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 journalArticleResearchpeer-review

    Abstract

    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
    Volume58
    Issue number12
    DOIs
    Publication statusPublished - 2016

    Fingerprint

    Acclimatization
    Hot Temperature
    Temperature
    Emergency Responders
    Axilla
    Skin Temperature
    Disasters
    Respiratory Rate
    Humidity
    Body Temperature
    Heart Rate
    Confidence Intervals

    Cite this

    Brearley, Matt B. ; Norton, Ian ; Rush, Daryl ; Hutton, Michael ; Smith, Steve ; Ward, Linda ; Fuentes, Hector. / Influence of Chronic Heat Acclimatization on Occupational Thermal Strain in Tropical Field Conditions. In: Journal of Occupational and Environmental Medicine. 2016 ; Vol. 58, No. 12. pp. 1250-1256.
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    title = "Influence of Chronic Heat Acclimatization on Occupational Thermal Strain in Tropical Field Conditions",
    abstract = "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.",
    author = "Brearley, {Matt B.} and Ian Norton and Daryl Rush and Michael Hutton and Steve Smith and Linda Ward and Hector Fuentes",
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    Influence of Chronic Heat Acclimatization on Occupational Thermal Strain in Tropical Field Conditions. / Brearley, Matt B.; Norton, Ian; Rush, Daryl; Hutton, Michael; Smith, Steve; Ward, Linda; Fuentes, Hector.

    In: Journal of Occupational and Environmental Medicine, Vol. 58, No. 12, 2016, p. 1250-1256.

    Research output: Contribution to journalArticleResearchpeer-review

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    AU - Brearley, Matt B.

    AU - Norton, Ian

    AU - Rush, Daryl

    AU - Hutton, Michael

    AU - Smith, Steve

    AU - Ward, Linda

    AU - Fuentes, Hector

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    N2 - 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.

    AB - 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.

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