Space Flight:
What We've Learned About OI & Bedrest from the Research

Prolonged bedrest has an impact on 2 other groups of people: astronauts and people who stay in the ICU a long time.

  • The research on space flight has told us more about orthostatic intolerance - what causes it and what is needed to prevent it from starting.

  • Women astronauts have more problem with orthostatic intolerance than the men.

  • More than 1/2 of the astronauts have lower back pain during space missions. More astronauts develop problems with the disks of their spine than the general public and than other army aviators.
Deconditioning and Space Travel

Space travel, specifically – being weightless,  has a major effect on the bodies of astronauts.10-13 A great deal of research has been done to find out how to prevent the changes so astronauts could spend longer time in space, to make trips to Mars.

They know that space travel affects the body in 3 ways:

  • Loss of proprioception – “motion sickness” because of changes in the system inside the ear that keeps us in balance. They tells us what is up and down, side ways. 
  • Changes in fluid distribution - where fluids are in the body, how much fluid is in the body.
  • Changes in bones and muscles.

People who spend 3 months in space develop problems with blood pressure, orthostatic intolerance, POTS;  they have problems doing exercise and take a long time to recover when they get back to earth. 

On earth, prolonged bedrest creates the same reactions in the body that happen with weightless and space travel. They study what happens to the body in healthy people who stay in bed  for long times. They test what it takes to keep the body from developing orthostatic problems and muscle atrophy, nerve dysfunction and resulting weakness and functional disability. (Functional disability = problems with daily self-care and function in everyday life12,13


 What does this mean for people with OI?

It has taken time for the experience and research to reach the physicians who do the research on OI (POTS and NMH). The research about bedrest/space travel results is not presented at the meetings or published in the general journals that most primary care doctors read, They present their findings at meetings about space travel; they publish their studies and their results in aerospace medical journals. 

Their experience does not always apply to people with OI due to medical conditions.   They have studied healthy people, mostly men, on forced bedrest. What they found works with these subjects is not always practical to use for people who are not healthy and on bedrest in the ICU or at home. Because it is with men, it may not necessarily apply to women because of the differences in muscle composition1 and the effect of hormones on the cardiovascular system.

Recent studies using what they have learned with people with POTS. It is only recently that they have come up with ideas that could be used. The first studies were with small numbers of people. New studies that are on-going will involve many more people. You can find more about this, in Managing OI and Recovering From OI.



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  10. Wikipedia. Effect of spaceflight on the human body. Accessed June 15. 2012.
  11. Lee et al.  Aerobic exercise deconditioning and countermeasures during bed rest. Aviation, Space, and Environmental Medicine January 2010;81(1): 52.63. Abstract.
  12. Hargens AR, Richardson S.  Cardiovascular adaptations, fluid shifts, and countermeasures related to space flight. Respir Physiol Neurobiol. 2009 Oct;169 Suppl 1:S30-3. Epub 2009 Jul 15.Abstract.
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Author: Kay E. Jewell, MD
Page Last Updated: June 25, 2012