[Dynamics of the orthostatic tolerance of cosmonauts after flights lasting from 2 to 63 days].

Changes in orthostatic tolerance were studied in 25 cosmonauts after their flights to 2 to 63 days in duration aboard the spacecraft Soyuz and the orbital station Salyut. Postflight orthostatic tolerance decreased to a greater extent in those cosmanauts in whom it was below the medium level preflight. Orthostatic intolerance increased with the flight time. The development of orthostatic intolerance in the crewmembers of the Salyut station was significantly delayed due to better environmental conditions and countermeasures against adverse effects of space flight. An application of countermeasures against postflight orthostatic intolerance and a gentle regimen of readaptation are indicated. An exposure to prolonged weightlessness changes significantly the structure of orthostatic responses. This ought to be taken into consideration when inflight orthostatic tests are being evaluated and when countermeasures against postflight orthostatic intolerance are developed.