[The reactions to weightlessness exposure: adaptation or disease?].

The arguments characterizing the poor theoretical validity and low profitability of the concept of "weightlessness disease" developed during recent few years by its authors are advanced. The morphofunctional rearrangements occurred in the body during space flights are considered as the result of adaptation-disadaptation rearrangements directed towards supporting the equilibrium with a set of reduced environmental requirements. Understanding the mechanisms of adaptation rearrangements creates the real but not forced basis for developing the measures for cosmonauts health stabilization and spaceflight safety.