本研究的主要目的檢證個體產生立即性的疲勞限制下，下肢勁度的調控機制。實驗參加者為18名體育相關科系之男性大學生（年齡為20.0 □ 1.6歲、身高175.9 □ 7.5公分、體重70.3 □ 9.1公斤），使用Vicon MX-F40動作分析系統記錄實驗參加者在Kistler三維測力板（1000Hz）上之雙手叉腰連續1分鐘垂直跳，本研究將前5次參數的平均數定義為疲勞前、最後5次參數的平均數定義為疲勞後。運動學及動力學參數經過相依樣本t檢定統計考驗（□ = .05），研究結果顯示，疲勞限制不會改變下肢勁度、髖關節、膝關節和踝關節勁度之值。膝關節著地角度、踝關節屈曲角度、踝關節角位移量、髖關節屈曲力矩和踝關節屈曲力矩在疲勞限制下皆明顯小於疲勞前（p < .05）。本研究顯示藉由踝關節屈曲及膝關節著地角度之調控，使下肢於疲勞限制下，下肢勁度之調控維持相似之值。也證明了個體在連續垂直跳下，肌肉－肌腱系統會固定下肢勁度，以儲存或輸出彈性能量。

The purpose of this study was to examine the adjustment of leg stiffness under individual constraint of fatigue through instant and intense exercise for the whole body. Eighteen volunteer male college students (age: 20 □ 1.6 years, height: 175.9 □ 7.5cm, weight: 70.3 □ 9.1 kg) were served as the participants and were asked to perform continuous counter movement jump (CMJ) on a Kistler Platform (1000Hz) for one minute. The Vicon MX-F40 motion analysis system was used to record the trajectories of reflective markers that were placed on the skin surface of lower extremity. The first five jumps defined as pre-fatigue, last five jumps defined as post-fatigue. Paired t test was used to test the statistical differences for kinematic and kinetic parameters with alpha level .05. The results showed there were no changes in leg stiffness on hip stiffness, knee stiffness and ankle stiffness between pre-fatigue and post-fatigue (p > .05). Knee angle when ground contact, ankle flexion angle, ankle angular displacement, hip moment and ankle moment smaller than pre-fatigue (p > .05). This study demonstrated that the individual was in constant leg stiffness to store or output elastic energy in muscle-tendon system during continuous CMJ.