I played 5 a side at a decent level until 45, then played after that for 2 more years socially but was finding I was in pain 3 days after. Would be walking like Steptoes Dad on a Monday at work. Gave up then. Miss 5 a side mind, absolutely loved that game - indoors, off the wall, absolutely relentless, wish I could still play. I would say play as long as you can but if the pain spoils it probably time.
Played a charity match, 11 a side, couple of years ago. Some ex pros in it and I turned up on the day to find it was serious. Hadnt played 11 a side in years. I hid myself away at right back but once the game got going I found myself making a run to put a cross in which got cleared and when I saw how far back to my position it was my heart sank. Thankfully we had rolling subs...