Climbing is similar to weight lifting in that you can injure yourself fairly easily with overtraining. The key is to work 'opposites', which I have read is 'the new thing' in working out. The theory is that if you overdevelop a set of muscles ("Push" muscles vs. "Pull" muscles) then you are in danger of hurting yourself.

Climbing, cycling often utilize more of your "Pull" muscles, whereas Lifting traditionally focuses on your "Push" muscles (there are exceptions, of course). It's the same reason that when you do your core training you not only focus on your abs, but on your back muscles.

K.