Exercise training in normobaric hypoxia in endurance runners. I. Improvement in aerobic performance capacity

Stéphane P. Dufour, Elodie Ponsot, Joffrey Zoll, Stéphane Doutreleau, Evelyne Lonsdorfer-Wolf, Bernard Geny, Eliane Lampert, Martin Flück, Hans Hoppeler, Véronique Billat, Bertrand Mettauer, Ruddy Richard (+1 others)
2006 Journal of applied physiology  
This study investigates whether a 6-wk intermittent hypoxia training (IHT), designed to avoid reductions in training loads and intensities, improves the endurance performance capacity of competitive distance runners. Eighteen athletes were randomly assigned to train in normoxia [Nor group; n ϭ 9; maximal oxygen uptake (V O2 max) ϭ 61.5 Ϯ 1.1 ml ⅐ kg Ϫ1 ⅐ min Ϫ1 ] or intermittently in hypoxia (Hyp group; n ϭ 9; V O2 max ϭ 64.2 Ϯ 1.2 ml ⅐ kg Ϫ1 ⅐ min Ϫ1 ). Into their usual normoxic training
more » ... oxic training schedule, athletes included two weekly high-intensity (second ventilatory threshold) and moderate-duration (24 -40 min) training sessions, performed either in normoxia [inspired O2 fraction (FIO 2 ) ϭ 20.9%] or in normobaric hypoxia (FI O 2 ϭ 14.5%). Before and after training, all athletes realized 1) a normoxic and hypoxic incremental test to determine V O2 max and ventilatory thresholds (first and second ventilatory threshold), and 2) an all-out test at the pretraining minimal velocity eliciting V O2 max to determine their time to exhaustion (T lim) and the parameters of O2 uptake (V O2) kinetics. Only the Hyp group significantly improved V O2 max (ϩ5% at both FIO 2 , P Ͻ 0.05), without changes in blood O 2-carrying capacity. Moreover, Tlim lengthened in the Hyp group only (ϩ35%, P Ͻ 0.001), without significant modifications of V O2 kinetics. Despite similar training load, the Nor group displayed no such improvements, with unchanged V O2 max (ϩ1%, nonsignificant), Tlim (ϩ10%, nonsignificant), and V O2 kinetics. In addition, Tlim improvements in the Hyp group were not correlated with concomitant modifications of other parameters, including V O2 max or V O2 kinetics. The present IHT model, involving specific high-intensity and moderate-duration hypoxic sessions, may potentialize the metabolic stimuli of training in already trained athletes and elicit peripheral muscle adaptations, resulting in increased endurance performance capacity. maximal oxygen uptake; time to exhaustion; competitive endurance runners AT SEA LEVEL, IT IS WELL KNOWN that the training-induced improvements in endurance performance progressively level off as the aerobic fitness progresses. Therefore, the use of the metabolic stimulus provided by living (i.e., living high-training low) or training at altitude (i.e., living low-training high) has
doi:10.1152/japplphysiol.00742.2005 pmid:16540709 fatcat:5fkmlma7xndidehhjcjsb4hmqu