Mathiassen S E
National Institute of Occupational Health, Department of Physiology, Solna, Sweden.
Eur J Appl Physiol Occup Physiol. 1989;59(1-2):80-8. doi: 10.1007/BF02396584.
Six sedentary students, six orienteers, and six soccer players were each subjected to 15 tests, comprising 120 s of repeated, maximal isokinetic knee extensions. The tests differed with respect to movement velocity (30 degrees.s-1, 120 degrees.s-1, and 300 degrees.s-1), and movement frequency (5 at each velocity). At a certain velocity, a rectilinear relationship was found between muscular performance intensity (expressed either as average power output or as exercise time ratio) and development of fatigue (expressed either as an absolute or as a fractional decline in work output). Significant inter-velocity differences existed between the slopes of these lines at some combinations of performance and fatigue expressions. Only tendencies towards a difference in x-intercept values were found. This x-intercept value can be taken as a measure of the greatest attainable intensity level of performance without the development of fatigue. This suggestion is valuable both in basic physiological research, and as a possible criterion for optimization of muscular performance. At a given exercise time ratio, increasing movement velocity produced increasing fatigue. However, at a given muscular power output--above 15 W approximately--fatigue developed to a greater extent at the low velocity than at the two higher ones, which did not differ significantly. Substantial individual variation was seen in the positions of the low-, medium-, and high-velocity lines. These variations did not depend on the training background. This implies that the validity of using single-velocity, single-frequency tests in determining isokinetic endurance is doubtful.
六名久坐不动的学生、六名定向越野运动员和六名足球运动员分别接受了15项测试，包括120秒的重复最大等速膝关节伸展运动。测试在运动速度（30度·秒⁻¹、120度·秒⁻¹和300度·秒⁻¹）和运动频率（每个速度下5次）方面有所不同。在一定速度下，发现肌肉表现强度（以平均功率输出或运动时间比表示）与疲劳发展（以工作输出的绝对下降或分数下降表示）之间存在线性关系。在某些表现和疲劳表达方式的组合中，这些直线的斜率存在显著的速度间差异。仅发现了x轴截距值存在差异的趋势。这个x轴截距值可以作为在不产生疲劳的情况下可达到的最大表现强度水平的度量。这一建议在基础生理学研究中以及作为优化肌肉表现的可能标准都很有价值。在给定的运动时间比下，增加运动速度会导致疲劳增加。然而，在给定的肌肉功率输出——大约高于15瓦——时，低速时疲劳的发展程度比两个较高速度时更大，而两个较高速度之间没有显著差异。在低速、中速和高速直线的位置上可以看到很大的个体差异。这些差异并不取决于训练背景。这意味着使用单速度、单频率测试来确定等速耐力的有效性值得怀疑。
