ACCLIMATIZATION AT HIGH-ALTITUDE IN GRADUAL AND ACUTE INDUCTION

The study assessed physiological responses to induction to high altitu de first to 3,500 m and then to 4,200 m and compared the time course o f altitude acclimatization in-two groups of male volunteers. The acute ly inducted group was transported by aircraft (AI) to 3,500 m in 1 h, whereas the gradually inducted group was transported by road (RI) in 4 days. Baseline recordings of basal cardiovascular, respiratory, and b lood gas variables were monitored at sea level as well as at 3,500 m o n clays 1, 3, 5, and 7. Blood gases were measured on day 10 also. Afte r 15 days at 3,500 m, the subjects were inducted to 4,200 m by road, a nd measurements were repeated on days 1, 3, and 5, except blood gas va riables, which were done on day 10 only. Acute mountain sickness sympt oms were recorded throughout. The responses of RI were stable by day 3 of induction at 3,500 m, whereas it took 5 days for AI. Four days in transit for RI appear equivalent to 2 days at 3,500 m for AI. Acclimat ization schedules of 3 and 5 days, respectively, for RI and Al are ess ential to avoid malacclimatization and/or high-altitude illness. Both groups took 3 days at 4,200 m to attain stability for achieving acclim atization.