Whole body heat loss is reduced in older males during short bouts of intermittent exercise

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DOI	Resolve DOI: https://doi.org/10.1152/ajpregu.00157.2013
Author	Search for: Larose, Joanie; Search for: Wright, Heather E.; Search for: Stapleton, Jill; Search for: Sigal, Ronald J.; Search for: Boulay, Pierre; Search for: Hardcastle, Stephen; Search for: Kenny, Glen P.
Format	Text, Article
Subject	aging; calorimetry; evaporative heat loss; thermal transients
Abstract	Studies in young adults show that a greater proportion of heat is gained shortly following the start of exercise and that temporal changes in whole body heat loss during intermittent exercise have a pronounced effect on body heat storage. The consequences of short-duration intermittent exercise on heat storage with aging are unclear. We compared evaporative heat loss (HE) and changes in body heat content (ΔHb) between young (20-30 yr), middle-aged (40-45 yr), and older males (60-70 yr) of similar body mass and surface area, during successive exercise (4 × 15 min) and recovery periods (4 × 15 min) at a fixed rate of heat production (400 W) and under fixed environmental conditions (35 °C/20% relative humidity). HE was lower in older males vs. young males during each exercise (Ex1: 283 ± 10 vs. 332 ± 11 kJ, Ex2: 334 ± 10 vs. 379 ± 5 kJ, Ex3: 347 ± 11 vs. 392 ± 5 kJ, and Ex4: 347 ± 10 vs. 387 ± 5 kJ, all P less than 0.02), whereas HE in middle-aged males was intermediate to that measured in young and older adults (Ex1: 314 ± 13, Ex2: 355 ± 13, Ex3: 371 ± 13, and Ex4: 365 ± 8 kJ). HE was not significantly different between groups during the recovery periods. The net effect over 2 h was a greater ΔHb in older (267 ± 33 kJ; P = 0.016) and middle-aged adults (245 ± 16 kJ; P = 0.073) relative to younger counterparts (164 ± 20 kJ). As a result of a reduced capacity to dissipate heat during exercise, which was not compensated by a sufficiently greater rate of heat loss during recovery, both older and middle-aged males had a progressively greater rate of heat storage compared with young males over 2 h of intermittent exercise.
Publication date	2013-09-15
Publisher	American Physical Society
In	AJP : Regulatory, Integrative and Comparative Physiology 305, no. 6: R619–R629.
Language	English
Peer reviewed	Yes
NRC publication	This is a non-NRC publication "Non-NRC publications" are publications authored by NRC employees prior to their employment by NRC.
NPARC number	23001207
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Record identifier	9ebf65a3-3476-425f-80e9-a061dac3f1d0
Record created	2017-01-05
Record modified	2020-06-02

Date modified:: 2024-07-27