NASA ISS Astronauts' Health: Journal of Bone and Mineral Research

NASA astronaut Jeffrey Williams, Expedition 22 commander, exercises using the Advanced Resistive Exercise Device (ARED) in the Tranquility node of the International Space Station. 

Image Credit: NASA.

A new study, published in the September 2012 issue of the Journal of Bone and Mineral Research, looked at the mineral density of specific bones as well as the entire skeleton of astronauts who used a new, stronger “weight lifting” machine.

Of course, weights don’t really “weigh” anything on the space station but resistance machines allow astronauts to get the same kind of workout.

The new Advanced Resistive Exercise Device (ARED), installed in 2008, doubles the maximum simulated weight to as much as 600 pounds.

Researchers compared measurements from 2006 until 2008, when astronauts used a less capable workout machine.

They found that astronauts using the advanced system came home with more lean muscle and less fat, and kept more of their whole body and regional bone mineral density.

Those same astronauts also consumed sufficient calories and vitamin D, among other nutrients. These factors are known to support bone health and likely played a contributing role.

"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 agency's Johnson Space Center in Houston and lead author of the publication.

Since the 1990s, resistance exercise has been thought to be a key method of protecting astronauts' bones.

Normal, healthy bone constantly breaks down and renews itself, a process called remodeling. As long as these processes are in balance, bone mass and density stay the same.

Earlier studies of Russian Mir space station residents found an increased rate of breakdown, but little change in the rate of regrowth, resulting in an overall loss in bone density.

In the new study, astronauts who used the ARED device still had increased bone breakdown, but their bone renewal tended to increase, likely resulting in a better balance in whole bone mineral density.

"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 Johnson and coauthor of the study.

NASA study: Omega-3 Fatty Acids Slows Bone Loss (Osteoporosis)

NASA-sponsored studies have found that omega-3 fatty acids found in fish oil may play a role in mitigating bone breakdown that occurs during spaceflight and in osteoporosis. Ongoing research for decades has looked for ways to stop bone density loss in astronauts. The solution could have significant implications for space travelers and those susceptible to bone loss on Earth.

The studies' results are published in the May issue of the Journal of Bone and Mineral Research. The paper reports on four types of studies using cell culture, ground-based bed rest, and data from both space shuttle and International Space Station crew members. NASA studies bone density loss because it is one of the main effects of exposure to the weightlessness of space.

Scientists hope to find ways to counteract the problem for astronauts on long-duration space voyages.