title: Simulated hypoxia does not further improve aerobic capacity during sprint interval training.
abstract: OBJECTIVE
  The aim of this study was to investigate the use of hypoxic sprint interval training (SIT) for the improvement of aerobic capacity.
  
  
  METHODS
  Twenty-seven participants (mean±SD), age 21±1 yrs, body mass 72.4±9.7 kg and height 175±7 cm, completed an V̇O2peak Incremental Exercise Test and time to exhaustion (TTE) trial (80% V̇O2peak) pre and post SIT. Participants were randomly assigned to either, control (CONT), normoxic (NORM) or hypoxic (FiO2: 0.15) (HYP) conditions. SIT involved 30 s sprints interspersed with 4 min rest. The number of sprints progressed from four to seven over six sessions separated by 1-2 days rest. Two-way mixed design ANOVA was performed to determine changes between conditions.
  
  
  RESULTS
  V̇O2peak improved (P<0.05) pre to post SIT in NORM (11.2±10.8%) and HYP (10.9±6.2%), but not CONT (0.7±14.3%). TTE post SIT was significantly improved from pre SIT in NORM and HYP but not CONT (CONT=1±6, NORM=56±25, HYP=34±25%, P<0.05). Peak and recovery heart rate was lower in NORM (P<0.05) than HYP as SIT sessions progressed. SpO2 (%) was lower in HYP (86.1±4.3%) compared to NORM (97.1±0.7%), decreasing within all HYP sessions, and increasing with SIT.
  
  
  CONCLUSIONS
  Hypoxic and normoxic SIT caused improvement in V̇O2peak and TTE compared to a control. Hypoxic SIT did not cause further improvements, indicating hypoxia based SIT offers no additional benefit for improvement of endurance performance.
authors.affiliation: Centre for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Eastbourne, UK - a.j. richardson@brighton.ac.uk.
authors.forename: A J
authors.initials: AJ
authors.lastname: Richardson
authors.forename: O R
authors.initials: OR
authors.lastname: Gibson
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology; D000328:Adult; D004734:Energy Metabolism / Q000502:physiology*; D005080:Exercise Test; D017079:Exercise Tolerance; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000502:physiology; D010101:Oxygen Consumption / Q000502:physiology*; D010807:Physical Endurance / Q000502:physiology*; D005082:Physical Exertion / Q000502:physiology*; D012420:Running