RESPONSE OF THE NORMAL HUMAN ANKLE JOINT TO IMPOSED SINUSOIDAL MOVEMENTS
RESPONSE OF THE NORMAL HUMAN ANKLE JOINT TO IMPOSED SINUSOIDAL MOVEMENTS
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DOI：
10.1113/jphysiol.1983.sp014953
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发表时间：
1983-01-01
影响因子：
5.5
通讯作者：
WALTERS, DKW
中科院分区：
文献类型：
--
作者：
EVANS, CM;FELLOWS, SJ;WALTERS, DKW
踝关节在一定的振幅和频率范围内进行正弦运动。记录小腿肌肉的肌电图（emg）和关节处的力。当腿放松时，踝关节用小的近似正弦的力抵抗施加的正弦运动。它对小运动的阻力比大运动的阻力更大，并且当关节背屈时比跖屈时阻力更大。如果受试者施加稳定的平均屈曲力，则所施加的正弦运动产生反射活动，该反射活动可以被记录为腓肠肌和比目鱼肌EMG的调制。对正弦运动的肌电反应在高频运动周期中比低频运动周期中发生得晚，这可以被认为是一种涉及延迟的反射通路。这种延迟显然在50到60毫秒之间，在这种情况下，脊髓牵张反射起了重要作用。阻力与运动的关系用矢量表示。随着频率的变化，这个矢量描述了一个循环路径，这是一个系统的特点，包括延迟或滞后;这个路径使人们能够得出结论的幅度和时间的反射阻力的运动。当受试者对正弦运动施加适度的弯曲力几分钟时，反射反应逐渐增强。反射反应通常轻微的受试者则可以对该踝部的运动表现出强烈的反射反应。脊髓反射活动的增强伴随着踝关节肌张力反射反应的增加。当受试者施加的平均屈曲力约为其最大值的1/5时，对正弦运动的反射反应最明显。非常小的运动（.+-. 0.5 °）产生很少或没有反射反应。随着运动幅度的增加，反射活动增加，但在一定幅度（因受试者和时间而异）下，反射机制似乎饱和，幅度的进一步增加并不伴随着反射反应的可比增加。随着10-15 Hz的运动，在交替周期中的EMG反应变大，在干预周期中的活动减少。在极端的情况下，emg活动被限制在交替的周期中，而在中间的周期中是电沉默的。这种肌电信号的交替变化通常伴随着力记录的类似变化，因此，每一个肌电信号活跃的周期之后，力就会上升到一个高水平。
Ankle joints were subjected to sinusoidal movements at a range of amplitudes and frequencies. Records were made of electromyograms (emg) in calf muscles, and of the forces at the joints. When the leg is relaxed, the ankle joint resists an imposed sinusoidal movement with a small, approximately sinusoidal force. It is stiffer in its resistance to small movements than to large ones, and this resistance is greater when the joint is dorsiflexed than when it is plantarflexed. If the subject exerts a steady mean flexing force, the imposed sinusoidal movement generates reflex activity which may be recorded as a modulation of the gastrocnemius and soleus emg. The emg response to the sinusoidal movement occurs later in cycles of movement at high than at low frequencies, as could be expected of a reflex pathway that involves a delay. This delay apparently is between 50 and 60 ms, and under these circumstances spinal stretch reflexes are playing the important part. The relation of the resisting force to the movement was displayed as a vector. As the frequency changes, this vector describes the circular path that is characteristic of a system which includes delays or lags; this path enables one to draw conclusions about the amplitude and timing of the reflex resistance to the movement. When a subject exerts a moderate flexing force against the sinusoidal movement for some minutes, the reflex response becomes progressively potentiated. A subject whose reflex responses are normally slight may then exhibit a vigorous reflex response to the movement of that ankle. This enhancement of spinal reflex activity was accompanied by an increase in the myotatic reflex response at the ankle. Reflex responses to sinusoidal movement were most clearly seen when the subject exerted a mean flexing force that amounted to about 1/5 of his maximum. Very small movements (.+-. 0.5.degree.) generated little or no reflex response. With large amplitudes of movement there was more reflex activity, but at some amplitude (which varied from subject to subject and from time to time) the reflex mechanism appeared to saturate, and further increases in amplitude were not accompanied by comparable increases in the reflex response. With movements of 10-15 Hz the emg response of became large in alternate cycles, with less activity in the intervening cycles. In extreme cases emg activity was confined to alternate cycles, with electrical silence in the intervening ones. This alternation of the emg signal was usually accompanied by similar changes in the force records, so that each cycle with vigorous emg activity was followed by one in which the force rose to a high level.