My DD is having a hard time relaxing and whipping the ball. So a good friend of mine who is in martial art explain to my DD the reason why you relax in martial arts to strike your opponent versus muscle tightness. He also explain to my DD how energy comes from the ground up and any tightness in muscles diminishes the energy coming out of your hand. In the end he showed us some cool drills to help my DD relax and make a game out of it. Well she started to get the concept that you don't need to tighten up to throw harder so this has made her arm whipping a lot better. If you like I can post a video of the drills he showed us. Anyway here is a video of martial arts expert explaining relaxation for power. Maybe this video can help one of your DD it did for mine.
Nick
[video=youtube_share;MUdls_IkUTs]http://youtu.be/MUdls_IkUTs[/video]
Nick
[video=youtube_share;MUdls_IkUTs]http://youtu.be/MUdls_IkUTs[/video]