| Summary: | 碩士 === 臺北市立大學 === 運動器材科技研究所 === 102 === Purpose: To exam the differences of physical characteristic among the game balls of the international tournaments with various age stages. Method: 36 baseball spheres collected from the 12U and 18U World Cup and Baseball World Classic (WBC) in 2013. The weight, circumference, seam width, seam height, coefficient of restitution (COR) and compression displacement (C-D) were measured. Results: After analysis of one-way ANOVA with repeated measures, all the specification of IBAF baseball spheres met the standard values in the baseball rule. The 12U spheres were the largest in circumference, seam height and seam width, as well as the softest in hardness. The 18U spheres were the lightest, smallest and hardest in weight, circumference and hardness. The WBC spheres were the heaviest and highest in weight and COR. Conclusion: The specifications of tournament baseball spheres among various age stages were significantly difference. Although the specifications of international tournament game balls among various age stages met the standard of baseball rule. These differences did not response to players’ physical and technical development among various age stages. Therefore, the findings suggested that the specification of baseball game balls for various age players should have classification based on players’ physical and technical development. It might be reduce the risk of injury and develop proper pitching mechanism for youth players.
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