Neatly matched knees may be behind Usain Bolt's speed

A pair of very symmetrical knees may be behind the record-breaking speed of Jamaican sprinter Usain Bolt, the world's fastest man, a new study suggests.
Researchers from Northumbria University, UK, found that the key to sprinting could be all in the similarity of your kneecaps.
They came to the conclusion after investigating the knees of Jamaicans, believed to be the finest sprinters in the world.
In 1996 they measured the width of the knees of 300 children aged about eight. A decade later they measured their knees again, then in 2010 they asked them to compete in a sprint.
Only 163 of the original sample stayed with the study until 2010, but those who did had more symmetrical knees - implying that knee symmetry is either an indicator of diligence or of a willingness to sprint, 'The Times' reported.

Among those who did sprint, speed was also correlated with symmetry.

"Jamaica is really disproportionately represented among the top-class sprinters around the world," Professor John Manning from Northumbria University said.
He added that more data was needed, but there was an indication that the Jamaican children were more symmetric than their Caucasian counterparts.
A possible explanation for the link between similar knees and sprinting success is that it represents a simple mechanical advantage.
"If you are symmetric in your legs, your legs are going to be more efficient. Any tiny increases in efficiency are going to translate into an effect in running," Manning said.

"That is the least interesting explanation and I don't think the right one," he said.
"The other explanation is the body has genetic instructions to develop symmetrically.
"When you think about it though, it is very difficult for the body to develop symmetrically. How does it do it? We don't know. But usually there is a millimetre or so difference. So this trait is a test of the viability of genes," Manning added.