Age-related differences in heat loss capacity occur under both dry and humid heat stress conditions

Par Conseil national de recherches du Canada

DOI	Trouver le DOI : https://doi.org/10.1152/japplphysiol.00123.2014
Auteur	Rechercher : Larose, Joanie; Rechercher : Boulay, Pierre; Rechercher : Wright-Beatty, Heather E.; Rechercher : Sigal, Ronald J.; Rechercher : Hardcastle, Stephen; Rechercher : Kenny, Glen P.
Format	Texte, Article
Sujet	aging; calorimetry; exercise; humidity; heat loss
Résumé	This study examined the progression of impairments in heat dissipation as a function of age and environmental conditions. Sixty men (n = 12 per group; 20–30, 40–44, 45–49, 50–54, and 55–70 yr) performed four intermittent exercise/recovery cycles for a duration of 2 h in dry (35°C, 20% relative humidity) and humid (35°C, 60% relative humidity) conditions. Evaporative heat loss and metabolic heat production were measured by direct and indirect calorimetry, respectively. Body heat storage was measured as the temporal summation of heat production and heat loss during the sessions. Evaporative heat loss was reduced during exercise in the humid vs. dry condition in age groups 20–30 (−17%), 40–44 (−18%), 45–49 (−21%), 50–54 (−25%), and 55–70 yr (−20%). HE fell short of being significantly different between groups in the dry condition, but was greater in age group 20–30 yr (279 ± 10 W) compared with age groups 45–49 (248 ± 8 W), 50–54 (242 ± 6 W), and 55–70 yr (240 ± 7 W) in the humid condition. As a result of a reduced rate of heat dissipation predominantly during exercise, age groups 40–70 yr stored between 60–85 and 13–38% more heat than age group 20–30 yr in the dry and humid conditions, respectively. These age-related differences in heat dissipation and heat storage were not paralleled by significant differences in local sweating and skin blood flow, or by differences in core temperature between groups. From a whole body perspective, combined heat and humidity impeded heat dissipation to a similar extent across age groups, but, more importantly, intermittent exercise in dry and humid heat stress conditions created a greater thermoregulatory challenge for middle-aged and older adults.
Date de publication	2014-07-01
Maison d’édition	American Physical Society
Dans	Journal of Applied Physiology 117, nº 1 : 69–79.
Langue	anglais
Publications évaluées par des pairs	Oui
Publication du CNRC	Cette publication n’est pas du CNRC Ce sont des publications qui ont été rédigées par un auteur du CNRC, mais avant que celui-ci soit employé du CNRC.
Numéro NPARC	23001148
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Identificateur de l’enregistrement	58894cc9-22af-4eb1-951c-d88cb2116bbb
Enregistrement créé	2016-12-15
Enregistrement modifié	2020-04-22

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Date de modification :: 2023-12-01