I was attempting to play Beethoven's Moonlight Sonata the other day (when I say 'play', I think 'murder' would be a more accurate description). I found the stretches in the right hand very difficult, and now I have a sore hand - a pain down the 5th finger side, which is worse when I try to lift things etc. I feel that I can't stretch this hand as much as the left hand now. Is this normal, and will it go away of its own accord? (Sorry, I realise this isn't a doctor's surgery, but just wanted to share!) Good thing I'm left handed....

Oh dear, I know what you mean. There are constant octaves on the RH, and sometimes stretches over an octave. I had problems with it as well, and my RH hurt a little then. Do you want to stop playing the piece for a couple of days?

Now my RH is hurting too. I think I could have sprained it during a bowling session. I suspect it is this:
http://www.handuniversity.com/topics.asp?Topic_ID=34

I am cutting down on playing the piano, though playing actually doesn't hurt. Using the computer mouse or carrying heavy stuff does. If it doesn't clear up next week, I will go to a doctor

Ah, Beethoven-hand. A common complaint, especially if like me you started by playing lots of Bach, then some Mozart, and then, suddenly all these big stretches.... Grieg-hand also a nasty one.

I don't know the science of it but I think it should be a case of muscle stretching more than normal (eg how your legs would feel the day after an aerobics class) than actual damage so ought to get better with practice.

I had shock the other day when I made bread for the first time in about 15 years - 10 minutes kneading followed foolishly by an attempt at Grieg's Piano Sonata - my hands were not happy!

When I'm learning something like this I take it slowly. I do short sessions on it until my hands have become accustomed to the stretches and always stop when I begin to feel the strain.
I suppose the ideal would be to do regular exercises which maintain the ability to stretch without it starting to hurt.

I read the title to this and thought it must be the Pathetique, but the moonlight will do it as well. Plenty of thought to relaxing your wrists will do it, you also need to build up the stamina for some of these pieces as sbhoa described

I once was concentrating so much on keeping my back and hands etc relaxed that when I finished playing I realised all the tension had gone to my left leg as that was the only bit of my body I wasn't using.

Oh, poor you! At least we can suffer together. Yes, I think I will put Beethoven to one side for a few days. Much as I love him, my poor hands can't cope!

missforte, have you recovered? I have made some good progress over the weekend, having tried some pain relieving rub and patches. If you are still having the aches, try Salonpas patches. I am feeling much better overnight already.

I think the patches not only relieved my pain, but also limited large movements in my wrist, such that it had the opportunity to heal. I applied 3 pieces on my right wrist. This morning, I hardly felt any strain.

Salonpas -- It works!
http://www.salonpas.us/salonpas.php

Tiger Balm Joint Rub -- Still evaluating...
http://www.tigerbalm.com/index.php?id=17

Of course, all these are temporary relief. I think I have to find a way to protect my hands. I have gotten back into my exercise regime after so many months of laziness, and have started to take supplements for joints.

Interestingly, I found a Trinity Grade 1 piano exam marking sheet from 1987, when I was still a young child. There was a statement on how softly I played, and that I should improve on forte. Maybe I am simply having weaker hands. Got to change that now!

EDIT: Has anyone tried wearing gloves of the therapeutic kind to support weak wrists/hands? Any reviews and recommendations? I am seriously considering that, because my day job involves 100% computer usage, so Repetitive Stress Injury is becoming a fact of life for me... Hopefully mine is not yet a permanent injury... So I would like to do some prevention.

Yes, I have recovered thankfully, glad you have too. I think heat is a good cure too - sitting with my hand round a cup of coffee seemed to work wonders! But I may stay off the Beethoven for a bit longer...