Borg David N, Stewart Ian B, Costello Joseph T
Institute of Health and Biomedical Innovation, School of Exercise and Nutrition Sciences, Queensland University of Technology, Brisbane 4059, Queensland, Australia.
Institute of Health and Biomedical Innovation, School of Exercise and Nutrition Sciences, Queensland University of Technology, Brisbane 4059, Queensland, Australia.
Physiol Behav. 2015 Aug 1;147:71-7. doi: 10.1016/j.physbeh.2015.04.018. Epub 2015 Apr 10.
Explosive ordnance disposal (EOD) often requires technicians to wear multiple protective garments in challenging environmental conditions. The accumulative effect of increased metabolic cost coupled with decreased heat dissipation associated with these garments predisposes technicians to high levels of physiological strain. It has been proposed that a perceptual strain index (PeSI) using subjective ratings of thermal sensation and perceived exertion as surrogate measures of core body temperature and heart rate, may provide an accurate estimation of physiological strain. Therefore, this study aimed to determine if the PeSI could estimate the physiological strain index (PSI) across a range of metabolic workloads and environments while wearing heavy EOD and chemical protective clothing.
Eleven healthy males wore an EOD and chemical protective ensemble while walking on a treadmill at 2.5, 4 and 5.5km·h(-1) at 1% grade in environmental conditions equivalent to wet bulb globe temperature (WBGT) 21, 30 and 37°C. WBGT conditions were randomly presented and a maximum of three randomised treadmill walking trials were completed in a single testing day. Trials were ceased at a maximum of 60-min or until the attainment of termination criteria. A Pearson's correlation coefficient, mixed linear model, absolute agreement and receiver operating characteristic (ROC) curves were used to determine the relationship between the PeSI and PSI.
A significant moderate relationship between the PeSI and the PSI was observed [r=0.77; p<0.001; mean difference=0.8±1.1a.u. (modified 95% limits of agreement -1.3 to 3.0)]. The ROC curves indicated that the PeSI had a good predictive power when used with two, single-threshold cut-offs to differentiate between low and high levels of physiological strain (area under curve: PSI three cut-off=0.936 and seven cut-off=0.841).
These findings support the use of the PeSI for monitoring physiological strain while wearing EOD and chemical protective clothing. However, future research is needed to confirm the validity of the PeSI for active EOD technicians operating in the field.
爆炸物处理（EOD）工作通常要求技术人员在具有挑战性的环境条件下穿着多层防护服。这些防护服会增加代谢成本，并减少散热，其累积效应使技术人员易承受高水平的生理压力。有人提出，使用热感觉主观评分和感知运动用力作为核心体温和心率替代指标的感知压力指数（PeSI），可能会准确估计生理压力。因此，本研究旨在确定在穿着重型爆炸物处理和化学防护服的情况下，PeSI能否在一系列代谢工作负荷和环境中估计生理压力指数（PSI）。
11名健康男性在相当于湿球黑球温度（WBGT）为21、30和37°C的环境条件下，以1%的坡度在跑步机上以2.5、4和5.5km·h⁻¹的速度行走时，穿着爆炸物处理和化学防护服。WBGT条件随机呈现，在单个测试日最多完成三次随机跑步机行走试验。试验最多持续60分钟或直至达到终止标准。使用Pearson相关系数、混合线性模型、绝对一致性和受试者工作特征（ROC）曲线来确定PeSI与PSI之间的关系。
观察到PeSI与PSI之间存在显著的中度关系[r = 0.77；p < 0.001；平均差异 = 0.8 ± 1.1任意单位（修正的95%一致性界限为 -1.3至3.0）]。ROC曲线表明，当使用两个单阈值临界值来区分低水平和高水平生理压力时，PeSI具有良好的预测能力（曲线下面积：PSI三个临界值 = 0.936，七个临界值 = 0.841）。
这些发现支持在穿着爆炸物处理和化学防护服时使用PeSI来监测生理压力。然而，未来需要进行研究以确认PeSI对在现场工作的现役爆炸物处理技术人员的有效性。
