Medial shoulder joint rotation (the act of rotating the upper arm inwardly on its long axis) is a key action in sports that involve throwing and hitting. In these actions the rotator cuff muscles, which are relatively small and usually weak, are heavily involved. Because of this, they are often injured.

A similar injury producing situation exists in weightlifting, especially when doing many repetitive movements in which the upper arm is involved. In this exercise you also involve the anterior deltoid, latissimus dorsi, pectoralis major and teres major. These muscles are involved in a manner that is not common to any of the major exercises for these muscles. Thus you can get extra development of these major muscles and at the same time help prevent injury to the rotator cuff.

Major Muscles Involved

The latissimus dorsi covers a very wide area of the lower half and the upper side of the back. It originates on the spinous processes of the lower six thoracic and all the lumbar vertebrae, the back of the sacrum, the crest of the ilium and the lower three ribs. It inserts on the intertubercular groove of the humerus (upper anterior side of the humerus) by a flat tendon attached parallel to the upper three fourths of the pectoralis major insertion.

The teres major is located on the upper sides of the back. A round muscle, it originates on the lower end of the lateral border of the dorsal surface of the scapula. It inserts on the ridge that forms the inner border of the intertubercular groove of the humerus parallel to and slightly lower than the insertion of the latissimus dorsi.

The subscapularis is located on the under (costal) surface of the scapula next to the ribcage. It originates on the entire costal surface of the scapula and inserts on the lesser tubercle of the humerus.

Muscle Action

In T-bench medial rotation, the upper arm undergoes inward rotation. The upper arm remains stationary (in line with the shoulders) while the humerus rotates on its long axis. The forearm, which is perpendicular to the arm, moves from the horizontal position to the vertical.

Sports Uses

This exercise is very important for prevention of injury in bodybuilding and to a limited extent, in developing mass and definition. It is most important in all sports that involve throwing, especially overhand throwing, and hitting in all sidearm, sidearm overhand and sidearm underhand patterns. Thus it is needed in baseball pitching, in overhead and sidearm hits in the racket sports, throwing the javelin, putting the shot, baseball batting, golf hits, volleyball spikes, handball, bowling, softball pitching, throwing a curve, screwball, etc. In essence, it is involved in almost all repetitive movements of the arm, which include the sports of swimming (all strokes), wrestling and bodybuilding.

Execution

Place two exercise benches of equal height perpendicular so that they form the letter T. Lie down on the long bench and place the edge of your shoulders on the far edge of the cross bench. Your feet should be flat on the floor and your hips and trunk in good support. Place your arms out to the side, bent 90 or more degrees in the elbow. Keep the elbows in contact with the far edge of the bench and with the forearms vertical, hold the dumbbells or a barbell in the hands.

When ready, inhale slightly more than usual and hold your breath as you lower the dumbbells backward and down past the head. Lower at a slow to moderate speed until the forearms are level with or slightly below the level of the bench. After reaching this position, reverse directions and raise the dumbbells back to the initial position in which the forearm is vertical and the entire arm is in a line with the shoulders. The elbows should remain in position and the angle in the elbow should not change during the entire execution. Exhale as you reach the finish position and then repeat after a slight pause.

Comments

During execution of the exercise there is no support under the head. If holding your head up is uncomfortable or too difficult, you should get another bench for support. You can also have your partner hold your head up as you execute the exercise. However, in these cases you must use dumbbells to ensure a full pathway. The barbell will hit the bench or partner in the lowest position.

This exercise develops mainly the subscapularis of the rotator cuff. To develop its counterpart, the teres minor and infraspinatus, which are often injured in the follow through in throwing and hitting and in some bodybuilding exercises, you should do lateral shoulder joint rotation. This can be done by assuming a kneeling position parallel to an exercise bench and placing your upper arm in contact with the bench while your forearm hangs down. You then raise your forearm as high as possible (usually to the height of the bench) while maintaining contact with the bench with the upper arm.

The T-bench medial rotation exercise is used most often with relatively strong athletes. Thus, if you find the T-bench exercise too difficult, you should do medial rotations lying on the floor. In this variant execution is the same but the range of motion is less, making it a good beginning exercise. However, when lying on the floor you should keep the elbow close to a 90 degree angle while you vary the position of the elbows.

Medial and lateral shoulder rotation can also be done with a Roto-Bar. In this variant you hold a Roto-Bar on straight arms in front of the body and level to the floor. To do the exercise, keep the arms straight and in place as you turn the arms palm up and palm down without stopping. It should be noted that much weight is not needed as the Roto-Bar weighs approx 20 - 25 pounds and when you turn the handles they turn against resistance. Thus just the bar is usually sufficient.

When doing medial rotations keep the elbows strictly in place on the bench. Usually athletes tend to lift the elbows as when doing dumbbell presses or triceps extensions, but this must be avoided. Maintain a firm, stable body and, especially, trunk position when doing the exercise.

For variety and if you are a pitcher, depending upon your technique, you can more closely duplicate some typical throwing patterns by holding the hand a little lower and then doing medial rotation. However, in this position you will not be able to use a barbell as the bar will hit your face. Also hold the same angle in the elbow joint at all times.

When first starting, use very light weights. 10 - 20 pound dumbbells seem to be more than adequate for most athletes. If you have rotator cuff problems, even 1 - 3 pounds can be very heavy. In terms of maximums, the most I have had an athlete do is 90 pounds. But this was after two years of training and gradually increasing the weights. Do not attempt very heavy weights early as they can cause severe injuries to the rotator cuff muscles.