The measurement of force/velocity relationships of fresh and fatigued human adductor pollicis muscle.

C J De Ruiter, D A Jones, A J Sargeant, A De Haan
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引用次数: 53

Abstract

The purpose of the study was to obtain force/velocity relationships for electrically stimulated (80 Hz) human adductor pollicis muscle (n = 6) and to quantify the effects of fatigue. There are two major problems of studying human muscle in situ; the first is the contribution of the series elastic component, and the second is a loss of force consequent upon the extent of loaded shortening. These problems were tackled in two ways. Records obtained from isokinetic releases from maximal isometric tetani showed a late linear phase of force decline, and this was extrapolated back to the time of release to obtain measures of instantaneous force. This method gave usable data up to velocities of shortening equivalent to approximately one-third of maximal velocity. An alternative procedure (short activation, SA) allowed the muscle to begin shortening when isometric force reached a value that could be sustained during shortening (essentially an isotonic protocol). At low velocities both protocols gave very similar data (r2 = 0.96), but for high velocities only the SA procedure could be used. Results obtained using the SA protocol in fresh muscle were compared to those for muscle that had been fatigued by 25 s of ischaemic isometric contractions, induced by electrical stimulation at the ulnar nerve. Fatigue resulted in a decrease of isometric force [to 69 (3)%], an increase in half-relaxation time [to 431 (10)%], and decreases in maximal shortening velocity [to 77 (8)%] and power [to 42 (5)%]. These are the first data for human skeletal muscle to show convincingly that during acute fatigue, power is reduced as a consequence of both the loss of force and slowing of the contractile speed.

新鲜和疲劳人体拇内收肌力/速度关系的测量。
本研究的目的是获得电刺激(80 Hz)人体拇内收肌(n = 6)的力/速度关系,并量化疲劳的影响。在原位研究人体肌肉有两个主要问题;第一个是系列弹性分量的贡献,第二个是由于加载缩短的程度而造成的力的损失。解决这些问题的方法有两种。从最大等距破伤风的等速释放中获得的记录显示力下降的后期线性阶段,并将其外推回释放时间以获得瞬时力的测量。这种方法提供的可用数据可达缩短速度,相当于最大速度的大约三分之一。另一种方法(短激活,SA)允许肌肉在等长力达到可在缩短过程中持续的值时开始缩短(本质上是等压方案)。在低速时,两种方案给出了非常相似的数据(r2 = 0.96),但在高速时,只能使用SA程序。在新鲜肌肉中使用SA方案获得的结果与在尺神经电刺激诱导的25秒缺血等距收缩疲劳肌肉的结果进行了比较。疲劳导致等长力降低[至69(3)%],半松弛时间增加[至431(10)%],最大缩短速度降低[至77(8)%],功率降低[至42(5)%]。这是人类骨骼肌的第一个数据,令人信服地表明,在急性疲劳期间,由于失去力量和收缩速度减慢,力量会减少。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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