Anatomia em Educação Física

Cevnautas da Anatomia,

   Um artigo sobre anatomia e esporte na revista Economist. Esquisito, mas precisamos de alguma alma altruista e poliglota que adote a tradução para publicarmos na biblioteca do CEV. Com crédito para o(a) tradutor(a). Pode colar direto aqui. Laercio

Athlete’s foot
Sprinters are different from other people

IS ATHLETIC prowess attained or innate? Those who have suffered the tongue-lashing of a tyrannical games master at school 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 Sabrina Lee of Simon Fraser University in Vancouver and 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.

Dr Lee and Dr Piazza already knew that sprinters tend to have a higher proportion of fast-twitching muscle fibres in their legs than more sedentary folk can muster. (These fibres, as their name suggests, provide instant anaerobic pulling power, rather than the sustained, oxygen-consuming effort that is needed by longer-distance runners.) They suspected, though, that they would find differences in the bone structure as well. And they did.
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They looked at seven university sprinters who specialise in the 100-metre dash and five 200-metre specialists, and compared them with 12 non-athletic university students of the same height. In particular, they looked at the sizes of bones of the toes and heel. They also used ultrasonic scanning to measure the sliding motion of the Achilles tendons of their volunteers 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.

Dr Lee and Dr Piazza found, as they report in the Journal of Experimental Biology, that the toes of their sprinters averaged 8.2cm in length, while those of non-sprinters averaged 7.3cm. The length of the lever of bone that the Achilles tendon pulls on also differed, being a quarter shorter in sprinters.

These 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 non-retractable claws that give a similar advantage.

The reason for the difference in the Achilles tendons, though, is less immediately 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% more force than the same muscles in a non-sprinter would be able to manage.

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

FONTE: http://www.economist.com/node/14843831

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