[Reactions of the human cardiovascular system to orthostasis following high altitude adaptation]

Orthostatic tolerance of 18 healthy test subjects (three groups of 6 persons each) who were exposed to an altitude of 2200 m for 12 days and 3200 m for 12 days was studied. The first group subjects remained in bed with minimized motor activity. The second group test subjects rested in bed and twice a day performed physical exercises with energy expenditures of 300 kcal/day. The third group subjects led a normal mode of life. The studies demonstrated that a prolonged restriction of motor activity and a decrease in the blood hydrostatic pressure of healthy test subjects in highlands resulted in their diminished orthostatic tolerance. Physical exercises proved ineffective in that case. The subjects who led a normal mode of life showed increased cardiovascular reactions to orthostatic tests.