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A circular momentum is generated when the body rotates around a vertical axis going through the center of gravity. The spring of the rear leg, the reaction force, and the force of the abdominal region are used to create a rotation of the hips, shoulders, and head in horizontal planes. The circular momentum is increased when the body is first twisted in the opposite direction, in a winding up motion, and by the antagonistic action of the hands (push-pull type of motion). These principles are used primarily in circular techniques.

A pendular momentum is generated when the hips swing backward and forward in a vertical plane going through the center of gravity. The pendular motion of the hips is used mainly in direct kicking techniques.

Concentration of force

The importance of the hips and abdominal region cannot be overemphasized. Because muscular force is of a cumulative nature, as many muscles as possible must be used in the motion (obviously these muscles have to be convergent and not antagonistic). Because of the reaction law, the long and flexible muscles of the extremities have to rest on the stronger and more stable muscles of the body to produce an effective result. Of all the profound muscles, the waist muscles are the strongest and therefore they must be contracted first to support the next closest muscles which in turn support adjacent long muscles and so on to the extremities of the body used for punching or kicking. The movement has to be executed fast to generate a high momentum. For the arm or foot to move quickly, muscles have to be strongly contracted. But if the muscular tension is kept throughout the motion, it will slow it down. Therefore the initial contraction of a muscle should be followed by a decontraction while the fist travels. At the time of impact, the muscles have to be tightened again to straighten the joints of the arm, insuring the maximum transmission of force. Otherwise, the reaction force will cancel out the force of the elbow. These periods of intense contraction and decontraction have to be well coordinated and it is only through intensive practice that one can develop a feeling for the right time at which the contraction or decontraction of the muscles should take place.