"Jumping" on groundies = loss of power

[flea]

I just read a thread in Classic Lessons on Open Stance re: weight transfer.

My limited interpretation is:
1) Jumping leads to loss of power.
2) Jumping is not the same as pushing off and using ground force to initiate the kinetic chain.

My questions are:
1) What are the typical reasons club players "jump" and are there fundamentals that can prevent this? (eg. good footwork with aligning the outside foot when tracking ball flight.)
2) Pro players are often in the air after they have hit their shots but are not "jumping". Are there ways to tell one from the other biomechanically?

[johnyandell]

If it look like the player is jumping then he or she probably is...Players who "jump" will tend to push off the balls of their feet more dramatically and this is part of the look of it.

If you lign up behind the ball, coil the shoulders and legs, use the appropriate stance and have a great swing pattern, it'll just happen. I'd worry about those things, not whether specifically you jumped on a certain ball.

[gzhpcu]

I tend to jump if someone hits a high-bounding topspin towards me and I don't have time to move back, because jumping enables me not to have to have such a high swing path when hitting back.