[Evaluation of the antiorthostatic reactions of the cerebral circulation].

On the basis of experiments on 122 healthy male test subjects the norms of reactions of cerebral circulation to antiorthostatic exposures, basic principles and evaluations of its antiorthostatic tolerance (AOT) were established. The level of AOT was found to increase in acrobats in the course of their training, in test subjects after 30-day head-down tilting, and in space crewmen postflight. This increase can be regarded as an adaptive reaction of cerebral circulation to the excess blood rush to the head both on the Earth and in weightlessness. The similarity of regulatory hemodynamic changes in the above groups shows the possibility and indicates approaches to the ground-based training of cerebral circulation aimed at facilitating and accelerating its adaptation to weightlessness.