Petra Golja1, Igor B Mekjavic. 1. Institute of Biomedical and Biomolecular Sciences, Department of Sports and Exercise Science, University of Portsmouth, Portsmouth, United Kingdom.
Abstract
INTRODUCTION: Selection of preferred skin temperature is a consequence of complex central neural integration of thermoafferent information in the polysynaptic pathway for behavioral thermoregulation. The present study tested the hypothesis that hypoxia alters behavioral temperature regulation. METHODS: Eight male volunteers participated in two separate trials. In each trial they were immersed in 28 degrees C water for 90 min, and inspired either room air (air trial) or a hypoxic gas mixture (hypoxia trial; 11.5% O2/88.5% N2). Their left hand was placed in a separate bath perfused with water. At regular intervals they were instructed to adjust the temperature of the water perfusing the hand bath to a comfortable temperature, defined as the 'preferred hand temperature' (Tpref). At minute intervals, esophageal (Tes), rectal (Tre), and skin (Tsk) temperatures, along with heat flux from the skin (Q) and ventilation (VI) were recorded. The observed responses were compared with a one-way ANOVA. RESULTS: With the exception of VI, there were no significant differences in any of the recorded variables between the two conditions. During the immersion, Tes and Tre decreased by 1.0 and 0.7 degrees C, respectively, in the air trial, and by 0.8 and 0.7 degrees C, respectively, in the hypoxia trial. Concomitant with decreases in core temperature, there was a significant increase (p < 0.05) in Tpref of 2.1 degrees C in the air trial and 2.4 degrees C in the hypoxia trial. The difference in Tpref between the air and hypoxia trials was not significant. DISCUSSION: Assuming that the selection of preferred hand temperature represents a behavioral thermoregulatory response, the present results suggest that moderate normobaric hypoxia does not affect human behavioral thermoregulation.
INTRODUCTION: Selection of preferred skin temperature is a consequence of complex central neural integration of thermoafferent information in the polysynaptic pathway for behavioral thermoregulation. The present study tested the hypothesis that hypoxia alters behavioral temperature regulation. METHODS: Eight male volunteers participated in two separate trials. In each trial they were immersed in 28 degrees C water for 90 min, and inspired either room air (air trial) or a hypoxic gas mixture (hypoxia trial; 11.5% O2/88.5% N2). Their left hand was placed in a separate bath perfused with water. At regular intervals they were instructed to adjust the temperature of the water perfusing the hand bath to a comfortable temperature, defined as the 'preferred hand temperature' (Tpref). At minute intervals, esophageal (Tes), rectal (Tre), and skin (Tsk) temperatures, along with heat flux from the skin (Q) and ventilation (VI) were recorded. The observed responses were compared with a one-way ANOVA. RESULTS: With the exception of VI, there were no significant differences in any of the recorded variables between the two conditions. During the immersion, Tes and Tre decreased by 1.0 and 0.7 degrees C, respectively, in the air trial, and by 0.8 and 0.7 degrees C, respectively, in the hypoxia trial. Concomitant with decreases in core temperature, there was a significant increase (p < 0.05) in Tpref of 2.1 degrees C in the air trial and 2.4 degrees C in the hypoxia trial. The difference in Tpref between the air and hypoxia trials was not significant. DISCUSSION: Assuming that the selection of preferred hand temperature represents a behavioral thermoregulatory response, the present results suggest that moderate normobaric hypoxia does not affect human behavioral thermoregulation.