本研究是利用運動生物力學的方法，探討淺蹲深跳練習(drop jumpDJ)和 深蹲DJ的力學要素，以了解不同牽張幅度下肌肉牽張縮短循環 (stretch-shortening-cycle SSC)的動作強度與表現。本次實驗以AMTI測力板和電子關 節角度計測量受試者在三種不同高度下的地面反作用力、膝關節角度的變化。受 試者11名，平均年齡為23.18±2.64歲，身高為173.0±4.03公分，體重為64.31±5.97 公斤。統計方法是以重覆量數t-test(α=.05)檢驗這些變數之差異。經由實驗處理 與討論，我們可以獲得以下的結果。 兩種不同牽張幅度的ssc跳法中，淺蹲DJ的25ms、50ms和PK2所產生的力量與負荷 率皆顯著大於深蹲跳法，即淺蹲跳法在離心初期承受較大的動作強度和負荷，意 味著淺蹲跳法必須具備更強的肌力，以避免運動傷害。此外，淺蹲跳法發展了較 大的離心末期力量，進而提升向心平均力量，所以淺蹲跳法可以產生較高向心力 量。雖然深蹲DJ動作不能產生較大的離心和向心力量，卻能因較長的動作支撐時 間而產生較大的衝量，最後跳出較佳的騰空高度。由以上事實得知，SSC動作時， 如果目標是要刺激較大的動作強度及發展較大的力量，則採淺蹲DJ;另一方面， 如果目標是為了跳出較佳的騰空高度，則建議採深蹲DJ。

　　　　　This experiment is to investigate the kinematic and dynamic variables of drop jumps (DJ)in order to understand the differences on force and sport performance between two differentstretch amplitudes of SSC movements. The short-stretch DJ and long-stretch DJ wereperformed by 11 subjects of jumpers and sprinters with average ages 23.18±2.64 years,heights 173.0 ± 4.03cm and weights 64.31 ± 5.97kg. AMIT force-platform and Pennyelectrical goniometer were used to record ground reaction forces and angular displacements.SPSS software was adopted to calculate the average values of the parameters and repeatedmeasures t-test was used to test the difference between short and long stretch DJ. Thesignificance level was set at.05. The short-stretch DJ endured larger work intensity of initial eccentric phase at the 25ms,50ms and PK2, developed larger force and loading rate at the end of pre-stretch andenhanced concentric average force. Although the long-stretch DJ didn't develop larger forcesduring concentric and concentric phases, it had a longer supporting time that helped toincrease the momentum and ended up with the higher flight-height. When we practice SSCexercise with the intent to increase the eccentric and concentric force, the method ofshort-stretch DJ should be adopted. If the purpose is to jump higher, the long-stretch DJ isrecommended.