If you wish that you had stronger, more sculpted biceps—and really, who doesn’t?—but you’re not seeing results from your regular strength training routine, science just came to the rescue: The American Council on Exercise (ACE) commissioned a study to find out which biceps exercise is head and shoulders above the rest.

After testing seven different biceps-toning moves—from the classic barbell curl to the preacher curl—on men and women between 18 and 24 years old, the researchers found that the concentration curl was the big winner, eliciting significantly higher muscle activation than any other exercise tested.

“The reason that this exercise is best for targeting the biceps is because it takes other muscles that may usually help with the bicep action out of the equation,” explains ACE expert and exercise physiologist Jacque Ratliff. “Because the biceps muscle’s connective tissue crosses both the shoulder and elbow joints, the anterior deltoid and brachioradialis muscles are activated when doing other biceps exercises. With the concentration curl, however, the movement of the shoulder joint is limited, which focuses the work within the biceps muscle itself.”

How To Perform a Concentration Curl

While sitting, lean forward and place your upper arm against your inner thigh, making sure there is plenty of clearance for your arm and a weight to curl up and down. Starting with the elbow extended, curl the dumbbell up until your elbow is fully flexed.

The Single Best Exercise for Toned Biceps, Says Science

Perform 3-6 sets of 6-12 repetitions with 30-90 seconds of rest between sets.