Stress injuries occur when more damage is done in one day than can be repaired in one day.

This happens when people are kidding themselves about how much they can do, are not listening to their bodies, and mostly, being lazy. If you are out of shape, you will slouch onto your joints, rather than use muscles to support yourself. This will lead to damage much faster.

Training in martial arts or dance will help tremendously with this.

RSI is a controllable factor. Don't get into bad habit, and most importantly, go to a good school.

Other techniques aren't nearly as physical, so there is a much lesser risk of RSI. They don't do the same things, and don't work on muscles so you can't compare them though. Only in the sense that they all work on the body, that's it.

Oh yeah. Hands. If you use your body properly, hands are just the instruments. The power for everything comes from your lower body and your relationship to gravity. Hands only fine tune this and transmit it. Proper therapists shouldn't have problems with their hands. Undertrained therapists, kinestheticly untilligent people, and lazy practitioners probably have lots of problems with this.