The American Council on Exercise states that the rotator cuff, in the shoulder, is made up of four muscles: the infraspinatus, the teres minor, the subscapularis, and the supraspinatus. Each of these muscles is individually responsible for a different arm movement. Additionally, these four muscle are attached to the various bones that make up the shoulder joint by the shoulder tendons, which are generally named for the muscles they attach, such as the infraspinatus tendon, subscapularis tendon, supraspinatus tendon, and teres minor tendon.
Infraspinatus and External Rotation
The first of the rotator cuff muscles is the infraspinatus. This muscle is attached at one end to the scapula, with the infraspinatus tendon, and at the greater tubercle of the humerus at the other end. This muscle is primarily responsible for external arm rotation. To properly train this muscle group, free weights or cable machines can be used. The exercise should focus on arm movements that focus in external rotation.
Teres Minor for External Rotation
The teres minor is a small muscle that is also part of the rotator cuff muscle group. It attaches to the scapula and humerus to allow for external arm rotation. In a sense, this muscle works along with the infraspinatus to achieve full external rotation. Training for this muscle is similar to the training used with the infraspinatus. When training one of the muscles, the other muscle is trained as well.
Subscapularis for Internal Rotation
The subscapularis muscle is another muscle of the rotator cuff that attaches to the scapula and humerus and is responsible, primarily, for internal rotation of the arm. Exercises for this muscle group involve movement of the arm, in toward the body, through internal arm rotation. Free weights or cable machines, with various hand attachments, can be used for effective training.
Supraspinatus for Arm Abduction
According to Kolber and Beekhuizen, in the April 2009 issue of the NSCA's Strength and Conditioning Journal, the supraspinatus attaches to the scapula at the supraspinous fossa and wraps around the humerus. They further state that the muscle is primarily responsible for shoulder joint stability in addition to the specific arm movement of arm abduction. Training this muscle can use free weights and cable machines and use arm movements that utilize arm abduction movements.
References
- "NSCA's Strength and Conditioning Journal"; The Empty Can Exercise: Considerations for Strengthening the Supraspinatus; April 2009
- "Personal Trainer Manual"; American Council on Exercise; 1997
- "Tendons, Ligaments, and Capsule of the Rotator Cuff"; JM Clark and DT Harryman; The Jounal of Bone and Joint Surgery;
- "NSCA's Strength and Conditioning Journal"; Prescription of External Rotation Exercise for the Shoulder; Gary Katz; 1988
