Can you bring your arm into a throwing position without your shoulder feeling tight, pinchy, or unstable? Shoulder external rotation is important for much more than throwing a baseball. It contributes to the backswing in golf, overhead lifting, swimming, serving in tennis, reaching behind your head, and many other athletic movements. When that motion is limited, athletes often compensate by: Arching the lower back Flaring the ribs Rotating the entire torso Shrugging the shoul