This following diagram explains what is demonstrated in the video:
The rear foot and the fixed point form a line, which aims at the centre (spine in most cases) of the opponent. The hand/elbow and the same fixed point through the opponent’s structure form the lever arm. By bringing the lever towards the line, energy shoots towards the opponent. Note that there are two applied forces, one is used to push towards the fixed point, and the other is pushed towards the line. The two forces are created by two different parts of the body. While the lever is squeezed towards the line, the fixed point (and the line) cannot be moved (tossed).
In the video, different fixed points are selected as well, e.g. rear kua, middle of the trunk, front kua.
{ 3 comments… read them below or add one }
You are sharing the rear foot.
You are using one hand to hold the opponent.
You are using the other hand to break the opponent’s line.
The two lines created by the two hands with the rear foot cannot be synchronized. They must be independent.
Great explanation of this! Diagram is very clear π
Thanks Kelvin for taking the time to make the useful video and share.