The View from the West

Winnipeg Free Press - PRINT EDITION

Athletes foot takes on whole new meaning in new study

By: The Economist

27/11/2009 1:00 AM | Comments: 0

IS athletic prowess attained or innate? Those who have suffered the tongue-lashing of a tyrannical gym teacher at might be forgiven for doubting the idea that anyone and everyone is capable of great sporting achievement, if only they would put enough effort into it.

Practice may make perfect, but not all are built in ways that make it worth bothering in the first place.

The latest evidence of this truth has been gathered by Dr. Sabrina Lee of Simon Fraser University in Vancouver and Dr. Stephen Piazza at Pennsylvania State University. They have looked at the anatomy of sprinters and found that their feet are built differently from those of couch potatoes.

They already knew that sprinters tend to have a higher proportion of fast-twitching muscle fibers in their legs than more sedentary folk. (These fibers, as their name suggests, provide instant anaerobic pulling power, rather than the sustained, oxygen-consuming effort that is needed by long-distance runners.) They suspected, though, that they would find differences in the bone structure as well. And they did.

They looked at seven university sprinters who specialize in the 100-meter dash and five 200-meter specialists, and compared them with 12 non-athletic students of the same height.

In particular, they looked at the sizes of toe and heel bones. They also used ultrasonic scanning to measure the sliding motion of the Achilles tendons as their feet moved up and down.

This allowed them to study the length of the lever created by the tendon as it pulls on the back of the heel to make the foot flex and push off the ground.

Lee and Piazza found, as they report in the Journal of Experimental Biology, that the toes of their sprinters averaged 8.2 centimeters (3.2 inches) in length, while those of non-sprinters averaged 7.3 centimeters (2.9 inches). The length of the lever of bone that the Achilles tendon pulls on also differed, being a quarter shorter in sprinters. The findings suggest sprinters get better contact with the ground by having longer toes. That makes sense, as it creates a firmer platform to push against.

In a sprint race, acceleration off the block is everything. Cheetahs, the champion sprinters of the animal kingdom, have nonretractable claws that give a similar advantage.

The reason for the difference in the Achilles tendons, though, is less obvious. At first sight, sprinters might be expected to have more Achilles leverage than average, not less.

First sight, however, is wrong. When muscles have to contract a long way, they usually do so quickly and with little force. When contracting short distances, though, they move more slowly and generate more force. Having a short Achilles lever allows the muscles that pull on the tendon to generate as much as 40 per cent more force than the same muscles in a non-sprinter.

It is possible that these anatomical differences are the result of long and rigorous training. But it is unlikely. More probable is that the old adage that great sprinters are born not made, is true. Everyone else, gym teachers included, should just get used to the idea.

Republished from the Winnipeg Free Press print edition November 27, 2009 A15

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