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Karate Twitch Muscles

I always urge students to relax and to tense the appropriate muscles for only a split second during the impact of a strike or block. Relaxing is one thing, but how should a student "tense" their muscles?

There are two types of muscles - fast twitch muscles and slow twitch muscles. In other words, some muscles are good for fast, snappy movement, and other muscles are good for slower, but more sustained movements. For striking, we need to develop and use fast twitch muscles. Slow twitch muscles are used for basic body movement (stepping and turning) and supporting the body.

I will give you a good example of a fast twitch muscle. Have you ever started to doze off and feel your arm or part of your body jerk? You were relaxed and yet your body moved very fast -- with no apparent effort. This is a fast twitch.

You can see fast twitch muscles in action in Kendo. They could not possibly hit that quickly using slow twitch muscles. Kendo people are fast because they train the fast twitch.

Fast twitch muscles become fatigued very quickly. If you were to twitch constantly, or a dozen times in rapid succession, you would become tired and your muscles would eventually fail. Slow twitch muscles can work much longer because they produce and consume energy gradually.

The key is to use fast twitch muscles and slow twitch muscles together and to use the right type of muscle for the right function. When moving from one position to another, you will generally use slow twitch muscles and keep your body as relaxed as possible. You should only use as much effort as is needed to move and maintain your body posture. Once in the optimum position, you will throw (release) the technique and fire your fast twitch muscles at the instant of contact. The coiling or wind up uses slow twitch muscles. The throwing/release use fast twitch muscles of the torso and the impact uses fast twitch muscles of the arm or leg.

The secret is to use the fast twitch muscles of the arm or leg (during kicks mostly) only when necessary. In this way, you will not become fatigued. All of the set up is done with slow twitch muscles or the fast twitch muscles of the torso. The fast twitch muscles of the arm or leg are used sparingly and have time to recover between each use.

One of the long term goals of Karate training is to develop the muscles -- fast twitch and slow twitch -- and to use them appropriately.


Charles C. Goodin