過肩投擲足壓模式之探討

A study of the characteristics of foot pressure distribution for over-arm throwing

投擲動作是運動技術及運動傷害方面研究重點項目，近來研究發現下肢是動力傳遞的主要來源，但其角色仍待進一步釐清，尤其下肢動作反映在各足底壓力區在關鍵時期的分佈情形。目的：在於比較大專女生投擲距離優秀與普通兩組手臂向前揮動初期軸心腳及球離手瞬間之引導腳，分別在前足（細分為五區）、中足及後足分區上壓力分佈差異以及壓力中心走向之差異。方法：以58名大專女生依據投擲距離分成優秀及普通兩組，透過Medilogic測力鞋墊（60Hz）及其分析軟體（Medilogic 3.8版）配合高速攝影機（JVC9800，60Hz），以Medilogic系統內建FAp-video軟體同步紀錄動作，並以t考驗分析兩組差異及質化分析探討兩組壓力中心走向差異，統計水準定為α＝.05。結果：優秀組顯示在手臂向前加速初期，軸心腳的壓力區已經集結到前足，但與普通組沒有達到顯著差異（t＝1.037，p＞.05）；球離手瞬間之引導腳壓力分佈仍是集中在前足區，優秀組集中的比例顯著高於普通組（t＝2.059，p＜.05），尤其在前足之其他蹠骨區，優秀組壓力分佈顯著高於普通組（t＝2.035，p＜.05）；在投擲整個時期壓力中心分佈圖形上，普通組散佈圖圖形為扁平圓形，優秀組散佈圖則形成鉤子形狀。結論：本研究結果顯示優秀組壓力分佈與壓力中心移動明顯與普通組有差異，優秀組中心向前移動趨勢相當明顯，表示腳步動作的確與腰部旋轉動作相關，建議體育教師需加強投擲腳步移動訓練。Purpose: The purpose of the study was to compare differences of center of pressure (COP) and foot pressure distribution on push-off and landing limb between the elite and normal group of college over-arm throw athletes. Methods: Fifty-eight subjects voluntarily participated in this study. In order to obtain athlete performance both in segmental motion and foot COP change, present study used high speed camera (60Hz) and COP measurement system (Medilogic) to collect data. Students test was used to examine performance between two test groups. The study adapted the t-test (α= .05) and qualitative analysis to compare the difference between elite and normal girls. Results: The results showed that two groups of subjects mainly put pressure on forefoot of push-off limb (t = 1.037, p > .05) at the initial phase of the acceleration period. At the initial phase of the ball leaving period, two groups of subjects put pressure on forefoot of landing limb (t = 2.059, p < .05). The elite group put higher pressure on other thumb area of forefoot (t = 2.035, p < .05) than that of normal group. The diagrams of COP distribution were different between the elite group (hook shape) and normal group (flat round shape). Conclusion: It was concluded that the distribution of foot pressure and COP change were different between the elite and normal group. The elite group showed that the trend of COP change move forward obviously. This suggested over-arm throw athletes should be strengthen on foot training.