system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How much if at all does the amount of physical activity early in life affect potential physical limits of an adult?

Would a 25 year old male who commited his life to weightlifting and eventually reached his peak results would have different peak results if he trained as a child? How would the answer be different depending where the muscle is or if instead of muscle strength we look at flexibility, lung capacity, etc.
gpt
Basically the younger you start the better you get. In optimal conditions. 

However optimal conditions only apply in lab experiments. If you trained too hard and broke something early on, you could get a lifelong detriment (injury etc. ) that will always hinder your performance. 

A lot of people who were forced to train at a young age, can’t train that sport in later stages of life coz they have trained too hard and are now broken in multiple places. 

Idk if this made any sense, but in the end of the day, you do you. And don’t train too hard. Life is a marathon not a hurdle.