Human H-reflexes are smaller in difficult beam walking than in normal treadmill walking
Human H-reflexes are smaller in difficult beam walking than in normal treadmill walking
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人类在困难平衡木行走中的 H 反射比在正常跑步机行走中小
DOI：
10.1007/bf00232189
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发表时间：
2004
影响因子：
2
通讯作者：
Arthur Prochazka
中科院分区：
文献类型：
--
作者：
M. Llewellyn;Jaynie F. Yang;Arthur Prochazka
当受试者在跑步机上行走和在窄梁上行走（宽3.5厘米，离地34厘米）时，比目鱼肌（SOL）会产生霍夫曼反射。每个受试者在跑步机上的行走速度选择与他们在光束行走时SOL肌肉的背景激活水平相匹配。在跑步机上行走时，正常的胫骨前肌和SOL肌的相互激活模式被一种在梁上以共同收缩为主的模式所取代。此外，阶跃周期持续时间变化更大，在梁上的摆动阶段花费的时间减少。h反射在两种任务中均呈高度调制，在站立阶段振幅高，在摇摆阶段振幅低。梁式步行时的h反射幅度比跑步机步行时平均低40%。h反射振幅与SOL肌电信号水平之间的关系通过两个变量之间的回归线进行量化。这条线的斜率平均比跑步机低41%。本研究中观察到的较低的h反射增益和在执行类似任务的猫中观察到的高水平的纺锤运动驱动表明，控制这一反射途径的兴奋性的两种机制（即纺锤运动作用和控制从肌梭到运动神经元突触的传递）可能是独立控制的。
SummaryHoffmann (H) reflexes were elicited from the soleus (SOL) muscle while subjects walked on a treadmill and on a narrow beam (3.5 cm wide, raised 34 cm from the floor). The speed of walking on the treadmill was selected for each subject to match the background activation level of their SOL muscle during beam walking. The normal reciprocal activation pattern of the tibialis anterior and SOL muscles in treadmill walking was replaced by a pattern dominated by co-contraction on the beam. In addition, the step cycle duration was more variable and the time spent in the swing phase was reduced on the beam. The H-reflexes were highly modulated in both tasks, the amplitude being high in the stance phase and low in the swing phase. The H-reflex amplitude was on average 40% lower during beam walking than treadmill walking. The relationship between the H-reflex amplitude and the SOL EMG level was quantified by a regression line relating the two variables. The slope of this line was on average 41% lower in beam walking than treadmill walking. The lower H-reflex gain observed in this study and the high level of fusimotor drive observed in cats performing similar tasks suggest that the two mechanisms which control the excitability of this reflex pathway (i.e. fusimotor action and control of transmission at the muscle spindle to motoneuron synapse) may be controlled independently.