Grey Michael J, Larsen Birgit, Sinkjaer Thomas
Center for Sensory-Motor Interaction, Aalborg University, Fredrik Bajersvej 7-D3, 9220, Aalborg Øst, Denmark.
Exp Brain Res. 2002 Aug;145(3):316-22. doi: 10.1007/s00221-002-1109-6. Epub 2002 Jun 14.
In comparison to the H-reflex, the task dependency of the human stretch reflex during locomotive and postural tasks has not received a great deal of attention in the literature. The few studies on reflex task dependency that have been performed to date have concentrated on either the group Ia mediated H-reflex or the short latency stretch reflex. In the present study the medium latency component of a mechanically evoked stretch reflex is investigated during walking, pedalling, and sitting. Stretch reflexes were evoked in the soleus muscle using dorsiflexion perturbations generated with a portable stretching device. Perturbations of equal amplitude and velocity (8 deg, 300 deg/s) were presented to 16 healthy subjects while they walked on a treadmill and pedalled a cycle ergometer. For eight of these subjects, an additional set of data was collected as they sat on the ergometer holding a steady posture. Perturbations were presented in the early to mid stance phase of walking and the downstroke of the pedal cycle. During all three conditions, the background soleus muscle activity was matched. The short (SLR) and medium (MLR) components of the soleus reflex responses were quantified by calculating the area of each burst in a 15-ms window centred on the peak of the respective burst. In addition, the stretch velocity-stretch reflex input-output curve was examined for the two locomotion tasks over a range of velocities from 100 to 400 deg/s. Peak latencies for the two reflex responses were observed at 52+/-5/77+/-6 ms (SLR/MLR) for walking, 51+/-3/76+/-6 ms (SLR/MLR) for pedalling, and 50+/-3/76+/-7 ms for sitting. A statistically significant increase in the magnitude of the MLR was observed during walking compared with pedalling and sitting ( P=0.007), whereas no difference in magnitude was observed between the three tasks for the SLR ( P=0.616). Furthermore, no difference was observed in the stretch velocity-stretch reflex input-output relationship between walking and pedalling. It is suggested that the medium component of the stretch reflex response is modulated to provide increased control for the postural demands of walking.
与H反射相比，人类牵张反射在 locomotive（可能是“运动性的”有误，推测为“运动”）和姿势任务中的任务依赖性在文献中并未受到太多关注。迄今为止，为数不多的关于反射任务依赖性的研究主要集中在Ia类介导的H反射或短潜伏期牵张反射上。在本研究中，研究了在行走、蹬踏板和坐姿期间机械诱发牵张反射的中潜伏期成分。使用便携式拉伸装置产生的背屈扰动在比目鱼肌中诱发牵张反射。在16名健康受试者在跑步机上行走和蹬踏自行车测力计期间，向他们施加等振幅和速度（8度，300度/秒）的扰动。对于其中8名受试者，当他们坐在测力计上保持稳定姿势时，还收集了另一组数据。在行走的早期至中期站立阶段和踏板周期的向下冲程期间施加扰动。在所有三种情况下，背景比目鱼肌活动相匹配。通过计算以各自爆发峰值为中心的15毫秒窗口内每个爆发的面积，对比目鱼肌反射反应的短潜伏期（SLR）和中潜伏期（MLR）成分进行量化。此外，在100至400度/秒的速度范围内，检查了两种运动任务的牵张速度-牵张反射输入-输出曲线。观察到两种反射反应的峰值潜伏期在行走时为52±5/77±6毫秒（SLR/MLR），蹬踏板时为51±3/76±6毫秒（SLR/MLR），坐姿时为50±3/76±7毫秒。与蹬踏板和坐姿相比，行走期间观察到MLR的幅度有统计学显著增加（P = 0.007），而SLR在三项任务之间的幅度没有差异（P = 0.616）。此外，行走和蹬踏板之间的牵张速度-牵张反射输入-输出关系没有差异。研究表明，牵张反射反应的中潜伏期成分受到调节，以增加对行走姿势需求的控制。
