School of Sport and Exercise Sciences, University of Kent, Canterbury, United Kingdom.
School of Sport and Health Sciences, University of Exeter, Exeter, United Kingdom.
J Appl Physiol (1985). 2024 Jul 1;137(1):99-110. doi: 10.1152/japplphysiol.00325.2023. Epub 2024 May 30.
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 [ = 208, = 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 ( = -3.29, = 0.001, β = -1.50 ΔμM, 95% CI [-2.40 to -0.61 ΔμM]) and affective valence ( = 6.12, = 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. 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.
疼痛是一种自然发生的现象，它通过施加无意识的神经生理改变（例如皮质脊髓变化）以及有意识的心理生理压力（例如共同的努力需求），始终抑制运动表现。尽管有几项研究表明，对于一定强度的感知努力，疼痛会导致较低的任务输出，但没有研究对此进行测试。因此，本研究通过高渗盐水注射来升高肌肉疼痛，以研究其对固定感知努力运动期间功率输出、心理生理、脑氧合和感知变化的影响。十名参与者完成了三次访问（1 次熟悉+2 次固定感知努力试验）。固定感知努力的自行车运动相当于气体交换阈值（GET）以上 15%[感知努力平均评分（RPE）= 15“硬”]。在 30 分钟的固定感知努力运动之前，参与者在股外侧肌中接受了随机的双侧高渗或等渗盐水注射。在运动期间记录了功率输出、心肺功能、脑氧合和感知标记（例如情感效价）。线性混合模型回归评估了条件和时间效应以及条件×时间的相互作用。显著的条件效应表明，在高渗条件下，功率输出显著降低[= 208，= 0.040，β= 4.77 W，95%置信区间（95%CI）[0.27 至 9.26 W]。同时，所有生理变量（例如心率、摄氧量、分钟通气量）均未显示出显著的条件效应。从基线开始，脱氧血红蛋白变化和情感效价均观察到条件效应[= -3.29，= 0.001，β= -1.50ΔμM，95%CI[-2.40 至-0.61ΔμM]和[= 6.12，= 0.001，β= 0.93，95%CI[0.63 至 1.23]）。结果推断，疼痛会影响固定感知努力运动的自我调节，因为在高渗盐水与等渗盐水给药后疼痛评分较高时，功率输出的差异主要发生。这项研究表明，通过高渗盐水注射升高肌肉疼痛会导致疼痛时的功率输出明显降低，但似乎不会以残留的方式影响运动行为。结果提供了一些证据，表明疼痛在心理生理水平上起作用，通过条件之间的大脑脱氧血红蛋白和其他感知参数的差异来改变运动行为的自我调节。
