O'Connor Fergus K, Richards Brodie J, Ioannou Leonidas G, Kenny Glen P
Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada.
Department of Automatics, Biocybernetics and Robotics, Jožef Stefan Institute, Ljubljana, Slovenia.
J Therm Biol. 2025 Feb;128:104077. doi: 10.1016/j.jtherbio.2025.104077. Epub 2025 Feb 18.
Cold fluid ingestion is recommended during work to maintain hydration status and physiological function. While monitoring the physiological strain index (PSI) during work in the heat is recommended, it is logistically challenging. Subjective estimates, i.e., perceptual strain index (PeSI), are thought to reflect PSI. However, it remains unclear if cold fluid influences an individual's perception of heat strain.
Twenty young adults (10 females) performed four 15-min bouts of moderate-intensity (200 W/m) cycling in the heat (40°C, 13% RH), each separated by 15-min rest. On separate days, participants consumed 2 boluses consisting of 5.2 g/kg of cold (0°C) or warm fluid (37.5°C) before the first and third work bout. Rectal temperature (Tc) and heart rate (HR) were recorded to calculate PSI (0-10 scale). Rating of perceived exertion (RPE) and thermal sensation (TS) were recorded to calculate PeSI (0-10 scale). Tc, HR, TS, and RPE were compared between experimental trials and across work bouts via two-way ANOVAs. Relation between PSI, PeSI and fluid temperature were evaluated via linear mixed models. Mean bias (95% limits of agreement [LoA]) between PSI and PeSI was assessed via Bland-Altman analysis.
Tc, HR, TS and RPE were not influenced by fluid temperature (P ≥ 0.09), nor was the relation between PeSI and PSI (P = 0.11). Mean bias [95% LoA] between PSI and PeSI was greater in cold (-2.1 [-5.7 - 1.5]) compared to the warm fluid condition (-1.8 [-4.8 - 1.2], P = 0.008).
While the relation between PeSI and PSI was not influenced by beverage temperature the agreement between measures was worsened following cold fluid ingestion.
建议在工作期间摄入冷流体以维持水合状态和生理功能。虽然建议在高温环境下工作时监测生理应激指数（PSI），但在实际操作中存在挑战。主观估计，即感知应激指数（PeSI），被认为可以反映PSI。然而，冷流体是否会影响个体对热应激的感知仍不清楚。
20名年轻成年人（10名女性）在高温环境（40°C，13%相对湿度）下进行了4次15分钟的中等强度（200W/m）骑行，每次骑行之间休息15分钟。在不同的日子里，参与者在第一次和第三次工作回合前分别饮用2大剂量由5.2g/kg冷（0°C）或温流体（37.5°C）组成的饮品。记录直肠温度（Tc）和心率（HR）以计算PSI（0-10分）。记录主观用力程度（RPE）和热感觉（TS）以计算PeSI（0-10分）。通过双向方差分析比较实验试验之间以及各工作回合之间的Tc、HR、TS和RPE。通过线性混合模型评估PSI、PeSI与流体温度之间的关系。通过Bland-Altman分析评估PSI和PeSI之间的平均偏差（95%一致性界限[LoA]）。
Tc、HR、TS和RPE不受流体温度影响（P≥0.09），PeSI与PSI之间的关系也不受影响（P=0.11）。与温流体条件（-1.8[-4.8-1.2]，P=0.008）相比，冷流体条件下PSI和PeSI之间的平均偏差[95%LoA]更大（-2.1[-5.7-1.5]）。
虽然PeSI与PSI之间的关系不受饮料温度影响，但摄入冷流体后测量值之间的一致性变差。
