title: Hydration and the physiological responses to acute normobaric hypoxia.
abstract: 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.
authors.affiliation: University of Brighton, Chelsea School Reseasrch Centre, Eastbourne, United Kingdom. a.j.richardson@brighton.ac.uk
authors.forename: Alan
authors.initials: A
authors.lastname: Richardson
authors.forename: Peter
authors.initials: P
authors.lastname: Watt
authors.forename: Neil
authors.initials: N
authors.lastname: Maxwell
mesh_terms: 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