Takaishi T, Yasuda Y, Moritani T
College of General Education, Nagoya City University, Japan.
Eur J Appl Physiol Occup Physiol. 1994;69(2):154-8. doi: 10.1007/BF00609408.
The purpose of this study was to estimate the differences in neuromuscular fatigue among prolonged pedalling exercises performed at different pedalling rates at a given exercise intensity. The integrated electromyogram (iEMG) slope defined by the changes in iEMG as a function of time during exercise was adopted as the measurement for estimating neuromuscular fatigue. The results of this experiment showed that the relationship between pedalling rate and the means of the iEMG slopes for eight subjects was a quadratic curve and the mean value at 70 rpm [1.56 (SD 0.65) microV.min-1] was significantly smaller (P < 0.01) than that at 50 and 60 rpm [2.25 (SD 0.54), and 2.22 (SD 0.68), respectively]. On the other hand, the mean value of oxygen consumption obtained simultaneously showed a tendency to increase linearly with the increase in pedalling rate, and the values at 70 and 80 rpm were significantly higher than those at 40 and 50 rpm. In conclusion, it was demonstrated that the degree of neuromuscular fatigue estimated by the iEMG changes for five periods of prolonged pedalling exercise at a given exercise intensity was different among the different pedalling rates, and that the pedalling rate at which minimal neuromuscular fatigue was obtained was not coincident with the rate at which the minimal oxygen consumption was obtained, but was coincident with the rate which most subjects preferred. These findings would suggest that the reason why most people prefer a relative higher pedalling rate, even though higher oxygen consumption is required, is closely related to the development of neuromuscular fatigue in the working muscles.
本研究的目的是评估在给定运动强度下，以不同蹬踏速率进行长时间蹬踏运动时神经肌肉疲劳的差异。采用运动过程中肌电图积分（iEMG）随时间变化定义的iEMG斜率作为评估神经肌肉疲劳的指标。本实验结果表明，八名受试者的蹬踏速率与iEMG斜率均值之间的关系呈二次曲线，70转/分钟时的均值[1.56（标准差0.65）微伏·分钟-1]显著小于50和60转/分钟时的均值[分别为2.25（标准差0.54）和2.22（标准差0.68）]（P<0.01）。另一方面，同时测得的耗氧量均值呈现出随蹬踏速率增加而线性增加的趋势，70和80转/分钟时的值显著高于40和50转/分钟时的值。总之，研究表明，在给定运动强度下进行五个阶段的长时间蹬踏运动时，通过iEMG变化评估的神经肌肉疲劳程度在不同蹬踏速率下有所不同，获得最小神经肌肉疲劳的蹬踏速率与获得最小耗氧量的速率并不一致，而是与大多数受试者偏好的速率一致。这些发现表明，即使需要更高的耗氧量，大多数人仍偏好相对较高蹬踏速率的原因与工作肌肉中神经肌肉疲劳的发展密切相关。
