Graduate School of Sport Sciences, Waseda University, Saitama, Japan.
Med Sci Sports Exerc. 2012 Aug;44(8):1512-8. doi: 10.1249/MSS.0b013e3182535da5.
The purpose of the present study was to examine a hypothesis that the musculotendinous behavior during a propelling action with a countermovement can be altered by a single practice session through modulation of neuromuscular activities.
Eight males performed unilateral maximal plantarflexion with (CMJ) and without (noCMJ) countermovement before and after a practice consisting of six sets of three repetitions of unilateral CMJ exercises. Measurements included EMG activities of the triceps surae and tibialis anterior muscles and the fascicle behavior of the gastrocnemius by ultrasonography, and impulse was calculated from the force-time data. The change in tendon length was also estimated.
The impulse in CMJ increased after the practice, but that in noCMJ did not. After the practice, the magnitude of fascicle lengthening and shortening in CMJ decreased, which was accompanied by an increase in tendon shortening without change in the ankle joint range of motion. The time lag from the onset of reaction force to that of EMG activities of the triceps surae muscles was shortened after the practice.
The results support the hypothesis and indicate that, as a neural modulation through a single practice, the muscle-tendon unit behavior during CMJ can be optimized to improve the performance.
本研究旨在检验一个假设，即在单次练习中通过调节神经肌肉活动，可以改变反冲动作中的肌肉肌腱行为。
8 名男性在进行单侧最大跖屈（CMJ）和无（noCMJ）反冲之前和之后进行了 6 组 3 次单侧 CMJ 练习，包括测量比目鱼肌和胫骨前肌的肌电图活动以及超声检查的腓肠肌肌束行为，并根据力-时数据计算冲量。还估计了肌腱长度的变化。
练习后 CMJ 的冲量增加，但 noCMJ 的冲量没有增加。练习后，CMJ 中肌束的伸长和缩短幅度减小，同时伴随着肌腱缩短而踝关节运动范围没有变化。练习后，从反作用力开始到比目鱼肌肌电图活动开始的时间滞后缩短。
结果支持假设，并表明作为单次练习的神经调节，可以优化肌肉-肌腱单元在 CMJ 中的行为，以提高性能。
