A few years ago I herniated two discs in my neck that pressed on a nerve...my left arm would go numb numerous times a day...I was unable to curl a 10 pound dumbbell but I could bench using a machine...it took about six months and a few rounds of Prednisone before I was able to do pull or curl movements...my left arm atrophied badly...I bet it shrunk a good 2-3 inches........