T Nation

Bone/muscle question.

Why do testosterone and estrogen levels decline in males supposedly by age 18-20 yet muscle strength/size supposedly increases (or so I heard by age 25) and bone grows (or so the proponents of the “Got Milk” campaign would like to have you believe) until age 30-35? I mean isn’t testosterone responsible for muscle growth and bone? Isn’t estrogen responsible for bones as well? Thanks.