百公尺途中跑支撐時期地面反作用力的控制與運動表現

百公尺跑是速度最快、競爭最為激烈的田徑項目，對技術動作及優異的速度表現要求較高，是教練在訓練指導上重要的課題，亦是運動生物力學研究的熱門運動之一。百公尺跑為一週期性運動，優秀短跑選手的最高速度一般出現在50 m ~ 60 m 處（途中跑階段），步幅與步頻呈現最佳組合、技術動作較為規範，因此途中跑的跑步技術動作是影響成績的關鍵因素。從跑步動作結構可知，人體在支撐時期（前支撐階段與後支撐階段）受到地面反作用力的影響，由動量定理（mV – mV0 = FΔt）可知，速度是由衝量（FΔt）來決定的，跑步支撐時期重心水平速度的變化與地面反作用力的水平衝量成正比，故欲提高短跑成績就必須設法提高作用力所產生的衝量。水平衝量（P_x）是來自於跑步動作，支撐腿在支撐時期地面反作用力（ground reaction force）在水平方向上的分力與時間的作用結果。當支撐腿著地至身體重心通過支點的正上方的這段期間（前支撐階段），水平衝量值為負，稱為制動衝量（P_(x-), braking impulse）。隨著位移，當重心於支點的正上方至腳離地的這段期間（後支撐階段），水平衝量值為正，稱為加速衝量（P_(x+), propelling impulse）。因此對途中跑的技術而言，如何減少前支撐階段制動衝量的產生，以及如何增加後支撐階段加速衝量的產生是途中跑技術動作的重要課題。本研究藉由相關文獻的探討，彙整所得，一、前支撐階段支撐腿著地動作，縮短著地距離及減小著地瞬間腳相對地面水平速度可以減少制動衝量的產生；二、後支撐階段，支撐腿推蹬離地瞬間膝關節角度未充分蹬伸，表現出屈蹬式的動作，加速衝量增加；三、下肢在跑動過程中，足—地接觸時的地面反作用力與步幅、步頻間的關係及其規律性可以用於運動訓練及檢測技術的優劣，提升競技成績。

關鍵字

地面反作用力；制動衝量；加速衝量

並列摘要

100-meter sprint is the fastest, and most competitive game in track events, which highly requires technical actions and brilliant speed. It is one of the most critical course for training and biomechanic research. 100-meter sprint is a periodical sport. A excellent runner usually reaches their fastest speed from 50 m to 60 m. Stride length and rate are both in the best combination, and technical actions are in a regular way. Therefore, the running technical posture is the keypoint which is able to influence the result of competition. From the structure of runner’s running posture, human body will be influenced by the ground reaction force in the supporting period (pre and post). According to momentum principle (mV - mV0 = FΔt), speed is determined by impulse (FΔt). The change of horizontal speed of center of gravity and the horizontal impulse of the ground reaction force are in direct proportion in running supporting period. As a result, in order to improve sprint game result, it is necessary to higher the impulse created by the force. Horizontal impulse originates from the running action, which is the outcome of the component of force’s influence with time created by the supporting leg’s ground reaction force. When supporting leg touches ground and reach the top of body’s center of gravity (pre-supporting period), the horizontal impulse is minus, called braking impulse (P_(x-)). With the movement, during the supporting leg leave ground and the center of gravity on top of the supporting point, the horizontal impulse is plus, called propelling impulse (P_(x+)). Consequently, for training technical running movement during the race, how to decrease braking impulse and increase propelling impulse are the most important topic. This research collects related documents’ discussion and makes a conclusion. First, for supporting leg’s posture in pre-supporting period, decreasing the distance of reaching ground and the interaction horizontal speed of immediate reaching point can lower the braking impulse. Second, during post-supporting period, the angle of the supporting knee joint doesn’t fully stretch and use bent-leg drive mode, which can increase the propelling impulse. Third, in the process of using the legs, the relation of the counterforce of foot and ground, and its regulation are able to facilitate sports training, examine the technique, and improve the result of competition.