To investigate the effects of gravity-related somatosensory information on spinal human reflexes, the soleus H-reflex was recorded in ten healthy subjects walking on a treadmill at 2.0 km/h on land and in water. The modulation pattern of the soleus H-reflex was determined in ten different phases of the step cycle. While the subjects were walking in water, the background electromyographic activity (BGA) of the soleus was lower than that on land; on the other hand, the soleus H-reflex amplitude while the subjects were walking in water showed no significant differences throughout the step cycle compared with that while the subjects were on land; the phase-dependent soleus H-reflex modulation pattern was well preserved while walking in water. There was a linear relationship between the BGA and the H-reflex amplitude in each condition; however, the soleus H-reflex gain while walking in water was significantly higher than that on land. These findings suggest that the somatosensory graviception can markedly reduce the spinal reflex excitability. Our findings are discussed in relation to human gait; therefore, further studies are needed to clarify the effect of somatosensory graviception on human neural mechanisms.
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机译：为了研究重力相关的体感信息对脊柱人类反射的影响，在地面和水中以2.0 km / h的速度在跑步机上行走的十名健康受试者中记录了比目鱼H反射。比目鱼H-反射的调制模式是在步进周期的十个不同阶段中确定的。当受试者在水中行走时，比目鱼的背景肌电图活动（BGA）低于陆地。另一方面，受试者在水中行走时的比目鱼H反射幅度与受试者在陆地上时相比，在整个踏步周期中均无显着差异。在水中行走时，相位相关的比目鱼H反射调制模式得到了很好的保留。在每种情况下，BGA和H反射幅度之间存在线性关系;但是，在水中行走时，比目鱼的H反射增益明显高于陆地。这些发现表明，体感重力感应可以显着降低脊柱反射兴奋性。我们的研究结果是关于人类步态的讨论;因此，需要进一步的研究来阐明体感重力感应对人类神经机制的影响。
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