Реферат: Dry Immersion (DI) and Head-Down Tilt Bed Rest (HDBR) are the primary ground-based models for simulating physiological effects of microgravity. The DI model more accurately reproduces support unloading, leading to a faster onset of systemic physiological deconditioning akin to spaceflight. The HDBR model, while less precise in replicating full support withdrawal, facilitates longer-duration experiments and better simulates some fluid shift-related phenomena. Thus, the choice of the model to use falls on the researcher and depends on the goals of the planned experiment and the technical possibilities of its implementation. In spite of the fact that both models have been widely used for years, no experiments directed to the comparison of their effects have been performed before. This study presents results from parallel 21-day DI (n=10) and HDBR (−6°, n=12) experiments with identical test protocols. The daily routine, diet and set of experimental studies in the two experiments were almost identical. All participants passed the medical commission at the IBMP of the RAS, and no pathologies excluding their participation in the experiment have been found. Before their final approval for the experiments, the subjects signed the informed consent to their participation in the study. The experiment was held at the IBMP of the RAS on the Dry Immersion Simulation and Training Facility, a component of the Unique Scientific Installations, Medical and Engineering Complex for Testing Innovational Technologies of Space Biomedicine for the Provision of Orbital and Interplanetary Missions, as well as for the Development of Practical Healthcare. Comparative analysis of equal-duration Dry Immersion (DI) and Head-Down Bed Rest (HDBR) revealed qualitatively similar systemic changes, including increased body length, weight loss, negative water balance, and reduced cardiovascular parameters. Quantitative differences were evident in their dynamics. The rate and magnitude of initial body-length increase were greater in DI, while recovery was faster post-HDBR. The accelerated spinal elongation in DI likely results from its superior replication of axial and support unloading, including a rapid decrease in postural muscle tone. This highlights DI's relevance for modeling spaceflight-induced body-length changes, which can pose operational risks. Cardiovascular responses also diverged: HDBR induced a more pronounced and sustained heart rate reduction, likely due to altered baroreflex engagement from fluid shifts, while DI led to a more persistent decrease in blood pressure, potentially linked to greater plasma volume loss. The hypogravitational spinal syndrome was more acute but shorter-lived in DI, consistent with its more complete postural unloading and rapid loss of anti-gravity muscle tone. These findings underscore that both models are valid, with DI providing a more rapid and intense simulation of axial unloading and HDBR better suited for prolonged studies of gradual cardiovascular adaptation. The choice of model should be guided by specific research objectives.

Библиографическая ссылка: Tomilovskaya E.S. , Rukavishnikov I.V. , Shigueva T.A. , Saveko A.A. , Bekreneva M.P. , Shpakov A.V. , Puchkova A.A. , Ponomarev I.I. , Glagoleva S.O. , Shishkin N.V. , Savinkina A.O. , Vassilieva G.Y. , Kitov V.V. , Orlov O.I.
Effects of equal duration Dry Immersion and Head-Down Bed Rest on human body
45th International Symposium on Gravitational Physiology (ISGP), Cologne, Germany, 25-29 May 2026 25-29 May 2026