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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