Preacclimatization in simulated altitudes.

UNLABELLED: Acute exposure to high altitude provokes the development of mountain illnesses and decrease of exercise performance. Thus, sufficient acclimatization is of utmost importance for mountaineers, trekkers, and athletes performing at high altitude. The main purpose of this paper was to review existing studies and observations on the effectiveness of preacclimatization at simulated altitude. DATA SOURCE: A PubMed search has been performed and preliminary observations from our laboratory have been included. Although some beneficial effects have been demonstrated, it is not possible to draw firm conclusions from the few available studies dealing with the effects of preacclimatization at simulated altitude on the reduction of acute mountain sickness (AMS) incidence and performance loss at high altitude. For the present, 1-4 h of daily exposures for 1-5 weeks to simulated altitudes of about 4,000 m seem to initiate ventilatory and autonomous nervous system adaptations to high altitude with the potential to reduce AMS development. At least for protocols of short duration, rest during hypoxic exposures seems to be similarly effective as exercise. For the more prolonged protocols, exercise may be included to enhance exercise performance in hypoxia.