factors have a specific effect on the fluid systems of the body. In turn, these changes have
direct and indirect effects on the physiological and metabolic functions of the body. Studying
the changes of restructuring water-electrolyte exchange during spaceflight and the early
postflight period is of great practical significance, since changes in water-electrolyte balance
play an important role in developing postflight orthostatic instability and other detrimental
changes in the cardiovascular system. Impedancemetry experiments aboard the space station
using the Sprut-K Set demonstrate that it is possible to perform automatic measurement of the
main fluid volumes of a crew member’s body in real time in long-term spaceflight conditions
and show the possibility for using the bioimpedance method in weightlessness. The results of
this experiment make it possible to use bioimpedance analysis for real-time medical monitoring
since a crew member’s hydration status can be determined using the onboard impedance
meter multiple times and at any moment.
RESULTS
Results of SPRUT-MBI showed that the gravitation factor played the most important role in
reaching another level of water-electrolyte homeostasis. The use of a non-invasive, spaceflight-
compatible method of bioimpedancemetry for the first time in the world’s space programs
made it possible to evaluate the hydration status of the human body directly during long-term
spaceflight. Use of the Sprut-K onboard impedancemeter allowed the first repeat
measurements in real time of the main fluid systems in 12 cosmonauts during 6-month orbital
flights and the diagnosis of the development of dehydration of the body. Analysis of the
obtained results showed that all 12 cosmonauts exhibited hydration decrease, and the range of
individual changes during flight was quite narrow: from 5 to 10% for various fluid systems. The
results showed the uniform loss of fluid from various fluid systems in the body during long-term
spaceflight.
The maximum values for the shortage of fluids were noted immediately after the cosmonauts
returned to Earth, which spoke to the particular intensity of the effects that the final phase of
flight and landing have on water-electrolyte exchange. The development in weightlessness of
hypohydration was discovered, expressed as a uniform decrease in fluid spaces, and
characteristic changes in body composition. Moreover, the changes in and tempo of the
reduction of fluid volumes, as well as the fat and muscle mass of the body, were closely
comparable in character and magnitude. The majority of cosmonauts studied showed, despite
individual variations, a clear reduction in the level of hydration during long-term exposure to
weightlessness accompanied by a simultaneous loss of muscle mass. One week after flight
completion, all parameters being studied showed a clear trend towards restoration of preflight
hydration status and body mass.
PUBLICATION(S)
Noskov VB, Nichiporuk IA, Grigoriev AI. Dynamics of the body liquids and composition in long-
duration Spaceflight (Bioimpedance Analysis). Human Physiology. 2011;37:821-825. doi:
10.1134/S0362119711070231.