Hyperthermia and cardiovascular strain during an extreme heat exposure in young versus older adults
Authors
Kenny, Glen PPoirier, Martin P
Metsios, George S.
Boulay, Pierre
Dervis, Sheila
Friesen, Brian J
Malcolm, Janine
Sigal, Ronald J
Seely, Andrew J E
Flouris, Andreas D
Issue Date
2016-09-30
Metadata
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We examined whether older individuals experience greater levels of hyperthermia and cardiovascular strain during an extreme heat exposure compared to young adults. During a 3-hour extreme heat exposure (44°C, 30% relative humidity), we compared body heat storage, core temperature (rectal, visceral) and cardiovascular (heart rate, cardiac output, mean arterial pressure, limb blood flow) responses of young adults (n = 30, 19-28 years) against those of older adults (n = 30, 55-73 years). Direct calorimetry measured whole-body evaporative and dry heat exchange. Body heat storage was calculated as the temporal summation of heat production (indirect calorimetry) and whole-body heat loss (direct calorimetry) over the exposure period. While both groups gained a similar amount of heat in the first hour, the older adults showed an attenuated increase in evaporative heat loss (p < 0.033) in the first 30-min. Thereafter, the older adults were unable to compensate for a greater rate of heat gain (11 ± 1 ; p < 0.05) with a corresponding increase in evaporative heat loss. Older adults stored more heat (358 ± 173 kJ) relative to their younger (202 ± 92 kJ; p < 0.001) counterparts at the end of the exposure leading to greater elevations in rectal (p = 0.043) and visceral (p = 0.05) temperatures, albeit not clinically significant (rise < 0.5°C). Older adults experienced a reduction in calf blood flow (p < 0.01) with heat stress, yet no differences in cardiac output, blood pressure or heart rate. We conclude, in healthy habitually active individuals, despite no clinically observable cardiovascular or temperature changes, older adults experience greater heat gain and decreased limb perfusion in response to 3-hour heat exposure.Citation
Kenny GP., Poirier MP., Metsios GS., Boulay P., Dervis S., Friesen B.J, Malcolm J., Sigal RJ., Seely AJ., Flouris AD. (2017) 'Hyperthermia and cardiovascular strain during an extreme heat exposure in young versus older adults', Temperature, 4(1) pp. 79-88. doi: 10.1080/23328940.2016.1230171Publisher
Taylor & FrancisJournal
TemperaturePubMed ID
28349096Additional Links
https://www.tandfonline.com/doi/full/10.1080/23328940.2016.1230171Type
Journal articleLanguage
enISSN
2332-8940ae974a485f413a2113503eed53cd6c53
10.1080/23328940.2016.1230171
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- Creative Commons
Except where otherwise noted, this item's license is described as https://creativecommons.org/licenses/by-nc-nd/4.0/
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