AIM: The aim of this study was to investigate the use of hypoxic sprint interval training (SIT) for the improvement of aerobic capacity. METHOD: Twenty-seven participants (mean±SD), age 21±1 yrs, body mass 72.4±9.7 kg and height 175±7 cm, completed an VO2peak Incremental Exercise Test and time to exhaustion (TTE) trial (80% VO2peak) pre and post SIT. Participants were randomly assigned to either, control (CONT), normoxic (NORM) or hypoxic (FiO2: 0.15) (HYP) conditions. SIT involved 30s sprints interspersed with 4min 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: VO2peak 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. CONCLUSION: Hypoxic and normoxic SIT caused improvement in VO2peak 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.
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