In this context, when you talk about power, is it in the sense that includes "external" strength -- driven by engaging extrinsic muscle groups?
Or, going back to the quote in the OP, is it murkier than that?
Well, using a simple two-handed push as an example (probably the easiest example to use): Ideally, in terms of the Yin-Yang cosmology you'd like to utilize the power from the solidity of the ground and the power from the weight of the body to do most of the work. The contributions of the "intrinsic strengths" of body (not counting much on the normal use of muscle) would then be brought into play using the "intent" to direct the body, the support from the ground and the power of the weight, as need be and in the direction(s) that you want. Those are the ideal powers; the use of muscle is secondary and considered the 'coarser' way to go.
That description would be Earth, Heaven, Man, respectively.