衝刺跑的著地時間與地面反作用力

Contact time and ground reaction force during the acceleration phase of sprinting

足部是跑步過程唯一與外在環境直接接觸的肢段，因此跑步的速度來源可以視為是足部與地面的不斷接觸，並且配合工作要求所形成的交互作用。著地的過程中在水平與垂直方向產生地面反作用力是跑步加速的關鍵，許多研究藉由運動學與動力學方法分析跑步著地期間的特徵。本研究採文獻回顧的方式，探討近年關於步頻、勁度、著地期地面反作用力與衝量對於跑步運動的影響，文獻結果提供藉由著地時間的操弄造成運動參數改變，探討著地時間推論勁度參數的可行性，而相關研究對於以著地時間辨別技能水平的看法不一，使用以相同方法推論非菁英跑者可能出現誤差。許多研究以不同的角度分析推進與煞車作用力對加速的重要性，在加速初期的推進作用力是主要影響因素，隨著速度提升減速衝量逐漸增加，對於速度的影響性也會變大。

The foot is the only segment that contact with the environment in running. The interaction among foot work, ground, and task intent is the source of speed increase to support and to propel the runner forward repeatedly. It is the essential factors that the act of horizontal and vertical ground reaction force to cause or to result the increase of running speed. There were many researches concerned with the characteristics of kinematics or kinetics for the duration of ground contact times in running. The aim of this study was to review the literatures of the manipulations of step frequency, leg stiffness, and the action of impulse during ground contact of running. The recent researches showed the manipulation of contact time might influence the parameter of the motion, and the derived issue of the stiffness from contact time. However, previous researches had different perspective on the discrimination of sprinter levels. It exists the treatment of validity to assess a non-elite sprinter. Previous researches indicated the importance of propulsive force and braking force for acceleration. The propulsive force is the key factor during the early acceleration phase. But the braking force is getting higher with sprint speed to influent the performance.