Effect of Intermittent Normobaric Hypoxic Exposure on Sea-level Performance in Rugby Players

Abstract

The “live-high/train-low” approach to altitude training produces worthwhile gains in endurance performance at sea level, but the effects of this approach using normobaric hypoxia to simulate altitude are more contentious. The effects of hypoxic exposure on brief high-intensity performance similar to that of team games also need further investigation. PURPOSE: To determine the effects of normobaric intermittent hypoxic exposure on sea-level performance in professional rugby players. METHODS: Ten players were randomly assigned to two groups. Players in each group received 9–14 sessions of either hypoxic (10–15% O2) or normoxic (21% O2) exposure over 14 days in a single-blind fashion. Each session consisted of six 6-min intervals of exposure delivered via a hand-held mask interspersed with 4-min recovery periods breathing room air. Performance measures obtained consecutively in a single testing session pre- and post-exposure were: maximum speed in a 20-m incremental running test, mean time in six 70-m repeated sprints, various mean measures in seven 5.5-min circuits of a rugby simulation, and mean time in a second set of sprints. Blood sampling was performed 7 and 14 days before and 2 days following exposure. Performance tests were performed 1–3 days prior to and 1–4 days after exposure. RESULTS: Effects of hypoxic exposure on maximum speed and sprint times were trivial (< 1.0%) but unclear (90% likely range ±5% to ±9%). In the rugby simulation, hypoxic exposure produced clear impairments of peak power in two scrums (15%, ±8%; 9%, ±7%) and clear impairments of time in offensive sprints (7%, ±8%) and tackle sprints (11 %, ±9%). Impairments were also observed in the 20-m sprint (1.6%, ±7.0%), 30-m sprint (2.0%, ±4.5%), and defensive sprint (3.5%, ±4.7%), although these were unclear. The effect on ball-passing accuracy was also unclear (2%, ±19%), as were effects on hemoglobin concentration (−2.0, ±4.7%), reticulocytes (0.7, ±36%) andferritin(11,±22%). CONCLUSIONS: Pending further research, rugby players would be unwise to use normobaric intermittent hypoxic exposure to prepare for games at sea level. Supported by the New Zealand Rugby Union.