Charles, from Derwood, MD commented in an email:
“When doing the form is it a good rule of thumb to never push off with the “full” leg, but simply bend the knee and relax the “empty” leg. It is always tempting in the postures to push off, for instance when executing a push, since this seems the natural way to push someone.”
I am taking your query and adding to it so I can speak about pushing, with clarity.
There are several methods of pushing. In none of them do you push off the full leg, and into the opponent. (Which is the question I want to answer, whether or not you intended to ask it.) Pushing into someone with your weight seems right, because it seems intuitive. And very little about push hands is intuitive. So be careful with your push. There are 2 dangers to pushing over your center and into your opponent: 1. If someone neutralizes you, you will go right over the full leg you just pushed off. 2. Even if balanced, if your push is not successful, your center of balance becomes apparent, and you are vulnerable. In any case, in pushing off you will be leaning on your opponent, and you may remember what Professor Cheng had to say about that: “Do not lean your meat on me, I am not a meat hook.”
There is a method of pushing involving the shifting of weight from one foot to the other, but it is important to note, do not let your weight or center go beyond your front foot and on into your partner/opponent, as that will leave you leaning on him, and make you vulnerable. If you lean, you can be pulled or pushed over yourself.
In this kind of a push you sit back, leading your opponent to vulnerability, and then, if you choose not to neutralize, make your body into one piece and move forward as a unit, allowing your body to provide momentum for the push. As you shift the weight from your back foot to your front foot, you feel your opponent’s center, so you know where to go. Professor Cheng called that listening to your opponent. You do not let your weight go beyond your front foot, only your momentum goes into your partner/opponent. There are some more specific directions to this push, but that is another lesson.
Another way to push is fa-jing. The first thing we need to say about fa jing is this: The technique does not work on dead weight. If you are facing a ton of steel on a slab, 4 ounces is going to move, well, four ounces, and fa-jing is not going to be of help to you. That said, to fa-jing, you place your weight all on one foot, typically the front foot. Then you spring or push out of the other foot, typically the back foot, into your partner/opponent. If he is alive, and not trained to listen to and neutralize fa-jing, he goes flying.
You do not do this with your weight, in fact, as in root, you need to keep your weight out of the equation. The front foot is the load bearing foot and the back foot is the spring. Push out of your spring.
Be aware, please be careful when pushing, especially with the fa-jing, as you can easily get carried away with it and hurt someone. So push gently with it. I rarely use the fa-jing for that reason.
So take care of your partner when playing push hands, and you will both grow in Tai Chi through your push hands practice.
In Tai Chi,