Monday 10 May 2010

Why are boys generally better at throwing a ball than girls?

The answer to this question is not, as you might think, one of strength. It’s one of balance.

Humans have a real problem maintaining balance. It takes quite a long time for us to learn how to stand up and move bout without falling over. An action like throwing a ball is especially destabilising. Throwing with your right arm requires a compensatory activation of the lower leg muscles to stop you from spinning round and falling flat on your face.

How does your brain know which muscles to stimulate and by how much? To start with, it doesn’t know because there are too many variables in the position of your shoulder, elbow and wrist. The brain is programmed to keep us as stable as possible, so to reduce the variations it freezes the joints, so that it can treat the arm as one solid unit. This maintains stability, but at the price of effectiveness, because muscles aren’t very effective when they’re frozen. The only way of getting power is to transfer the kinetic energy from your trunk and legs. This is why when you see someone throw a ball who’s not used to doing it, they look very stiff, they have to put a lot of effort into it, and they may well jump at the same time. Because boys tend to play more ball games than girls, they are more likely to have got past this stage.

Gradually, with practice, the brain works out which combination of muscle stimulation is the most efficient, and starts to unlock the joints. This allows the elastic energy in tendons to be released, so that the ball is thrown further. In the end, the brain works out the most energy-efficient method of carrying out the task. This is an individual thing – different people with different statures and muscle tone shouldn’t come to the same answer.

By this time, the athlete is likely to have developed an effortless, natural-looking style, although it can look slightly unusual in some people, for instance Michael Johnson’s very upright running style.

The ideal is that the person finds their own solution to the problem. Direct coaching, telling someone how to do it, hinders the process of self-discovery. It can give them short term solutions for specific situations, but there’s evidence that skills acquired through self-discovery (implicit learning) are much less likely to fail under pressure than when people have been instructed precisely how to do something (explicit learning).

When people are taught explicitly, their performance in a match situation is likely to be inferior to how they perform in practice. Also, there’s evidence that long-term accumulative injuries can occur from early attempts to acquire techniques which are often anatomically inappropriate for particular individuals. This has been a particular problem for fast bowlers in cricket.

For more information please visit http://www.donneroptometrists.co.uk/sports-vision.htm

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