I just wanna ask people if there are any studies that confirm what I am about to say.

So I have a friend who is 21 years old and have been using no lower than 500 MG test a week and no higher than 1.5 grams for 6 years. That's right, he started at only 15 years old, which is quite sick but to what my point is.. When he started on steroids, he was 5'8 inches tall and is now 6'1, that means he has grown 4 inches AFTER starting using steroids, and my question/point is which I have heard from several other people aswell, is it the POST cycle that stunts your height? And not the actual cycle? This is a theory that I have built but I don't know of a study to prove this. help me out