Joanie Larose1, Heather E Wright, Ronald J Sigal, Pierre Boulay, Stephen Hardcastle, Glen P Kenny. 1. 1Human and Environmental Physiology Research Unit, Faculty of Health Sciences, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, CANADA; 2Clinical Epidemiology Program, Ottawa Health Research Institute, Ottawa, Ontario, CANADA; 3Faculties of Medicine and Kinesiology, Departments of Medicine, Cardiac Sciences and Community Health Sciences, University of Calgary, Calgary, Alberta, CANADA; 4Faculty of Physical Education and Sports, University of Sherbrooke, Sherbrooke, Quebec, CANADA; and 5CanmetMINING, Natural Resources Canada, Sudbury, Ontario, CANADA.
Abstract
INTRODUCTION: Aging is associated with a reduction in the body's capacity to dissipate heat. To date, few studies have examined age-related changes in thermoregulatory function during short exercise periods in the heat in older females. PURPOSE: This study aimed to investigate the effects of age on whole-body heat loss during intermittent exercise in the heat in young and older females. METHODS: Direct and indirect calorimetry was used to measure whole-body evaporative heat loss (EHL), change in body heat content, and metabolic heat production. Eleven young (Y) (mean ± SD age = 24 ± 4 yr) and 13 older (O) (51 ± 8 yr) females matched for body surface area (Y, 1.72 ± 0.15; O, 1.75 ± 0.12 m²) and fitness (V(˙)O(2max)) (Y, 36.7 ± 6.8 mL O₂·kg⁻¹·min⁻¹; O, 33.8 ± 8.0 mL O₂·kg⁻¹·min⁻¹) performed four bouts of 15-min cycling (Ex1, Ex2, Ex3, and Ex4) at a constant rate of heat production (300 W) at 35°C and 20% relative humidity. Each exercise bout was separated by 15 min of rest. RESULTS: EHL was reduced in O compared with Y during Ex1 (O, 199 ± 6 W; Y, 240 ± 9 W; P = 0.001), Ex2 (O, 238 ± 4 W; Y, 261 ± 9 W, P = 0.023), and Ex3 (O, 249 ± 4 W; Y, 274 ± 11 W; P = 0.040). EHL was not different between groups during Ex4 or during the recovery periods. Older females had a greater change in body heat content compared with young females (O, 270 ± 20 kJ; Y, 166 ± 20 kJ; P = 0.001). CONCLUSION: These findings suggest that older females have a lower capacity for whole-body EHL compared with younger females during short intermittent exercise in the heat performed at a fixed rate of metabolic heat production.
INTRODUCTION: Aging is associated with a reduction in the body's capacity to dissipate heat. To date, few studies have examined age-related changes in thermoregulatory function during short exercise periods in the heat in older females. PURPOSE: This study aimed to investigate the effects of age on whole-body heat loss during intermittent exercise in the heat in young and older females. METHODS: Direct and indirect calorimetry was used to measure whole-body evaporative heat loss (EHL), change in body heat content, and metabolic heat production. Eleven young (Y) (mean ± SD age = 24 ± 4 yr) and 13 older (O) (51 ± 8 yr) females matched for body surface area (Y, 1.72 ± 0.15; O, 1.75 ± 0.12 m²) and fitness (V(˙)O(2max)) (Y, 36.7 ± 6.8 mL O₂·kg⁻¹·min⁻¹; O, 33.8 ± 8.0 mL O₂·kg⁻¹·min⁻¹) performed four bouts of 15-min cycling (Ex1, Ex2, Ex3, and Ex4) at a constant rate of heat production (300 W) at 35°C and 20% relative humidity. Each exercise bout was separated by 15 min of rest. RESULTS: EHL was reduced in O compared with Y during Ex1 (O, 199 ± 6 W; Y, 240 ± 9 W; P = 0.001), Ex2 (O, 238 ± 4 W; Y, 261 ± 9 W, P = 0.023), and Ex3 (O, 249 ± 4 W; Y, 274 ± 11 W; P = 0.040). EHL was not different between groups during Ex4 or during the recovery periods. Older females had a greater change in body heat content compared with young females (O, 270 ± 20 kJ; Y, 166 ± 20 kJ; P = 0.001). CONCLUSION: These findings suggest that older females have a lower capacity for whole-body EHL compared with younger females during short intermittent exercise in the heat performed at a fixed rate of metabolic heat production.
Authors: Anthony S Leicht; Andreas D Flouris; Antonia Kaltsatou; Andrew J Seely; Christophe L Herry; Heather E Wright Beatty; Glen P Kenny Journal: Temperature (Austin) Date: 2018-03-15
Authors: Robert D Meade; Naoto Fujii; Gregory W McGarr; Lacy M Alexander; Pierre Boulay; Ronald J Sigal; Glen P Kenny Journal: J Appl Physiol (1985) Date: 2019-01-17
Authors: Joanie Larose; Pierre Boulay; Heather E Wright-Beatty; Ronald J Sigal; Stephen Hardcastle; Glen P Kenny Journal: J Appl Physiol (1985) Date: 2014-05-08
Authors: Heather E Wright-Beatty; Stephen G Hardcastle; Pierre Boulay; Joanie Larose; Glen P Kenny Journal: Eur J Appl Physiol Date: 2014-06-19 Impact factor: 3.078
Authors: Antonia Kaltsatou; Andreas D Flouris; Christophe L Herry; Sean R Notley; Andrew J E Seely; Heather Wright Beatty; Glen P Kenny Journal: Eur J Appl Physiol Date: 2020-01-01 Impact factor: 3.078