Zurawlew Michael J, Mee Jessica A, Walsh Neil P
Extremes Research Group, College of Human Sciences, Bangor University, Bangor, United Kingdom.
Front Physiol. 2018 Dec 18;9:1824. doi: 10.3389/fphys.2018.01824. eCollection 2018.
Hot water immersion (HWI) after exercise on 6 consecutive days in temperate conditions has been shown to provide heat acclimation adaptations in a recreationally active population. Endurance athletes experience frequent, sustained elevations in body temperature during training and competition; as a consequence, endurance athletes are considered to be partially heat acclimatized. It is therefore important to understand the extent to which endurance trained individuals may benefit from heat acclimation by post-exercise HWI. To this end, we compared the responses of eight endurance trained and eight recreationally active males (habitual weekly endurance exercise: 9 h vs. 3 h) to a 6-day intervention involving a daily treadmill run for 40 min (65% O) in temperate conditions followed immediately by HWI (≤40 min, 40°C). Before (PRE) and after the intervention (POST), hallmark heat acclimation adaptations were assessed during a 40-min treadmill run at 65% O in the heat (33°C, 40% RH). The 6 day, post-exercise HWI intervention induced heat acclimation adaptations in both endurance trained and recreationally active individuals. Training status did not significantly influence the magnitude of heat acclimation adaptations from PRE to POST (interactions > 0.05) for: the reduction in end-exercise rectal core temperature ( , mean, endurance trained -0.36°C; recreationally active -0.47°C); the reduction in resting (endurance trained -0.17°C; recreationally active -0.23°C); the reduction in at sweating onset (endurance trained -0.22°C; recreationally active -0.23°C); and, the reduction in mean skin temperature (endurance trained -0.67°C; recreationally active -0.75°C: PRE to POST < 0.01). Furthermore, training status did not significantly influence the observed reductions in mean O, mean metabolic energy expenditure, end-exercise physiological strain index, perceived exertion or thermal sensation (PRE to POST < 0.05). Only end-exercise heart rate was influenced by training status ( < 0.01, interaction); whereby, recreationally active but not endurance trained individuals experienced a significant reduction in end-exercise heart rate from PRE to POST ( < 0.01). In summary, these findings demonstrate that post-exercise HWI presents a practical strategy to reduce thermal strain during exercise-heat-stress in endurance trained and recreationally active individuals.
在温和环境下连续6天运动后进行热水浸泡（HWI）已被证明能使有休闲运动习惯的人群产生热适应变化。耐力运动员在训练和比赛期间经常会经历持续的体温升高；因此，耐力运动员被认为部分适应了热环境。所以，了解耐力训练个体通过运动后热水浸泡实现热适应能获得多大益处很重要。为此，我们比较了8名耐力训练男性和8名有休闲运动习惯的男性（每周习惯性耐力运动时间：9小时对3小时）对一项为期6天的干预措施的反应，该干预包括在温和环境下每天在跑步机上跑40分钟（65%最大摄氧量），随后立即进行热水浸泡（≤40分钟，40°C）。在干预前（PRE）和干预后（POST），在33°C、40%相对湿度的高温环境下以65%最大摄氧量进行40分钟跑步机跑步期间，评估标志性的热适应变化。为期6天的运动后热水浸泡干预在耐力训练个体和有休闲运动习惯的个体中均诱导出了热适应变化。训练状态对从PRE到POST热适应变化的幅度没有显著影响（交互作用>0.05），具体表现为：运动结束时直肠核心温度的降低（平均而言，耐力训练个体降低0.36°C；有休闲运动习惯的个体降低0.47°C）；静息心率的降低（耐力训练个体降低0.17°C；有休闲运动习惯的个体降低0.23°C）；出汗起始时心率的降低（耐力训练个体降低0.22°C；有休闲运动习惯的个体降低0.23°C）；以及平均皮肤温度的降低（耐力训练个体降低0.67°C；有休闲运动习惯的个体降低0.75°C：PRE到POST，P<0.01）。此外，训练状态对观察到的平均摄氧量、平均代谢能量消耗、运动结束时生理应激指数、主观用力程度或热感觉的降低没有显著影响（PRE到POST，P<0.05）。只有运动结束时的心率受训练状态影响（P<0.01，交互作用）；由此，有休闲运动习惯但未经过耐力训练的个体从PRE到POST运动结束时心率显著降低（P<0.01）。总之，这些发现表明，运动后热水浸泡是一种实用策略，可降低耐力训练个体和有休闲运动习惯的个体在运动热应激期间的热应激。
