its far from crystal clear - each body is different, what builds one breaks another one (even if fitness levels are similar). genetics is not fair.
our bodies require challenge, otherwise they get weak and fragile. challenge too much, it will break. this point of diminished return is again different for each of us, and varies over time for same person.
BUT - if you give it enough time to fortify itself - I don't mean muscles, they grow faster than rest of the body. I mean when bones, tendons, ligaments and generally joints catch up (ie for climbing it takes years of gradual progression to train your fingers), they hold the body together better (knees, feet, spine etc.) and can manage stress put on it, even till high age. I have a friend who is 80 year old mountain guide and he still climbs easier stuff.
But to find the balance, the edge of benefits vs losses that is never stable and unique to each of us is very hard
our bodies require challenge, otherwise they get weak and fragile. challenge too much, it will break. this point of diminished return is again different for each of us, and varies over time for same person.
BUT - if you give it enough time to fortify itself - I don't mean muscles, they grow faster than rest of the body. I mean when bones, tendons, ligaments and generally joints catch up (ie for climbing it takes years of gradual progression to train your fingers), they hold the body together better (knees, feet, spine etc.) and can manage stress put on it, even till high age. I have a friend who is 80 year old mountain guide and he still climbs easier stuff.
But to find the balance, the edge of benefits vs losses that is never stable and unique to each of us is very hard