Related Experiment Videos
The autonomous regulation system functional reserves evaluation in 7-day head down bedrest
R M Baevsky1, A G Chernicova, I I Funtova
1State Research Center RF Institute of Biomedical Problems RAS, Moscow, Russia. baevsky@pike.net.ru
Journal of Gravitational Physiology : a Journal of the International Society for Gravitational Physiology
|October 21, 2005
Summary
Head-down bedrest (HDBR) increased sympathetic nervous system activity and reduced regulatory reserves, indicating potential orthostatic intolerance. This suggests heightened sympathetic activity during simulated microgravity is a poor prognostic sign.
Area of Science:
- Cardiovascular Physiology
- Autonomic Nervous System Function
- Space Medicine
Background:
- Head-down bedrest (HDBR) simulates microgravity effects on the human body.
- Assessing autonomic regulation is crucial for understanding physiological adaptation to altered gravity.
Purpose of the Study:
- To diagnose autonomous regulation using heart rate variability during a 7-day HDBR experiment.
- To investigate the impact of simulated microgravity on sympathetic activity and regulatory reserves.
Main Methods:
- Utilized the "Pneumocard" device for novel physiological measurements.
- Applied a fixed respiration test to assess autonomic responses.
- Analyzed heart rate variability to quantify sympathetic activity and regulatory function.
Main Results:
- Observed increased sympathetic activity and reduced functional reserves of regulatory mechanisms during HDBR.
- Two volunteers with significant sympathetic index (SI) increase showed orthostatic intolerance post-experiment.
- Data supports the hypothesis linking increased sympathetic activity in microgravity to reduced regulatory reserves.
Conclusions:
- Simulated microgravity via HDBR elevates sympathetic nervous system activity.
- Reduced regulatory mechanism reserves accompanying sympathetic activation are unfavorable prognostic indicators.
- Findings highlight the importance of monitoring autonomic function during spaceflight analog studies.