One of the most important techniques in Taijiquan, as well as in almost all martial arts, is the need to rotate your waist while you are executing various forms. This is true whether you are doing warm up exercises, doing the forms in one of the Taijiquan form sets (e.g., the Simplified Yang Style 24 Form), or executing sophisticated Qin Na1/Self Defense techniques. From both the health perspective and the martial arts perspective, it is important to rotate the waist.
From the health perspective, you are exercising more parts of your body when you rotate your waist. For example, in a simple warm up exercise of “wave hands like clouds” when the hands are moving 180 degrees out of phase, if you are just moving your arms and hands, then you are exercising only your arms and hands. However, if you also rotate your waist, together with rotating your knees and your shoulders, then you are adding the exercising of your knees, waist, and shoulders in addition to exercising your arms and hands. Furthermore, when your eyes also follow the direction of your rotation, then you are also exercising your eyes. Once you have gone beyond natural breathing and start using your lower abdomen to help breathe during the breathing cycle, then you are massaging, or exercising, the internal organs in your lower abdomen.
This is why the two2 out-of-phase “wave hands like clouds” exercises, combining with several other simple warm up exercises can form a set of simple exercises that almost anyone, including senior citizens in their seventies or eighties or even nineties, can do to improve their health. In particular, the combination that I have used successfully to teach my 94 year-old mother-in-law consists of seven simple exercises. Besides the two “wave hands like clouds” exercises when the hands are moving 180 degrees out-of-phase, the other five simple exercises are a waist rotation exercise together with swinging the hands to slap the top of the shoulder halfway between the neck and the edge of the shoulder, the two “wave hands like clouds” exercises when the hands are moving in phase, the deep knee bend and rotation exercise, and the closing form exercise that is the final form in many Taijiquan form sets in which you bring your hands up above the head while breathing in, and then bring them down and to the side while breathing out and bending your knees slightly. This simple set of seven exercises can be learned in a few short lessons. They exercise many parts of your body, can loosen and strengthen many joints in your body, can increase your leg strength, and can regulate your breathing. This set of seven exercises is doable by almost anyone, can be done in about 15 minutes (or about two minutes per exercise). Doing it twice a day, once in the morning and once in the evening, should significantly improve your general health.
We now discuss waist rotation from the perspective of martial arts application. Waist rotation helps to increase the power of a punch or a kick. For example, if you punch with your right hand and keep the waist stationary, then the power of the punch comes from the arm only. However, if while you are punching, you also rotate your waist in a counterclockwise direction, then the rotating torque of the body adds to the power of the punch. Furthermore, if you bend your knees slightly and when you punch, you also rotate your knees/legs in a counterclockwise direction, then the power from the rotation of the legs are also conveyed to the right hand via the rotation of the waist. Thus the power of your punch combines the power from the motion of the arm and the motion of the legs and waist.
Besides being a good warm up exercise, “wave hands like clouds” also has its martial application in the form of a block. (If you want to see photographs of the martial applications of various forms discussed in this article, please see the article “Martial Applications of Taijiquan.” If someone tries to punch or kick you, then you can use the “wave hands like clouds” motion to block the punch or kick. Whether you use your right hand or left hand, or whether you use a clockwise or counterclockwise motion depends on the relative position of you and your opponent and on the height of the punch or kick. Again, if you move only your hand, then the power of your block comes from your hand only. However, if you combine the motion of the hand with the rotation of the waist and knees/legs, then the power of your block combines the power from the motion of the hand and the motion of the knees/legs and waist.
Similarly, when you use the form “wild horse shakes its mane” to lock the opponent’s arm while pressing him backward, if you keep your waist stationary, then the power of your pressing the opponent backward comes from only your arm. However, if you also rotate your waist and knees during the execution of this form, then the power of your pressing the opponent backward comes from your arm and the rotation of your legs and waist.
Another form that is used often in Taijiquan martial application is “roll back.” The crux of roll back is really waist rotation. Suppose someone is trying to push you back by pressing against your chest, by rotating your waist, you are turning your chest along the same direction of your opponent’s push, thus causing the opponent’s hand to slide off your chest. Your opponent is now pushing against air and starts to get off balance. You can accelerate his getting off balance by using your hands to pull him either along his direction of motion or at a slight angle from his direction of motion.
The final martial application that we want to discuss comes from Qin Na. Suppose someone grabs your right wrist with his right hand. You can counter his hold by first putting your left hand on top of his right hand, and then rotate your right wrist in a clockwise direction until your right hand is now above his right wrist. Then you can use your right hand to grab his right wrist. Now turn your right hand clockwise and at the same time turn your left hand counterclockwise. So you are twisting your opponent’s hand above the wrist in a clockwise direction and you are simultaneously twisting your opponent’s hand below the wrist in a counterclockwise direction, resulting in excruciating pain on your opponent’s wrist, and making him drop to his knees or to the ground. By rotating your waist in a clockwise direction while you are executing the above motion, you are adding the power from the rotation of your waist to the twisting motion around his wrist. Executing this precisely and properly can even break the wrist of your opponent.
In summary, we see the importance of waist rotation from the health perspective because it exercises more parts of the body, and we see the importance of waist rotation from the martial application perspective because it adds more power to whatever you are trying to accomplish. On the surface, waist rotation may appear to be simple, but it requires a lot of practice to execute it properly either while you are doing the forms or while you are engaged in martial arts.
 Qin Na is the Chinese grappling technique and is an integral part of self defense in Chinese martial arts.
 One in which the right hand is moving clockwise and the left hand is moving counterclockwise, and the other in which the right hand is moving counterclockwise and the left hand is moving clockwise.