Originally Posted by ski racer
Toly, could you explain how one could practically employ arm and wrist to increase racquet head speed? specifically what is upper arm horizontal flexion, internal roatation and how could these be applied to ones game?
Internal shoulder rotation is counterclockwise upper arm rotation.
In picture below Serena Williams is trying to hit hard FH winner. Here is original video http://www.youtube.com/watch?v=BJg5cWEviZo
Her main armís motions around contact are:
1. Arm flexion.
2. Internal shoulder rotation.
3. Forearm pronation.
4. Wrist ulnar deviation.