Why is the Rotator Cuff Important?

By Grant Uyemura, DPT Student

Rotator cuff tendinopathies affect 20-30% of the general population and becomes more prevalent and disabling with age. 1 The rotator cuff is made up of 4 muscles supraspinatus, infraspinatus, teres minor, and subscapularis. These muscles help stabilize the humeral head within the glenoid fossa and prevent superior humeral head migration during overhead movements. 2

Weakness of the rotator cuff can lead to shoulder impingement, tendonitis, bursitis, and labral tears. Looking at Jobe’s instability continuum. 3
1. Rotator cuff weakness generally occurs first
2. Functional instability follows prolonged rotator cuff weakness
3. Capsular laxity, which develops over time
4. Subluxation due to inability of the humeral head to center in the glenoid during motion
5. Rotator cuff/labral tearing (late-stage disease of secondary impingement)

Best Exercises

Reinold et al., 2,4 found that the best supraspinatus exercise was a standing or prone full can. A standing full can was found to have decreased deltoid activation compared to the prone full can. Sidelying external rotation with 0º of abduction was found to be the best exercise to strengthen the infraspinatus and teres minor. Internal rotation at 0º or 90º of abduction was the best exercise to strengthen the subscapularis. Click here or photos for link to videos.

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These isolated exercises are a good starting point and are great for a basic home program.  However, for best results they should be used in conjunction with a more comprehensive and integrated rehab routine.

img_2534Blog post written by Grant Uyemura, DPT Student from University of St. Augustine. At the time of publishing Grant was in a clinical rotation with me at Catz PTI.


1. Wies JT, Humphreys H, Latham M, et al. A randomized placebo-controlled trial of PT for RTC tendinopathies [abstract]. J Orthop Sports Phys Ther. 2005;35:A5.

2. Reinold MM, Escamilla R, Wilk KE. Current Concepts in the Scientific and Clinical
Rationale Behind Exercises for Glenohumeral and Scapulothoracic Musculature. J Orthop
Sport Phys Ther. 2009;39(2):105-117. doi:10.2519/jospt.2009.2835.

3. Page P, Frank C, Lardner R. Assessment And Treatment Of Muscle Imbalance. Champaign [etc.]: Human kinetics; 2010.

4. Reinold MM, Wilk KE, Fleisig GS, et al. Electromyographic Analysis of the Rotator Cuff
andDeltoid Musculature During Common Shoulder External Rotation Exercises. J Orthop
Sport Phys Ther. 2004;34(7):385-394. doi:10.2519/jospt.2004.34.7.385.

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