Pain arising from exercise potentiates fatigue and impairs the performance of endurance exercise. We assessed neurophysiological and perceptual responses to endurance exercise performed under experimentally induced muscle pain by a model that separates muscle pain from muscle fatigue. After a series of pilot studies investigating different hypertonic saline volumes, 17 healthy males performed a preliminary VO_2PEAK test before performing a familiarization of the cycling time-to-exhaustion exercise (80% of the peak power output in the VO_2PEAK test). Participants, performed a baseline exercise session before the sessions with hypertonic and isotonic saline injections in the vastus lateralis of both legs, in a crossover and counterbalanced design. Neurophysiological and perceptual responses such as electroencephalography (EEG) in frontal, prefrontal, parietal, and motor cortex, electromyography (EMG) of the vastus lateralis and biceps femoris muscles, ratings of perceived exertion (RPE), pain sensation, and affective valence were measured at rest and during exercise. The hypertonic injection reduced the resting EEG alpha-beta ratio in the frontal and prefrontal cortex. When compared to exercise performed after the isotonic injection (430.5 ± 152.6 s), hypertonic injection shortened the time-to-exhaustion (357.5 ± 173.0 s), reduced the EMG of the assessed muscles, and increased the muscle co-contraction during exercise. The hypertonic injection also reduced the EEG alpha-beta ratio in the prefrontal and parietal cortex, increased RPE and pain sensation, and reduced affective valence during exercise. This proof-of-concept study showed that hypertonic injection-induced muscle pain reduced endurance performance, promoting centrally mediated alterations in motor command and cortical activation, as well as an interplay of perceptual responses.

中文翻译：

---

实验性肌肉疼痛对耐力表现的影响：一项评估神经生理学和知觉反应的概念验证研究

运动引起的疼痛会加剧疲劳并损害耐力运动的表现。我们通过将肌肉疼痛与肌肉疲劳区分开来的模型，评估了在实验诱发的肌肉疼痛下进行的耐力运动的神经生理学和知觉反应。在对不同的高渗盐水体积进行了一系列初步研究后，17 名健康男性进行了初步的 VO _2PEAK测试，然后再进行熟悉的骑车时间到力竭运动（VO _{2PEAK中峰值功率输出的 80%）}测试）。在交叉和平衡设计中，参与者在双腿股外侧肌注射高渗和等渗盐水之前进行了基线锻炼。测量神经生理学和知觉反应，例如额叶、前额叶、顶叶和运动皮层的脑电图 (EEG)、股外侧肌和股二头肌的肌电图 (EMG)、感知用力 (RPE) 等级、痛觉和情感效价在休息和运动时。高渗注射降低了额叶和前额叶皮层的静息脑电图 α-β 比率。与等渗注射后进行的运动（430.5 ± 152.6 s）相比，高渗注射缩短了疲劳时间（357.5 ± 173.0 s），降低了评估肌肉的 EMG，并增加运动过程中的肌肉协同收缩。高渗注射还降低了前额叶和顶叶皮层的脑电图 α-β 比率，增加了 RPE 和疼痛感，并降低了运动期间的情感效价。这项概念验证研究表明，高渗注射引起的肌肉疼痛会降低耐力表现，促进中枢介导的运动命令和皮质激活改变，以及感知反应的相互作用。