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Hack 88. Think Yourself Strong

You can train your strength and skill with imagination alone, showing that there's a lot more to limb control than mere muscle size.

How your brain controls your muscles is something you don't notice until it goes wrong. When you drop a plate for no good reason, when disease or age rob you of the ability to will your muscles to move just like that, when you can't stop your legs trembling (even though that is possibly the least useful thing they could be doing in your situation), then you notice the gap between what you want to happen and what your muscles do. Normally the coordination of body movement happens so smoothly and (seemingly) instantaneously that it's hard to really believe there are any gaps in these processes. Hold your finger up in front of your face. Watch it carefully. And . . . ready . . . curl it. Magic. How did that happen? It's impossible to truly introspect about the control system involved: our bodies appear to be the ultimate pieces of invisible technology.

But that doesn't mean there isn't a very complex system of control in place. It needs to be complex for the range of jobs done, at the speeds they're done. The standard visuomotor feedback loop (the delay between acting and getting visual information to update or correct that action) is 100-200 milliseconds,1 so much of this control has to happen without the aid of direct guidance from the senses. Movement must be controlled, at least in part, by processes that do not require immediate sensory feedback.

There's that number again: 100-200 ms! It occurs all over this book, and I think this may be the root of it; the commonly found window for conscious experience [Hack #27] may be this size because of the uncertainty introduced by the delay between our senses and reactions. So this is the range over which our brain has developed the ability to predict, by simulation, the outcome of our actions.

T.S.

The thing is, movements are often so quick it doesn't feel as if feedback loops are intimately responsible. Rather, it often does feel as if you send a "go" signal to your hand to stretch a finger or catch a ball. So how can we show this is actually what's happening? One way is to work on developing the control system itself and see how that influences the resulting movement. If these systems do indeed exist, then developing them without simultaneously developing your muscles should still improve performance.

In Action

Using your imagination alone you can train the motor signals from your brain so that you are stronger, faster, and more skillful. This example takes 3 months to work, so you may want to just listen to how the experiment was done rather than doing it yourself. It's taken from a study led by Vinoth Ranganathan,2 who was following up on a study done 12 years previously by Guang Yue in the Lerner Research Institute department of biomedical engineering.3

The study involved volunteers training, in two different ways, the muscle responsible for pushing outward the little finger. (To see what they were doing, put your hand palm downward on the table, fingers together, then imagine you're pushing a weight out by moving your little finger only to the side). They trained for 12 weeks, 15 minutes a day, 5 days a week. Some volunteers trained by actually tensing the muscle, but others were instructed to merely imagine doing so.



After 12 weeks, Ranganathan measured the force that the volunteers could exert with their little finger muscle. Both groups had become stronger, those actually tensing their muscles during training improving by 53%, those using imagination by 35%. That's not a large gap, especially if you consider that training just using your imagination is probably the harder task to do.

How It Works

The Ranganathan study used the little finger muscle because it is not used much. It is easier to see changes in strength here than in more primary muscles, such as those in the arms or legs.

In the same study by Ranganathan et al., another group of volunteers showed they could increase the strength of a more important muscletheir elbow flexorusing just mental training too.

 

As well as measuring the force exerted by the volunteers before and after training, the researchers also measured the control signals sent by the brain to the muscle using EEG [Hack #2] and other measures. They were able to conclude that the main reason for the increase in strength was an increase in the strength of the signal from the motor regions of the brain to the muscle, not an increase in the size and strength of the physical muscle.

This fits with other findings, including one that training muscles on one side of the body can increase the strength of the corresponding muscle on the untrained side.

The major part of any initial improvement in muscle control may be getting the signal right, rather than training the muscle. Correspondingly, the contextual interference effectpracticing skills in a random order is a better way to improve performance [Hack #86] has been shown to work with mental practice too.4


Date: 2015-12-11; view: 601


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Hack 80. Act Without Knowing It | Three Kinds of Motor Control
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