What's the secret to running and swimming faster? The position of your belly button, say scientists

The reason why black people make better sprinters and white people dominate swimming races has been explained by scientists - it's down to their belly buttons.

Whether it sticks in or out is not relevant but researchers found that the position of the navel in relation to the rest of their body affects athletic ability. This is because the naval is the body's centre of gravity.

A higher naval means a higher centre of gravity - so your body is pulled forward faster - while a lower navel means a longer torso which makes for a better swimmer.

The researchers say their findings prove why black people are more likely to sprint faster while white people make swifter swimmers.

Duke University professor Andre Bejan, the lead author of the study published in the International Journal of Design and Nature and Ecodynamics, explains: 'What matters is not total height but the position of the belly-button, or centre of gravity.

'It so happens that in the architecture of the human body of West African-origin runners, the centre of gravity is significantly higher than in runners of European origin which puts them at an advantage in sprints on the track.

'Individuals of West African-origin have longer legs than European-origin athletes, which means their belly-buttons are three centimeters (1.18 inches) higher than whites.'

That means the black athletes have a "hidden height" that is three percent greater than whites', which gives them a significant speed advantage on the track.

Professor Bejan adds: 'Locomotion is essentially a continual process of falling forward, and mass that falls from a higher altitude, falls faster.'

In the pool, meanwhile, whites have the advantage because they have longer torsos, so their belly-buttons sit lower on the body.

Swimming is the art of surfing the wave created by the swimmer,' said Prof Bejan. 'The swimmer who makes the bigger wave is the faster swimmer, and a longer torso makes a bigger wave. Europeans have a three-percent longer torso than West Africans, which gives them a 1.5-percent speed advantage in the pool,' he said.

Asians have the same long torsos as Europeans, giving them the same potential to be record-breakers in the pool.

But they often lose out to whites because whites are taller, said Prof Bejan.

Many scientists have avoided studying why blacks make better sprinters and whites better swimmers because of what the study calls the "obvious" race angle.

But Prof Bejan said the study he conducted with Edward Jones, a professor at Howard University in Washington, and Duke graduate Jordan Charles, focused on the athletes' geographic origins and biology, not race, which the authors of the study call a "social construct."

They charted and analyzed nearly 100 years of records in men's and women's sprinting and 100-meters freestyle swimming for the study.

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