At least in the sports I watch (tennis, track), considered the most dependent on physical strength, stamina and mental acuity, the guys at the top are 30-35. I'm talking about Usain Bolt, Roger Federer, Justin Gatlin, etc. In fact, this guy
https://en.wikipedia.org/wiki/Bernard_Lagat is almost 41 and still at the top of the running world. I guess that's refreshing to know?