The change in thermoregulatory capacity as a function of age

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Proceedings titleMedicine and Science in Sports and Exercise
Conference60th Annual Meeting and 4th World Congress on Exercise, May 28-June 1, 2013, Indianapolis, Indiana
AbstractIt is generally accepted that older adults have a lower tolerance to exercise in the heat relative to younger counterparts. The apparent reductions in thermoregulatory capacity are often reported to be related to differences in physical characteristics (e.g. body weight, surface area, and fat mass) and/or to the level of fitness between young and older adults. It remains unclear, however, if age per se affects the body’s capacity to thermoregulate during exercise in hot environments.Purpose: To determine if the residual amount of heat stored within the body following exercise in the heat increases as a function of age.METHODS: Eighty-five males ranging in age from 20-70 yrs performed 4 successive bouts of 15-min cycling at a fixed rate of heat production (∼400 W) separated by 15-min of rest in the heat (35°C, 20% relative humidity). The cumulative change in body heat content was measured using simultaneous direct and indirect calorimetry. The age groups were divided as follows; 20-30 yrs (n=17), 40-44 yrs (n=15), 45-49 yrs (n=15), 50-55 yrs (n=22), and 56-70 yrs (n=16).RESULTS: The younger males had a lower residual heat gain (170±69 kJ) compared to males aged 40-44 yrs (266±68 kJ), 45-49 yrs (288±60 kJ), 50-55 yrs (254±74 kJ), and 56-70 yrs (266±90 kJ), all P<0.05. The correlation between age and the change in body heat content was significant, r=0.381, P<0.05. Age accounted for 15% of the variance in the change in body heat content.CONCLUSION: We show that during exercise in the heat at a fixed rate of metabolic heat production, and consequently a similar requirement for heat loss (i.e. sum of metabolic and environmental heat load), adults aged 40-70 yrs stored more heat compared to young adults aged 20-30 yrs. Advancing age was responsible for at least some of the increase in body heat storage in older adults.
Publication date
PublisherAmerican College of Sports Medicine
Peer reviewedYes
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NPARC number23001349
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Record identifier92cea113-09f1-41d9-83df-d3db10adf1b2
Record created2017-01-20
Record modified2017-01-20
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