Begin by kneeling with the band or tubing secured under one hand and maintaining tension with the other hand, forearm on your abdomen. Start the exercise by externally rotating the shoulder (a), then abduct and extend the arm simultaneously, pointing your thumb toward the ceiling (b). Hold; then slowly return, first bringing your elbow into your side.
Squeeze your shoulder blades at the top of the movement for more scapular muscle activation.
Keep your back and neck straight throughout the exercise. Return the band to the start position very slowly.