優秀青少年競走選手下肢動作的生物力學分析

田徑運動的競走項目是近年來東方人在奧運會中屢創佳績、嶄露頭角的競技項目，優異的成績表現取決於成熟的技術能力，其中許多文獻指出下肢動作是主要的技術關鍵。本研究目的欲探討國內優秀青少年競走選手在不同速度(高速90%、低速60%)的下肢動作技術之差異。方法：國內優秀青少年競走選手八名（身高：1.64 ±0.08公尺、體重：55.5±6.5公斤、年齡：14.6±0.7歲、訓練年齡3±0.5年）參與實驗。使用兩台測力板 (Kistler, 1000 Hz) 和8台紅外線攝影機（Vicon, 200Hz）拍攝競走動作，實驗中取五次成功的兩個週期步態，以其中最穩定的一步（Step）擷取運動學和動力學參數，所得之數據使用成對樣本 t 檢定 (Paired-Simples t Test) 進行比較分析，顯著水準為α = .05。結果：步態支撐期的腳跟觸地階段（Heel Strike），下肢踝關節的背屈（Dorsiflexion）角度，呈現高速大於低速。腳尖離地階段（Toe-Off）踝關節的蹠屈（Plantarflexion）角度，呈現高速小於低速。下肢膝關節於腳跟觸地階段，伸展角度呈現低速大於高速。左、右腳於支撐期著地的最大地面反作用力（GRF）皆呈現高速顯著大於低速之情形。高速時，擺盪期的時間比顯著大於低速呈現49：51。結論：（1）以低速進行長距離的訓練，選手的下肢關節在支撐期有較佳的關節角度控制，並使其能完全伸展下肢動作，進而有效增加關節活動度的使用。（2）高速時，支撐期的地面反作用力較大，有效率地使用踝關節力量能幫助身體的向前帶動。（3）高速時，支撐期的時間減少，擺盪期的時間隨之增加。

關鍵字

競走；青少年；生物力學；下肢動作

並列摘要

Introduction: In recent years, Asian athletes have become more competitive in the field of race walking, most notably in their performance at the Olympics. The improvement in performance can be attributed to more advanced training techniques. Previous studies indicate that lower limb movement is the most important factor in overall performance of race walkers. The purpose of this study is to compare the lower limb movements of Taiwanese elite junior race walkers at two different speeds (high speed 90% and low speed 60%) in order to observe any differences in technique. Methods: Eight elite junior race walkers in Taiwan ( 4 males and 4 females, height: 1.64 ±0.08 m, weight: 55.5±6.5 kg, age: 14.6±0.7 years, training age: 3±0.5 years, ) participated in this study. Eight Vicon Motion System cameras ( 200Hz ) and two Kistler force plates ( 1000Hz ) were used in conjunction to capture lower limb movement. Five successful gait cycles for two speeds were collected, of which the most stable gait cycle out of the captured movements was used for comparison of the kinematic and dynamic parameters. A paired sample t test was performed for statistical analysis ( α = .05 ). Results: At the point of the heel strike, the ankle’s angle of dorsiflexion is significantly larger when walking at the higher speed, while the knee does not extend as fully for both speeds. In toe off phase, the ankle’s angle of plantar flexion is significantly smaller at higher speed. Both left and right feet’s GRF in the stance phase is considerably larger at higher speed. At high speed, the stance phase to swing phase time ratio is 48.9 : 51.1, while at low speed the time ratio is 51.9 : 48.1. As the speed increases, time spent in stance phase decreases, while time spent in swing phase increases. Conclusion:（1）When training at low speed for long distances, the athlete’s lower limb joints have more control over the angle of movement in stance phase and can fully extend their movements, therefore effectively increasing utilization of joint mobility.（2）At higher speed, the GRF during stance phase is greater and efficient use of ankle strength can help to drive the body forward.（3）Also at higher speed, time spent in stance phase is reduced, while time spent in swing phase is accordingly increased.