ROLE OF MUSCLE STIFFNESS IN MEETING CHANGING POSTURAL AND LOCOMOTOR REQUIREMENTS FOR FORCE DEVELOPMENT BY ANKLE EXTENSORS
ROLE OF MUSCLE STIFFNESS IN MEETING CHANGING POSTURAL AND LOCOMOTOR REQUIREMENTS FOR FORCE DEVELOPMENT BY ANKLE EXTENSORS
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DOI：
10.1111/j.1748-1716.1972.tb00227.x
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发表时间：
1972-01-01
期刊：
影响因子：
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通讯作者：
GRILLNER, S
中科院分区：
文献类型：
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作者：
GRILLNER, S
在猫比目鱼肌和腓肠肌外侧，探讨了肌肉活动的长度和僵硬(力/长度变化)与运动单位被分布刺激供应肌肉的腹侧根所激活的速率之间的关系。当刺激率相当于运动时的刺激率(15-55p/S)时，肌肉僵硬的峰值出现在肌肉长度，也用于运动时。在较低的刺激率下，相当于去大脑猫紧张性拉伸反射的刺激率，肌肉僵硬的峰值出现在较长的肌肉长度上，但这些长度在用于研究反射的范围内。然后将这些实验结果与一组理论推导的结果进行比较，这些结果涉及：a)当脚踝和跖趾角度相对于机械轴改变时，脚踝伸肌所需的力量，以抵消沿垂直轴施加在后肢上的载荷；以及b)在缓慢行走过程中，脚踝伸肌产生的力量。在所有情况下(理论和实验)，结果表明所需力量、肌肉长度和肌肉僵硬之间存在密切的相关性。还计算了运动单位放电变化和张力发展之间的时间间隔，以揭示在许多情况下(特别是疾驰)，只有肌肉僵硬可以提供负荷补偿，而延迟太长，不能允许反射性诱导的负荷补偿。
The relationship between the length and stiffness (force/length change) of active muscle and the rates at which motor units are activated by distributed stimulation of divided ventral rootlets supplying the muscle has been explored in cat soleus and lateral gastrocnemius. At stimulus rates equivalent to those used in locomotion (15—55 p/s) peak muscle stiffness is at muscle lengths also used in locomotion. At lower rates of stimulation equivalent to those developed in the tonic stretch reflex of the decerebrate cat, peak muscle stiffness occurs at larger muscle lengths but these lengths are within the range of those used for investigation of the reflex. These experimental results were then compared to the sets of theoretically derived results concerning: a) the amount of force needed from the ankle extensors to counteract a load applied to the hindlimb along a vertical axis when ankle and metatarsophalangeal angles are changed relative to the mechanical axis; and b) the amount of force developed by ankle extensors during slow walking. In all cases (theoretical and experimental) the results reveal a close correlation between required force, muscle length and muscle stiffness. The time lag between a change in motor unit discharge and tension development was also calculated to reveal that in many situations (notably gallop) only muscle stiffness can provide a load compensation, whereas the delays are too long to allow a reflexly induced load compensation.