>when I got to my late 30's the power went out of my body
Do you mean strength? Obviously everyone is different. But from my experience in martial arts, men in their 40s, 50s and even 60s are still plenty strong. But you do lose a bit of flexibility and speed as you get older.
Maybe it's different for other people, but I just couldn't move the way I used to, I had less gas, less snap, my reactions were poorer. There's a thing of power coming from your gut/core... that's what lets you really move and use leverage, and that really faded. Competing with guys in their mid twenties was the shocker. I guess that there's a think where experience and training builds advantage but then you go over a cliff where the physical difference just overwhelms that.
Look, we don't see professional athletes in their 40's much if at all. Mike Tyson was the best fighter (ever?) and looked in shocking good shape - but he still lost to that goon.
Do you mean strength? Obviously everyone is different. But from my experience in martial arts, men in their 40s, 50s and even 60s are still plenty strong. But you do lose a bit of flexibility and speed as you get older.