| Summary: | 碩士 === 國立臺灣師範大學 === 體育學系在職進修碩士班 === 97 === Influence of the batting performance to the batting average for junior league baseball players
Graduate student：Ho-Chi Chen
Professor：Jia-Hao Chang
Abstract
Purpose: to evaluate the relation between the batting performance and the batting average of the junior league baseball players. Methods: nine junior league baseball lineup players (age: 14.33±1.0 years, height: 170.22 ± 6.41 cm, and weight: 65.56 ± 6.4 Kg) in Taipei County participated in this study. The batting average (0.326 ± 0.089) of all participants was reported from the games held by the Taipei County in 2008. Two Redlake high-speed cameras (sampling at 250 Hz) were utilized to capture the player’s batting movements. Kwon3D was used to calculate the kinematical data including elbow angle, translation of the long axis of the trunk, duration of hitting, and the path of hitting. Pearson method was used to assess the relationship of the kinematics data by using SPSS. The significant level was set as α = .05. Results: (1) no correlation between the batting average and batting duration, from the beginning of stepping forward to the end of batting swing, was found (p = .110), however, the correlation between the batting average and batting duration, from the end of stepping forward to the end of batting swing, was found (r = -.696, p = . 037); (2) significant correlation between the swing speed in the impact phase and the batting average was found (r = .702, p = . 035), and the result also showed significant correlation between horizontal swing path and horizontal batting speed (r = .763, p = .017); (3) significant correlations between the elbow angle in the initial ball impact and horizontal batting speed, and between the elbow angle in the initial ball impact and ball speed were found (r = .893, p = .001; r = .724, p = .027, respectively); (4) significant correlation was also found between the translation of the long axis of the trunk in horizontal and the batting average. (r = -.669, p = .049). Conclusion: shorter batting duration, faster swing in the initial ball impact, less translation of the long axis of the trunk in horizontal, and more horizontal swing path, would improve the batting performance of the junior league baseball players. Suggestion: the player should practice to adjust the batting posture, fix the rotation axis of the trunk, and adjust the elbow angle at ball impact.
Keywords: Swing duration, elbow angle, swing path, horizontal swing
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