Sports Med 2009;

663 1. Rotator Cuff Biomechanics and Function in Rehabilitation Exercises . 667 1.1 Supraspinatus . 667 1.2 Infraspinatus and Teres Minor . 671 1.3 Subscapularis . 676 2. Deltoid Biomechanics and Function in Rehabilitation Exercises . 678 3. Scapular Muscle Function in Rehabilitation Exercises . 681 3.1 Serratus Anterior . 681 3.2 Trapezius . 682 3.3 Rhomboids and Levator Scapulae . 682 4. Conclusions . 683 Abstract The rotator cuff performs multiple functions during shoulder exercises, including glenohumeral abduction, external rotation (ER) and internal rotation (IR). The rotator cuff also stabilizes the glenohumeral joint and controls humeral head translations. The infraspinatus and subscapularis have significant roles in scapular plane abduction (scaption), generating forces that are two to three times greater than supraspinatus force. However, the supraspinatus still remains a more effective shoulder abductor because of its more effective moment arm. Both the deltoids and rotator cuff provide significant abduction torque, with an estimated contribution up to 35–65% by the middle deltoid, 30% by the subscapularis, 25% by the supraspinatus, 10% by the infraspinatus and 2% by the anterior deltoid. During abduction, middle deltoid force has been estimated to be 434N, followed by 323N from the anterior deltoid, 283N from the subscapularis, 205N from the infraspinatus, and 117N from the supraspinatus. These forces are generated not only to abduct the shoulder but also to stabilize the joint and neutralize the antagonistic effects of undesirable actions. Relatively high force from the rotator cuff not only helps abduct the shoulder but also neutralizes the superior directed force generated by the deltoids at lower abduction angles. Even though anterior deltoid force is REVIEW ARTICLE Sports Med 2009; 39 (8): 663-685 0112-1642/09/0008-0663/$49.95/0The rotator cuff performs multiple functions during shoulder exercises, including glenohumeral abduction, external rotation (ER) and internal rotation (IR). The rotator cuff also stabilizes the glenohumeral joint and controls humeral head translations. The infraspinatus and subscapularis have significant roles in scapular plane abduction (scaption), generating forces that are two to three times greater than supraspinatus force. However, the supraspinatus still remains a more effective shoulder abductor because of its more effective moment arm. Both the deltoids and rotator cuff provide significant abduction torque, with an estimated contribution up to 35–65% by the middle deltoid, 30% by the subscapularis, 25% by the supraspinatus, 10% by the infraspinatus and 2% by the anterior deltoid. During abduction, middle deltoid force has been estimated to be 434N, followed by 323N from the anterior deltoid, 283N from the subscapularis, 205N from the infraspinatus, and 117N from the supraspinatus. These forces are generated not only to abduct the shoulder but also to stabilize the joint and neutralize the antagonistic effects of undesirable actions. Relatively high force from the rotator cuff not only helps abduct the shoulder but also neutralizes the superior directed force generated by the deltoids at lower abduction angles. Even though anterior deltoid force is REVIEW ARTICLE Sports Med 2009; 39 (8): 663-685 0112-1642/09/0008-0663/$49.95/0 a 2009 Adis Data Information BV. All rights reserved.