Control of heat-induced cutaneous vasodilatation in relation to age |
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Authors: | W Larry Kenney |
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Institution: | (1) Laboratory for Human Performance Research, The Pennsylvania State University, University Park, 16802, PA, USA |
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Abstract: | Summary Well matched unacclimatised older (age 55–68, 4 women, 2 men) and younger (age 19–30, 4 women, 2 men) subjects performed 75 min cycle exercise ( 40%
) in a hot environment (37°C, 60% rh). Rectal temperature (T
re), mean skin temperature (¯T
sk), arm blood flow (ABF, strain gauge plethysmography), and cardiac output (Q, CO2 rebreathing) were measured to examine age-related differences in heat-induced vasodilatation.T
re and¯T
sk rose to the same extent in each group during the exposure. There was no significant intergroup difference in sweat rate (older: 332±43 ml · m–2 · h–1, younger: 435±49 ml · m–2 · h–1; mean±SEM). However, the older subjects responded to exercise in the heat with a lower ABF response which could be attributed to a lower
for the same exercise intensity. The slope of the ABF-T
re relationship was attenuated in the older subjects (9.3±1.3 vs 17.9±3.3 ml · 100 ml–1 · min–1 · °C–1,p <0.05), but theT
re threshold for vasodilatation was about 37.0°C for both groups. These results suggest an altered control of skin vasodilatation during exercise in the heat in older individuals. This attenuated ABF response appears to be unrelated to
, and may reflect an age-related change in thermoregulatory cardiovascular function. |
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Keywords: | Ageing Skin blood flow Cardiac output Heat Temperature regulation |
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