Moderate-intensity intermittent work in the heat results in similar low-level dehydration in young and older males

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DOIResolve DOI: http://doi.org/10.1080/15459624.2013.817676
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TypeArticle
Journal titleJournal of Occupational and Environmental Hygiene
ISSN1545-9624
1545-9632
Volume11
Issue3
Pages144153
Subjectheat stress; aging; core temperature; dry and humid environments
AbstractOlder individuals may be more susceptible to the negative thermal and cardiovascular consequences of dehydration during intermittent work in the heat. This study examined the hydration, thermal, and cardiovascular responses to intermittent exercise in the heat in 14 Young (Y, Mean ± SE; 25.8 ± 0.8 years), Middle-age (MA, 43.6 ± 0.9 years), and Older (O, 57.2 ± 1.5 years) healthy, non-heat acclimated males matched for height, mass, body surface area, and percent body fat. Rectal temperature (Tre), heart rate (HR), local sweat rate (LSR), and hydration indices were measured during 4 × 15-min moderate to heavy cycling bouts at 400 W heat production, each followed by a 15-min rest period, in Warm/Dry (35°C, 20% relative humidity [RH]) and Warm/Humid (35°C, 60% RH) heat. No differences were observed between the age groups for Tre, Tre change, HR, LSR, mass change, urine specific gravity, and plasma protein concentration in either condition, irrespective of the greater level of thermal and cardiovascular strain experienced in the Warm/Humid environment. Plasma volume changes (Dry Y: −5.4 ± 0.7, MA: −6.2 ± 0.9, O: −5.7 ± 0.9%, Humid Y: −7.3 ± 1.0, MA: −7.9 ± 0.8, O: −8.4 ± 1.0%) were similar between groups, as were urine specific gravity and plasma protein concentrations. Thus, physically active Young, Middle-age, and Older males demonstrate similar hydration, thermal, and cardiovascular responses during moderate- to high-intensity intermittent exercise in the heat.
Publication date
PublisherTaylor and Francis
LanguageEnglish
Peer reviewedYes
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NPARC number23001215
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Record identifier42bdea39-c3d5-468a-998e-ebe479b3fb94
Record created2017-01-05
Record modified2017-01-05
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