Abstract：
In the present experiment, we evaluated the impact of rapid heat stress (RHS) on salivary cortisol and C-reactive protein production pre-RHS, post-RHS, and 24 and 48 h post-RHS exposure among firefighters. Previous research has demonstrated that RHS increases salivary cortisol during RHS and immediately post-RHS exposure. However, no research has evaluated the duration necessary to return to baseline cortisol levels following RHS. Additionally, no studies have analyzed the impact of RHS on inflammatory biomarkers, such as C-reactive protein. This study hypothesized that salivary cortisol and C-reactive protein levels would increase following RHS and then return to pre-RHS levels within 24 h post-exposure. Twenty-four participants performed a steady-state treadmill protocol in an environmental chamber (35 °C; 45% humidity) in full firefighter personal protective equipment until reaching either a core temperature (Tc) of 39 °C or a volitional maximum. The subjects had their saliva collected via the passive drool protocol pre-RHS, post-RHS, and 24 and 48 h post-RHS. Pre-RHS of 0.23 ± 0.03 μg/dL increased post-RHS to 0.51 ± 0.06 μg/dL (p < 0.001). This finding supports previous literature demonstrating the immediate impact of RHS. There were no changes in C-reactive protein. The novel finding of this study is that salivary cortisol levels return to baseline in the 24 h post-RHS exposure. This indicates that 24 h is recommended to recover from RHS and should be applied to prevent the chronic stress response.
摘要：
在本实验中,我们评估了快速热应激（RHS）对唾液皮质醇和C反应蛋白产生的影响，RHS后，消防员在RHS暴露后24小时和48小时。先前的研究表明，RHS在RHS期间和RHS暴露后立即增加唾液皮质醇。然而,没有研究评估RHS后恢复基线皮质醇水平所需的持续时间.此外,没有研究分析RHS对炎症生物标志物的影响，如C反应蛋白。这项研究假设RHS后唾液皮质醇和C反应蛋白水平会增加，然后在暴露后24小时内恢复到RHS前水平。24名参与者在完整的消防员个人防护设备中在环境室（35°C；湿度为45％）中执行稳态跑步机方案，直到达到39°C的核心温度（Tc）或最高自愿温度。受试者通过RHS前的被动口水方案收集唾液，RHS后，以及RHS后24和48小时。前RHS为0.23±0.03μg/dL,后RHS增加至0.51±0.06μg/dL(p<0.001)。这一发现支持了先前的文献，证明了RHS的直接影响。C反应蛋白无变化。这项研究的新发现是唾液皮质醇水平在RHS暴露后24小时恢复到基线。这表明建议从RHS恢复24小时，并应应用于防止慢性应激反应。
