Hill Ethan C, Housh Terry J, Smith Cory M, Cochrane Kristen C, Jenkins Nathaniel D M, Schmidt Richard J, Johnson Glen O
Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, NE, USA.
Department of Kinesiology and Health Promotion, California State Polytechnic University, Pomona, Pomona, CA, USA.
Int J Exerc Sci. 2017 Jul 1;10(4):580-591. doi: 10.70252/TONN2278. eCollection 2017.
The purpose of the present study was to examine the effects of 2 different work-to-rest ratios, but the same mean load, cycle time, and total duration of the exercise bout, on maximal voluntary isometric contraction torque and neuromuscular responses to fatiguing, intermittent, submaximal, isometric, forearm flexion muscle actions. Ten men performed 2 fatiguing protocols with different work-to-rest ratios (4 s contraction, 4 s rest vs. 4 s contraction, alternating 6 and 2 s rest) that consisted of 50 intermittent, submaximal (65% of maximal voluntary isometric contraction), isometric, forearm flexion muscle actions. Electromyographic and mechanomyographic signals from the biceps brachii were recorded before, during, immediately and 5 min after performing the fatiguing protocols. In addition, maximal voluntary isometric contraction torque was assessed before, immediately and 5 min after. Both protocols resulted in decreases in maximal voluntary isometric contraction torque, electromyographic mean power frequency, and mechanomyographic mean power frequency, but no changes in electromyographic amplitude or mechanomyographic amplitude. The results of the present study indicated that differences in work-to-rest ratio did not affect maximal voluntary isometric contraction torque or the associated neuromuscular parameters as a result of fatiguing, intermittent, isometric muscle actions when mean load, cycle time, and total duration of exercise were equivalent.
本研究的目的是检验两种不同的工作-休息比（但平均负荷、周期时间和运动组总时长相同）对最大自主等长收缩扭矩以及对疲劳性、间歇性、次最大等长前臂屈曲肌肉动作的神经肌肉反应的影响。十名男性进行了两种具有不同工作-休息比的疲劳方案（4秒收缩、4秒休息与4秒收缩，交替进行6秒和2秒休息），每种方案由50次间歇性、次最大（最大自主等长收缩的65%）等长前臂屈曲肌肉动作组成。在进行疲劳方案之前、期间、之后立即以及5分钟后，记录肱二头肌的肌电图和机械肌电图信号。此外，在之前、之后立即以及5分钟后评估最大自主等长收缩扭矩。两种方案均导致最大自主等长收缩扭矩、肌电图平均功率频率和机械肌电图平均功率频率降低，但肌电图幅度或机械肌电图幅度没有变化。本研究结果表明，当平均负荷、周期时间和运动总时长相等时，工作-休息比的差异不会影响因疲劳性、间歇性等长肌肉动作导致的最大自主等长收缩扭矩或相关神经肌肉参数。
