Taijiquan attaches great importance to the lower abdomen, because "when the lower abdomen is relaxed and calm qi arises naturally” (Wang Zongyue). Situated in the lower abdomen is the dantian that "is the source of the movements of Taijiquan" (Wang Zhuanghong). “The strength of the whole body is emitted from the dantian, and also received and stored in the dantian” (Chen Xin); also "all movements and breathing in Taijiquan are dictated by the dantian; the dantian effects and the dantian supplies" (Li Yaxuan).
The peristaltic motions of the soft viscera in the lower abdomen facilitates the internal rotational movements of the dantian that in turn effects a driving force for the whole body. Two reasons are given for this: First, the weight and peristaltic motions of the organs naturally produce motions such as centrifugal, centripetal and rolling force; Second, in an upright position, the body parts by virtue of gravity are concentrated in this region and forms the body’s centre (of gravity). The position of the centre (dantian) is determined by the movements and harmonisations of all parts of the body. Therefore adjustments and balancing of the various parts of the body are necessary for the centre to be maintained. Based on the above two points, Taijiquan requires that all movements should originate from the dantian, return to the dantian, obey the dantian and support the dantian.
All parts of the body have an impact on the centre, among which the most direct are 1. the rise and fall of the diaphragm with breathing; 2. the retraction of the abdominal muscles; 3. the push and pull of the mingmen and the navel; 4. the substantial and insubstantial changes of the left and right kua; 5. the lifting of the huiyin; 6. the movement and positioning of the tailbone; 7. the inward and outward tilt of the pelvis. But all of them are affected by the movements of each other.
Although the centre is constantly changing in movements, the change is like a piano glide (glissando); although it is a sweep, the sweep demands that each key along the way is pressed and not one should be missed or skipped.
The internal dantian rotation should be smooth and circular, no matter if the direction is front or back, left or right, up or down, or oblique. In all cases the centre is naturally relaxed downwards by gravity with its own weight, rather than being pushed or pulled. The relationship between the centre and the legs is that force is sent downwards through the pelvis (kua), in order to facilitate the substantial and insubstantial changes in the legs (weight bear). Even if the upper body wants to borrow the rebound force from the ground, the centre should stay loosened down, and the upper body can only borrow the reactive force of the pushing down of the legs and feet. It's not the leg pushing directly upwards to move the centre. Like an acrobat walking in a ball, the ball rotates and moves by the changing of the centre, rather than being pushed from outside the ball. So the centre (dantian) determines how the body moves. The exact route is always related to relevant movements, to relaxation and to mental intention.
