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Relationships between wet bulb globe temperature and evaporative cooling responses under heat stress.

机译：热应力下湿球温度与蒸发冷却响应之间的关系。

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摘要

The aim of the present study was to compare the evaporative losses response in a sample of thirty unacclimatized subjects (sixteen males and fourteen females), ages 19 to 44. Most of the participants considered themselves physically active, while six of them perceived themselves as sedentary. Participants performed three, ten-minute exercise trials of moderate, intermittent exercise on a wooden step in an environmentally controlled chamber at an average temperature of 84.31 +/- 1.8 °F, 42 +/- 10% of relative humidity, and 73.46 +/- 1.5 °F of wet bulb globe temperature (WBGT). Repeated measurements of transepidermal water loss (TEWL) were performed on the subjects' forearm prior to and post exercise. The routine procedures of this study included: a brief interview with the subject which included the reading and signing of the consent form, a baseline TEWL measurement in the neutral environment, a second TEWL measurement inside the controlled room environment prior to exercise, and a third TEWL measurement inside the controlled room environment post exercise. Each subject performed three consecutive exercise trials, meaning that pre- and post- exercise TEWL measurements were taken a second and third time as well.;TEWL readings differed significantly between subjects and showed significant trial-to-trial variation. Total TEWL levels prior to exercise (overall mean for the 3 exercise trials = 26.73 g/m2h) were significantly higher than total TEWL levels post exercise (overall mean for the 3 exercise trials =11.67 g/m2h) under thermal stressed conditions inside the environmentally controlled chamber. It was not until the last of three ten-minute time frames that the post exercise TEWL level (27.09 g/m 2h) varied, indicating that lesser cooling actually took place via evaporation over time. In comparison, post exercise TEWL levels for the first and second exercise trial time frames measured 16.08 g/m2h and 28.56 g/m 2h respectively.;There was evidence that there is a gender difference in TEWL levels for unacclimatized participants when exercising under heat stress controlled conditions. At similar heat stress levels, men experienced a greater evaporative cooling response evidenced by greater TEWL levels (overall mean for the 3 exercise trials = 46.33 g/m2h without baseline = 52.83 g/m2h), compared to women (overall mean for the 3 exercise trials = 17.43 g/m2h without baseline = 19.20 g/m2h). However, there was not enough evidence to conclude that there were any significant differences in TEWL levels when observing age and activity levels for unacclimatized participants.;The VapoMeter(TM) (Delfin Technologies Ltd, Kuopio, Finland) measured TEWL with consistency during the exercise trials and yielded values similar to those previously reported in the literature. It was easy to use and yielded information that appeared consistent with less user-friendly devices and invasive techniques. Therefore, the potential of TEWL measurements to be used as an additional and practical tool for routine monitoring may be helpful as part of an established heat stress prevention program in sports and occupational settings. However, for use in clinical studies, the significant variations across subjects would make changes induced by predisposing conditions difficult to reliably detect.;Evaporative losses were affected by the exercise intensity, heat acclimation, and individual characteristics of the participants. Sweat rate varied greatly between participants across the exercise trials. Even though sweat rate depends upon a variety of factors including wind speed, ambient, temperature, and relative humidity, there was not a clear relationship between the environmental conditions and TEWL, which strongly indicates that subjects' evaporative cooling responses depended on possible interference factors stemming from inter-individual variability. These findings along with other studies raise the question as to whether or not it is appropriate to rely solely on the use of the WBGT thermal risk marker for the prevention of the occurrence of heat-related illness under different combinations of temperature and relative humidity.
机译：本研究的目的是比较19位至44岁的30位未经适应训练的受试者（16位男性和14位女性）的蒸发损失反应。大多数参与者认为自己身体活动，而其中6位认为自己久坐。参与者在环境控制室内平均温度84.31 +/- 1.8°F，相对湿度42 +/- 10％和73.46 + /的环境控制室内的木台阶上进行了三分钟，十分钟的运动试验，进行了中度间歇运动。 -湿灯泡温度（WBGT）为1.5°F。运动前和运动后对受试者的前臂进行反复的表皮水分流失（TEWL）测量。这项研究的常规程序包括：对受试者的简短访谈，包括阅读并签署同意书，在中性环境中进行基线TEWL测量，在运动前在受控房间环境中进行第二次TEWL测量以及第三次运动后在受控房间环境内进行TEWL测量。每个受试者进行了三个连续的运动试验，这意味着运动前后的TEWL测量也分别进行了第二次和第三次；受试者之间的TEWL读数显着不同，并且显示出不同试验之间的显着差异。在环境内部处于热应激条件下，运动前的总TEWL水平（3个运动试验的总平均值= 26.73 g / m2h）显着高于运动后的总TEWL水平（3个运动试验的总平均值= 11.67 g / m2h）。控制室。直到三个十分钟的时间框架中的最后一个，运动后的TEWL水平（27.09 g / m 2h）才发生变化，这表明随着时间的流逝实际上发生的冷却较少。相比之下，第一次和第二次运动试验时间段的运动后TEWL水平分别为16.08 g / m2h和28.56 g / m 2h .;有证据表明，在热应激条件下锻炼的未适应参与者的TEWL水平存在性别差异控制条件。在类似的热应激水平下，男性经历了更大的蒸发降温反应，表现为更高的TEWL水平（3个运动试验的总平均值= 46.33 g / m2h，无基线= 52.83 g / m2h），而女性（3个运动的总体平均值）试验= 17.43 g / m2h，无基线= 19.20 g / m2h）。但是，没有足够的证据得出结论，当观察未适应训练的参与者的年龄和活动水平时，TEWL水平存在显着差异。； VapoMeter（TM）（Delfin Technologies Ltd，Kuopio，芬兰）在锻炼过程中对TEWL进行了一致性测量试验和得出的值与文献先前报道的相似。它易于使用，并且产生的信息看上去与用户友好程度较低的设备和侵入性技术一致。因此，将TEWL测量作为常规监测的附加实用工具的潜力，可以作为在体育和职业环境中建立的预防热应激计划的一部分而有所帮助。但是，在临床研究中使用时，受试者之间的显着差异将使由易患条件引起的变化难以可靠地检测到。蒸发损失受锻炼强度，热适应和参与者的个体特征的影响。在整个运动试验中，参与者之间的出汗率差异很大。即使出汗率取决于风速，环境，温度和相对湿度等多种因素，环境条件与TEWL之间也没有明确的关系，这强烈表明受试者的蒸发冷却反应取决于可能产生的干扰因素。来自个体间的变异性。这些发现以及其他研究提出了一个问题，即在温度和相对湿度的不同组合下，仅依靠使用WBGT热风险标记物来预防与热相关的疾病的发生是否合适。

著录项

  • 作者

    Rodriguez, Monica.;

  • 作者单位

    Purdue University.;

  • 授予单位 Purdue University.;
  • 学科 Environmental Health.;Health Sciences Public Health.
  • 学位 Ph.D.
  • 年度 2010
  • 页码 196 p.
  • 总页数 196
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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