So much food for thought in the above replies. I like the idea of some form of aiming for advancement as an athlete, but does that mean there's an age cut-off? Logic says we cannot improve physically for ever and at some stage we start getting slower and weaker (particularly if you've always been reasonably fit, less so if you start getting fit later in life). I know that despite always exercising and taking part in sport I am much slower and less strong than I was when I turned 50, some 17 years ago. I'm a stronger cyclist, but that's just because I wasn't cycling then. Can advancement be defined as slowing down normal deterioration in performance.

Can a person in their 80s who is fitter/faster/stronger than most of their peers and still works at it be considered an athlete, just as someone in their 20s would be within their age group?

I would hope so.