Originally Posted by Emily Mattes
I thought it wasn't physiologically possible to gain more than 3-4lbs of muscle a month?
Depends on genetics, current bodyweight, stimulus on the muscles, hormones, etc.
Those who have "good" genetics (maybe less myostatin for example), very light 6'0" 120 lbs, are squatting and DLing extremely heavy and having a high T/GH output, etc. are going to have a very strong adaptation to lifting heavy weights.