I guess everyone's body responds differently...I seem to have no problem gaining muscle mass (and fat mass, for that matter), especially in my lower body, just doing 1-2 "endurance" workouts per week with a 40-lb barbell (e.g., Power Hour, Muscle Endurance). I'm frightened to see what I'd look like if I went "heavy"! I'm trying to lean my legs out and have taken up running and lots of cardio, but it seems my muscle is here to stay. I guess I should count my blessings. I'm willing to donate 5 lb of muscle from each of my thighs, if anyone is interested.
Holly