Long-duration bed rest as an analog to microgravity

摘要: Long-duration bed rest is widely employed to simulate the effects of microgravity on various physiological systems, especially for studies bone, muscle, and cardiovascular system. This analog also extensively used develop test countermeasures microgravity-altered adaptations Earth gravity. Initial investigations bone loss horizontal with view that this model represented closest approximation inactivity minimization hydrostatic effects, but all Earth-based analogs must contend constant force gravity by adjustment G vector. Later concerns about lack similarity between headward fluid shifts in space those encouraged use 6 degree head-down tilt (HDT) as pioneered Russian investigators. Headward may redistribute from legs head. At present, HDT normal volunteers most common simulation loss, muscle cardiac atrophy, orthostatic intolerance, reduced strength/exercise capacity. Also, current physiologic are focused long-duration missions such Mars, so review we emphasize durations 30 days longer. However, recent results suggest less representative an other important problems flight shifts, spinal dysfunction radiation hazards.