U.S. Army Research Institute of Environmental Medicine, Natick, MA.
Med Sci Sports Exerc. 2021 May 1;53(5):1050-1055. doi: 10.1249/MSS.0000000000002545.
This study aimed to characterize HTT specificity and to determine any effect of HA on the outcome.
Thirteen unacclimatized, healthy men (V˙O2peak, 43.0 ± 4.8 mL·kg-1⋅min-1) with no previous history of heat illness completed 8 d of HA using the HTT protocol (40°C/40% RH; 120 min; 5 km·h-1 and 2% grade). Heart rate (HR) and core temperature (Tcore) recorded every 5 min during exercise and at the end of 120 min (terminal value) were compared between days 1 and 8. Test specificity (given no previous history of heat illness, the probability of being heat tolerant) was calculated on days 1 and 8.
There was a significant reduction in HR and Tcore between days 1 and 8, indicating successful HA. All volunteers successfully completed 120 min of walking on all days. HTT specificity ranged between 54% and 85% on day 1 and between 77% and 92% on day 8, depending on the HTT criteria used.
Young healthy men without any previous heat illness experienced a 15% to 46% false-positive fail rate for the HTT without HA. After HA, the false-positive fail rate decreased to between 8% and 13%. Outcomes of the HTT are significantly affected by the criteria used and by HA status. The use of HTT for RTA decisions should be done with the recognition of these effects.
本研究旨在描述 HTT 的特异性，并确定 HA 对结果的任何影响。
13 名未经适应训练的健康男性（峰值摄氧量，43.0 ± 4.8 mL·kg-1·min-1），无热病史，采用 HTT 方案（40°C/40% RH；120 min；5 km·h-1 和 2%坡度）完成 8 天的 HA。运动期间和 120 min 结束时（终值）每 5 min 记录心率（HR）和核心温度（Tcore），并比较第 1 天和第 8 天的结果。根据第 1 天和第 8 天的无热病史，计算测试特异性（即耐热的可能性）。
第 1 天和第 8 天 HR 和 Tcore 均显著降低，表明 HA 成功。所有志愿者在所有天均成功完成 120 min 的步行。HTT 特异性在第 1 天为 54%至 85%，在第 8 天为 77%至 92%，具体取决于 HTT 标准。
没有任何先前热病史的年轻健康男性在没有 HA 的情况下，HTT 的假阳性失败率为 15%至 46%。HA 后，假阳性失败率降至 8%至 13%之间。HTT 的结果受到所使用的标准和 HA 状态的显著影响。在做出 RTA 决策时使用 HTT，应认识到这些影响。
