title: Hyperthermic-induced hyperventilation and associated respiratory alkalosis in humans.
abstract: The purpose of this study was to determine if increased environmental heat leads to hyperthermic-induced hypocapnia and associated alkalosis during prolonged self-paced cycling. Nine male cyclists completed three 100 km stochastic time trials in hot (34 degrees C), neutral (22 degrees C) and cold (10 degrees C) environments. Intermittent measurements of rectal and skin temperature, expired gases, blood pH, PaCO(2), PaO(2), and bicarbonate were made throughout. Rectal temperature increased significantly throughout all trials (P < 0.001) and was significantly correlated with increases in the ventilatory equivalent for carbon dioxide (Ve/ VCo2; r = 0.77; P < 0.001) and blood pH (r = 0.69; P < 0.05). Rectal temperature was also negatively correlated with a reduction in PaCO(2) (r = -0.80; P < 0.001). PaO(2) and bicarbonate concentration remained constant throughout all trials. This study has shown that prolonged self-paced cycling is associated with a hyperthermic-induced hyperventilation, causing a decrease in arterialized carbon dioxide tension and consequential respiratory alkalosis.
authors.affiliation: School of Exercise, Biomedical and Health Sciences, Edith Cowan University, 100 Joondalup Drive, Joondalup, WA, 6027, Australia. c.abbiss@ecu.edu.au
authors.forename: Chris R
authors.initials: CR
authors.lastname: Abbiss
authors.forename: Kazunori
authors.initials: K
authors.lastname: Nosaka
authors.forename: Paul B
authors.initials: PB
authors.lastname: Laursen
mesh_terms: D000136:Acid-Base Equilibrium / Q000502:physiology; D000328:Adult; D000465:Algorithms; D000472:Alkalosis, Respiratory / Q000209:etiology* / Q000503:physiopathology*; D015308:Anaerobic Threshold / Q000502:physiology; D001642:Bicycling / Q000502:physiology; D001784:Blood Gas Analysis; D001831:Body Temperature / Q000502:physiology; D002245:Carbon Dioxide / Q000097:blood; D003080:Cold Temperature; D003627:Data Interpretation, Statistical; D015444:Exercise / Q000502:physiology; D005334:Fever / Q000150:complications* / Q000503:physiopathology*; D006358:Hot Temperature; D006801:Humans; D006985:Hyperventilation / Q000209:etiology* / Q000503:physiopathology*; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D015656:Respiratory Mechanics / Q000502:physiology; D012881:Skin Temperature / Q000502:physiology; D013696:Temperature
chemical_list: D002245:Carbon Dioxide