Repetitive strain injuries are all too common among guitarists, especially those who neglect warming up. In metal especially (my genre), our fingers must fly across the neck, and we must play some extremely large stretches. As a blogger, a gamer, and a martial artist in addition to being a musician, I find myself very prone to injuries such as carpel tunnel and tendinitis.
Recently in fact, I've been recovering from such a strain personally. All it takes is one instance of failing to warm up and trying to dive into add-9 chords too quickly. However, aside from the ease of warming up, there's other encouraging news.
One can quite easily cure carpel tunnel.
Aside from the typical methods of using ice and/or heat and resting, there are also very potent stretches that, if done diligently, very quickly reverse the symptoms of carpel tunnel and mild tendinitis. Disclaimer: I am NOT a medical professional, only sharing my own experience.
Begin by rolling the wrist, first clockwise, then counter-clockwise, perhaps something like fifteen rotations in either direction. You can also flap your arms and allow your wrists to shake, if this does not aggravate whatever pain your condition may be causing you.
Next, hold your arm out straight, paying special attention that the elbow does not bend. Your fingers should be touching, and begin with your palm facing the floor. Then, SLOWLY (there's almost no such thing as too slow) bend your wrist backward with the other hand, trying to keep your fingers pointing straight ahead. At the peak of the stretch, your fingers and your forearm should form a right angle. If it hurts at any point, STOP.
Second, again extend your arm and fingers out straight, but your palm should face the ceiling. This is essentially the inverse of the first stretch; in this case, draw your wrist down with the other hand, trying to keep your fingers pointing to the floor. This the crucial one; this will work right through the commonly affected points of carpel tunnel. Hold this for as long as you can, and go as far as you are able without pain. As long as it doesn't hurt, do this one as much as you possibly can. It's impossible to do too much. But make sure that you do the preceding stretches first. It is important that your wrist joint be limber beforehand, or you could do more harm than good with this wonderful stretch.