Graduate School of Engineering, Shibaura Institute of Technology, 307 Fukasaku, Minuma, Saitama 337-8570, Japan.
J Electromyogr Kinesiol. 2010 Jun;20(3):406-12. doi: 10.1016/j.jelekin.2009.04.003. Epub 2009 May 7.
The purpose of this study was to test whether the spinal reflex excitability of the soleus muscle is modulated as posture changes from a supine to a passive upright position. Eight healthy subjects (29.6+/-5.4 yrs) participated in this study. Stretch and H-reflex responses were elicited while the subjects maintained passive standing (ST) and supine (SP) postures. The passive standing posture was accomplished by using a gait orthosis to which a custom-made device was mounted to elicit stretch reflex in the soleus muscle. This orthosis makes it possible to elicit stretch and H-reflexes without background muscle activity in the soleus muscle. The results revealed that the H-reflex amplitude in the ST was smaller than that in the SP condition, which is in good agreement with previous reports. On the other hand, the stretch reflex was significantly larger in the ST than in the SP condition. Since the experimental conditions of both the stretch and H-reflex measurements were exactly the same, the results were attributed to differences in the underlying neural mechanisms of the two reflex systems: different sensitivity of the presynaptic inhibition onto the spinal motoneuron pool and/or a change in the muscle spindle sensitivity.
本研究旨在测试从仰卧位到被动直立位时，跟腱反射兴奋性是否会随着姿势的改变而发生变化。8 名健康受试者（29.6±5.4 岁）参与了这项研究。当受试者保持被动站立（ST）和仰卧（SP）姿势时，引出伸展反射和 H 反射。通过使用步态矫形器来完成被动站立姿势，该矫形器安装了一个定制的装置，以引发跟腱肌肉的伸展反射。这种矫形器使得在没有跟腱肌肉背景活动的情况下，能够引出伸展反射和 H 反射。结果表明，ST 时的 H 反射幅度小于 SP 时的幅度，这与先前的报告一致。另一方面，ST 时的伸展反射明显大于 SP 时的反射。由于伸展反射和 H 反射测量的实验条件完全相同，因此这些结果归因于两种反射系统的潜在神经机制的差异：对脊髓运动神经元池的突触前抑制的敏感性不同和/或肌梭敏感性的变化。
