Ortega Dolores G, Housh Terry J, Smith Robert W, Arnett Jocelyn E, Neltner Tyler J, Anders John Paul V, Schmidt Richard J, Johnson Glen O
Exercise Physiology Laboratory, Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, NE 68510, USA.
The Exercise Science Program, Department of Human Sciences, The Ohio State University, Columbus, OH 43210, USA.
J Funct Morphol Kinesiol. 2023 Aug 10;8(3):114. doi: 10.3390/jfmk8030114.
This study examined the effects of joint angle (JA) on maximal voluntary isometric contraction (MVIC) and neuromuscular responses following fatiguing tasks anchored to RPE. Nine men (mean ± SD: age = 20.7 ± 1.2 yrs) performed forearm flexion MVICs at elbow JAs of 75° and 125° before and after sustained, isometric forearm flexion tasks to failure at fatiguing joint angles (FJA) of 75° and 125° anchored to RPE = 8. The amplitude and frequency of the electromyographic and mechanomyographic signals were recorded. Neuromuscular efficiency was calculated by dividing normalized torque by normalized electromyographic amplitude. A dependent -test was used to assess the mean difference for time to task failure (TTF) between FJA. Repeated measure ANOVAs were used to assess mean differences for pre-test to post-test MVIC and neuromuscular responses. There was no significant difference between FJA for TTF ( = 0.223). The MVIC (collapsed across FJA and MVIC JA) decreased from pre-test to post-test (51.1 ± 5.0 vs. 45.3 ± 5.6 Nm, < 0.001). Normalized neuromuscular parameters remained unchanged ( > 0.05). The FJA resulted in similar torque and neuromuscular responses, and the decreases in MVIC were not tracked by changes in the neuromuscular parameters. Thus, the neuromuscular parameters were not sensitive to fatigue, and pre-test to post-test measures may be compared between different FJA.
本研究考察了关节角度（JA）对最大自主等长收缩（MVIC）以及基于主观用力程度（RPE）的疲劳任务后神经肌肉反应的影响。九名男性（平均±标准差：年龄 = 20.7 ± 1.2岁）在75°和125°的肘关节角度下进行前臂屈曲MVIC，分别在以RPE = 8为标准、在75°和125°的疲劳关节角度（FJA）下持续进行等长前臂屈曲任务直至力竭前后进行。记录肌电图和机械肌电图信号的幅度和频率。通过将归一化扭矩除以归一化肌电图幅度来计算神经肌肉效率。采用配对t检验评估FJA之间任务失败时间（TTF）的平均差异。重复测量方差分析用于评估测试前到测试后MVIC和神经肌肉反应的平均差异。FJA之间的TTF无显著差异（P = 0.223）。测试前到测试后MVIC（跨FJA和MVIC JA合并）降低（51.1 ± 5.0 vs. 45.3 ± 5.6 Nm，P < 0.001）。归一化神经肌肉参数保持不变（P > 0.05）。FJA导致相似的扭矩和神经肌肉反应，并且MVIC的降低未被神经肌肉参数的变化所追踪。因此，神经肌肉参数对疲劳不敏感，并且可以在不同的FJA之间比较测试前到测试后的测量值。
