Human Physiology Research Group, Vrije Universiteit Brussel, Brussel, Belgium; Endurance Research Group, School of Sport and Exercise Sciences, University of Kent, Canterbury, United Kingdom.
Human Physiology Research Group, Vrije Universiteit Brussel, Brussel, Belgium.
Physiol Behav. 2019 Apr 1;202:36-44. doi: 10.1016/j.physbeh.2019.01.011. Epub 2019 Jan 15.
The aim of this study was to test the hypothesis that subjective thermal strain can reduce endurance performance independently from the general physiological strain normally associated with impaired endurance performance in the heat.
In 20 °C and 44% relative humidity, 12 endurance-trained athletes (1♀ 11♂; mean ± SD; age: 27 ± 6 y; VO: 61 ± 6 ml/kg/min) performed a time to exhaustion (TTE) test in two different experimental conditions: with an electric heat pad applied to the subjects' upper back (HP) and control (CON: without heat pad). In both conditions, subjects cycled to volitional exhaustion at 70% of their VO. Cardiorespiratory, metabolic, thermoregulatory and perceptual responses were measured throughout the TTE test and compared at 0%, 50% and 100% isotime and at exhaustion.
TTE was reduced by 9% in HP (2092 ± 305 s) compared to CON (2292 ± 344 s; p = .023). The main effect of condition on thermal discomfort at isotime (p = .002), the effect of condition on thermal sensation at 0% isotime (p = .004) and the condition by isotime interaction on rating of perceived exertion (p = .036) indicated higher subjective thermal strain in HP compared to CON. None of the measured cardiorespiratory, metabolic and thermoregulatory variables differed significantly between conditions.
Our novel experimental manipulation (HP) was able to induce significant subjective thermal strain and reduce endurance performance in a temperate environment without inducing the general physiological strain normally associated with impaired endurance performance in the heat. These results suggest that subjective thermal strain is an important and independent mediator of the heat-induced impairment in endurance performance.
本研究旨在验证一个假设，即主观热应激可以独立于通常与热环境中耐力表现受损相关的一般生理应激，降低耐力表现。
在 20°C 和 44%相对湿度下，12 名耐力训练有素的运动员（1 名女性，11 名男性；平均±标准差；年龄：27±6 岁；VO₂：61±6 ml/kg/min）在两种不同的实验条件下进行了力竭时间（TTE）测试：一种是在上背部应用电加热垫（HP），另一种是对照（CON：无加热垫）。在两种条件下，受试者以 70%的 VO₂ 意愿性地进行自行车骑行直至力竭。在 TTE 测试过程中测量了心肺功能、代谢、体温调节和感知反应，并在 0%、50%和 100%等时和力竭时进行比较。
与 CON（2292±344 s）相比，HP 下的 TTE 减少了 9%（2092±305 s；p=0.023）。条件对等时热不适的主要影响（p=0.002）、条件对 0%等时热感觉的影响（p=0.004）以及条件与等时交互作用对感知用力的影响（p=0.036）表明，与 CON 相比，HP 下的主观热应激更高。两种条件下的心肺功能、代谢和体温调节变量均无显著差异。
我们的新型实验操作（HP）能够在温和环境中引起明显的主观热应激，降低耐力表现，而不会引起通常与热环境中耐力表现受损相关的一般生理应激。这些结果表明，主观热应激是热诱导耐力表现受损的一个重要且独立的介导因素。
