A Biomechanical Analysis among the Breakingball in High School Pitchers

• Main Authors: Yu-LinChen, 陳右霖
• Other Authors: Rung-Tai Wang
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/46633880922651415649

碩士 === 國立成功大學 === 工程科學系碩博士班 === 101 === Introduction： 　　How to pitch the breaking balls effectively in addition to the fastball is an important task in baseball competition. However, learing a new kind of breaking ball is a difficult process, compared to the fastball, the pitching motion of the pitcher's shoulders, elbows, wrists and knees need to be adjusted. In the other hand, different risk of injurys and burdens of body may occur in practicing breaking ball with differet pitching motions. Purpose： 　　To investigate the changes of kinematics, kinetics and muscle strengh of high school baseball pitcher's shoulders and elbows after throwing a certain number of different types of pitches, thus suggest the muscle training policy for each type of pitch to reduce the risk of injury in throwing the breakingball. Method 　　Nine Taiwanese high school baseball pitchers of group A. The pitchers participated fastball, curveball and slider test on different dates respectively. In one test, the pitcher executed 50~60 pitches according to the affordability of the pitcher after adequate warm-up, the pitching motion of each pitch was captured with outdoor three dimensional motion analysis system. The range of motion and muscle strength were recorded at pre-test, post-test and Day1 for studying the changes after pitching. Statistical methods using repeated measures ANOVA and paired t-test. Significant at p 〈 0.05. Result 　　Out of 96 kinematic parameters, 21 parameters in curveball test, 24 parameters in fastball test and 25 parameters in slider test were significantly different after pitching, respectively. Out of 56 kinetic parameters, 12 parameters in curveball test, 13 parameters in fastball test and 21 parameters in slider test were significantly different after pitching, respectively. 　　Between fastball and curveball, 46 of 96 kinematic parameters and 33 of 56 kinetic parameters were significantly different. Between slider and curveball, 54 of 96 kinematic parameters and 41 of 56 kinetic parameters were significantly different. Between fastball and slider, 44 of 96 kinematic parameters and 21 of 56 kinetic parameters were significantly different. Discussion and Conclusion 　　When the pitcher throws curveball, there is a higher value at wrist dorsi flexion moment relative to fastball, and the elbows bear larger forces and moments in the late stage of pitching motion(Arm Deceleration phase). Therefore, more training of elbows and wrists may reduce the risk of injuries for the pitchers who throw curveball often. 　　In the late stage of the pitching motion, the shoulder horizontal abduction moment and shoulder internal rotation moment showed higher values in throwing slider relative to the other two balls, and after repeatedly throwing slider, the values of the elbow anterior force, flexion moment and rotation moment become larger in entire pitching process, more forces and moments that exert on the elbow and shoulder become larger in the late stage of the pitching motion. Therefore, the pitchers may proceed more training for the muscle near the shoulder and elbow to reduce the risk of injuries with throwing slider often. 　　On the other hand, both curveball and slider have significantly differences at the forearm pronation angle after a certain number of pitches. This may cause the pitching mechanism to change, further increase the risk of injury and decrease the stability of pitching, so training the muscle of forearm pronation and supination is suggested for practicing curveball and slider in this study.