牽張縮短循環（stretch-shortening cycle, SSC）是一種自然的骨骼肌工作形式，過去學者為了瞭解SSC作用的增益效果，通常使用蹲踞跳、下蹲反跳與著地反彈跳等動作深入推論。在測力板進行這些跳躍動作的測試能提供高精準度、高採樣頻率的動作訊息，但是，卻有價格昂貴與分析技術繁雜的問題。為了讓教練能在訓練場上即時獲取動作訊息，就有電阻式應變墊等操作較為便捷的設備反應接觸時間、騰空時間，進而評估SSC對垂直跳的貢獻。本文解釋預牽張擴增百分比、離心利用率、反應性力量、反應性力量指標、修正式反應性力量指標等指標的公式與涵義，以作為日後運動訓練工作效果監控之參考。

The stretch shortening cycle (SSC) is a natural form of skeletal muscle work. The movements of squat jump, countermovement jump, and drop jump were usually used to insight into the effect of enhancement for SSC in past studies. The force platform provide the accuracy and the high sampling rate of information for the measurement of these jump movements. However, it is an issue of the expensive cost and the complicated analyze in the quantitation of force platform. The equipment of switch that is the strain gauge transducer is convenient and portable in field to feedback the jump information of contact and flight durations real time. The contribution of the SSC would be assessed to provide for the coach or athlete. This study explains the methodologies and meanings of the parameters of pre-stretch augmentation percentage (PSAP), eccentric utilization ratio (EUR), reactive strength (RS), reactive strength index (RSI), reactive strength index modified (RSI_(mod)) to monitor and diagnose the effects of strength training in the future.