Do older firefighters show long-term adaptations to work in the heat?

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Journal titleJournal of Occupational and Environmental Hygiene
Subjectcore temperature; physiological strain; perceptual strain; dry and humid heat; repeated heat stress
AbstractOlder experienced firefighters may show signs of heat adaptation, and thus reduced physiological strain, due to repeated occupational heat stress exposure. The aim was to examine physiological and perceptual strain, and hydration, responses to intermittent exercise in the heat in 12 older Non-Firefighter (Non-FF) and experienced Firefighter (FF) males, pair matched for age (Group mean ± SE: Non-FF = 51.7 ± 1.5, FF = 49.8 ± 1.1 years), VO(2peak) (Non-FF = 39.4 ± 2.2, FF = 40.7 ± 1.8 mL·kg(-1)·min(-1)), body surface area (Non-FF = 1.94 ± 0.04, FF = 2.03 ± 0.03 m(2)), and percent body fat (Non-FF = 24.4 ± 2.3, FF = 19.3 ± 1.8%). Rectal (Tre) and mean skin (MT(sk)) temperatures, heart rate (HR), local sweat rate (LSR), hydration indices, and ratings of thermal sensation and perceived exertion were measured during 4 ×15-min (rest 15-min) moderate-to-heavy cycling bouts (400 W heat production) in Dry and Humid heat (35°C, ∼20 and ∼60% relative humidity, respectively). No differences were observed between the Non-FF and FF for T(re), T(re) change, MT(sk), HR,% max HR, LSR, physiological strain index (PhSI), or % plasma volume change. Plasma protein concentration was reduced at baseline for the Non-FF (7.6 ± 0.1 g·100 mL(-1)) than FF (8.0 ± 0.1 g·100 mL(-1)). The Perceptual Strain Index overestimated PhSI for Non-FF and FF in both thermal conditions. At the end of exercise, the Non-FF showed a greater Tre difference between thermal conditions (0.27 ± 0.05°C) compared to the FF (0.10 ± 0.09°C). Although the Non-Firefighters and Firefighters demonstrate similar cardiovascular and hydration responses during moderate-to-heavy intensity exercise within each of the thermal conditions, the attenuated thermal effects between the two heat stress conditions in the Firefighters suggests a protective adaptation.
Publication date
PublisherTaylor and Francis
Peer reviewedYes
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This is a non-NRC publication

"Non-NRC publications" are publications authored by NRC employees prior to their employment by NRC.

NPARC number23001209
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Record identifierafbf2017-dbb6-4d53-83e8-f4bf90133860
Record created2017-01-05
Record modified2017-01-05
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