Black Christopher D, Gonglach Alexander R, Renfroe Jessica B, Hight Robert E
University of Oklahoma, Department of Health and Exercise Science, Norman, OK 73019, USA.
University of Oklahoma, Department of Health and Exercise Science, Norman, OK 73019, USA.
Physiol Behav. 2016 Jul 1;161:1-6. doi: 10.1016/j.physbeh.2016.04.005. Epub 2016 Apr 7.
Exercise acutely reduces pain sensitivity, termed exercise-induced hypoalgesia (EIH). The mechanisms underlying EIH remain unclear. Caffeine, a non-specific adenosine receptor antagonist has been shown to attenuate EIH in animals-suggesting the involvement of the adenosinergic system. This pilot study investigated the effects of caffeine on pain sensitivity following cycling exercise in college-aged men. Pressure pain threshold (PPT) and thermal pain threshold (TPT) were assessed in thirteen low caffeine consuming men prior to ingestion of a counter-balanced 5mg·kg(-1) dose of caffeine or a placebo (Pre), 60min following ingestion (Post-In), and then following a 15min bout of cycling exercise (Post-Ex) at an intensity eliciting a quadriceps muscle pain rating of 3 out of 10. Nine of the men completed follow-up testing which was identical except that the exercise consisted of 10min of cycling eliciting a pain rating of 5 out of 10. Caffeine had no effect compared to placebo on PPT (p≥0.15) or TPT (p≥0.41) 60min following ingestion and following exercise. PPT increased from 599±176kPa to 648±202kPa (p=0.009) and from 578±217kPa to 666±278kPa (p=0.01) following 15 and 10min of cycling, respectively. TPT increased from 46.2±2.9°C to 46.8±2.6°C (p=0.008) following the 15min exercise bout, but did not change (46.4±3.6°C vs. 46.8±3.3°C; p=0.24) following the shorter, higher intensity exercise bout. The results from this study indicate cycling exercise reduces pain sensitivity, especially to pressure stimuli. Caffeine ingestion did not alter the EIH response-suggesting adenosine may not play a prominent role in the EIH response in humans.
运动能迅速降低疼痛敏感性，即运动诱导性痛觉减退（EIH）。EIH背后的机制尚不清楚。咖啡因是一种非特异性腺苷受体拮抗剂，已被证明可减轻动物的EIH，这表明腺苷能系统参与其中。这项初步研究调查了咖啡因对大学年龄男性骑行运动后疼痛敏感性的影响。在13名低咖啡因摄入男性中，在摄入5mg·kg(-1)剂量的咖啡因或安慰剂（预测试）之前、摄入后60分钟（摄入后）以及在以引起股四头肌疼痛评分为10分制中的3分的强度进行15分钟骑行运动后（运动后），评估压力痛阈（PPT）和热痛阈（TPT）。其中9名男性完成了后续测试，测试内容相同，只是运动改为10分钟骑行，引起的疼痛评分为10分制中的5分。与安慰剂相比，摄入咖啡因后60分钟以及运动后，咖啡因对PPT（p≥0.15）或TPT（p≥0.41）均无影响。分别在15分钟和10分钟骑行后，PPT从599±176kPa增加到648±202kPa（p=0.009）和从578±217kPa增加到666±278kPa（p=0.01）。在15分钟运动回合后，TPT从46.2±2.9°C增加到46.8±2.6°C（p=0.008），但在较短、强度较高的运动回合后未发生变化（46.4±3.6°C对46.8±3.3°C；p=0.24）。这项研究的结果表明骑行运动可降低疼痛敏感性，尤其是对压力刺激的敏感性。摄入咖啡因并未改变EIH反应，这表明腺苷可能在人类的EIH反应中不发挥突出作用。
