class="enumerated" style="list-style-type:decimal">The objective of the study was to investigate the amplitude and modulation of the human soleus Hoffmann (H) reflex during walking and during running at different speeds.EMGs were recorded with surface electrodes from the soleus, the medial and lateral head of the gastrocnemius, the vastus lateralis and the anterior tibial muscles. The EMGs and the soleus H reflex were recorded while walking on a treadmill at 4.5 km h−1 and during running at 8, 12 and 15 km h−1.The amplitudes of the M wave and the H reflex were normalized to the amplitude of a maximal M wave elicited by a supramaximal stimulus just after the H reflex to compensate for movements of the recording and stimulus electrodes relative to the nerve and muscle fibres. The stimulus intensity was set to produce M waves that had an amplitude near to 25% of the maximal M wave measured during the movements. As an alternative, the method of averaging of sweeps in sixteen intervals of the gait cycle was applied to the data. In this case the amplitude of the H reflex was expressed relative to the maximal M wave measured whilst in the standing position.The amplitude of the H reflex was modulated during the gait cycle at all speeds. During the stance phase the reflex was facilitated and during the swing and flight phases it was suppressed. The size of the maximal M wave varied during the gait cycle and this variation was consistent for each subject although different among subjects.The peak amplitude of the H reflex increased significantly (P = 0.04) from walking at 4.5 km h−1 to running at 12 and 15 km h−1 when using the method of correcting for variations of the maximal M wave during the gait cycle. The sweep averaging method showed a small but non-significant decrease (P = 0.3) from walking to running at 8 km h−1 and a small decrease with running speed (P = 0.3). The amplitude of the EMG increased from walking to running and with running speed.The relatively large H reflex recorded during the stance phase in running indicates that the stretch reflex may influence the muscle mechanics during the stance phase by contributing to the motor output and enhancing muscle stiffness.
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机译：class =“ enumerated” style =“ list-style-type：decimal”> <！-list-behavior =枚举前缀-word = mark-type = decimal max-label-size = 0-> 这项研究的目的是研究人比目鱼霍夫曼（H）反射在步行和跑步过程中在不同速度下的振幅和调制。 EMGs用比目鱼，比目鱼肌和比目鱼肌的表面电极记录腓肠肌外侧头，外侧股外侧肌和胫骨前肌。在跑步机上以4.5 km h -1 行走时以及在8、12和15 km h -1 跑步时记录肌电图和比目鱼H反射。 将M波和H反射的振幅归一化为在H反射之后由超最大刺激引起的最大M波的振幅，以补偿记录电极和刺激电极相对于神经和神经的运动。肌肉纤维。设置刺激强度以产生M波，其振幅接近运动中测得的最大M波的25％。作为选择，将步态周期的十六个间隔中的扫描平均的方法应用于数据。在这种情况下，H反射的幅度表示为相对于站立状态下测得的最大M波。 H反射的幅度在步态周期中以所有速度调节。在站立阶段，反射被促进，在挥杆和飞行阶段，反射被抑制。最大M波的大小在步态周期中有所变化，尽管每个对象之间有所不同，但每个对象的这种变化是一致的。 H反射的峰值幅度从在4.5步时开始显着增加（P = 0.04）。使用校正步态周期中最大M波变化的方法时，km h -1 在12和15 km h -1 下运行。扫描平均法显示，从步行到以8 km h -1 的速度跑步，其下降幅度很小但不显着（P = 0.3），而随着跑步速度的减小幅度很小（P = 0.3）。 EMG的振幅从步行到跑步并随跑步速度增加。 在站立阶段，跑步过程中记录到的相对较大的H反射表明，伸展反射可能在站立阶段影响肌肉力学运动输出并增强肌肉僵硬。
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