The theory of muscular contraction in tai chi

Studying tai chi requires persistent and continual practice. Reading a book cannot teach you tai chi. Yet, without a good understanding of theory, you might waste a huge amount of your valuable practice time, if you are able get there at all in the first place. The theory of muscular contraction in tai chi is simple, yet important. Reading this article is of no practical use if you do not practice tai chi or other mind-body exercise. "Understanding" with no practice is not understanding.

The theory of muscular contraction starts with two observations:

1. We can feel the exertion of muscular contraction when we contract our contraction muscles (contractors), and we can feel relaxed when we contract our extension muscles (extensors) - see picture below.
2. When we feel tensed psychologically or mentally, our contractors contract, and when we feel relaxed, our extensors contract.

The definitive requirement of doing tai chi is that our contractors and our extensors shall contract at almost the same magnitude, with one just slightly more than the other to make movement possible. The slow movement of tai chi is a natural outcome of a practitioner mindful balancing these two forces at all times during practice. In other words, the subjective feeling is not "to do slow movement", rather "to balance the forces so that slow (and graceful) movement will result". In other words, a tai chi practitioner contracts his muscles in a special way, rather than relaxes all his muscles during practice.

"Use Jing (or Yi) instead of Li" (用勁/意不用力) is an important tai chi essential. If we can feel we are exerting our muscles, we are overly using our contractors. When we are balanced in our muscular contraction, we do not feel the exertion (or Li). Our internal muscular feeling will be "muscles-as-one" or "body-filled-with-molten-lead".

In our working lives, most of the time we overly use our contractors. The result is that our joints (mainly our shoulder and hip joints) will likely be moved into slight misalignment when we approach middle-age, if not earlier, resulting in various kinds of pain in our body. And in our hectic lives full of psychological stress (which is normal rather than unusual), our emotional stress will be trapped inside our muscles and joints.

The practice of tai chi aims at releasing such misalignment and trapped energy, and to bring about good physical and mental health. In order that such benefits can be achieved (rather than just bragged about), a student of tai chi has to understand the theory of muscular contraction in tai chi and put its implications into practice. Needless to say this is only the beginning of everything.