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November 16th, 2009
04:26 PM ET

Tracking fitness in zero G’s

By Caleb Hellerman
CNN Medical News senior producer

The space shuttle Atlantis lifts off this afternoon, on a mission to deliver spare parts to the International Space Station. I feel an extra connection, because in the past few weeks I’ve been talking to and emailing with Dr. Robert Satcher, an astronaut and orthopedic surgeon who specializes in treating cancer cases. He’s going into space for the first time, and as a preview, he and two of the NASA trainers showed off versions of his spacesuit and the treadmill that astronauts can use to stay fit while spending long months on the space station. (Watch Video)

One twist you don’t see at the gym: Astronauts have to strap themselves to the treadmill with a heavy cable, to keep from floating away when they try to run.

The thrust of the Atlantis mission is maintenance, not medical, but crew members spent a chunk of their pre-mission training, practicing what to do in case of a medical emergency. Satcher also points out that he’s part of “this ongoing tradition of experimentation, human experimentation, what happens to the body when you go into outer space.”

One thing I thought was interesting: On a space mission, you get taller - anywhere from half an inch to an inch and a half. Satcher explains that in zero gravity, fluid is redistributed in the body and the spine gets longer. You also lose bone and muscle mass as the body adapts to the lesser demands of zero gravity. It’s sort of the opposite of what happens when you lift weights at the gym, where your body responds by growing muscle. Astronauts are also prone to sleep disturbances; many crew members take the hormone melatonin as a sleep aid, to try to keep their body clocks adjusted.

In between maintenance work, the Atlantis crew will take measurements to help track musculoskeletal changes, and samples of blood and saliva to try to identify possible changes to the immune system.

Satcher, who likes to be called Bobby, says he’s thrilled to be flying into space for the first time. I hope he can find time to tell us about it, while he’s in orbit.

What would you like to hear about, from a doctor in outer space?

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soundoff (5 Responses)
  1. Kraig Rasool

    Since there are many effects of space on the body..Im wondering if they are any on the brain. Is your thinking affected in anyway? The
    mind and body work together here on earth so I imagine that in space
    the relationship should change since the body goes through so many
    ups and downs....Your spine and spinal fluid is vital and anything that
    adjusts it would and should have a great impact on the body after
    returning to normal gravity...However I for one would not take melatonin to keep my sleep habits in order....I feel that you should let
    them go haywire for awhile and let them adjust to space (depending
    on how long you are out there).

    November 17, 2009 at 11:53 | Report abuse | Reply
  2. Anu Rang

    This is a very interesting and informative article. The brain is most sensitive to oxygen supply. In zero gravity with more fluid flow to the brain, there is more oxygen supply to brain. Would astronauts on long term zero gravity living suffer any brain damage. Or is it avoided by creating artificial centrifugal gravity? For that matter how long can the brain with stand zero gravity? Most missions via space shuttle are only of a few days/weeks duration.

    November 18, 2009 at 06:52 | Report abuse | Reply
  3. A. Smith, Oregon

    @Anu, I would expect with more blood flow and therefore a greater oxygen supply to the brain tissue, that area of the body would be protected and perhaps even rejuvinated by extended zero G's.

    Perhaps Dr. Gupta could tell us what extensive Neurological Changes occur in extended zero G's. NASA has been doing research on this for years, although little if any is found in public NASA documents.

    November 18, 2009 at 23:30 | Report abuse | Reply
  4. Kai Collins

    i use a mechanical treadmill at home and it seems adquate for basic exercise'`-

    October 6, 2010 at 14:17 | Report abuse | Reply
  5. Pedestal Table 

    i prefer to use mechanical treadmills over electric treadmills;';

    October 20, 2010 at 17:13 | Report abuse | Reply

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Get a behind-the-scenes look at the latest stories from CNN Chief Medical Correspondent, Dr. Sanjay Gupta, Senior Medical Correspondent Elizabeth Cohen and the CNN Medical Unit producers. They'll share news and views on health and medical trends - info that will help you take better care of yourself and the people you love.