NASA More Hopeful on Astronauts' Fitness for Long Missions

A study announced Aug. 24 by the agency proves a new workout machine and a diet offering sufficient calories and vitamin D, among other nutrients, allowed ISS crew members to retain more bone mineral density.

For years, NASA has studied and sought to solve the problem of bone density loss in astronauts during long-term spaceflights. International Space Station (ISS) crew members long have used exercise machines to attempt to reduce bone loss, and now a study published in the September 2012 issue of the Journal of Bone and Mineral Research shows the latest methods are succeeding.

The study -- by six authors from the Johnson Space Center's Human Adaptation and Countermeasures Division, the University of Bonn's Department of Nutrition and Food Science, the Profil Institute for Metabolic Research GmbH (Neuss, Germany), and the Universities Space Research Association's Division of Space Life Sciences (Houston) -- found a new workout machine and a diet offering sufficient calories and vitamin D, among other nutrients, allowed ISS crew members to retain more bone mineral density.

The machine is the Advanced Resistive Exercise Device was installed on the station in 2008. It doubles the maximum simulated weight crew members can lift, to a total of 600 pounds. The six researchers compared bone density measurements from 2006 until 2008 and found astronauts coming home after using ARED and the better diet had more lean muscle, less fat, and kept more of their bone density.

"After 51 years of human spaceflight, these data mark the first significant progress in protecting bone through diet and exercise," said Dr. Scott M. Smith, NASA nutritionist at the Johnson Space Center in Houston and lead author of the study. "Although more research needs to be done in this regard, our study marks a significant milestone in our long search to find ways to help ensure crew health and performance on long-duration missions. These data will be critical in enabling us to send humans, once again, to destinations beyond low Earth orbit."

He and his colleagues found astronauts who used the ARED still had increased bone breakdown, but their bone renewal tended to increase, according to NASA's news release.

"The increase in both bone breakdown and formation suggests that the bone is being remodeled, but a key question remains as to whether this remodeled bone is as strong as the bone before flight," said Dr. Jean Sibonga, NASA bone discipline lead at JSC and co-author of the study.

According to NASA, astronauts in the past have lost an average of 1 to 2 percent of their bone density per month, compared with an elderly person who loses about 1 to 2 percent per year.

An experiment now being conducted on ISS is studying the benefits of lowering crew members' sodium intake, according to the release.

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