Hydration and the physiological responses to acute normobaric hypoxia.
OBJECTIVE
The effect hydration status has on exposure to hypoxia is unclear. The purpose of the study was to identify how hydration status, above and below euhydrated levels, affects the physiological responses and onset of acute mountain sickness symptoms during acute normobaric hypoxia.


METHODS
Eight males completed intermittent walking tests under normobaric hypoxic conditions (FIo2 = 0.13) after controlled hyperhydration, hypohydration, and euhydration protocols. A range of physiological, psychological, and altitude illness markers were monitored throughout the 125-minute exposure.


RESULTS
Heart rate, core temperature, peripheral arterial oxygen saturation, urine osmolality, and mean self-reported Lake Louise Questionnaire acute mountain sickness scores were significantly different between euhydration, hypohydration, and hyperhydration, respectively, and closely correlated with environmental symptoms questionnaire, Lake Louise questionnaire, and headache scores (P < .05). Other measures of ventilation and lung function were also significantly different between hydration conditions (P < .05).


CONCLUSIONS
Hydration state above and below euhydration has detrimental consequences on physiological strain and onset of acute mountain sickness symptoms when exposed to acute normobaric hypoxia.
Richardson
Alan
A
University of Brighton, Chelsea School Reseasrch Centre, Eastbourne, United Kingdom. a.j.richardson@brighton.ac.uk
Watt
Peter
P
Maxwell
Neil
N
D000532:Altitude Sickness / Q000453:epidemiology / Q000209:etiology; D018592:Cross-Over Studies; D003681:Dehydration / Q000503:physiopathology* / Q000523:psychology; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology* / Q000523:psychology; D008168:Lung / Q000502:physiology; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D011795:Surveys and Questionnaires; D016138:Walking / Q000502:physiology*; D014882:Water-Electrolyte Balance / Q000502:physiology*; D014883:Water-Electrolyte Imbalance / Q000503:physiopathology* / Q000523:psychology; D055815:Young Adult