Avela J, Komi P V
Department of Biology of Physical Activity, University of Jyväskylä, Finland.
Eur J Appl Physiol Occup Physiol. 1998 Oct;78(5):403-10. doi: 10.1007/s004210050438.
It has been suggested that during repeated long-term stretch-shortening cycle (SSC) exercise the decreased neuromuscular function may result partly from alterations in stiffness regulation. Therefore, interaction between the short latency stretch-reflex component (M1) and muscle stiffness and their influences on muscle performance were investigated before and after long lasting SSC exercise. The test protocol included various jumps on a sledge ergometer. The interpretation of the sensitivity of the reflex was based on the measurements of the patellar reflexes and the M1 reflex components. The peak muscle stiffness was measured indirectly and calculated as a coefficient of the changes in the Achilles tendon force and the muscle length. The fatigue protocol induced a marked impairment of the neuromuscular function in maximal SSC jumps. This was demonstrated by a 14.1%-17.7% (n.s. - P < 0.001) reduction in the mean eccentric forces and a 17.3%-31.8% (n.s. - P < 0.05) reduction in the corresponding M1 area under the electromyograms. Both of these methods of assessing the short latency reflex response showed a clear deterioration in the sensitivity of the reflex after fatigue (P < 0.05-0.001). This was also the case for the eccentric peak stiffness of the soleus muscle which declined immediately after fatigue by 5.4% to 7.1% (n.s. - P < 0.05) depending on the jump condition. The results observed would suggest that the modulation of neural input to the muscle was at least partly of reflex origin from the contracting muscle, and furthermore, that the reduced muscle stiffness which accompanied the decreased reflex sensitivity could have been partly responsible for the weakened muscle performance due to impaired utilization of elastic energy.
有人认为，在反复进行的长期拉伸-缩短循环（SSC）运动中，神经肌肉功能下降可能部分源于刚度调节的改变。因此，研究了长期SSC运动前后短潜伏期牵张反射成分（M1）与肌肉刚度之间的相互作用及其对肌肉性能的影响。测试方案包括在雪橇测力计上进行各种跳跃。反射敏感性的解释基于髌反射和M1反射成分的测量。间接测量峰值肌肉刚度，并将其计算为跟腱力变化与肌肉长度变化的系数。疲劳方案导致最大SSC跳跃中神经肌肉功能明显受损。这表现为平均离心力降低14.1%-17.7%（无显著性差异 - P < 0.001），相应的肌电图下M1面积降低17.3%-31.8%（无显著性差异 - P < 0.05）。这两种评估短潜伏期反射反应的方法均显示疲劳后反射敏感性明显下降（P < 0.05 - 0.001）。比目鱼肌的离心峰值刚度也是如此，根据跳跃条件，疲劳后立即下降5.4%至7.1%（无显著性差异 - P < 0.05）。观察到的结果表明，肌肉神经输入的调节至少部分源于收缩肌肉的反射，此外，伴随反射敏感性降低的肌肉刚度降低可能部分是由于弹性能利用受损导致肌肉性能减弱的原因。
