[Mechanisms reducing orthostatic stability of humans in long-term space flight]

Investigations conducted in and following space flights showed consistent decreases in cosmonauts' orthostatic stability due to the effects of long-term microgravity. Degree of this orthostatic disturbance depends on many factors prime of which is adequacy of countermeasures and least consequential is length of space flight, personal features, and others. Shifts in initial circulatory status and establishment of a new level of circulation and functioning of the other body systems in microgravity appear to play the central role in loss of orthostatic stability. The paper contains an in-depth analysis of processes occurring in human body during long-term stay in microgravity impacting orthostatic stability post flight.