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Context: The reliable measurement of shoulder strength is important when assessing athletes involved in overhead activities. Swimmers' shoulders are subject to repetitive humeral elevation and consequently have a high risk of developing movement-control issues and pain. Shoulder-strength tests performed in positions of elevation assist with the detection of strength deficits that may affect injury and performance. The reliability of isometric strength tests performed in positions of humeral elevation without manual stabilization, which is a typical clinical scenario, has not been established. Objective: To establish the relative and absolute intrarater reliability of shoulder-strength tests functional to swimming in 3 body positions commonly used in the clinical setting. Design: Repeated-measures reliability study. Setting: Research laboratory. Subjects: 15 university students and staff (mean ± SD age 24 ± 8.2 y).Intervention: Isometric shoulder-strength tests were performed in positions of humeral elevation (flexion and extension in 140° abduction in the scapular plane, internal and external rotation in 90° abduction) on subjects without shoulder pain in supine, prone, and sitting. Subjects were tested by 1 examiner with a handheld dynamometer and retested after 48 h. Main Outcome Measures: Relative reliability (ICC3,1) values with 95% CI. Absolute reliability was reported by minimal detectable change (MDC). Results: Good to excellent intrarater reliability was found for all shoulder-strength tests (ICC .87-.99). Intrarater reliability was not affected by body position. MDC% was <16% for every test and ≤11% for tests performed in supine. Conclusions: Shoulder flexion, extension, and internal- and external-rotation strength tests performed in humeral elevation demonstrated excellent to good intrarater reliability regardless of body position. A strength change of more than 15% in any position can be considered meaningful.
McClaine, Kitic, Fell, and Bird are with the Faculty of Health Sciences, University of Tasmania, Launceston, Australia. Ginn is with the Discipline of Biomedical Science, University of Sydney, Sydney, Australia.