Aerobic Fitness Influences the Response of Maximal Oxygen Uptake and Lactate Threshold in Acute Hypobaric Hypoxia

Abstract

We studied 12 highly trained athletes, 6 male ice-hockey players and 6 cross-country skiers (2 females, 4 males). All of them participated in a maximal electrically braked bicycle ergometer test in a hypobaric chamber at the simulated altitude of 3000 m (520 mmHg) and in normobaric conditions two days apart in random order. The maximal oxygen uptake was 57.4 ± 7.1 (SD) ml/ kg/min in normobaria (VO_2maxnorm) and 46.6 ± 4.9 (SD) ml/kg/min in hypobaric hypoxia (VO_2maxhyp). The decrease in maximal oxygen uptake (Δ VO₂max) at the simulated altitude of 3000 m correlated significantly (p < 0.05, r = 0.61) to the maximal oxygen uptake in normobaric conditions (VO_2maxnorm). The lactate threshold was 43.5 ± 6.4 (SD) ml/kg/min in normobaria (VO_2LTnorm) and 36.5 ± 4.2 (SD) ml/kg/min in hypobaric hypoxia (VO_2LThyp). The decrement (Δ VO_2LT) of lactate threshold in hypoxia correlated significantly (p < 0.01, r = 0.68) with the lactate threshold in normobaric conditions (VO_LTnorm). Thus we observed the largest reduction of both maximal oxygen uptake and lactate threshold during exercise at hypobaric hypoxia in the most fit athletes.