Kallio J, Linnamo V, Komi P V
Neuromuscular Research Center, Department of Biology of Physical Activity, University of Jyväskylä, P.O. Box 35, 40351 Jyväskylä, Finland FIN-40100.
J Electromyogr Kinesiol. 2004 Jun;14(3):411-21. doi: 10.1016/j.jelekin.2003.10.004.
The purpose of the present study was to investigate the combined effects of muscle history, activation and stretching velocity on short latency stretch response (SLR). Stretches (70, 120 and 200 deg s-1) were elicited to both passive and active (10-25% MVC) triceps surae muscle with constant (ISO), lengthened (LEN) or shortened (SHO) muscle length. Under the passive SHO pre-condition both SLR amplitude and reflex torque (RT) decreased where as latency increased compared with the passive ISO pre-condition. Such observations were absent in active trials. Stretches applied to a lengthening passive muscle (LEN) resulted in smaller SLR amplitude and RT compared with passive ISO. In active muscle the stretch response increased with stretching velocity in ISO and SHO. However, in LEN there was large interindividual variability and no velocity dependent increase in SLR amplitude was observed. Smaller amplitude and longer latency of passive SLR in SHO could result from increased slack in the intrafusal fibres, which may be compensated by fusimotor activation during the active condition. The mechanism behind the smaller amplitude in passive LEN and the lack of velocity dependence in active LEN may be related to changes in motoneuron pool excitability or changes in the spindle sensitivity to stretch.
本研究的目的是调查肌肉历史、激活状态和拉伸速度对短潜伏期拉伸反应（SLR）的综合影响。以70、120和200度/秒的速度对被动和主动（10 - 25%最大自主收缩）的小腿三头肌进行拉伸，肌肉长度保持恒定（ISO）、延长（LEN）或缩短（SHO）。与被动ISO预拉伸条件相比，在被动SHO预拉伸条件下，SLR幅度和反射扭矩（RT）均降低，而潜伏期增加。在主动试验中未观察到此类现象。与被动ISO相比，对延长的被动肌肉（LEN）进行拉伸会导致SLR幅度和RT较小。在主动肌肉中，ISO和SHO条件下的拉伸反应随拉伸速度增加。然而，在LEN条件下，个体间差异较大，未观察到SLR幅度随速度增加的情况。SHO条件下被动SLR幅度较小和潜伏期较长可能是由于肌梭内纤维松弛增加所致，在主动状态下，这可能由肌梭运动神经元激活来补偿。被动LEN条件下幅度较小以及主动LEN条件下缺乏速度依赖性的背后机制可能与运动神经元池兴奋性的变化或肌梭对拉伸的敏感性变化有关。
