INCREASED AMPLITUDE OF CUTANEOUS REFLEXES DURING HUMAN RUNNING AS COMPARED TO STANDING
INCREASED AMPLITUDE OF CUTANEOUS REFLEXES DURING HUMAN RUNNING AS COMPARED TO STANDING
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DOI：
10.1016/0006-8993(93)90903-z
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发表时间：
1993-06-11
期刊：
影响因子：
2.9
通讯作者：
DIETZ, V
中科院分区：
文献类型：
--
作者：
DUYSENS, J;TAX, AAM;DIETZ, V
与站立相比，行走过程中H反射的幅度降低，而与行走相比，跑步过程中H反射幅度进一步降低。皮肤刺激引起的反射是否也有类似的减少？为了回答这个问题，记录了股二头肌(BF)和胫骨前肌(TA)对20ms的5个电脉冲的肌电反应。这种刺激作用于脚踝的腓肠神经，或者是在8公里/小时的跑步机上跑步的志愿者的16个不同阶段，或者是在同一受试者站立时TA和BF的不同等长收缩水平下，模拟不同阶段的步伐周期的姿势。所有受试者BF中主要反应的平均潜伏期为76ms。10例受试者中有6例出现类似反应(P2)，潜伏期为79ms。在不同水平的等长收缩中，对于恒定的刺激强度(2倍知觉阈值)，早期姿势模拟的BF和TA反应的平均反射比(反射/背景)分别为1.07和0.53，而跑步时这两个肌肉的平均反射比(反射/背景)分别为1.78和1.1。在跑步中较高的反射率主要是由于受试者在站立时的大部分踏步周期中都存在较大的易化反应，而在自愿收缩时很少出现这种反应。然而，在摇摆阶段结束时，BF和TA的反应主要是抑制性的，就像大多数对站立受试者的刺激反应一样。跑步和站立之间反射幅度的差异取决于刺激强度。在1.5×T(其中T=知觉阈值)时，站立和奔跑状态下的反应相似，而在2.5 x T时，两者的反应显著不同。后者的差异是由于站立过程中高刺激强度下抑制深度的增加。结论是，与站立相比，跑步是一种任务，在此期间，除了在末端挥杆时的一段短暂时间外，腓肠神经的便利反射普遍增强。研究表明，这些反射有助于步态周期中BF和TA等肌肉的正常激活。
The amplitude of H-reflexes is decreased during walking as compared to standing and a further reduction is seen during running as compared to walking. Does a similar reduction occur for reflexes elicited by cutaneous stimulation? To answer this question, the electromyographic (EMG) responses in biceps femoris (BF) and tibialis anterior (TA) to a 20 ms train of 5 electrical pulses, were recorded. This stimulus was applied to the sural nerve at the ankle, either at 16 different phases of the step cycle in human volunteers running on a treadmill at 8 km/h or at different isometric contraction levels of TA and BF in the same subjects during standing, imitating the postures of different phases of the step cycle. The mean latency of the main responses in BF of all subjects was 76 ms. Similar responses (P2), with a latency of 79 ms were seen in TA in 6 of the 10 subjects. For a constant strength of stimulation (2 times perception threshold) during isometric contractions at different levels in early stance imitation, the mean reflex ratio's (reflex/background) of BF and TA responses were 1.07 and 0.53, respectively, while the ratio's for these 2 muscles during running were 1.78 and 1.1. The higher reflex ratio's in running were primarily due to the large facilitatory responses, which were present during most of the step cycle but rarely during voluntary contractions in the subjects during standing. At the end of the swing phase, however, the responses in BF and TA were predominantly suppressive, as were most of the responses to stimulation applied to the standing subjects. The difference in reflex amplitudes between running and standing depended on stimulus intensity. At 1.5 x T (where T = perception threshold) the responses were similar for both the standing and run conditions while they were significantly different for pulses at 2.5 x T. The latter difference was due to an increment in the depth of suppression at high stimulus intensities during standing. It is concluded that running is a task during which there is, in comparison with standing and with the exception of a brief period at end swing, a general enhancement of sural nerve facilitatory reflexes. It is suggested that these reflexes contribute to the normal activation of muscles such as BF and TA during the step cycle.