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Techniques>Movement>Don't be jerky

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Don't be jerky


Jerky movements appear to be fast, but they are slow; smooth movements appear to be slow, but they are fast.


To survive in nature, the eyes of living things have evolved so they are able to detect sudden movement. This helps them spot predators and stay alive. Therefore, predators, both animal and human, have learned to stalk their prey by moving slowly or by moving fast and but smoothly while trying to blend with their surroundings.

Sudden, jerky movements are perceived as quick, even though they are relatively slow. It is the suddenness of the movement that elicits a quick nervous system response in the prey. Sudden or jerky movement means danger, so we react quickly. Fast, smooth movements are more difficult to detect, and, even when detected, there is less danger associated with the movement, so reaction time is slower.

Fast versus jerky

As we have learned from martial arts training, fast, powerful movement of a hand or foot is a sequence of smaller movements that start from the feet and continue until the hand or foot finally moves. For example, let’s examine a reverse/cross punch. The punch starts at the base, which is the feet, where they contact the ground. From a calm, relaxed state, the body begins pushing against the immovable feet. As the pushing force travels through the body, all the muscles throughout the body add their forces to it sequentially until finally the fist quickly and smoothly starts moving and accelerating straight toward its target, reaching its top speed just as it reaches its target.

To the opponent, the only movement detected is the attacking fist appearing to get larger as it gets closer. This movement appears slow because it is subtle and steady and there is little movement of the fist over the background. The punch is powerful because of the sequential forces that have built up behind it and are pushing it at an ever-increasing rate toward the target.

In a jerky punch, the entire body suddenly tenses just before the fist suddenly accelerates. This tension only causes the body to move slightly, but this movement is easily detected because the body movement covers a large portion of the background. This sudden movement causes the opponent to react instinctively to the attack. In a jerky punch, the body suddenly contacts and then releases all its energy in a quick burst. There is a sudden acceleration of the fist followed by a gradual deceleration and lessening of speed until it reaches its target. Therefore, jerky punches are initially quick, but then they slow and weaken as they travel toward the target.

In a proper punch, the body stays relatively relaxed during the punch until it tenses at impact. At that moment, the body tenses to a rigid structure from the fist to the feet so all the punching forces are transferred to the target. In a jerky punch, the body tenses before the fist moves and is relaxed at impact with the target. The sudden tension before the jerky punch causes stress to the body, and the relaxation at impact can cause injury to the puncher. This sudden tension with an explosive release is fatiguing and leads to even less powerful subsequent attacks.

Jerky movements may look quick, but it is all show and no go; it is all an illusion. Real speed and power come from smooth, fast attacks that devastate the target while protecting the puncher from injury.

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