Abstract：
We investigated the utility of heart rate (HR) and heart rate variability (HRV) for identifying individuals who may terminate work early due to excessive heat strain. Forty-eight men and women (median = 36 years; Q1 = 20 years; Q3 = 54 years) attempted 180 min of moderate-intensity work at a fixed metabolic rate (∼200 W/m2; ∼3.5 METs) in a hot environment (wet-bulb globe temperature: 32 °C). Receiver operating characteristics (ROC) curves were used to identify the ability of indices of HR (absolute HR, percentage of maximum HR, percentage of HR reserve) and HRV (root-mean-square of successive differences (RMSSD), high-frequency power, and detrended fluctuation analysis component alpha 1 (DFA α1)) to discriminate between participants who completed the 180 min work bout or terminated prematurely. Participants who terminated work prematurely (n = 26) exhibited higher HR and percentage of HR measures, as well as reduced RMSSD and DFA α1 after the first hour of work compared to participants who completed the bout. The discriminative utility of HR and HRV indices was strongest within the first hour of work, with percentage of HR reserve demonstrating excellent discriminative power (ROC area under curve (AUC) of 0.8). Stratifying participants by age and sex improved ROC AUC point estimates for most indices, particularly in female participants. The study provides preliminary evidence supporting the use of noninvasive cardiac monitoring for predicting work tolerance in healthy individuals exposed to occupational heat stress. HR and percentage of HR reserve were suggested to discriminate work termination most effectively. Further investigations are warranted to explore the influence of individual factors and refine the discriminative thresholds for early identification of excessive occupational heat strain.
摘要：
我们调查了心率（HR）和心率变异性（HRV）在识别可能由于过度的热应变而提前终止工作的个体中的实用性。48名男女（中位数=36岁；Q1=20岁；Q3=54岁）在高温环境（湿球温度[WBGT]：32°C）下以固定的代谢率（〜200W/m2；〜3.5MET）尝试进行180分钟的中等强度工作。受试者工作特征(ROC)曲线用于鉴定HR(绝对HR,最大HR的百分比，HR储备百分比)和HRV(RMSSD，高频(HF)电源,和DFAα1）来预测参与者是否完成了180分钟的工作回合或过早终止。过早终止工作的参与者(n=26)，表现出更高的HR和HR指标百分比，以及与完成回合的参与者相比，工作的第一个小时后RMSSD和DFAα1降低。在工作的第一个小时内，HR和HRV指数的判别效用最强，HR储备百分比显示出优异的判别力(ROC曲线下面积(AUC)为0.8)。按年龄和性别对参与者进行分层改善了大多数指标的ROCAUC点估计，尤其是女性参与者。该研究提供了初步证据，支持使用无创心脏监测来预测暴露于职业性热应激的健康个体的工作耐受性。观察到HR和HR储备百分比可以最有效地预测工作终止。有必要进行进一步的调查，以探索各个因素的影响，并完善区分阈值，以早期识别过度的职业热应变。
