I found Wii Sports gave me nasty RSI in a way I'd never experienced before if I tried to play it "seriously" for any length of time. All that vigorous motion but with no weight or resistance was really, really bad. It also allowed a much faster pace of action than the real sports it mimicked, which probably didn't help—no stopping to fetch the ball or wait for people to get into position in tennis or baseball, for instance.

Waggling the controller with one's wrist was more effective in game and didn't hurt after 15-20 minutes like playing "for real" did. It also wasn't really any more fun than playing with a normal controller—so, fun, but nothing special.

I'd expect to hurt myself trying to get a workout with something like this, based on that experience.