Abstract
The primary purpose of this study was to investigate whether the baseball pitchers have asymmetric characteristics of muscle thickness (MT) in upper extremities, trunk, and lower extremities because of repetitive pitching. The secondary purpose of this study was to investigate the relationship between MT and ball speed. Twenty-six college baseball pitchers participated in this study. Twenty-six sites were selected to quantify the asymmetric characteristics of MT. The MT was measured by a B-mode ultrasound. The ball speed, measured by a radar gun, was used to quantify the pitching performance. The MT of forearm, subscapula, and chest in dominant side (pitching side) were significantly greater than those in nondominant side, and the MT of abdomen, lateral abdomen, and anterior thigh in nondominant side were significantly greater than those in dominant side. On the other hand, the MT of forearm in both sides and the MT of lateral abdomen in dominant side were significantly and positively correlated with ball speed. These results suggest that asymmetric muscle thickness in upper extremity, trunk, and lower extremity in baseball pitchers resulted from repetitive pitching, and the MT of forearm and lateral abdomen are related to the ball speed.
