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

doi:10.1097/JOM.0000000000000902

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 journal › Article › peer-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 language	English
Pages (from-to)	1250-1256
Number of pages	7
Journal	Journal of Occupational and Environmental Medicine
Volume	58
Issue number	12
DOIs	https://doi.org/10.1097/JOM.0000000000000902
Publication status	Published - 2016

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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",

year = "2016",

doi = "10.1097/JOM.0000000000000902",

language = "English",

volume = "58",

pages = "1250--1256",

journal = "Journal of Occupational and Environmental Medicine",

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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 journal › Article › peer-review

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T1 - Influence of Chronic Heat Acclimatization on Occupational Thermal Strain in Tropical Field Conditions

AU - Brearley, Matt B.

AU - Norton, Ian

AU - Rush, Daryl

AU - Hutton, Michael

AU - Smith, Steve

AU - Ward, Linda

AU - Fuentes, Hector

PY - 2016

Y1 - 2016

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

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