在躍起著地時誘發疲勞運動對下肢關節和地面反作用力的影響

The Influences of Fatigue Induced Exercise on Lower Extremity Joint and Ground Reaction Force during Landing from a Jump

目的：本研究目的在探討在躍起著地時，誘發疲勞運動是否對下肢關節和地面反作用力產生影響。方法：本實驗共招募10名健康男性受試者（年齡23.7±0.7歲、身高173.6±3.0公分、體重71.3±7.9公斤），利用十台Vicon紅外線攝影機(200Hz)和一塊Kistler測力板(1000Hz)同步收集全身動作資料和地面反作用力。受試者需進行向前的躍起著地，動作為雙腳起跳，支撐腳單腳著地。誘發疲勞運動包括連續進行蹲踞(squat)、舉踵(heelraise)的動作（身上負重為三分之一的體重），直到受試者自覺無法再進行為止。使用成對樣本t考驗來比較疲勞前後的差異，結果：疲勞後所測得的髖關節的最大屈曲角度、活動動範圍和膝關節的活動範圍在疲勞後皆顯著小於疲勞前的結果(p<.05)。到達最大膝關節屈曲角度的時間在疲勞後會減少(p<.05)；疲勞後會產生較大的地面反作用力(p<.05)；結論：本研究發現，經誘發性疲勞運動後，個體會採取較為僵硬的著地動作，其目的是為了要快速緊急地維持姿勢的穩定，但也造成著地後的衝擊力無法有效地減少，因此可能會提升傷害的風險。

Purpose: The purpose of this study was to investigate the effects of fatigue induced exercise on lower extremity joint and ground reaction force during landing from a jump. Methods: Ten healthy males (23.7±0.7 years old; 173.6±3.0 cm; 71.3±7.9 kg) were recruited for this study. A ten-camera motion analysis system (200Hz) and one force plate (1000Hz) were used to collect whole body motion data and ground reaction forces， respectively. All subjects needed to perform a forward jump-landing protocol， including a double-leg jumping and a single-leg landing (supporting leg only). Fatigue induced exercise included repeated squatting and heel raising motions with about one third loading of each subject’s body weight until subjects felt exhausted. Paired-samples t test was used to compare each parameter between pre-fatigue and post-fatigue. Results: The peak hip flexion angle， the hip and knee range of motions were significant less than pre-fatigue (p< .05)， the less time to peak knee flexion angle and the greater peak ground reaction force occurred after muscle fatigue (p< .05). Conclusions: To our results， we found that individual’s landing posture would change with a stiff landing movement to maintain postural stability rapidly after fatigue induced exercise. Hence， a stiff landing with greater impact force might result in increasing the injury risk.