Dry Immersion as a Ground-Based Model of Microgravity Physiological Effects

Abstract

Dry immersion (DI) is one of the most widely used ground models of microgravity. DI accurately and rapidly reproduces most of physiological effects of short-term space flights. The model simulates such factors of space flight as lack of support, mechanical and axial unloading as well as physical inactivity. The current manuscript gathers the results of physiological studies performed from the time of the model’s development. This review describes the changes induced by DI of different duration (from few hours to 56 days) in the neuromuscular, sensory-motor, cardiorespiratory, digestive and excretory, and immune systems, as well as in the metabolism and hemodynamics. DI reproduces practically the full spectrum of changes in the body systems during the exposure to microgravity. The numerous publications from Russian researchers, which until present were mostly inaccessible for scientists from other countries are summarized in this work. These data demonstrated and validated DI as a ground-based model for simulation of physiological effects of weightlessness. The magnitude and rate of physiological changes during DI makes this method advantageous as compared with other ground-based microgravity models. The actual and potential uses of the model are discussed in the context of fundamental studies and applications for Earth medicine.

Ground-Based Analogs for Human Spaceflight

“…Whereas methods such as HDT and supine bed rest redistribute stress to the posterior of the body, a lack of a support device means no loading effects are experienced the body. The effects of microgravity are demonstrated by dry immersion on a faster timeline than methods like HDT, presenting similar results to a 21-day HDT study in just 3 days (Tomilovskaya et al, 2019). 17% loss in plasma volume, comparable to loss experienced after spaceflight, is seen after 2 days of dry immersion (Treffel et al, 2017).…”

The Effect of Five-Day Dry Immersion on the Nervous and Metabolic Mechanisms of the Circulatory System

“…DI reproduces cardiovascular, motor and other changes similar to those observed in space flights. Moreover, the severity and directionality of adaptation processes under immersion exposure are with those observed in space flights of various durations (Tomilovskaya et al, 2019).…”

“…273 dated June 23, 2010), and the written voluntary Informed consent was obtained from the participating in the study testers. To simulate the physiological effects of microgravity, the subjects were immersed in water in lying down to the level of the shoulder upper third (water t = 33-34 • C) without contact with it, since they were separated from the water by a waterproof, freely fixed to the sides fabric, being freely "hung out" in an immersion environment (Tomilovskaya et al, 2019). During DI, the volunteers were not subjected to either pharmacological or any other additional influences aimed at preventing developing adaptive shifts in physiological systems.…”

Does simulated microgravity induce significant changes in human gut microbiota? New answers with dry immersion, an innovative ground-based model.

“…Unlike the bedrest, this model completely limits the possibility for the subject to rest on supports. Recent studies on cardiovascular, postural and neuromuscular changes and comparisons of the effects of 21 days of bedrest and 3 days of Dry Immersion have shown similar effects in their amplitude, suggesting that the immersion induces physiological changes in the weightlessness much faster [12]. This allows us to be as close as possible to the modalities of muscular inactivity encountered in real situations in space compared to the classic bed rest model [13].…”