Egawa K, Oida Y, Kitabatake Y, Maie H, Mano T, Iwase S, Miwa C
Motor Control Laboratory, Physical Fitness Research Institute, Meiji Life Foundation of Health and Welfare, Hachioji, Tokyo, Japan.
Environ Med. 2000 Dec;44(2):117-20.
To test our hypothesis that somatosensory inputs would influence postural modulation of soleus H-reflex, eleven subjects were investigated under the head-out water immersion (HOWI) conditions. Subjects were supine or standing on a tilting bed in each condition. They were instructed to maintain an upright posture with both legs. The water was filled to the subject's neck level in a test tank to reduce 95% of the gravitational effect by buoyancy. Surface electromyography of the soleus and tibialis anterior was measured. The soleus H-reflex was elicited at a stimulation intensity of 1.05 times the motor threshold. The recruitment profile of the motor response was unchanged between the conditions. The background activities of the soleus and tibialis anterior were not detected in any condition. The peak-to-peak amplitude of the H-reflex was significantly different between the conditions while the stimulation intensity (small M size) was not different. The soleus H-reflex during standing was significantly decreased compared with being supine in the control condition, whereas it did not in the HOWI condition. It was concluded that somatosensory inputs due to gravity exert an influence on postural modulation of the soleus H-reflex to maintain static posture in humans.
为了验证我们的假设，即躯体感觉输入会影响比目鱼肌H反射的姿势调制，我们对11名受试者在头部露出水面的水浸（HOWI）条件下进行了研究。在每种条件下，受试者均仰卧或站立在倾斜床上。他们被要求双腿保持直立姿势。在测试水箱中，水被填充到受试者的颈部水平，以通过浮力减少95%的重力影响。测量了比目鱼肌和胫骨前肌的表面肌电图。在刺激强度为运动阈值的1.05倍时引出比目鱼肌H反射。在不同条件下，运动反应的募集曲线没有变化。在任何条件下均未检测到比目鱼肌和胫骨前肌的背景活动。在刺激强度（小M尺寸）无差异的情况下，不同条件下H反射的峰峰值幅度存在显著差异。在对照条件下，站立时的比目鱼肌H反射与仰卧时相比显著降低，而在HOWI条件下则没有。研究得出结论，重力引起的躯体感觉输入会影响比目鱼肌H反射的姿势调制，以维持人体的静态姿势。
