In my opinion, average gamers usually put a lot of exaggeration of movements when it comes to playing stuff like the Move, Kinect or Wiimotes. If you exaggerate on movements then usually you will get yourself hurt. There is a space given to you so safety is in hand. but as we may all know that all human aren't perfect, they don't follow the direction so then thats how you get hurt.
Also, I own all 3 consoles with Move and kinect, but never experienced injuries not even a cut (Seriously).