“Zhongzheng is not biased” is the fundamental axiom that delineates Taijiquan walking. When moving, “upper sag” means that the movement is not biased; when rotating, “keeping the central axis” is core. The “axis” concept implies a circle, but it is not necessarily restricted to a vertical manifestation. In fact, there are two important axes for human movement: one is the central axis and the other is the oblique axis.
      The central axis runs from “Baihui Point” to “Perineal Point”, vertically up and down, and is also the location of the body’s pulse. The central axis is beneficial to the horizontal rotation of the body, that is, the turning the of the waist. Generally speaking, turning the waist 45 degrees to the left and right is the limit of comfort. Excessive rotation requires a strong counter-rotational balance of the lower limbs, which can easily cause the body to lose its loose and natural atmosphere. The function of the this axis is mainly to balance oneself and maintain a leading edge. Even when moving, with this approach, the whole can still maintain a solid balance. This fundamental is generally applied in defense and during positional adjustments. The central axis does not aid lower limb movement, so this axis does not have to descend to the ground, this is the difference between the central axis and the mid-line.
      The oblique axis runs from “Baihui” through the body, reaching the heel along the hind legs. At this time, the front legs are supported upright. In the two-footed state, this is the most powerful rotating structure that penetrates from top to bottom, and is most obviously manifested when attacking. Loose hips are the source of power for the rotation of the inclined axis in conjunction with an integrated body. The entire body and upper limbs rotate in three dimensions along the inclined axis. Note that the two arms do not rotate around the axis, but instead rotate with the axis, and the axis and the body are integrated. If you need to leverage your footwork to adjust your position, you should immediately switch to the vertical central axis to allow your body to align with gravity and maintain balance and stability while in flight.