GrandMaster HUANG - 13 Questions and Answers - Question 9

Q9. What is the rationale for relaxing the abdomen and withdrawing the coccyx (or tailbone)?
Qi is stored in the Dan Tien as a result of using consciousness to sink the Qi to this point. From here Qi should circulate to the whole body. If Qi just remains in the Dan Tien, then the abdomen will have the sensation of being stuffed. Only when Qi circulates throughout the body will the abdomen be relaxed and pliable. After a time, the abdomen will acquire some "bouncy" or "springy" effect and Qi would have been circulating to the whole body. Qi can be occluded or absorbed into the backbone. The Song of the Thirteen Postures says, "If the abdomen is thoroughly relaxed, then the Qi will rise." So do not just store the Qi in the abdomen otherwise it will simply bloat. Having the coccyx withdrawn means there is no protrusion of the buttocks while making sure at the same time that the hip joints are not "sliding" forward. This must be combined with relaxing the abdomen and both requirements must be met at the same time. Otherwise, there is no rootedness while the waist is stiff resulting in vertical imbalance or disequilibrium. It is important to maintain the uprightness of the central axis of the body in order to achieve central equilibrium. A test can be made as follows to see whether all this has been done correctly all along; use one thumb to press the abdomen and release the thumb suddenly. There should be a bouncing or springy effect of the abdomen. At the same time, the seat of the buttocks behind should be very soft to the touch.