The rotator cuff is a group of small muscles originating on a person's shoulder blade. These muscles include the supraspinatus, infraspinatus, subscapularis and teres minor, which insert on the uppermost end of the humerus or arm bone. Repetitive movements, such as lifting boxes overhead and tennis serves, increase a person's risk of rotator cuff complications.
Unstable Joint Capsule
The glenohumeral joint, formed by the large head of the humerus and the glenoid fossa, or shallow cup of a person's shoulder blade, is surrounded by ligaments that are relatively lax, enabling a person to move his arms through a greater range of motion. Lax ligaments and a shallow hole for a large bone predispose his shoulder joints to dislocation at the very end of each movement. A weak glenohumeral joint forces the muscles of the rotator cuff to stabilize the shoulder, increasing a person's risk of chronic strain and inflammation to his rotator cuff, according to Sandra Shultz and colleagues in their book, "Examination of Musculoskeletal Injuries."
Impingement
Impingement of a person's rotator cuff muscles may occur from inflammation to the pillow-like sacs or bursas in her shoulder. Irritation may result from repetitive, overhead movements, such as throwing. Impingement may also occur if the bony processes around the rotator cuff are abnormally shaped. A person's rotator cuff becomes less vascular or has a decrease in blood flow, increasing her risk of injury to her cuff muscles. Age also decreases the amount of space under the bony processes in which a tendon of her rotator cuff muscles can move, according to Schultz.
Immobilization
Long-term immobilization of the shoulder following any type of shoulder injury increases a person's risk of frozen shoulder syndrome. Frozen shoulder syndrome develops when scar tissue builds up around the joint capsule. The rotator cuff muscles and the ligaments surrounding his joint may shorten. Both conditions severely decrease the range of motion of his shoulder and decrease the function of his rotator cuff.
Lack of Development
People commonly neglect the rotator cuff muscles in their weight training programs. A person lifting heavy weights to strengthen her deltoids, pecs and back muscles increases her risk of straining and spraining her rotator cuff if the cuff muscles have been neglected. A person can prevent this imbalance by performing internal and external rotation exercises at the end of her upper body workout. She may use a cable pulley, an exercise band or a dumbbell to work her humerus by turning her arm inward and outward.
References
- "ACSM's Certified News"; The Structure and Function of the Rotator Cuff; Peter Ronai; September 2002
- National Library of Medicine: Shoulder Injuries and Disorders
- "Examination of Musculoskeletal Injuries"; Sandra Shultz, Peggy Houglum and David Perrin; 2005
