Faist M, Blahak C, Duysens J, Berger W
Department of Clinical Neurology and Neurophysiology, University of Freiburg, Germany.
Exp Brain Res. 1999 Apr;125(3):265-70. doi: 10.1007/s002210050682.
During gait it is generally accepted that there is a reduction in amplitude of H-reflexes as compared to standing. For short-latency stretch reflexes, however, it is less clear whether a similar reduction in reflex gain is present during locomotion. Stretches of constant amplitude are hard to produce under these circumstances and for this reason some previous studies on the biceps femoris (BF) have used "reduced gait" in which the stimulated leg is stepping on the spot while the contralateral leg is walking on a treadmill. With this method it was possible to show that BF tendon jerk reflexes are larger at end swing and therefore are likely to contribute to the EMG burst normally occurring in that part of the step cycle when the BF is rapidly stretched. In the present study two questions were addressed: first, whether the reflex is different in size during gait compared to standing and, second, whether it is modulated in size during the gait cycle not only during reduced but also during normal gait. It was found that during both types of gait there was a general reflex depression with regard to the respective control values obtained during standing at similar EMG activity levels. In previous studies on soleus and quadriceps, discrepancies between EMG activity and reflex amplitude have been ascribed to changes in presynaptic inhibition of Ia terminals mediating the afferent volley of the reflex. Based on the data presented, this may also be true for the BF. In both normal and reduced gait the reflex was similarly modulated in size, showing a maximum at the end of swing. This similarity implies that reduced gait may be useful as an acceptable alternative for normal gait in studies on phase-dependent reflex modulation during locomotion.
在步态过程中，与站立相比，H反射的幅度普遍被认为会降低。然而，对于短潜伏期牵张反射，在运动过程中是否存在类似的反射增益降低尚不清楚。在这种情况下，很难产生恒定幅度的牵张，因此，之前一些关于股二头肌（BF）的研究采用了“简化步态”，即受刺激的腿原地踏步，而对侧腿在跑步机上行走。通过这种方法可以表明，股二头肌肌腱抽搐反射在摆动末期更大，因此可能有助于在股二头肌快速伸展的步周期部分正常出现的肌电图爆发。在本研究中，探讨了两个问题：第一，与站立相比，步态过程中反射大小是否不同；第二，在步态周期中，反射大小不仅在简化步态期间，而且在正常步态期间是否受到调制。结果发现，在两种步态类型中，与在相似肌电图活动水平下站立时获得的各自对照值相比，都存在普遍的反射抑制。在之前关于比目鱼肌和股四头肌的研究中，肌电图活动和反射幅度之间的差异被归因于介导反射传入冲动的Ia终末突触前抑制的变化。根据所呈现的数据，这对于股二头肌可能也是如此。在正常和简化步态中，反射大小的调制方式相似，在摆动末期达到最大值。这种相似性意味着，在研究运动过程中与相位相关的反射调制时，简化步态可能是正常步态的一个可接受的替代方案。
