This post is applies to everyone but it is aimed at those working with young kids especially. The ability to create rotational power is a natural movement pattern for the human body. In the video below I use an 8 Board (developed by fellow tennis coach Jack Broudy) to demonstrate how the hips are the engine for rotational power. Developing good tennis strokes is directly related to being efficient at this movement pattern. I am not even sure if the 8 board is still in production. I have had mine for a while but it has been a fantastic teaching tool because it allows you to feel the movement.

Now for those of you working with little ones this is my son using a full size racket hitting off an air tee in my driveway. If you put relatively heavy things in kids hands and allow them to experiment with swinging it you will be amazed at how quickly they get the rotational power movement. This is why I steer people away from light aluminum rackets and to heavier 25, 26 and sometimes even 27 inch rackets. Small light ones can be easily swung with just the arm but with something heavy the body is forced to use the hips and that is what you want for the foundation of a tennis stroke in the long term.