Thumbs-Down Supraspinatus Exercises

The supraspinatus muscle is one of four rotator cuff muscles in the shoulder region that produces movement of the shoulder joint. The supraspinatus is a commonly injured shoulder muscle. Strengthening exercises such as the "empty can" exercise can be performed to condition the supraspinatus muscle.

Supraspinatus Muscle

The supraspinatus muscle originates on top of the shoulder blade and attaches to the humerus, or upper arm bone. This muscle is important for abduction -- moving the arm out to the side and up toward the ear. It works along with the other three rotator cuff muscles to keep the ball of the humerus aligned in the shoulder socket with shoulder movement.

"Empty Can" Exercise

The supraspinatus muscle can be strengthened by performing the "empty can" exercise, named for the position used to empty a can. Stand with your arm hanging next to your side. Rotate your arm until your thumb is pointing toward the floor. This will bring the shoulder into internal rotation. Lift your arm out to the side and away from your body until it is parallel to the floor. Hold this position for three seconds, then slowly return to the starting position. Repeat 10 times and work up to three sets of 10 repetitions. A hand weight can be added to increase resistance.

Shoulder Impingement

The "empty can" exercise is controversial among orthopedic health practitioners. The shoulder joint is a ball and socket joint that interacts with a bone called the acromion. The acromion sits above the ball of the humerus and forms a roof over the supraspinatus tendon. The "empty can" position can cause impingement, or pinching of the supraspinatus tendon between the ball of the humerus and the acromion. A technique called the "empty can test" is used to diagnose rotator cuff tendonitis or potential tear in the tendon. The examiner places the patient's arm in the "empty can" position, applies manual resistance and assesses for pain or weakness.

"Full Can" Exercise

The "full can" exercise is another technique that can be used to strengthen the supraspinatus. The "full can" exercise is performed the same as the "empty can" exercise, but with the arm externally rotated -- thumb pointed upward. This position maintains the space between the ball of the humerus and the acromion as the arm is raised, and significantly reduces the risk of impingement of the supraspinatus tendon.