國小學童投擲動作分期時間百分率與球速關係

The Relationship Between Elementary School Students’ Time Percentage of Throwing Motion Phases and Speed

兒童時期的丟、投、拋與甩等動作，在日常生活中是相當常見的上肢動作，而動作分期時間百分比、揮臂速度、出手瞬間主要關節角度等運動學參數與投擲的球數有關。本研究目的在探討國小五、六年級學童過肩投擲球速與動作分期時間的關係。對象以8位國小五年級學童，8位國小六年級學童。以二部高速攝影機(300Hz)，以同步方法擷取三次學童過肩投擲之動作，並將動作分成跨步期、觸發期、揮臂期等三個階段進行分析。影片以Kwon3D動作分析軟體進行運動學參數分析，利用皮爾遜積差相關檢驗動作分期時間與球速的相關性。以及利用獨立樣本t考驗，比較五年級與六年級投擲球速與揮臂期時間百分率之差異性，統計水準定為α＝.05。結果發現投擲動作總時間與球速無相關，跨步期時間百分率與球速無相關，觸發期時間百分率與球速無相關，揮臂期時間百分率與球速負相關。另外，五年級與六年級學童投擲球速之t考驗達到顯著，五年級與六年級學童投擲揮臂期時間百分率之t考驗亦達到顯著。

Flinging， tossing， and throwing， are commen upper limbs motions in human childhoods. The kinematic parameters: percentage of time of motions， arm swinging speed， instant shot of main joint angle， are related to the numbers of throwing. The purpose of this study was to investigate the fifth and sixth grade students’ over-shoulder throwing with the motion staging. Objects are eight fifth graders and 8 sixth graders. Synchronizly retrieve children’s over -shoulder throwing motions for three times with two high-speed cameras (300 Hz). Divide motions into stride period， motion trigger period and windup period to analysis. Use the Kwon3D motion analysis software to analyse kinematic parameters. Inspect motion staging time with the throwing speed in Pearson's product-moment correlation. Using independent samples t-test， comparing the difference of fifth grade and sixth grade students throwing speed with the windup period of time percentage. Statistical level was set at α = .05. The results found that the total time of throwing and throwing speed is no related. The percentage of time of stride period was no correlation with throwing speed. The percentage of time of trigger period was no correlation with throwing speed. The percentage of time of the windup period with throwing speed was negatively correlated. In addition， the t-test of throwing speed of fifth grade and sixth grade students achieved significant. The t-test of time percentage of fifth grade and sixth grade students’ windup period of throwing was significant， too.