IntroIn hip rotation, a hip rotates around a pivot point to add power to a technique. The pivot point of the rotation is different depending on the technique being used. The pivot point may be the nonmoving hip, such as when performing a rear leg round kick, or it both hips rotating around the centerline of the body, such as when executing a jab from a front stance.
Use of hip rotationHip rotation is used in combination with other body movements to achieve maximum power in any technique, whether it be punches, kicks, or blocks. As stated in the force equation F=ma, force is increased by increasing mass and/or acceleration. For example, the fist has a small mass, but, by linking it to the mass of the entire body with hip rotation, the striking force of the fist increases. Although the fist may be small and thus have a small amount of mass, this makes it easier to increase its acceleration, which means an increase in its striking force.
Techniques that only use arm or leg muscles for power have less striking force. Using other muscles to create hip rotation to add body mass to a technique ensures the technique will carry the maximum power the body can generate. Hip rotation can increase the speed of a technique.
Hip rotation is based on two principles
- Summation of forces. Hip rotation reinforces the transfer of mass to into a technique. To properly use the summation of forces in a technique, the initial movement must be started by the larger, stronger, generally slower, muscles of the body (the hips and thighs) and then other muscle groups will be added along the way until the movement culminates at impact with the target.
- 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. For example, in a rear leg front kick, if the hip starts moving first, the lagging leg will be automatically be stretched before it leaves the floor. The stretch reflex is why techniques are chambered/cocked before they are executed.
Performing hip rotation
- The rotating hip should still be rotating toward the target when contact is made. If the rotation stops before impact, the power of the technique will be weakened. In a linear attack, such as a rear leg front side kick, the attack will be weakened if the rotation continues past the line of attack. Remember, in a linear attack, all forces, including those gained from hip rotation, must be directed into the line of attack.
- If the rotation is around a hip, the hip joint around which the rotation is occurring may remain in place or it may move toward the target. If the hip is allowed draw away from the target, the power of the technique will be weakened.
- Hip rotation may be described as forward or reverse. In forward rotation, the direction of rotation and direction of the technique are the same, such as when using a reverse punch, jab, or round kick. In reverse rotation, the rotation and the direction of the technique are opposite, such as when using an inside-to-outside middle forearm block where the hip rotates backward as the block is performed forward.
- Don’t cock the hip prior to movement by pulling it backward; this will alert the opponent to an attack. You may use the cocking motion as a feint by a faking a cocking motion with one hip and then attack with a rotation of the other hip. To master the hip rotation, concentrate on using it with every technique.
- In some kicks, such as side thrust kick, the hip rotates inward at the end of the kick and sort of "turns over" into the kick to give it an extra jolt of power.
Hip snapAs you become more proficient with hip rotation, the movement will develop into an even more powerful and quicker type of hip rotation called hip snap.
- Hip snap is hip rotation but with less movement and more quickness and therefore, more power.
- The hip suddenly snaps forward with maximum force for a short distance at the moment the technique impacts the target to add a jolt of force to the impact power.
- When punching and blocking, use hip snap in conjunction with the simultaneous retraction of the trailing arm to gain extra power.
To improve hip motion
- Train to improve hip and ankle flexibility and overall strength so proper posture can be maintained and the ankles and hips can easily flex to the positions required.
- Notice which muscles in the hips and legs cause rotation to happen and learn to use them properly by stimulating them with high repetitions of simple movements.
- Train slowly at first while concentrating on making large motions and using proper form. After the proper form is achieved, speed up the motions by making them shorter.
Key points in the execution of hip rotation include:
- Rotation must be smooth and in one continuous movement, no stops or hesitations.
- Keep the hips level with the floor.
- Both hips must rotate along a horizontal plane, no tilting.
- Don’t allow the hips to rise.
- The faster the hip rotation the stronger the technique.
- Remember to use the rear leg and foot to reinforce hip movement and to increase total power.
- Shoulders must rotate with the hips, not before or after.
- Keep the body vertical, no leaning.
- Hips, shoulders, and feet must rotate simultaneously.
- Use hip snap in punches and blocks.
- Use hip rotation and hip rolling/turnover in kicks.
- When moving forward, lag hip rotation to maintain stability.
- Letting the nonmoving hip joint move backward during a kick.
- Impacting the target after rotation has stopped.
- Keeping the back too straight. The lower back should have a slight, normal curve. Some men and women's buttocks protrude more than average so some instructors teach these people to tuck their hips up further than normal, but this flattens the lower back and should not be done.