{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,21]],"date-time":"2026-08-21T13:03:36Z","timestamp":1787317416113,"version":"build-2736575974"},"reference-count":21,"publisher":"SAGE Publications","issue":"11","license":[{"start":{"date-parts":[[2009,9,22]],"date-time":"2009-09-22T00:00:00Z","timestamp":1253577600000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/journals.sagepub.com\/page\/policies\/text-and-data-mining-license"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Am J Sports Med"],"published-print":{"date-parts":[[2009,11]]},"abstract":"<jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>Throwing athletes with shoulder pain have been shown to have decreased rotator cuff muscle strength. Shoulder internal impingement and labral peel-back mechanism, as may occur during the late cocking phase of throwing motion, are thought to cause rotator cuff injury and type II superior labrum anterior and posterior lesions. Therefore, the objective of this study was to assess the effect of rotator cuff muscle force on internal impingement and the peel-back of the superior labrum by quantifying maximum external rotation, glenohumeral contact pressure, and position of the cuff insertion relative to the glenoid.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Hypothesis<\/jats:title>\n                    <jats:p>A change in rotator cuff muscle force will lead to increased external rotation, glenohumeral contact pressure, and overlap of the cuff insertion relative to the glenoid.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Study Design<\/jats:title>\n                    <jats:p>Controlled laboratory study.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>Eight fresh-frozen cadaveric shoulders were tested at the simulated late cocking position. Glenohumeral contact pressure, location of the cuff insertion relative to the glenoid, and maximum humeral external rotation angle were measured. The forces of the supraspinatus, subscapularis, and infraspinatus muscles were determined based on published clinical electromyographic data. To assess the effect of cuff muscle imbalance, each muscle force was varied. Horizontal abduction positions of 20\u00b0, 30\u00b0, and 40\u00b0 with respect to the scapular plane were tested.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>Decreased subscapularis strength resulted in a significant increase in maximum external rotation ( P &lt;.001) and increased glenohumeral contact pressure ( P &lt;.01). The cuff insertion overlapped the edge of the glenoid at 30\u00b0 and 40\u00b0 of horizontal abduction for all muscle loading conditions.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>Decreased subscapularis muscle strength in the position simulating the late cocking phase of throwing motion results in increased maximum external rotation and also increased glenohumeral contact pressure.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Clinical Relevance<\/jats:title>\n                    <jats:p>Athletes with decreased subscapularis muscle strength, such as fatigue with repetitive throwing, may be more susceptible to rotator cuff tears and type II superior labrum anterior and posterior lesions. Subscapularis muscle strengthening exercises may be beneficial for preventing these injuries.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1177\/0363546509337450","type":"journal-article","created":{"date-parts":[[2009,9,22]],"date-time":"2009-09-22T22:30:19Z","timestamp":1253658619000},"page":"2222-2227","source":"Crossref","is-referenced-by-count":55,"title":["Effect of Rotator Cuff Muscle Imbalance on Forceful Internal Impingement and Peel-Back of the Superior Labrum"],"prefix":"10.1177","volume":"37","author":[{"given":"Teruhisa","family":"Mihata","sequence":"first","affiliation":[{"name":"Orthopaedic Biomechanics Laboratory, Long Beach VA Healthcare System and University of California, Irvine, California"},{"name":"Department of Orthopedic Surgery, Shoulder & Elbow Biomechanics Laboratory, Osaka Medical College, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jeffrey","family":"Gates","sequence":"additional","affiliation":[{"name":"Orthopaedic 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Q.","family":"Lee","sequence":"additional","affiliation":[{"name":"Orthopaedic Biomechanics Laboratory, Long Beach VA Healthcare System and University of California, Irvine, California"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"179","published-online":{"date-parts":[[2009,9,22]]},"reference":[{"key":"b1-0372222","first-page":"179","volume":"88","author":"Alberta FG","year":"2006","journal-title":"J Bone Joint Surg Am"},{"key":"b2-0372222","first-page":"17","volume":"50","author":"Andrews JR","year":"2001","journal-title":"Instr Course 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