if you have constant injury related to training for climbing and this means you're losing out on climbing, I recommend you reconsider how you train.
Overtraining is complex. In wikipedia, they explain the process a little: http://en.wikipedia.org/wiki/Overtraining Good to look a it.
I was so tired that I hardly can do my job and some days, I slept 13 hours in a row. I thought that it could be lime disease. I was under stress and training for almost five years. Two or three years ago, when I had the operation for carpal tunel, i continue and try to recover. but i never be able to do the load of exercise that I did before.
Irritability, loss of concentration and motivation is also to consiider. Climbing over my pro begin to be harder. I had a shoulder dislocation in that time. Took eight week to come back to climb. and i push again to do a big wall. this summer, my body hurt me and I realise that some thing go wrong.
Training was good, but all the other aspect of my life change and i have more stress. for example, I drove 11 hours each week end to climb. It is great, but it is hard.