Lie on side with legs separated for support. Grasp dumbbell and position elbow against side and forearm across belly.
Lift dumbbell by rotating shoulder. Return and repeat. Flip over and continue with opposite arm.
Maintain elbow against side and fixed elbow position (90° angle) throughout exercise. Placing towel roll under arm increase infraspinatus and teres minor EMG signal 20% to 25% compared to no towel roll (Reinold MM, etal. 2004). Also see Dumbbell Shoulder External Rotation Errors.