BackgroundVagal activity has analgesic effects that are attributed to exercise‐induced hypoalgesia (EIH). High vagal tone and low pain sensitivity are reported in individuals who routinely exercise yet, their association is unclear. Furthermore, it is unknown if the heightened vagal tone following high physical activity predicts and intensifies EIH.MethodsFifty‐one healthy participants (27 low–moderately physically active; 27 females) underwent a resting‐state electrocardiogram followed by heart rate variability analysis. Pain measurements, including pressure (PPT) and heat (HPT) pain thresholds, ratings of tonic heat pain (THP) and conditioned pain modulation (CPM) paradigm, were conducted pre‐ and post‐exercise on a cycle ergometer.ResultsThe highly active group demonstrated higher vagal tone compared to the low–moderately active (root mean square of successive differences between R–R intervals: 63.96.92 vs. 34.78 ms, p = 0.018; percentage of successive R–R intervals that exceed 50 ms: 24.41 vs. 11.52%, p = 0.012). Based on repeated‐measure ANOVA, the highly active group showed higher PPT at pre‐exercise, compared to the low–moderately active group (382 kPa vs. 327 kPa; p = 0.007). Post‐exercise, both groups demonstrated EIH, increased HPT (p = 0.013) and decreased THP ratings (p < 0.001). Linear regression revealed that only in the low–moderately active group, higher vagal tone was associated with more efficient pre‐exercise CPM and a greater reduction in THP ratings post‐exercise (p ≤ 0.01).ConclusionsHighly active individuals demonstrate greater vagal tone and lower pain sensitivity but no greater EIH. Vagal tone moderates pain inhibition efficiency and EIH only in low–moderately active individuals. These findings suggest that physical activity level moderates the vagal–pain association via the endogenous analgesia system.SignificanceHighly physically active individuals exhibit greater vagal tone and reduced sensitivity to experimental pain, yet they do not benefit more from exercise‐induced hypoalgesia (EIH) compared to low–moderately active individuals. Moreover, low–moderately active individuals with greater vagal tone exhibited more efficient endogenous pain inhibition and greater EIH, suggestive of the moderation effect of physical activity level on vagal–pain associations.

中文翻译：

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迷走神经张力、疼痛敏感性和运动引起的痛觉减退：体力活动水平的影响

背景迷走神经活动具有镇痛作用，归因于运动诱发的痛觉减退（EIH）。据报道，经常锻炼的人迷走神经张力高，疼痛敏感性低，但它们之间的关系尚不清楚。此外，尚不清楚高体力活动后迷走神经张力增高是否会预测和加剧 EIH。 方法 51 名健康参与者（27 名低度至中度体力活动；27 名女性）接受静息态心电图检查，然后进行心率变异性分析。疼痛测量，包括压力 (PPT) 和热 (HPT) 疼痛阈值、强直性热痛 (THP) 评级和条件性疼痛调节 (CPM) 范式，在运动前和运动后在自行车测力计上进行。结果高度活跃组与低-中活跃组相比，迷走神经张力更高（R-R间隔之间连续差异的均方根：63.96.92 vs. 34.78 ms，p= 0.018；连续 R–R 间隔超过 50 毫秒的百分比：24.41 与 11.52%，p= 0.012）。根据重复测量方差分析，与中低活动组相比，高活动组在运动前表现出更高的 PPT（382 kPa vs. 327 kPa；p= 0.007)。运动后，两组均表现出 EIH、HPT 增加（p= 0.013) 并降低了 THP 评级 (p< 0.001）。线性回归显示，仅在中低活动组中，较高的迷走神经张力与更有效的运动前 CPM 以及运动后 THP 评分的更大降低相关（p≤ 0.01)。结论高度活跃的个体表现出更大的迷走神经张力和更低的疼痛敏感性，但没有更高的 EIH。迷走神经张力仅在中低度活跃个体中调节疼痛抑制效率和 EIH。这些发现表明，体力活动水平通过内源性镇痛系统调节迷走神经-疼痛关联。低度至中等活跃度的个体。此外，迷走神经张力较大的中低活动个体表现出更有效的内源性疼痛抑制和更大的 EIH，这表明体力活动水平对迷走神经疼痛关联具有调节作用。