Bosco C, Tihanyi J, Komi P V, Fekete G, Apor P
Acta Physiol Scand. 1982 Dec;116(4):343-9. doi: 10.1111/j.1748-1716.1982.tb07152.x.
Stretch-shortening cycle refers to the mechanical condition in which store and recoil of elastic energy occur in the skeletal muscle. This leads to a greater work output when compared to a simple shortening contraction. The subjects performed vertical jumps with and without preliminary counter-movement and with small and large knee angular displacement. The results indicated that those subjects who had more fast twitch (FT) fibers benefited more from the stretching phase performed with high speed and short angular displacement. The amounts of elastic energy stored in this phase were 30 and 26 N X kgBW-1, respectively, for FT and slow twitch (ST) type subjects. The recoil of elastic energy was proportional to the amount of energy storage. In large amplitude jumps where transient period between stretch and shortening is long the both types of subjects demonstrated similar amount of storage of elastic energy (17 and 16 N X kgBW-1, respectively). However, the re-use of this elastic energy was greater in ST group (24%) as compared to the FT group (17%). The results can be interpreted through differences in sarcomere crossbridge life times between fast and slow muscle fibers. The slow type muscle may be able to retain the cross-bridge attachment for a longer period of time and therefore it may utilize elastic energy better in a slow type ballistic motion.
拉长-缩短循环是指骨骼肌中发生弹性能量储存和回弹的力学状态。与简单的缩短收缩相比，这会导致更大的功输出。受试者进行了有和没有预加载反向动作以及不同大小膝关节角位移的垂直跳跃。结果表明，那些具有更多快肌纤维的受试者从高速和小角位移的拉伸阶段中获益更多。在这个阶段，快肌型和慢肌型受试者储存的弹性能量分别为30和26 N×kgBW-1。弹性能量的回弹与能量储存量成正比。在拉伸和缩短之间的过渡时间较长的大幅度跳跃中，两种类型的受试者储存的弹性能量相似（分别为17和16 N×kgBW-1）。然而，慢肌型组对这种弹性能量的再利用（24%）比快肌型组（17%）更大。这些结果可以通过快慢肌纤维之间肌节横桥寿命的差异来解释。慢肌型肌肉可能能够在更长时间内保持横桥附着，因此在慢肌型弹道运动中可能能更好地利用弹性能量。
