So I got my powerball yesterday.. and I used it quite a bit. Probably... 2 hours. Anyway, I did most of the powerballing with my right hand and some with my left. When i woke up this morning, my left wrist was shot. it was completely soar and stiff, and it has a sharp pain whenever i move it too far in 1 direction. It's very depressing. Good news my first day RPM is over 11500.