Abstract：
Pain is a naturally occurring phenomenon that consistently inhibits exercise performance by imposing unconscious, neurophysiological alterations (e.g., corticospinal changes) as well as conscious, psychophysiological pressures (e.g., shared effort demands). Although several studies indicate that pain would elicit lower task outputs for a set intensity of perceived effort, no study has tested this. Therefore, this study investigated the impact of elevated muscle pain through a hypertonic saline injection on the power output, psychophysiological, cerebral oxygenation, and perceptual changes during fixed perceived effort exercise. Ten participants completed three visits (1 familiarization + 2 fixed perceived effort trials). Fixed perceived effort cycling corresponded to 15% above gas exchange threshold (GET) [mean rating of perceived effort (RPE) = 15 \"hard\"]. Before the 30-min fixed perceived effort exercise, participants received a randomized bilateral hypertonic or isotonic saline injection in the vastus lateralis. Power output, cardiorespiratory, cerebral oxygenation, and perceptual markers (e.g., affective valence) were recorded during exercise. Linear mixed-model regression assessed the condition and time effects and condition × time interactions. Significant condition effects showed that power output was significantly lower during hypertonic conditions [t107 = 208, P = 0.040, β = 4.77 W, 95% confidence interval (95% CI) [0.27 to 9.26 W]]. Meanwhile, all physiological variables (e.g., heart rate, oxygen uptake, minute ventilation) demonstrated no significant condition effects. Condition effects were observed for deoxyhemoglobin changes from baseline (t107 = -3.29, P = 0.001, β = -1.50 ΔμM, 95% CI [-2.40 to -0.61 ΔμM]) and affective valence (t127 = 6.12, P = 0.001, β = 0.93, 95% CI [0.63 to 1.23]). Results infer that pain impacts the self-regulation of fixed perceived effort exercise, as differences in power output mainly occurred when pain ratings were higher after hypertonic versus isotonic saline administration.NEW & NOTEWORTHY This study identifies that elevated muscle pain through a hypertonic saline injection causes significantly lower power output when pain is experienced but does not seem to affect exercise behavior in a residual manner. Results provide some evidence that pain operates on a psychophysiological level to alter the self-regulation of exercise behavior due to differences between conditions in cerebral deoxyhemoglobin and other perceptual parameters.
摘要：
疼痛是一种自然发生的现象，它通过强加无意识来不断抑制运动表现，神经生理学改变(例如，皮质脊髓变化)以及有意识的，心理生理压力(例如，共同的努力要求)。虽然,几项研究表明，疼痛会导致较低的任务产出，以设定的感知努力强度，没有研究对此进行过测试。因此,这项研究调查了通过注射高渗盐水引起的肌肉疼痛对功率输出的影响，心理生理学，脑氧合,固定感知努力运动过程中的感知变化。十名参与者完成了三次访问(一次熟悉+两次固定感知努力试验)。固定的感知努力循环对应于高于气体交换阈值15%(平均RPE=15;硬)。在30分钟的固定感知努力练习之前，参与者接受了随机的，股外侧肌双侧注射高渗或等渗盐水。功率输出,心肺，脑氧合,和感知标记(例如，情感效价）在运动过程中记录。线性混合模型回归评估了条件和时间效应以及条件×时间相互作用。显著的条件效应表明高渗条件下功率输出显著降低(t_107=2.08,p=0.040,β=4.77瓦,95CI[0.27至9.26瓦])。同时所有生理变量(例如，心率,氧气吸收，分钟通气）没有明显的条件影响。从基线观察到脱氧血红蛋白变化的条件效应(t_107=-3.29,p=.001,β=-1.50ΔµM,95CI[-2.40至-0.61ΔµM]）和情感效价（t_127=6.12，p=.001，β=0.93,95CI[0.63,1.23]）。结果推断疼痛会影响固定感知努力运动的自我调节，因为功率输出的差异主要发生在高渗与等渗盐水给药后疼痛评分较高时。
