We do exercises with a partner to learn how to establish and maintain the ground path and combine it with peng jin.
But some people who see a photo like the one here make the mistake of thinking, "That's useless. You can't use that in a fight."
In this photo, Colin is pushing into my right elbow and I am grounding the push into the ground through my left foot.
Colin is not supposed to push with too much force, although as you can see in the picture, this particular drill is used to show that you can, in fact, set up a pretty strong structure using the ground.
The ground path is generally practiced without too much force because the idea is not to make you Superman, to meet force with force.
The idea is to provide internal strength to your body structure, but as you hold that strength in, for example, a self-defense situation, your goal will not be to meet force with force, you will learn to maintain your structure as you adapt to incoming force, neutralize it and overcome it.
The beach ball situation in the Internal Strength DVD is the answer. When I jump on the ball in the pool, it gives, but it maintains its structural integrity, the pressure builds and there is a point when the ball springs back and spins me into the water. It doesn't meet force with force but it wins, anyway.
So by practicing the ground path exercises, the goal is to learn to maintain that structural integrity when force comes in. Maintaining that structure through all the movements of the form is the next goal, and then you apply it to push hands and other self-defense concepts and applications.
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