I'm 38 yrs old 5'10" and approx. 200lbs. I've been weightlifting for about 7 years and can truly say that routines with powerlifting exercises: deadlift; bench press(close and wide grip); squats; military press; bent over rows, are what put on mass. Forget machines and isolation exercises until you gain the mass you want. Also, do approx. 4 sets of 6-7 reps to failure each time. (use a Smith machine if no spotter). These exercises done in this way actually naturally increase lean muscle mass by stimulating testosterone and hGH production. I am also a physician. Good Luck