Attenuation of the cutaneous blood flow response during combined exercise and heat stress |
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Authors: | Mark J. Patterson Duncan Warlters Nigel A. S. Taylor |
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Affiliation: | (1) Department of Biomedical Science, University of Wollongong, Northfields Avenue, NSW 2522 Wollongong, Australia |
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Abstract: | Skin blood flow (SkBF) was measured in six male subjects using laser-Doppler velocimetry, with zero-gradient auditory canal temperature (Tac) used as an index of body core temperature (Tc). Subjects performed incremental, upright cycling commencing at 40% peak power (peak: 10 min), increasing every 4 min by 5 % peak thereafter. Trials were conducted in hot (ambient temperature (Ta) 36.7 ±0.2°C, relative humidity (rh) 46.1 ±3.2%; peak ±S.D.), and neutral environments (Ta 19.6 ±0.3°C, rh 50.2 ±1.4%). SkBF increased with Tac in all subjects. Attenuation of SkBF occurred at the same Tac, relative SkBF and cardiac frequency (fc) between environments, but at a lower exercise intensity (40.8 ±0.8% versus 55.8 ±3.0% peak) in the hot environment (p<0.05). Data indicate that Tc thresholds for SkBF attenuation may exist. However, it is suggested that attenuation thresholds coincided with a reduced central blood volume, which may occur at a critical level of cutaneous blood pooling. |
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Keywords: | Exercise Laser-Doppler velocimetry Skin blood flow Temperature regulation |
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