Athletes do it all the time, usually to their eventual detriment. What about CG players?
My mechanics aren't great; I read as much as I can on LH mechanics in particular as this seems to cause the most problem. As you might expect, the views on LH thumb placement, barre techniques, stretches, etc. are always good for a long discussion thread. That is to say, there is plenty of disagreement and conflict. On one point, however, all seem to agree: it should not hurt to play the guitar.
So, in an effort to play better, get better sound form the guitar, trying to test different ideas, I did hurt myself. I really did not think this was possible. I have always had a reputation of having "vice-grip" strength in my hands, seldom beaten in arm wrestling, workout, yadda, yadda, yadda. Get "hurt" playing guitar? Sheesh, gimme a break! Yet it happened, in the quest to improve tone and sound in general. I'm sure many of you are nodding and laughing AT me, and I deserve it!
That being said, I did not take the usual advice of resting from the guitar. My work travel schedule keeps me away from the guitar more than enough already. So, I decided to "play hurt", with the idea I could heal at the same time. I re-read the various views on LH topics. This time, however, I had a built-in sensor to tell me if the described technique was bad for me -- pain, sharp pain. I felt if I could play pain free (or at least minimal pain) while injured, I was probably on my way to understanding what worked best for me and my own hand mechanics.
I am learning, and every now and then slip into a wrong hand position out of habit and my hand advises me to adjust. But I am still playing, sometimes more than an hour at a setting (that is pretty durative for me and my schedule). Playing hurt helped me understand my own body mechanics, and I think I can heal fully and avoid injury in the future. To those who offered such great discussion on the matter of LH mechanics, THANK YOU! Although I must reject some of your advice, the advice I have taken came out of the same discussions, and might not have been brought to light otherwise.
Body mechanics are as unique as the individual, and every person's mechanical system has some flexibility, but if it is misaligned too long, injury will happen. It is just simple physics.
Anyone have a similar story to share?