In order to stay balanced something has to give way and open up. Oftentimes it’s the hips. To open the hips you must first figure out what is meant by open. The physical explanation is the femur and hip socket mildly separate from each other. If you apply the liu he (more on this later) visualization to it, you will coax the hip joint to open up/down, left/right, front/back and from in to out. The open-close principle of in to out, or expanding outwardly in all directions from a center, to grow from a point to a sphere and back to a point describes the actual activity.
Hip gong or qua gong….imagine the hip is the foot … the hip touches the ground in the way the feet do (which we are accustomed to thinking). The qi travels through the leg bones through the bubbling well and into the earth. It can travel through the space between the legs or even all around outside the body.
Envisioning and practicing the more linear aspect of zhong ding entails recognizing an “opposing force” of up/down, left-right, front-back in the movements. Once you familiarize yourself with that concept you can practice it and refine it over time. Single basic moves is the path towards command of the concept.