Test-retest reliability of eccentric peak torque values for shoulder medial and lateral rotation using the Biodex isokinetic dynamometer.

In order for the Biodex isokinetic dynamometer to be used in clinical research, it must be documented to be a reliable measurement tool. The purpose of this study was to determine eccentric peak torque test-retest reliability for glenohumeral medial and lateral rotator muscles using the Biodex isokinetic dynamometer. Eighteen healthy men and women volunteers ranging in ages from 18 to 30 who exhibited no prior history of glenohumeral injury were studied. The subjects were tested bilaterally for eccentric glenohumeral medial rotation (MR) and lateral rotation (LR) at 90 and 120 degrees/sec using 0 degrees of shoulder abduction so that the subject's arm was in contact with his or her trunk. Seven days following the initial test, a retest was administered using the identical protocol. Data collection of pretesting and posttesting was done using the IBM basic computer and the Biodex software program. Test data were analyzed using the intraclass correlation coefficient. The test-retest results indicated: dominant LR at 90 degrees/sec, r = 0.86, and at 120 degrees/sec, r = 0.83; dominant MR at 90 degrees/sec, r = 0.76, and at 120 degrees/sec, r = 0.77; nondominant LR at 90 degrees/sec, r = 0.76, and at 120 degrees/sec, r = 0.83; and nondominant MR at 90 degrees/sec, r = 0.75, and at 120 degrees/sec, r = 0.83. The results demonstrate the isokinetic eccentric mode of the Biodex dynamometer to be reliable for the test-retest measure of peak torque. These data may be used to support future clinical research of the eccentric isokinetic mode of the Biodex isokinetic dynamometer.