I had a shoulder replacement, which was a very painful operation. |I slept sat up for around six weeks, my friend who is a nurse emphasised that I must religiously do the exercises given by the physio afterwards, which I did, and I was progressing very well, until the resistance band, (which is a part of one of the exercises) snapped, and ripped all of my tendons, resulting in a further operation to attempt (unsuccessfully) to repair them, the upshot being, I have irreversible restricted mobility, and am in constant pain and on morphine patches and strong painkillers for the rest of my life, but am convinced that if this resistance band hadn't snapped, I would have been fine, so go for it!