"A sprinter's body is inclined forward in the direction of motion when he is down on the starting thingy. Hence a compression along the length of the body will have a forward component. But as a dancer you cannot afford to have a strong incline into the direction of motion - you may have a strong incline against the direction of motion, be vertical, or a very miniscule incline into the motion in a few select settings (tipsy, etc).
I am saying that you do not have compression in a forward direction unless the body part being compressed as a forward component to its orientation."
You seem to imply by the above statements that to have a forward component of compression one's entire frame must be inclined in the direction of movement (as in the example of a sprinter). That is an incorrect assumption.
Look at it this way, The leg is being compressed and the lower leg (ankle to knee) is definitely inclined in the direction of motion. So there's a body part with a forward component for you. Also during compression one gets one's 'centre of weight' ahead of the 'point of pressure' of the supporting leg into the floor. This means that during the compression action the force applied onto the floor is at an angle. Therefore there is a forward (vector) component of force being applied by the supporting leg, in the compression action, even though the upper body is fairly upright.
I should clarify that one should not consider compression to be the receiving of weight onto the new supporting leg, with the accompanying relaxing of the knee. Compression is the action that follows, that is the use of the supporting leg in continuing the movement forward onto the new supporting leg.
Dave, what you were saying earlier is quite plausable.
Rha