Relaxation-tension-relaxation

There are several wrong times to tense the body:

• At the beginning of a movement. Typical symptoms of this mistake are grunts, gritted teeth, tensed neck, shoulders pulled up near the ears, and chin pulled down. The first motion of any movement must be sudden and explosive, no preliminaries or useless motions.
• At the half-way point of a motion. For example, in the front snap kick. The foot comes off the floor and the knee comes up. Beginners tend to stop here for a moment and then continue the kick. To do this, they tense the leg and body and the head bobs. People also tend to tense at the start of the last part of stepping, attacking, and blocking.
• Tensing body while kicking. During kicks, the upper body should be completely relaxed, with the hands ready to attack or defend.
• Tensing too long at the point of contact. The tension at the end of technique should last only a slit second. The duration of the tension depends upon what is intended. If muscle conditioning is being emphasized, then a longer, isometric contraction may be used. In a split second snap back technique, power is derived from the motion of the body, rather than locking into the technique.
• Tensing unnecessarily while waiting in a stance. Some muscles are needed to maintain proper posture, but many people tense too many muscles, and much harder than needed. As a result, they are rigid and immovable. They must relax to move, but by then it is usually too late.