2. Chen Tai Ji Chuan's hip technique mainly trains the strength of waist and legs, which is the centripetal force and centrifugal force reflected by the dive of qi and the guidance of waist rotation, and also the key for Chen Tai Ji Chuan to exert his strength up and down and dominate the whole body movements. Flexible hip exercises and proper use of waist and leg strength are not only conducive to maintaining the balance of the whole body, but also to the precise command, scheduling and application of the nerve coordination and external force connection ability of each joint muscle in the pusher, as well as to the filling of internal strength and the reunion of breath.
3. Chen Taiji's transmission of crotch strength is the key to the transformation of octahedral support ring. When the crotch is not open, people are like a "big" font; When the crotch is open, the herringbone joint is like an inverted U-shape, which has both support and anastomosis, similar to the "bridge arch principle" in modern mechanics. The general rule of running line before and after crotch strength is generally ∞ shape, which is called "back line buckle" and "arc crotch adjustment" in terminology. In addition, the running requirement of crotch strength is: "Front crotch strength is indispensable, and rear crotch strength is indispensable." Divide the front and rear crotch force, that is to say, the change of the actual situation and the rotation adjustment of the crotch force should always rotate in the state that the front crotch is closed, the rear crotch is opened and the crotch force is round. It is required that the air impact holes at the front side of the crotch root should always be nested, and there should be no ups and downs such as protrusion and height during exercise, and there should be no disadvantages such as pointed crotch, crotch clamping, crotch washing, crotch twisting, crotch pushing and crotch swinging. If the crotch is transported to the upper arc, the crotch is adjusted to the upper arc; If the crotch is transported to the lower arc, it is adjusted to the lower arc; If the crotch is strong in the back arc, adjust it with the back arc. If the crotch is S-shaped, adjust it with the back line.