Work capacity in acute exposures to altitude.

Abstract

Four men ranging in age from 19 to 74 were subjects in 3 Balke tests on the von Dobeln ergometer at each of 4 pressures, 740, 535, 485, and 455 mm Hg, the last 3 pressures being in the altitude chamber without prior acclimatization. The effects of training on altitude performance were balanced out and, at the same time, training effects were assessed. Observations made included work capacity, VE max [maximum vertillation rate], VO2 max [maximum rate of O2 consumption], R, the time course of heart rate, blood pressure, and VE; in recovery, heart rate and blood pressure were observed for 5 min. Blood was obtained for lactate in the 6th min. of recovery. Taking VO2 max at 740 as 100 the relative values were 90 at 535, 86 at 485, and 81 at 455. VE max was independent of altitude as was maximum blood pressure. Maximum heart rate was slightly but significantly less at 455 than at 740. Lactate was not significantly less at 455 than at 740. It appears that in the first stage of acclimatization in chronic exposures to altitude, performance is inferior to that in acute exposures.