Eccentric and Concentric Strength of the Shoulder and Arm Musculature in Collegiate Baseball Pitchers

Abstract

Many pitching injuries occur during deceleration of the upper extremity when the muscles of the shoulder and arm are acting eccentrically. Published information regarding eccentric muscular strength in baseball pitchers is nonexistent. The purpose of this study was to assess bilateral isokinetic eccentric and concentric muscular strength of the shoulder's external and internal rotator muscles and the elbow's flexor and extensor muscles in a group of collegiate baseball pitchers (N = 25). Isokinetic strength was assessed at 1.6, 3.7, and 5.2 rad/sec. Our findings indicate that the internal rotator muscles were always stronger than the external rotator muscles and that the concentric and eccentric external-to-internal strength ratios ranged from 62% to 81%. The eccentric strength of the shoulder rotator muscles averaged 114% that of concentric strength. The concentric and eccentric elbow extension-to-flexion strength ratios ranged from 71% to 110%; eccentric strength averaged 33% higher than concentric strength. No differences were noted between dominant and nondominant limbs for any of the strength measures or ratios. Clinically, the findings of this study can serve as a reference during the evaluation, rehabilitation, and conditioning of throwing athletes.