I'm 71 and have been shooting archery about 25 years, more seriously in the last 10 years than in the years before that. I think I've been able to maintain my accuracy through continued learning, and dropping down in bow weight as needed. My strength isn't what it was. When I first started, I thought 55# was a good target bow that I could shoot all day, and I regularly shot a 65# bow, although I dropped down to a 60# bow for hunting pretty quickly, just because I realized that I wouldn't usually be shooting my hunting bow under ideal conditions.
Now my regular target bow is 40#, and I've pretty much decided that my hunting bow should be 45# rather than 50#, for more or less the same reason I dropped from 65# to 60# 25 years ago. It's not that I can't shoot a 50# bow anymore, it's just that I think I have a better chance of hitting what I'm aiming at with a 45# bow.
Thanks to God I haven't had any debilitating injuries that have cut my archery career short, just normal wear and tear, like an old engine.