The shoulder bones are held together by a group of muscles known as the rotator cuff muscles. These muscles (supraspinatus, infraspinatus, subscapularis and teres minor) are responsible for the shoulder’s fine movements, such as throwing a ball. Because of the shoulder’s shallow socket and lack of ligament strength, any weakness of the small, rotator cuff muscles makes it easy for the head of the shoulder to slide around in the joint.
If the shoulder joint is continually stressed with the arm in an overhead position, as it is in softball, tennis, volleyball, swimming and weight training, the small rotator cuff muscles begin to stretch out. This allows the head of the joint to become loose within the shoulder socket. If the head of the shoulder is loose, when the arm is extended backwards over the shoulder the head will slide forward, catching the tendon of short head of the biceps between the ball and the socket. The same thing happens when the arm is raised to the side above parallel to the ground. The head will drop in the socket and the tendon of the long head of the biceps or the supraspinatus becomes impinged.
This impingement causes the tendons to become inflamed and painful. Tennis players feel the pain when they try to hit an overhead or serve. The same thing can happen to golfers in both the backswing and the follow-through when their shoulders are above parallel to the ground.
The treatment for such injuries usually involves a range of anti-inflammatory drugs but if the injury happens again the patient may have to enter a program that will strengthen the rotator calf muscle easing the pain.
