Effect of Intermittent Normobaric Hypoxic Exposure at Rest on Rugby Players?? Performance at 1650 m: 2731

Team-sport athletes who normally reside at sea level sometimes play “away” games at altitudes sufficient to impair endurance performance. Prior adaptation to hypoxia at sea level may offset the impairment. PURPOSE: To investigate the effect of intermittent normobaric hypoxic exposure on performance in generic and game-specific tests at altitude. METHODS: Club and junior representative rugby players who were sea-level residents performed baseline tests before single-blind random assignment to one of three groups: hypoxia-altitude (n=9), normoxia-altitude (n=6), and normoxia-sea level (n=7). The hypoxia-altitude group experienced 9–13 sessions of intermittent hypoxic exposure over 15 days, then repeated the performance tests within 12 hours of traveling to an altitude of 1650 m. The normoxia-altitude group experienced placebo exposures by breathing room air before performing the tests at altitude, whereas the normoxia-sea level group experienced placebo exposures before performing the tests at sea level. Hypoxic exposure sessions consisted of alternately breathing through a handheld face mask 6 min hypoxic gas and 4 min ambient air for 1 hour at rest. Oxygen in the gas was reduced progressively (Day 1, 13%; Day 15, 9%). Ambient air replaced hypoxic gas for the placebo exposures. Performance measures gathered at each testing session were: maximum speed, submaximum heart-rate speed and submaximum lactate speed during a 20-m incremental running test, mean time in six 70-m sprints, various mean measures from seven 5.5-min circuits of a rugby simulation, and mean time in a second set of sprints. RESULTS: At altitude there were clear impairments in maximum and heart rate-speed, defensive sprint time, and scrum power (2% to 16%), and a clear improvement in 30-m sprint time (−4%). Relative to the normoxia-altitude group, the hypoxia-altitude group experienced a clear improvement in heart-rate speed (10%; 90% confidence limits ±7%) and an unclear improvement in lactate speed (2%; ±4%); effects on all other performance variables were trivial (<1.5%) and in most cases unclear (±3% to ±14%). CONCLUSIONS: Altitude of 1650 m had a positive effect on some sprints but a detrimental effect on 20-m running performance and scrum power. Intermittent hypoxic exposure improved some physiological measures of performance but otherwise had little effect in preparing rugby players for performance at altitude.