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 activity compared to no towel roll (Wilk KE 2002), although subsequent study found no significant difference (Reinold MM 2004). Also see Dumbbell Shoulder External Rotation Errors.