Why can't I run fast?
Presenter Greg Foot investigates whether humans will be able to run faster and continue to break world records, or if there is a limit to human performance. Greg explains that running involves exerting a force against the ground which in turn exerts a counter-force on the human body. The greater the force exerted by the leg muscles, the faster a sprinter can run. He demonstrates the force exerted by running over a pressure pad and explains the force is measured in Newtons. A top athlete can exert a force of four times their body weight but this force is limited by our genes. Greg explains the difference between slow-twitch and fast-twitch muscle fibres and why sprinters need genes that ensure they have more fast-twitch fibres than most other people. He then explains why four legs are better than two legs and investigates if having longer legs would enable us to run faster.