title: Hypobaric versus normobaric hypoxia: same effects on postural stability?
abstract: OBJECTIVE
  To test the hypothesis that postural stability would be more affected during acute exposure in hypobaric (HH) than in normobaric (NH) hypoxia.
  
  
  METHODS
  In separate trials, 12 subjects stood on a posturographic platform for two successive 25.6 sec tests in three conditions: eyes open (EO), eyes closed (EC), and verbal dual task (DT). Ambient pressure in O(2) was matched between HH and NH at 1700 and 3000 m, respectively.
  
  
  RESULTS
  Compared to NH, the length of Centre of Pression trajectory in Y-axis was increased (p<0.05) in HH for EO at 1700 m, EC at 1700 and 3000 m, and for DT at 1700 m, whereas the variance of speed of CoP was decreased (p<0.05) in EO, EC, and DT at 1700 m. Compared to normobaric normoxia (NN; 400 m), the surface of CoP trajectory was increased (p<0.05) in HH in EO and EC at 3000 m.
  
  
  CONCLUSIONS
  HH deteriorated postural stability in the antero-posterior plane, for the variance of speed and the surface of CoP in 3 conditions, whereas no difference was observed between NH and NN. These results suggest that hypobaria instead of hypoxia per se plays an important role to the altered balance classically reported in altitude.
authors.affiliation: Institute of Sport Sciences (ISSUL), Department of Physiology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland. francis.degache@unil.ch
authors.forename: Francis
authors.initials: F
authors.lastname: Degache
authors.forename: Gabriele
authors.initials: G
authors.lastname: Larghi
authors.forename: Raphael
authors.initials: R
authors.lastname: Faiss
authors.forename: Olivier
authors.initials: O
authors.lastname: Deriaz
authors.forename: Gregoire
authors.initials: G
authors.lastname: Millet
mesh_terms: D000293:Adolescent; D000328:Adult; D000531:Altitude; D001274:Atmospheric Pressure; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology*; D008297:Male; D010100:Oxygen; D004856:Postural Balance / Q000502:physiology*; D013647:Task Performance and Analysis; D055815:Young Adult
chemical_list: D010100:Oxygen