title: Exposure to a combination of heat and hyperoxia during cycling at submaximal intensity does not alter thermoregulatory responses.
abstract: In this study, we tested the hypothesis that breathing hyperoxic air (FinO2 = 0.40) while exercising in a hot environment exerts negative effects on the total tissue level of haemoglobin concentration (tHb); core (Tcore) and skin (Tskin) temperatures; muscle activity; heart rate; blood concentration of lactate; pH; partial pressure of oxygen (PaO2) and carbon dioxide; arterial oxygen saturation (SaO2); and perceptual responses. Ten well-trained male athletes cycled at submaximal intensity at 21°C or 33°C in randomized order: first for 20 min while breathing normal air (FinO2 = 0.21) and then 10 min with FinO2 = 0.40 (HOX). At both temperatures, SaO2 and PaO2, but not tHb, were increased by HOX. Tskin and perception of exertion and thermal discomfort were higher at 33°C than 21°C (p < 0.01), but independent of FinO2. Tcore and muscle activity were the same under all conditions (p > 0.07). Blood lactate and heart rate were higher at 33°C than 21°C. In conclusion, during 30 min of submaximal cycling at 21°C or 33°C, Tcore, Tskin and Tbody, tHb, muscle activity and ratings of perceived exertion and thermal discomfort were the same under normoxic and hyperoxic conditions. Accordingly, breathing hyperoxic air (FinO2 = 0.40) did not affect thermoregulation under these conditions.
authors.affiliation: Department of Sport Science, University of Würzburg, Judenbühlweg 11, 97082 Würzburg, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Zinner
authors.affiliation: Institute of Training Science and Sport Informatics, German Sport University Cologne, Am Sportpark Müngersdorf 6, 50933 Cologne, Germany; The German Research Centre of Elite Sport, German Sport University Cologne, Am Sportpark Müngersdorf 6, 50933 Cologne, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Krueger
authors.affiliation: Faculty of Health Sciences, University of Ottawa, ON, Canada.
authors.forename: J L
authors.initials: JL
authors.lastname: Reed
authors.affiliation: University of Applied Sciences Koblenz, RheinAhrCampus Remagen, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Kohl-Bareis
authors.affiliation: Swedish Winter Sports Research Centre, Department of Health Sciences, Mid Sweden University, Östersund, Sweden.
authors.forename: H-C
authors.initials: HC
authors.lastname: Holmberg
authors.affiliation: Department of Sport Science, University of Würzburg, Judenbühlweg 11, 97082 Würzburg, Germany; Swedish Winter Sports Research Centre, Department of Health Sciences, Mid Sweden University, Östersund, Sweden.
authors.forename: B
authors.initials: B
authors.lastname: Sperlich
keywords: Heat stress; Hyperthermia; Skin blood flow; Thermoregulation; Vasoconstriction