If you're ready for the piece there should be no injuries. I recently started learning the 3rd movement and it's less physically stressful so far for me than learning pathetique 1st movement, probably because I wasn't as technically ready for nonstop octaves when i started the pathetique. Now the left hand tremolos in the 3rd movement of the Appassionata are no problem, when if i had tried playing it a little while ago it would've felt very strenuous and extremely difficult.
Also another thing, I've been reading a bunch of posts recently and have come across some people talking about playing this piece, but the way they describe it's difficulty, it's hard for me to believe that they've actually played the piece. So many point out the descending arpeggios in the end as being a very difficult part of the piece, but so far I've found that one of the easiest. It took me less than a day's practice to learn that, while I've been practicing several other parts for days and still have trouble with them. I guess my point is don't listen to people on some message board, i guess not even me, but you'll see what i mean, if you're ready for this piece the descending arpeggios should be nothing compared to other much more treacherous sections.