Bleh. Fit folks, if you start taking up rock climbing please be more careful than I was. The tricky bit here is that compared to average folks I'm in pretty solid shape for climbing. I'm not carrying a ton of extra weight, I have great balance, my arms are strong with pulling motions. But that actually can lead to more issues, when the rest of you is strong you can more easily put yourself into situations where the smaller tendons in your hands and fingers just can't hold up to the strain that your body gets put into. The experienced climber that I was starting with basically told me that I'd be at risk for this type of stuff since I was strong, but not a climber. And sure enough, my third time out I had to quickly hang all of my weight off of one hand coming off an overhang and sprained one of my pulley tendons pretty bad. If I wasn't as strong I probably would have just fallen, but by hanging my weight I totally fudged up my hand.
http://www.nicros.com/training/articles/finger-tendon-pulley-injury/
Luckily I don't seem to have popped the tendon, but the recovery is still annoying. The rest of my body still seems fine, but I can't grip easily with my right hand so lots of my usual fitness stuff is off the table for a while.