The jab is the simplest example of linear motion applied to punching. In its most basic form, the rear leg pushes the hips and body toward the target, while the front knee and ankle bend in the direction of the target. The leading side of the body is pushed toward the target. The lead hand snaps straight to the target with the body weight. To cover more distance, the front foot may shift toward the target. To cover even more distance, the front foot and then the rear foot shift forward.The side kick takes advantage of linear motion to create power. In the lead leg side kick, both the hip and the target lie on the same straight line. To be effective, the kick must be thrust down that same straight line, with the base foot thrusting the hips toward the target. At the moment of impact, the hips should be closer to the target than the base foot to allow the support leg to thrust the kick toward the target.Moving upward while delivering a technique is usually a mistake unless the target is almost directly above you or the surface of the target is tilted toward the ground. Upper cuts to the body and head make use of this upward motion.Dropping the body weight while striking downward is the only method that does not make direct use of reaction force as its primary source of power. Dropping power involves lowering the body and delivering the technique in harmony with gravity. This can be done by dropping to a lower stance or after first jumping in the air.

Circular motion (hip rotation)

Hip rotation helps achieve maximum power in any technique, whether it be using punches, kicks, or blocks. It is used in combination with other body movements to complete a technique. As stated above in the equation F = ma, force is increased by increasing mass or acceleration. The fist has a small mass, but, by linking it to the mass of the entire body, the striking force of the fist increases. Techniques that only use arm or leg muscles for power do not draw on the power of the other muscles of the body or the mass of the body. Using other muscles to drive hip rotation and then using the rotation to add power to a technique insures the technique will carry the maximum power the body can generate. Hip rotation also increases the speed of a technique.

Hip rotation is based on two principles:

• Summation of forces. Hip rotation reinforces the transfer of mass to into the technique. To properly use the summation of forces in a technique, the movement must be started by the larger, stronger, generally slower, muscles of the body (the hips and thighs) so they will be moving into the target along with the quicker hands or feet together at the moment of impact.
• Stretch reflex.In the stretch reflex, a muscle is stretched immediately before it is contracted so it will contract more forcefully than if it had not been stretched. If the hips start moving first, the lagging leg will be stretched before it moves into the kick.The lower back should have a slight, normal curve. Some women's buttocks protrude further than most males so some instructors try to make these women tuck their hips up further than normal so that their profile looks similar to a male profile. This flattening of the lower back should not be done.

The rotation usually happens around the hip joint that is serving as the center of rotation, not the center of the body. This would be the left hip joint, during a right hand reverse punch. The hip joint around which the rotation is occurring should remain firmly in place or move toward the target. The technique will be weakened if that hip joint is allowed draw away from the target. The hip joint on the punching arm side should still be rotating toward the target when contact is made. The technique will be weakened if the rotation stops before impact is made. The technique will also be weakened if the rotation continues past the point where it was going toward the target. Remember, in a linear attack the hips must rotate into the line of attack.

The pivot point in hip rotation changes, depending upon the situation. It may be at either of the hip/leg joints or along the center line of the body. When the body is stationary, rotation is usually around the body's center line, such as when executing a jab from a front stance. To gain move power in the jab, the front foot may slide forward so the pivot point changes to the trailing hip/leg joint, thus adding more rotation and more power to the punch. When the body is moving, rotation usually pivots at one of the hip/leg joints, such as when executing a trailing leg side kick.

Hip rotation may be described as regular or reverse. In a regular rotation, the direction of rotation and direction of the technique are the same, such as with a reverse punch, jab, or round kick. In reverse rotation, the rotation and the direction of the technique are opposite, such as with an inside-to-outside middle forearm block. Hip rotation may also be used with a lead punch but the lead hip must drive toward the target. The rotation occurs around the rear hip joint.You master hip rotation through regular and constant training. As you become more proficient with hip rotation, the movement develops into an even more powerful and quicker movement called hip snap.

Hip snap is hip rotation but with less movement and more "snap" and therefore, more power. Think of a technique as an arrow. To fire the arrow, the bowstring is pulled back and it bends the bow backward to store energy in it. When the string is released, the energy stored in the bow snaps the arrow forward. Firing a technique operates under the same principle. The hip is twisted backward to store energy that is snapped to apply the mass of the body into the technique.