I think there are two aspects to force being generated from the legs.
One is using the force generated by the legs to move your own centre of gravity. Another is to use the force to turn your body (trunk), which in turn changes the direction of the force from the legs and applies it to another direction through the arms.
These two are non independent of each other. In fact, they are to be used in combination, so that you bring force to bear (by moving your centre of gravity) in the right direction (with your body as the axis).
And one of the best ways to train this is through basic exercises. There are basic exercises where the focus is on changing the direction of the force through the body, basic exercises on how to use the legs to move your centre of gravity, and basic exercises that combine both. I guess this will be the focus of my training for a while as I pursue this inkling.
