Pang M Y, Yang J F
Department of Physical Therapy and Division of Neuroscience, University of Alberta, Edmonton, Alberta, Canada T6G 2G4.
J Physiol. 2000 Oct 15;528 Pt 2(Pt 2):389-404. doi: 10.1111/j.1469-7793.2000.00389.x.
Hip extension and low load in the extensor muscles are important sensory signals that allow a decerebrate or spinal cat to advance from the stance phase to the swing phase during walking. We tested whether the same sensory information controlled the phases of stepping in human infants. Twenty-two infants between the ages of 5 and 12 months were studied during supported stepping on a treadmill. Forces exerted by the lower limbs, surface electromyography (EMG) from muscles, and the right hip angle were recorded. The whole experimental session was videotaped. The hip position and the amount of load experienced by the right limb were manipulated during stepping by changing the position of the foot during the stance phase or by applying manual pressure on the pelvic crest. Disturbances with different combinations of hip position and load were used. The stance phase was prolonged and the swing phase delayed when the hip was flexed and the load on the limb was high. In contrast, stance phase was shortened and swing advanced when the hip was extended and the load was low. The results were remarkably similar to those in reduced preparations of the cat. They thus suggest that the behaviour of the brainstem and spinal circuitry for walking may be similar between human infants and cats. There was an inverse relationship between hip position and load at the time of swing initiation, indicating the two factors combine to regulate the transition.
髋关节伸展以及伸肌的低负荷是重要的感觉信号，能使去大脑或脊髓猫在行走过程中从站立阶段过渡到摆动阶段。我们测试了相同的感觉信息是否控制人类婴儿的迈步阶段。在跑步机上对22名5至12个月大的婴儿进行了支撑迈步研究。记录了下肢施加的力、肌肉的表面肌电图（EMG）以及右髋关节角度。整个实验过程都进行了录像。在迈步过程中，通过在站立阶段改变足部位置或对骨盆嵴施加手动压力来操纵髋关节位置和右下肢所承受的负荷量。使用了不同髋关节位置和负荷组合的干扰。当髋关节屈曲且肢体负荷较高时，站立阶段延长，摆动阶段延迟。相反，当髋关节伸展且负荷较低时，站立阶段缩短，摆动提前。结果与猫的简化标本中的结果非常相似。因此表明，人类婴儿和猫之间用于行走的脑干和脊髓回路的行为可能相似。在摆动开始时，髋关节位置和负荷之间存在反比关系，表明这两个因素共同调节过渡。
