners which have way more slow-twitch fibres, whilst sprinters like Bolt are born with a naturally high fast-twitch fibre proportion of muscle fibres.

Usain Bolt’s legs, however, have a higher proportion of fast-twitch to slow-twitch fibres than the average man at 80% compared with 50%, respectively

So, you may be hoping to become an elite athlete, and physical training can help you aim towards this superhuman quality to an extent. However, genetics appear to give that edge of superhuman status as displayed by Bolt.