Isokinetic evaluation of shoulder rotational strength in high school baseball pitchers

Abstract

Isokinetic, shoulder rotational strength was evaluated in 26 high school baseball pitchers before the start of spring practice. Using the Cybex II (Cybex, Division of Lumex, Inc., Ronkonkoma, NY), test data were gath ered on the dominant and nondominant shoulders in the supine 90° abducted test position (90° AbTP) and the standing neutral test position (neutral TP). Tests were performed at 90 and 240 deg/sec. The HUMAC (Computer Sports Medicine, Inc., Flemington, NJ) com puter system was used to analyze data. Means and standard deviations for peak torque, total work, peak torque to body weight ratios, and agonist/antagonist ratios are presented. Comparison of dominant to non dominant sides and 90° AbTP to neutral TP values are reported. Peak torque and total work values for the throwing side internal rotators were significantly higher than the nonthrowing side in all tests. Pitching side externai rotators falled to show this dominance. Exter nal/internal rotation ratios for peak torque and total work were significantly lower on the pitching side, suggesting a relative imbalance of cuff musculature compared to the nonpitching shoulder. Significant dif ferences existed between data gathered in the two different test positions. In the 90° AbTP, external ro tation peak torque and total work values and external/ internal rotation peak torque and total work ratios were higher than the equivalent values gathered in the neutral TP. Internal rotation peak torque and total work values tended to be higher in the neutral TP than in the 90° AbTP. The rotator cuff imbalances exhibited in the pitching shoulder of participants in this study draw attention to the need for structured exercise to prevent and correct this deficit, which can act as a predisposing factor to injury in the throwing athlete. Significant dif ferences in torque data gathered in two commonly used shoulder rotational test positions suggest the need for multiple position testing for complete evaluation and the requirement of specifying test position when com paring shoulder rotational torque values clinically or experimentally.