A debate concerning the correct form of tai-chi stand has been popular among Tai-chi enthusiasts. I am talking about the issue of single-leg-weight (單重) or double-leg-weight (雙重). A correct stand is indeed important for anyone interested in practicing tai-chi because it would affect the effectiveness of building up one’s structure, can enable one to have the desired degree of mobility and power as well as an avoidance to possible harm to one’s knee joints. It is interesting to note that the classics said that one should avoid double-leg-weight (雙重), because it is less mobile and can easily be unbalanced by one’s opponent. Hence every debater would say that his particular style is not double-leg-weight (雙重)!
From another perspective, if one puts all his weight on only one leg, he will also surely be lacking in mobility as well as can easily be unbalanced by his opponent. Let us look at the above pictures (the left is Wu-style whereas the right is Yang-style).
As can be seen from the picture, the Yang-style practitioner did put his weight between his feet. It can be argued that his front foot has 70% of his weight whereas his rear foot has 30% of his weight. Hence it is not double-leg-weight (雙重). The Wu-style practitioner however did put all his weight on his front foot. However he was also exerting a force towards the ground through his rear foot. It is being argued that this is the correct form of putting 100% of weight on one foot.
Which stand is better? Well, it depends on what you want. In actual combat situation, a martial artist does need to put 100% of his weight on one foot, with the other foot acting as stabilizer (like a block of building having the building on its left being torn down, structural poles at an angle have to be erected on its left to ensure stability of the building). If we watch a tennis player in action (or any competitive sports that requires both mobility and powerful strikes), we can see that the player, when he is on alert to receive a serve, he will constantly change his full weight between his feet, either on his left or on his right. And when he is serving back the ball, he will put his full weight on one foot and with the other foot as stabilizer (he can’t do powerful serve without a strong stabilizer).
Having said that in practicing the tai-chi form as a kind of exercise for body building, sometimes putting all one’s full weight on one foot may cause too much pressure on the knee joints (of course it can also be alleviated with a higher stand). And should a practitioner wants to condition himself to real combat situations, it would be beneficial to him if he can put 100% of his weight on one foot with the other foot acting a stabilizer, at least for some of his practice time.PS: As a matter fact, the debate will never end... :)