When it comes to speed, humans have got nothing on cheetahs - or greyhounds, kangaroos or zebras for that matter. It’s over long distances we really come into our own: when running for hours or even days, our body structure and excellent sweating skills make us able to outpace much faster mammals.

But what are the limits of human endurance? Can we run ever further and faster, and what’s the best diet to fuel such ambitions?

Presenter: Marnie Chesterton

(Photo: a runner in the Spartathlon ultramarathon, with kind permission from the International Spartathlon Association)