Pain at our joints affect most of us when we approach middle age, affecting avid sportsmen as well as couch potatoes. A standard advice for many doctors in Hong Kong is to get rest to alleviate the pain, swallow some pain killers and in future, when "it is cured", refrain from strenuous exercises, no more jogging and no more badminton. The theory goes like this, "after decades of wear-and-tear at our joints, we have to accept the situation, after all, ligaments between joints cannot repair themselves". In severe cases, i.e. even the above cannot help, surgery will be needed. The above advice looks sound to most people, but not to practitioners of zhan zhuang chi kung whose practice has such healing effect. What is the theory behind such claimed healing? I shall explain.
The fact is that total wear-off of ligaments between joints is rare. In most cases, pain at joints is caused by bones in joints being pressed together, which is in turn caused by blockages limiting joint movement. Such blockages will inevitably accompanied by weakness in muscles that are supposed to be responsible for otherwise possible movements. Lack of usage causes a weakening of the muscles concerned. This explain the case why seasoned athletes can also suffer from joint pains. They may be able to move smoothly in ways demanded by their sports, other degrees of movements can be hindered due to insufficient usage.
In zhan zhuang chi kung, joint opening/relaxation (song 鬆）is of primary importance. The ultimate requirement of the practice of song is an internal sensation of "floating", most significantly (and importantly) being felt in our major ball and socket joints, our hip joints (kua 胯 ) and our shoulder joints. Whereas floating is the condition or sensation achieved by the advanced students (and whose continual training rests on the basis of floating joints), the intermediate students' training focus is to open the blockages. The simple rule is that when in nano or mega movements (the former refer to "movements" generated by our breathing muscles in zhan zhuang), our focus should be in the points of maximum resistance. Focusing as such requires a highly focused mind resulting an internal experience of exercise effect.
In standard zhan zhuang or combat stance, the process is called "listening to Jing" (聼勁, a tai chi lingo, in Yi-Chuen, it is called six direction tag-of-force 六面爭力). A practitioner has to patiently find the blockage or point of maximum resistance (which has to be listened/tested in three-dimensions, therefore six ways) and to direct jing (or force generated by breathing muscles that activates our body holistically) to ease open the blockages. It needs regular practice with a focused mind. When one blockage is cleared, the next blockage will appear. With a focused mind, your body will lead your way.