透過IMU裝置對少棒打者擊中球與揮棒落空之動作分析

Abstract

目的：本研究主要目的為透過慣性感測器 (IMU) 針對少棒選手的打擊動作進行生物力學分析。探討在擊中球與揮棒落空兩種打擊結果中的運動學差異，並釐清打擊過程中軀幹的旋轉角速度及肢段部位的動作時序，與前述兩種打擊結果之間的相關性，並作為少棒選手打擊動作技術之參考。方法：以16位少棒選手受試者參與研究。八顆 IMU 分別黏貼於受試者髖部、胸骨、雙手手腕、雙手手背、前側手臂及後側大腿等處，每名受試者站立於少棒硬式球之投捕距離的打擊區內，皆須全力揮棒打擊發球機所投出之10顆球，採集打擊過程中受試者擊中球與揮空各3顆球之運動學參數，以SPSS23.0 (顯著水準設為α< .05) 統計軟體中的成對樣本t檢定 (Paired-Sample t test) 分析肢段部位的動作時序與軀幹角加速度峰值，藉以探討兩者之間的運動學之差異。結果：本研究結果發現在16位受試者在擊中球與揮空時的動作時序有顯著性差異 (雙手背、雙手腕及前側手臂等皆p < .05)。軀幹及後大腿等平均旋轉角速度峰值之間皆無顯著差異。結論：少棒選手肢段部位的動作時序與擊中球和揮棒落空兩者結果之間有直接的相關性。而其打擊動作過程中軀幹旋轉角速度則與兩種打擊結果無直接或間接的相關性。另外，雖少棒選手因本身協調性及打擊機制尚未成形穩定之故，但仍可透過IMU結合數位軟體系統或線上應用程式之分析與規畫，作為追蹤選手未來訓練時的參考依據。Objective: The primary objective of this study is to conduct a biomechanical analysis of the batting actions of youth baseball players using inertial measurement units (IMUs). The research aims to explore the kinematic differences between successful hits and missed swings, clarify the relationship between trunk rotational angular velocity and the sequence of limb segment initiation during the batting process, and how these factors relate to the aforementioned batting outcomes. This study will serve as a reference for the batting techniques of youth baseball players. Methods: The study involved 16 youth baseball players as subjects. eight IMUs were attached to each subject's hips, sternum, wrists, backs of the hands, front arms, and back thighs. Each subject stood in the batting zone at the official pitching distance for youth baseball and was required to swing with full effort to hit 10 balls thrown by a pitching machine. Kinematic parameters were collected for each subject's three hits and three misses during the swinging process. The paired-sample t-test in SPSS 23.0 statistical software (significance level set at α < .05) was used to analyze the action timingand trunk angular acceleration peak values of different body segments to investigate the kinematic differences between hitting and missing. Results: The results of this study found significant differences in the timing of movements between hitting the ball and swinging without contact among the 16 participants (with p-values less than .05 for both the back of the hands, wrists, and anterior forearms). There were no significant differences in the peak average rotational angular velocities of the trunk and the posterior thighs. Conclusion: There is a direct correlation between the action timing of the body segments of youth baseball players and the results of hitting and missing the ball. However, the rotational angular velocity of the trunk during the batting process does not have a direct or indirect correlation with the two hitting outcomes. Additionally, although the coordination and hitting mechanics of youth baseball players have not yet fully developed or stabilized, the analysis and planning through IMUs combined with digital software systems or online applications can still serve as a reference for tracking the players' future training.