Understanding and Managing the Limits of Physiological Tolerance in Heat Vulnerable Canadians During Rest and Physical Exercise

Detailed Summary

Climate change not only affects the planet's natural resources, but also severely impacts human health. An individual's ability to adequately cope with short- or long-term increases in ambient temperature is critical for maintaining health and wellbeing. Prolonged increases in temperature (heatwaves) pose a serious health risk for older adults, who have a reduced capacity to efficiently regulate body temperature. However, information regarding the impact of age on body temperature regulation during prolonged exposure to extreme heat is lacking, as is research on the effectiveness of interventions aimed at reducing heat strain in such situations. This project will address these important knowledge gaps by exposing healthy young and older adults to a prolonged (9 hour) heat exposure, with conditions representative of heatwaves in temperate continental climates. An additional cohort of older adults will complete the same heatwave simulation but will be briefly (2 hours) exposed to cooler conditions (22-23°C) mid-way through the session (akin to visiting a cooling centre or cooled location). The investigators will evaluate age-related differences in the capacity to dissipate heat via direct air calorimetry (a unique device that permits the precise measurement of the heat dissipated by the human body) and their effect on the regulation of body temperature. The investigators anticipate that older adults will exhibit progressive increases in the heat stored in the body throughout the simulated heatwave, resulting in progressive increases in body core temperature. Further, older adults exposed to brief-mid day cooling will rapidly gain heat upon re-exposure to high ambient temperatures. As a result, by the end of exposure body temperatures will be similar to the group not removed from the heat.

Study Details

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Interventions