Know concentration curls? Yeah, the ones Arnold did in Pumping Iron. Man, those things are dated, right?
Well, only if you consider huge biceps dated. According to an American Council on Exercise study, seated dumbbell concentration curls yield 97% biceps activity, in contrast to cable curls or chinups (80%), barbell curls (76%), EZ-bar curls (wide grip 75%; narrow grip, 71%), incline curls (70%), and preacher curls (69%).
“Since the upper arm is stabilized against the back of the thigh, it isolates the biceps muscle,” says ACE chief science officer Cedric Bryant, Ph.D. He recommends training bi’s two to three times a week, with 48–72 hours between sessions for recovery. “But to really get size, include concentration curls at least once a week.”