Normobaric hypoxia reduces VO2 at different intensities in highly trained runners

The primary aim of this study was to determine the influence of 14 days of normobaric hypoxic simulated altitude exposure at 3000 m on the human plasma metabolomic profile.

At a glance:

• For threshold and maximal aerobic sessions, descending to 1400m would be beneficial in helping to defend oxygen flux.
• Middle distance race-pace sessions may be completed at moderate altitude with little change in physiological stimulus compared to sea-level training.
• Completing high-intensity interval running at a simulated altitude of 2100m is likely to induce a lower VO2 and greater anaerobic contribution to exercise when compared to training at 580m.

Full reference and abstract:

Sharma, A. P., Saunders, P. U., Garvican-Lewis, L. A., Clark, B., Gore, C. J., Thompson, K. G. & Periard, J. D. (2019). Normobaric hypoxia reduces VO2 at different intensities in highly trained runners. Medicine and Science in Sports and Exercise, 51(1), 174-182.

Introduction: We sought to determine the effect of low and moderate normobaric hypoxia on oxygen consumption and anaerobic contribution during interval running at different exercise intensities.

Methods: Eight runners (age, 25 ± 7 yr, VO2max: 72.1 ± 5.6 mL.kg.min^-1) completed three separate interval sessions at threshold (4 x 5min, 2-minrecovery),VO2max (8 x 90 s, 90-s recovery), and race pace (10 x 45 s, 1 min 45 s recovery) in each of; normoxia (elevation: 580 m, FiO2: 0.21), low (1400 m, 0.195) or moderate (2100 m, 0.18) normobaric hypoxia. The absolute running speed for each intensity was kept the same at each altitude to evaluate the effect of FiO2 on physiological responses. Expired gas was collected throughout each session, with total VO2 and accumulated oxygen deficit calculated. Data were compared using repeated-measures ANOVA.

Results: There were significant differences between training sessions for peak and total VO2, and anaerobic contribution (P < 0.001, P – 0.01 respectively), with race pace sessions eliciting the lowest and highest responses respectively. Compared to 580 m, total VO2 at 2100 m was significantly lower (P < 0.05), and anaerobic contribution significantly higher (P < 0.05) during both threshold and VO2max sessions. No significant differences were observed between altitudes for race pace sessions.

Conclusions: To maintain oxygen flux, completing acute exercise at threshold and VO2max intensity at 1400 m simulated altitude appears more beneficial compared with 2100 m. However, remaining at moderate altitude is suitable when increasing the anaerobic contribution to exercise is a targeted response to training.

Keywords: Altitude training, accumulated oxygen deficit, endurance training, anaerobic contribution, oxygen consumption