The American Council on Exercise (ACE), known as “America’s Workout Watchdog”, teamed up with the exercise scientists from the Clinical Exercise Physiology program at the University of Wisconsin—LaCrosse to determine which exercises are most effective for strengthening the deltoid muscles. The shoulder is a complex ball-and-socket joint that’s capable of flexion, extension, rotation and more, and there are three distinct muscles required to perform these movements—the anterior, medial and posterior deltoids. To determine which exercises are most beneficial for activating shoulder muscles, researchers compiled a list of the 10 exercises most often performed by both recreational lifters and athletes and most commonly prescribed by trainers. The list included the dumbbell shoulder press, push-up, cable diagonal raise, dips, dumbbell front raise, battling ropes, barbell upright row, bent-arm lateral raise, 45-degree incline row and seated rear lateral raise.