We are not boxers........
I doubt any of us are, put swinging at air is less impact than hitting something where you have impact
They take warm up swings with a bat or some other object
And you are swinging with a Wii-mote
It's completely different then bowling with a ball, the ball takes all the momentum of your arm. I have done both and the only similarity is the motion of the arm.
Right, it's the same motion without the stress that a heavy ball puts on your arm and wrist. Hence, less impact.
These are the same as baseball, without a ball to take the impact of your swing your stuck stopping a full strength swing with your body.
Do you stop swinging a bat or tennis raquette immediately after contact with a ball? Nor should you with the controller.
Like i said it's the unnatural motion of stopping your movement that causes problems