Concentric isokinetic shoulder internal and external rotation strength in professional baseball pitchers

Abstract

Objective measurement of shoulder internal and external rotation strength is an important part in the comprehensive evaluation and rehabilitation of athletes who perform predominantly unilateral upper extremity movement patterns. Apparatus- and population-specific descriptive data are needed to enhance the interpretation of results from isokinetic dynamometers. The primary purpose of this study was to measure isokinetically glenohumeral joint internal and external rotator peak torque and work in professional baseball pitchers and determine whether significant differences exist between the dominant (throwing) extremity and nondominant extremity. One hundred twenty-five healthy professional baseball pitchers were tested bilaterally on a Cybex 300 series isokinetic dynamometer at 210 and 300 degrees/sec for concentric internal and external rotation of the glenohumeral joint with the arm in 90 degrees of abduction. A standardized protocol and testing guidelines were strictly followed. A dependent t test was used to test for differences between extremities for peak torque and single repetition work isokinetic parameters. No significant difference between the dominant and nondominant shoulder was found for external rotation peak torque or single repetition work at either testing speed. Significantly greater (p < .001) dominant arm shoulder internal rotation was measured for both peak torque and single repetition work at 210 and 300 degrees/sec compared with the nondominant extremity. The results of this study are important for the application and interpretation of isokinetic data on unilaterally dominant upper extremity athletes. The use of a population-specific, descriptive isokinetic data profile is important in both rehabilitation and prevention of shoulder injuries.