[The following is an exact transcript of this podcast.]

Through the years, evolution has cooked up some pretty remarkable adaptations. The finch’s beak, the giraffe’s neck and sprinter’s toes. Yes, scientists at Penn State University have found that for runners who ace the 100-yard dash, the thrill of victory may spring from the ankles and the feet.

When the starting pistol fires, sprinters launch into the race with a burst of acceleration. That initial velocity depends, in part, on the length of their toes. The scientists examined the feet of a dozen collegiate sprinters and a dozen non-athletes of a similar height. They measured foot length and used ultrasound imaging to watch Achilles tendons in action. And they found two things.

First, the sprinters have longer toes. That could give them an advantage by allowing them to maintain maximum contact with the ground as they push off the starting block. Second, their Achilles tendons have less leverage. That might sound bad, but it actually allows their leg muscles to produce greater force.

So next time you see someone like Olympic champion Usain Bolt whip through a 100-meter sprint in less than 10 seconds, remember: his toes are a big part of such an amazing feat.

—Karen Hopkin