1320 THE JOURNAL OF BONE AND JOINT SURGERY Isokinetic and Isometric Measurement of Strength of External Rotation and Abduction of the Shoulder*

ABSTRACT: The strength of active external rotation and of abduction of the shoulder when the humerus was in the plane of the scapula (30 degrees of horizon-tal flexion anterior to the coronal plane) was measured isokinetically and isometrically in thirty-nine normal volunteers, who were stratified by age and sex. The angles at which peak torque was produced were similar when tested isokinetically and isometrically; these an-gles were similar for external rotation (at 60 and 30 degrees of internal rotation) and for abduction (at 30 and 60 degrees of abduction). Isometric peak torque was greater than slow-speed (90 degrees per second) isokinetic peak torque, which in turn was greater than fast-speed (210 degrees per second) isokinetic peak torque. There were highly significant differences i