Get toned arms minus the flab with this must-know move from Shape . It's simple and scientifically proven!
If you've been on a quest to build strong, svelte arms and are curious which exercise will best target your biceps, the American Council on Exercise  (ACE®) now has your answer. With the help of the research team at the University of Wisconsin-La Crosse, eight of the most common biceps-building exercises were put to the test to see which move reigns supreme.
In the study, 16 men and women completed each of the following biceps exercises: cable curl, barbell curl, concentration curl, chin-up, wide grip EZ curl, narrow grip EZ curl, incline curl, and preacher curl. To determine the amount of muscle activity elicited during each move, researchers affixed electrodes to the biceps brachii — the main muscle that most people think of when showing off "the guns" — as well as to the anterior deltoid and brachioradialis, neighboring muscles in the shoulder and forearm, respectively. (When training the biceps, other muscle — like the anterior deltoid and brachioradialis — can assist with the lift, thereby taking some of the load away from the targeted biceps brachii and causing less activity in that particular muscle.)
After crunching the numbers, researchers discovered that the concentration curl  elicited significantly higher muscle activity in the biceps than any of the others. This exercise, which is performed with the upper arm pressed against the leg, allows for much greater isolation of the biceps muscle, according to lead researcher John Pocari, Ph.D. The upper arm is unable to sway during the movement. "Some of the other exercises called into play the front of the shoulder more, and for a lot of those it's almost natural to swing your whole arm or shoulder forward to stabilize before you lift."
While the isolated nature of the concentration curl does deliver the most targeted biceps-building results, that doesn't mean you should ditch your other favorite arm-sculpting exercises. Since many other exercises strengthen the biceps along with other muscles of the arms, these moves can offer great functional benefits. For best results, opt to pair a sampling of the exercises featured in the study — along with any of your other favorite upper-body moves  — with the concentration curl for a more effective strength-training experience.