Effects of series compliance on twitches superimposed on voluntary contractions.
Effects of series compliance on twitches superimposed on voluntary contractions.
复制标题
系列顺应性对叠加在随意收缩上的抽搐的影响。
DOI：
10.1152/jappl.1992.73.2.516
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发表时间：
1992
期刊：
影响因子：
--
通讯作者：
Hershenson,MB
中科院分区：
文献类型：
--
作者：
Loring,SH;Hershenson,MB
骨骼肌在自主等长收缩过程中的激活通过测量叠加的最大电击对运动神经造成的力的增加来评估(抽动插值法)。当肌肉保持等长时，刺激增加的力(叠加的抽动力)随着自愿力的增加而减少，通过数据拟合的直线可以外推到零抽动力轴处的最大自愿力。在以前的一篇论文中，我们质疑这种技术在高顺应性允许肌肉在叠加抽动过程中缩短的情况下的适用性。为了探索顺应性的影响，我们用顺应性和非顺应性加载装置测量了随意等长收缩时拇内收肌的力量。使用顺应性加载装置时，叠加扭动力系统地小于非顺应性加载装置，并且叠加扭动力与自愿力的关系曲线通常是向上凹陷的，从而避免了容易地外推到最大自愿力。这些发现与肌肉的力-速度特征是一致的，并表明当肌肉在叠加抽动过程中没有保持等长时，必须谨慎地解释抽动内插数据。
The activation of skeletal muscle during voluntary isometric contraction has been assessed by measuring the increase in force caused by a superimposed maximal shock to the motor nerve (the twitch-interpolation technique). When the muscle is held isometric, the increase in force with stimulation (superimposed twitch force) decreases with increasing voluntary force, and a line fit through the data can be extrapolated to maximal voluntary force at the zero twitch force axis. In a previous paper we questioned the applicability of this technique in situations where a high series compliance allows the muscle to shorten during the superimposed twitch. To explore effects of series compliance, we measured force of the adductor pollicis during voluntary isometric contractions with noncompliant and compliant loading devices. With the compliant loading device, superimposed twitch force was systematically less than with the noncompliant device, and the plot of superimposed twitch force vs. voluntary force was often concave upward, preventing easy extrapolation to maximal voluntary force. These findings are consistent with force-velocity characteristics of muscle and suggest that twitch-interpolation data must be interpreted with caution when the muscle is not held isometric during the superimposed twitch.