I am going to have my test. checked next week. My buddy is same age as me, 40, and he is on replacement by injection. He says he feels 30 again.
Test. will help your overall vitality but you wont make muscle gains unless you lift weights.
HGH on the other hand is more of a youthful rejuvenator. But it is very expensive and you cant just get it from your doctor. Their is a lot of junk out their on the internet so be careful.