Department of Kinesiology, The Pennsylvania State University, University Park, Pennsylvania.
College of Public Health, University of South Florida, Tampa, Florida.
J Occup Environ Hyg. 2022 Jul;19(7):415-424. doi: 10.1080/15459624.2022.2076859. Epub 2022 Jun 7.
Little is known about the separate and combined influences of humidity conditions, sex, and aerobic fitness on heat tolerance in unacclimatized males and females. The purpose of the current study was to describe heat tolerance, in terms of critical WBGT (WBGT), in unacclimatized young males and females in hot-dry (HD) and warm-humid (WH) environments. Eighteen subjects (9 M/9F; 21 ± 2 yr) were tested during exercise at 30% V̇O in a controlled environmental chamber. Progressive heat stress exposures were performed with either (1) constant dry-bulb temperature (T) of 34 and 36 °C and increasing ambient water vapor pressure (P) (P trials; WH); or (2) constant P of 12 and 16 mmHg and increasing T (T trials; HD). Chamber T and P, and subject esophageal temperature (T), were continuously monitored throughout each trial. After a 30-min equilibration period, progressive heat stress continued until subject heat balance could no longer be maintained and a clear rise in T was observed. Absolute WBGT and WBGT adjusted to a metabolic rate of 300 W (WBGT), and the difference between WBGT and occupational exposure limits (OEL; ΔOEL) was assessed. WBGT, WBGT, and ΔOEL were higher in WH compared to HD ( < 0.0001) for females but were the same between environments for males ( ≥ 0.21). WBGT was higher in females compared to males in WH ( < 0.0001) but was similar between sexes in HD ( = 0.44). When controlling for metabolic rate, WBGT and ΔOEL were higher in males compared to females in WH and HD (both < 0.0001). When controlling for sex, V̇O was not associated with WBGT or ΔOEL for either sex (r ≤ 0.12, ≥ 0.49). These findings suggest that WBGT is higher in females compared to males in WH, but not HD, conditions. Additionally, the WBGT is lower in females, but not males, in HD compared to WH conditions.
对于未适应的男性和女性，湿度条件、性别和有氧健身对耐热能力的单独和综合影响知之甚少。本研究的目的是描述在热干 (HD) 和暖湿 (WH) 环境中未适应的年轻男性和女性的耐热能力，以临界 WBGT (WBGT) 表示。18 名受试者（9 男/9 女；21 ± 2 岁）在受控环境室中的 30% V̇O 下进行运动时接受测试。通过以下两种方式进行逐步热应激暴露：（1）恒定干球温度 (T) 为 34 和 36°C，环境水蒸气压力 (P) 逐渐升高（P 试验；WH）；或（2）恒定 P 为 12 和 16mmHg，T 逐渐升高（T 试验；HD）。整个试验过程中，连续监测室温和 P 以及受试者食管温度 (T)。在 30 分钟的平衡期后，继续进行逐步热应激，直到受试者无法维持热平衡并观察到 T 明显升高。评估绝对 WBGT 和代谢率为 300W 时的 WBGT（WBGT），以及 WBGT 与职业暴露限值 (OEL) 之间的差异（ΔOEL）。女性在 WH 下的 WBGT、WBGT 和 ΔOEL 均高于 HD（<0.0001），但男性在两种环境下的 WBGT 相同（≥0.21）。女性在 WH 下的 WBGT 高于男性（<0.0001），但在 HD 下男女之间相似（=0.44）。当控制代谢率时，WH 和 HD 下男性的 WBGT 和 ΔOEL 均高于女性（均<0.0001）。当控制性别时，V̇O 与任何性别的 WBGT 或 ΔOEL 均无关（r≤0.12，≥0.49）。这些发现表明，在 WH 条件下，女性的 WBGT 高于男性，但在 HD 条件下并非如此。此外，与 WH 条件相比，HD 条件下女性的 WBGT 较低，而男性的 WBGT 则较高。
