The effect of intermittent training in hypobaric hypoxia on sea-level exercise: a cross-over study in humans

Abstract.

The purpose of this study was to examine the effect of intermittent training in a hypobaric chamber on physical exercise at sea level. Over a 10 day period, 16 male triathletes trained for 2 h each day on a cycle ergometer placed in a hypobaric chamber. Training intensity was at 60%–70% of the heart rate reserve. There were 8 subjects who trained at a simulated altitude of 2,500 m, the other 8 trained at sea level. A year later, a cross-over study took place. Baseline measurements were made on a cycle ergometer at sea level, which included an incremental test until exhaustion and a Wingate Anaerobic Test. Altogether, 12 subjects completed the cross-over study. At 9 days after training in hypoxia, significant increases were seen in maximal power output ($\dot W_{{\rm max}}$ )(5.2%), anaerobic mean power (4.1%), and anaerobic peak power (3.8%). A non-significant increase in maximal oxygen uptake (V˙O_2max) of 1.9% was observed. At 9 days after training at sea level, no significant changes were seen in $\dot W_{{\rm max}}$ (2.1%), V˙O_2max (2.0%), anaerobic mean power (0.2%) and anaerobic peak power (0.2%). When comparing the results of the two training regimes, the anaerobic mean power was the only variable that showed a significantly larger increase as a result of training at altitude. And, although the differences in percentage change between the two training protocols were not significant, they were substantial for $\dot W_{{\rm max}}$ as well as for anaerobic peak power. The results of this study indicate that intermittent hypobaric training can improve the anaerobic energy supplying system, and also, to a lesser extent, the aerobic system. It can be concluded that the overall results of the cross-over study showed predominantly improvements in the anaerobic metabolism at variance with the previous study of our own group, where the relative V˙O_2max and $\dot W_{{\rm max}}$ increased by 7%.