Influence of Chronic Heat Acclimatization on Occupational Thermal Strain in Tropical Field Conditions

Matt B. Brearley, Ian Norton, Daryl Rush, Michael Hutton, Steve Smith, Linda Ward, Hector Fuentes

    Research output: Contribution to journalArticle


    Objective: To examine whether non-heat acclimatized (NHA) emergency responders endure greater physiological and perceptual strain than heat acclimatized (HA) counterparts in tropical field settings. 

    Methods: Eight HA and eight NHA men urban search and rescue personnel had physiological and perceptual responses compared during the initial 4 hours shift of a simulated disaster in tropical conditions (ambient temperature 34.0 8C, 48% relative humidity, wet bulb globe temperature [WBGT] 31.4 8C). 

    Results: From the 90th minute through to end of shift, HA (38.5 8C) sustained a significantly higher gastrointestinal temperature than NHA (38.1 8C) (mean difference 0.4±0.2 8C, 95%confidence interval [CI] 0.2 to 0.7 8C, P=0.005) despite comparable heart rate (P=0.30), respiratory rate (P=0.88), and axilla skin temperature (P=0.47). Overall, perception of body temperature was similar between cohorts (P=0.87). 

    Conclusions: The apparent tolerance of greater physiological strain by HA responders occurred in the absence of perceptual differences.

    Original languageEnglish
    Pages (from-to)1250-1256
    Number of pages7
    JournalJournal of Occupational and Environmental Medicine
    Issue number12
    Publication statusPublished - 2016


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