title: Exercise during Short-Term and Long-Term Continuous Exposure to Hypoxia Exacerbates Sleep-Related Periodic Breathing.
abstract: OBJECTIVE
  Exposure to hypoxia elevates chemosensitivity, which can lead to periodic breathing. Exercise impacts gas exchange, altering chemosensitivity; however, interactions between sleep, exercise and chronic hypoxic exposure have not been examined. This study investigated whether exercise exacerbates sleep-related periodic breathing in hypoxia.
  
  
  METHODS
  Two experimental phases. Short-Term Phase: a laboratory controlled, group-design study in which 16 active, healthy men (age: 25 ± 3 y, height: 1.79 ± 0.06 m, mass: 74 ± 8 kg) were confined to a normobaric hypoxic environment (FIO2 = 0.139 ± 0.003, 4,000 m) for 10 days, after random assignment to a sedentary (control, CON) or cycle-exercise group (EX). Long-Term Phase: conducted at the Concordia Antarctic Research Station (3,800 m equivalent at the Equator) where 14 men (age: 36 ± 9 y, height: 1.77 ± 0.09 m, mass: 75 ± 10 kg) lived for 12-14 months, continuously confined. Participants were stratified post hoc based on self-reported physical activity levels. We quantified apnea-hypopnea index (AHI) and physical activity variables.
  
  
  RESULTS
  Short-Term Phase: mean AHI scores were significantly elevated in the EX group compared to CON (Night1 = CON: 39 ± 51, EX: 91 ± 59; Night10 = CON: 32 ± 32, EX: 92 ± 48; P = 0.046). Long-Term Phase: AHI was correlated to mean exercise time (R(2) = 0.4857; P = 0.008) and the coefficient of variation in night oxyhemoglobin saturation (SpO2; R(2) = 0.3062; P = 0.049).
  
  
  CONCLUSIONS
  Data indicate that exercise (physical activity) per se affects night SpO2 concentrations and AHI after a minimum of two bouts of moderate-intensity hypoxic exercise, while habitual physical activity in hypobaric hypoxic confinement affects breathing during sleep, up to 13+ months' duration.
authors.affiliation: Vrije Universiteit Brussels, Human Physiology & Sports Medicine Department, Brussels, Belgium.|Royal Military Academy of Brussels, VIPER Research Unit, Brussels, Belgium.
authors.forename: Helio Fernandez
authors.initials: HF
authors.lastname: Tellez
authors.affiliation: Department of Automation, Biocybernetics, and Robotics, Jozef Stefan Institute, Ljubljana, Slovenia.|Institute of Clinical Neurophysiology, University Clinical Centre, Ljubljana, Slovenia.
authors.forename: Shawnda A
authors.initials: SA
authors.lastname: Morrison
authors.affiliation: Royal Military Academy of Brussels, VIPER Research Unit, Brussels, Belgium.|Royal Military Academy Brussels, CISS, Brussels, Belgium.
authors.forename: Xavier
authors.initials: X
authors.lastname: Neyt
authors.affiliation: Vrije Universiteit Brussels, Human Physiology & Sports Medicine Department, Brussels, Belgium.|Sleep Laboratory & Unit for Chronobiology-Brugmann University Hospital Free University of Brussels (U.L.B./V.U.B), Brussels, Belgium.
authors.forename: Olivier
authors.initials: O
authors.lastname: Mairesse
authors.affiliation: Vrije Universiteit Brussels, Human Physiology & Sports Medicine Department, Brussels, Belgium.|Department of Movement, Human and Health Sciences, University of Rome Foro Italico, Rome, Italy.
authors.forename: Maria Francesca
authors.initials: MF
authors.lastname: Piacentini
authors.affiliation: JF Intensive Care Unit, Addenbrooke's Hospital, Cambridge, United Kingdom.|Institut polaire français Paul-Emile Victor, Technopôle Brest-Iroise, Plouzané, France.
authors.forename: Eoin
authors.initials: E
authors.lastname: Macdonald-Nethercott
authors.affiliation: Institute of Clinical Neurophysiology, University Clinical Centre, Ljubljana, Slovenia.
authors.forename: Andrej
authors.initials: A
authors.lastname: Pangerc
authors.affiliation: Institute of Clinical Neurophysiology, University Clinical Centre, Ljubljana, Slovenia.
authors.forename: Leja
authors.initials: L
authors.lastname: Dolenc-Groselj
authors.affiliation: Department of Environmental Physiology, Swedish Aerospace Physiology Centre, Royal Institute of Technology, Stockholm, Sweden.
authors.forename: Ola
authors.initials: O
authors.lastname: Eiken
authors.affiliation: Vrije Universiteit Brussels, Human Physiology & Sports Medicine Department, Brussels, Belgium.|Royal Military Academy of Brussels, VIPER Research Unit, Brussels, Belgium.|Experimental and Applied Psychology Department, Brussels, Belgium.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Pattyn
authors.affiliation: Department of Automation, Biocybernetics, and Robotics, Jozef Stefan Institute, Ljubljana, Slovenia.
authors.forename: Igor B
authors.initials: IB
authors.lastname: Mekjavic
authors.affiliation: Vrije Universiteit Brussels, Human Physiology & Sports Medicine Department, Brussels, Belgium.|School of Public Health, Tropical Medicine and Health Sciences, James Cook University, Townsville City, Queensland, Australia.
authors.forename: Romain
authors.initials: R
authors.lastname: Meeusen
mesh_terms: D000328:Adult; D000531:Altitude; D001642:Bicycling / Q000502:physiology; D062485:Breath Holding; D015444:Exercise / Q000502:physiology*; D006801:Humans; D000860:Hypoxia / Q000378:metabolism*; D008297:Male; D010100:Oxygen / Q000378:metabolism; D057185:Sedentary Behavior; D057566:Self Report; D012890:Sleep / Q000502:physiology*; D013997:Time Factors
chemical_list: D010100:Oxygen
keywords: Antarctica; confinement; cycling; high altitude; oxygen saturation; sleep apnea