One of my good friends that I play with regularly is "79" years old and his break is a good bit stronger than mine. He started playing when he was very young and he's played his whole life. The man can really play, but he admits he's lost a step or two mainly in the stamina department. If you want to play him a race to 11 in 9 ball prepare yourself for a tough match. He's a great guy that hates to lose and his game keeps a smile on his face since he doesn't lose too often. To answer your question I think you can compete at "50", but the younger players have an advantage in strength and stamina. If you want it bad enough you can find a way.......
James
For some reason, your post brought to mind some memories of T F Whittington. I do miss that guy!
Steve