Test-retest reliability of glenohumeral internal and external rotator strength

Objective: To establish test-retest reliability for a strength testing protocol of the glenohumeral internal and external rotator muscles using a KinCom (Chattanooga Group, Hixson, TN) isokinetic dynamometer. Design: Prospective test-retest reliability study. Setting: Rehabilitation research laboratory. Participants: Fourteen volunteers between the ages of 27 and 35 years participated in the study. Subjects had no history of traumatic shoulder injury and no overuse-based shoulder pain interfering with activity within the last 6 months. Nine of the 14 subjects were not participating in more than 6 hours weekly of arm-based sporting activities, while the remaining five subjects were involved in swim training at workout volumes of no greater than 3000 in per week. Intervention: Subjects performed three test sessions of four maximal repetitions each of concentric and eccentric shoulder internal and external rotation bilaterally in a standardized sitting position. An average of 5.9 days occurred between consecutive test sessions (range, 2-21 days). Main Outcome Measures: Average torque data were collected for concentric and eccentric internal and external rotation tests bilaterally. Intraclass correlation coefficients were calculated to compare the data across sessions. Pearson product moment correlation coefficients were calculated to assess reliability between sessions. Results: High test-retest reliability, ranging from 0.82 to 0.97, was demonstrated for all tests. Conclusions: The results indicate that a reliable test protocol has been determined for shoulder internal and external rotation strength testing on the KinCom isokinetic dynamometer.