Rack P M, Westbury D R
J Physiol. 1984 Feb;347:479-95. doi: 10.1113/jphysiol.1984.sp015077.
A new method has been used to measure the stiffness of the entire tendinous component of the soleus muscle of the cat. During sinusoidal stretching of the muscle-tendon combination, the motor nerves were stimulated repetitively in such a way that the force of contraction offset the movement, and the muscle fibres remained at constant length. The afferent endings of muscle spindles were used to detect extension of the muscle fibres. In this null situation, when the spindles did not 'see' any movement, all of the applied movement was assumed to have been taken up in the tendinous components, and measurements of the movement and force allowed the stiffness to be calculated. Precautions were taken to avoid the effects of fusimotor stimulation. The stiffness of the entire tendinous component increased with increasing muscle force by approximately 2 N/mm per Newton mean force from 2 N/mm at low force to about 25 N/mm at 11 N; the method could not be used for larger forces. Independent measurements of the stiffness of the external part of the tendon were made by both static and dynamic methods. The entire tendinous component was much less stiff than the external tendon. Measurements of the dimensions of the tendon allowed Young's modulus for the tendon to be calculated. It increased from about 250 N/mm2 at 2.5 N to about 450 N/mm2 at 10 N mean force. Measurements of dissected muscles allowed comparisons to be made between the stiffness of the external tendon and the stiffness of the entire tendinous component in the muscles. Scaling of the stiffness of the external part of the tendon to the length of the entire tendinous component gave a value of stiffness which was similar to that measured by the spindle null method. The compliance of tendons has implications for the control of movement which are discussed.
一种新方法已被用于测量猫比目鱼肌整个腱性成分的刚度。在肌肉 - 肌腱组合进行正弦拉伸时，以这样一种方式重复刺激运动神经：收缩力抵消运动，使肌肉纤维保持恒定长度。利用肌梭的传入末梢来检测肌肉纤维的伸展。在这种无效状态下，当肌梭“看不到”任何运动时，假定所有施加的运动都被腱性成分吸收了，通过测量运动和力就可以计算出刚度。已采取预防措施以避免肌梭运动神经元刺激的影响。整个腱性成分的刚度随肌肉力增加而增大，从低力时的2 N/mm每牛顿平均力增加约2 N/mm，在11 N时达到约25 N/mm；该方法不适用于更大的力。通过静态和动态方法对肌腱外部部分的刚度进行了独立测量。整个腱性成分的刚度远低于外部肌腱。对肌腱尺寸的测量使得能够计算出肌腱的杨氏模量。其从2.5 N时的约250 N/mm²增加到平均力为10 N时的约450 N/mm²。对解剖后的肌肉进行测量，以便比较外部肌腱的刚度与肌肉中整个腱性成分的刚度。将肌腱外部部分的刚度按整个腱性成分的长度进行缩放，得到的刚度值与通过肌梭无效方法测得的值相似。讨论了肌腱的顺应性对运动控制的影响。
