Exercise Physiology Laboratory, Department of Nutrition and Health Sciences, University of Nebraska - Lincoln, Lincoln, NE, USA -
Exercise Physiology Laboratory, Department of Nutrition and Health Sciences, University of Nebraska - Lincoln, Lincoln, NE, USA.
J Sports Med Phys Fitness. 2024 Jun;64(6):505-515. doi: 10.23736/S0022-4707.24.15721-0. Epub 2024 Mar 4.
Ratings of perceived exertion (RPE) can be used to regulate exercise intensity. This study examined the effect of anchor scheme on performance fatigability and neuromuscular responses following fatiguing forearm flexion tasks.
Twelve men (age 20.9±2.2 years; height 179.8±5.3 cm; body mass 80.2±9.9 kg) performed sustained, isometric forearm flexion tasks to failure anchored to RPE=6 (RPEFT) and the torque (TRQFT) that corresponded to RPE=6. Pre-test and post-test maximal voluntary isometric contractions (MVIC) were performed to quantify changes in the amplitude (AMP) and mean power frequency (MPF) of the electromyographic (EMG) and mechanomyographic (MMG) signals. Neuromuscular efficiency (NME) was calculated by dividing normalized torque by normalized EMG AMP. A dependent t-test was used to assess the mean difference for time to task failure (TTF). Repeated measures ANOVAs were used to compare mean differences for performance fatigability and normalized neuromuscular parameters.
The RPEFT had a greater TTF than the TRQFT (P<0.001). MVIC and NME decreased from pre-test to post-test following the RPEFT and TRQFT (P<0.05) with no differences between anchor schemes. Following the TRQFT, normalized EMG MPF decreased from pre-test to post-test (P=0.004). Following the RPEFT, normalized MMG MPF increased from pre-test to post-test (P=0.021). There were no changes in normalized EMG AMP or MMG AMP (P>0.05).
These findings indicated anchor scheme-specific neuromuscular responses and TTF, despite no difference in performance fatigability. Furthermore, performance fatigability was likely due to peripheral fatigue (based on normalized EMG MPF and NME) following the TRQFT, but peripheral and central fatigue (based on normalized MMG MPF and NME) following the RPEFT.
感知用力（RPE）评分可用于调节运动强度。本研究考察了疲劳前臂弯曲任务后，锚定方案对运动疲劳性和神经肌肉反应的影响。
12 名男性（年龄 20.9±2.2 岁；身高 179.8±5.3cm；体重 80.2±9.9kg）进行了持续的等长前臂弯曲任务，直至疲劳，锚定到 RPE=6（RPEFT）和与 RPE=6 对应的扭矩（TRQFT）。进行预测试和后测试最大自主等长收缩（MVIC），以量化肌电图（EMG）和机械肌电图（MMG）信号的幅度（AMP）和平均功率频率（MPF）的变化。神经肌肉效率（NME）通过将归一化扭矩除以归一化 EMG AMP 来计算。使用配对 t 检验评估任务失败时间（TTF）的平均差异。使用重复测量方差分析比较运动疲劳性和归一化神经肌肉参数的平均差异。
RPEFT 的 TTF 大于 TRQFT（P<0.001）。MVIC 和 NME 在 RPEFT 和 TRQFT 后从预测试到后测试均下降（P<0.05），但锚定方案之间无差异。在 TRQFT 后，从预测试到后测试，归一化 EMG MPF 下降（P=0.004）。在 RPEFT 后，从预测试到后测试，归一化 MMG MPF 增加（P=0.021）。归一化 EMG AMP 或 MMG AMP 没有变化（P>0.05）。
尽管运动疲劳性没有差异，但这些发现表明了特定于锚定方案的神经肌肉反应和 TTF。此外，TRQFT 后运动疲劳性可能归因于外周疲劳（基于归一化 EMG MPF 和 NME），而 RPEFT 后则归因于外周和中枢疲劳（基于归一化 MMG MPF 和 NME）。
