This is, by far, the most important function of the rotator cuff muscles as you will soon see. Finally, underneath the rotator cuff lies the loose pouch known as the shoulder capsule. This is a very loose group of ligaments that envelops the shoulder joint and helps hold the ball and socket in place. The rotator cuff muscles help to rotate the shoulder and upper arm and to stabilize or securely hold the ball and socket in place. Both of these functions are very important to the golf swing.
Full rotation is necessary for an appropriate back swing and follow-through.
A stable shoulder allows for efficient transition of the explosive forces generated in the legs, hips and trunk on through to the hands and club head during the swing. Thus, a strong and properly functioning rotator cuff is essential to proper swing mechanics. Repetitive swinging or excessive practice can lead to fatigue of the rotator cuff muscles. When fatigue sets in, the cuff can not adequately stabilize the ball within the socket and excessive motion can occur within the shoulder joint. This, in turn causes the rotator cuff to work even harder to do a job that is becoming more and more inefficient.