Brown Harry A, Topham Thomas H, Clark Brad, Woodward Andrew P, Ioannou Leonidas G, Flouris Andreas D, Telford Richard D, Smallcombe James W, Jay Ollie, Périard Julien D
Research Institute for Sport and Exercise Science (UCRISE), University of Canberra, Bruce, ACT, Australia.
Faculty of Health, University of Canberra, Bruce, ACT, Australia.
Temperature (Austin). 2024 May 5;11(3):254-265. doi: 10.1080/23328940.2024.2347161. eCollection 2024.
This study aimed to investigate seasonal heat acclimatization in active adolescents following summer. Fifteen (5 females) active adolescents (14.6 ± 1.0 y) completed a 45-min heat response test (HRT) walking at 60% O in 40°C and 30% relative humidity before and after summer (i.e. November 2022 and March 2023). During the HRT, gastro-intestinal temperature (T), skin temperature (T), heart rate, local sweat rate (LSR) and whole-body sweat loss (WBSL) were recorded. Carbon monoxide rebreathing and dual-energy X-ray absorptiometry scans determined resting hematological measures and body composition. Participants completed physical activity (PA) diaries and wore an accelerometer for two one-week periods (pre- and post-summer). Daytime wet-bulb globe temperature (WBGT) was calculated for each summer day. Data are presented as posterior mean and 90% credible intervals. Participants reported 7 ± 4 h·wk of outdoor PA, and daytime WBGT was 21.2 ± 4.6°C. Following summer, resting T and heart rate were reduced by 0.2°C [-0.3, -0.1; probability of direction = 99%] and 7 beats·min [-10, -3; 100%], respectively. During the HRT, there was an earlier onset of sweating (-0.2°C [-0.3, -0.0; 98%]), an attenuated rise of T (0.2°C [-0.5, 0.0; 92%]) and mean T changed by -0.2°C [-0.5, 0.1; 86%]. There was minimal evidence for heat adaptations in LSR or WBSL, hematological parameters or perceptual measures. This is the first study to demonstrate seasonal heat adaptations in active adolescents. Reductions in resting T and exercising T and a lower T at the onset of sweating were associated with a smaller rise in T during the HRT following summer.
本研究旨在调查活跃青少年在夏季过后的季节性热适应情况。15名（5名女性）活跃青少年（14.6±1.0岁）在夏季前后（即2022年11月和2023年3月），于40°C、相对湿度30%的环境中，以60%的摄氧量步行完成了一项45分钟的热反应测试（HRT）。在HRT期间，记录了胃肠道温度（T）、皮肤温度（T）、心率、局部出汗率（LSR）和全身出汗量（WBSL）。通过一氧化碳再呼吸和双能X线吸收法扫描测定静息血液学指标和身体成分。参与者完成了身体活动（PA）日记，并在两个为期一周的时间段（夏季前后）佩戴了加速度计。计算了每个夏季白天的湿球黑球温度（WBGT）。数据以均值后验和90%可信区间表示。参与者报告每周有7±4小时的户外PA，白天WBGT为21.2±4.6°C。夏季过后，静息T和心率分别降低了0.2°C[-0.3，-0.1；方向概率=99%]和7次/分钟[-10，-3；100%]。在HRT期间，出汗开始时间提前了（-0.2°C[-0.3，-0.0；98%]），T的上升减弱（0.2°C[-0.5，0.0；92%]），平均T变化了-0.2°C[-0.5，0.1；86%]。几乎没有证据表明LSR或WBSL、血液学参数或感知指标存在热适应。这是第一项证明活跃青少年存在季节性热适应的研究。静息T和运动T的降低以及出汗开始时较低的T与夏季后HRT期间T的较小上升有关。
