Astronaut Bone Strength

Astronaut bone loss is not something we think about often in our earthbound lives. But new research by NASA has revealed some surprising conclusions that may be beneficial to us all. The benefits of good nutrition and regular exercise in humans is common knowledge. If we eat a variety of nutritious foods and establish an exercise routine (including resistance training and moderate cardio), any extra pounds we may be carrying will disappear, and our bodies will reset to a healthy weight. We’ll also achieve a number of health benefits that will make any routine check-up with the family doctor a pleasant one – including, but not limited to, a healthy cholesterol level, perfect blood pressure, and a decreased risk of falling victim to some serious medical conditions in the future (diabetes, heart disease and cancer being the major diet-related killers in modern Western society).

But the advantages of eating well and exercising right aren’t just limited to those of us who are earthbound. Recent research from NASA has highlighted the positive effects that a good diet and resistance training have on astronauts (and in particular, astronaut bone loss) in space. Astronaut osteoporosis has been a long-running dilemma for NASA nutritionists and scientists. Loss of bone density is an issue with no easy answer, even with some of the most highly trained minds in one of the most prestigious scientific organizations on Earth working on it.
NASA has found that eating right and exercising hard in space protects the bones of the International Space Station astronauts, in a finding that has possibly led us closer to solving one of the key issues facing future explorers traveling outside of low Earth orbit.

In the study, published on September 2012 in the Journal of Bone and Mineral Research, NASA nutritionists looked at specific bone mineral density, as well as the entire skeleton of astronauts, using a new “weightlifting” machine modified to provide extra resistance. In zero gravity, the weights are very light, but the new resistance machines allow astronauts to get a similar type of training as if they were using resistance machines back on Earth. The Advanced Resistive Exercise Device (ARED), installed in 2008, provides twice the maximum simulated weight, reaching about 600 pounds.

Astronaut bone strength

The researchers compared the astronauts’ body measurements from 2006 to 2008, when an exercise machine with much less resistance was being used. They found that when using the advanced system, astronaut bone loss was less pronounced, and the astronauts came back with much more muscle and less fat. They also kept more of their whole body and regional bone mineral density. They also kept their calorie consumption to a sufficient level and supplemented their diet with vitamin D and other important nutrients. Bone health is dependent upon the body receiving enough calories and the correct ratio of essential vitamins and minerals, so it’s also highly likely that these factors contributed to the positive outcome.

“After 51 years of space travel, these data mark the first significant advance in protecting bones through diet and exercise,” said Dr. Scott M. Smith, a nutritionist from the NASA Johnson Space Center in Houston and lead author of the paper.

The importance of resistance training

Resistance training has been a mainstay in the preparation and training programs of astronauts, particularly as a means of protecting bones, ever since the 1990s. Heading into zero gravity can cause astronauts to lose 1 to 2 per cent of their bone density each month. Back on Earth, elderly adults typically lose this amount each year. Remodeling is a natural process that occurs in our bodies, where healthy bones leach and reabsorb minerals. In space, the reabsorption doesn’t happen, causing this huge loss of bone density. However, if these processes are in balance, bone mass and density will remain the same. Previous studies conducted on astronauts in the Russian Mir space station found an increase of breakdown rates of bone density, but with very little change in regrowth rates, resulting in a total loss of whole body bone density.

In the 2012 study, the astronauts using the ARED still experienced bone loss and increased bone turnover, but their bone renewal increased, likely resulting in a better balance of the 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 NASA Johnson Space Center, and co-author of the study.
This study shows that with proper exercise and nutrition, crew members on long journeys in space can return home with much a much healthier ratio of bone mineral density. To answer the crucial question about whether the astronauts’ bones are as strong as before they traveled into space, additional studies on bone strength before and after flight are currently underway.

Aside from bone strength, further studies on exercise and diet combinations are required to understand what is best for the long-duration astronaut teams. An experiment being conducted on the International Space Station is examining how different proportions of animal protein and potassium in the diet affect bone health. Another experiment is assessing the benefits of reduced sodium intake. NASA’s space food menu has been updated and reformulated by its nutritionists, with over 80 items having had their sodium content reduced.
“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,” said Smith. “These data will be critical in enabling us to send humans, once again, to destinations beyond low Earth orbit.”

What can we learn from NASA?

The research conducted by NASA on the health of their astronauts has far-reaching consequences for the rest of humanity, particularly with regards to bone health as we age, and the importance of diet and exercise to prevent major losses in bone density.

While research is ongoing, the evidence is stacking up that resistance training is one of the most effective ways of maintaining a healthy body weight, and there are few things we can do that will provide more protection against bone loss as we age.

Combine resistance training with a healthy diet and some moderate cardio activity (e.g. walking, running, swimming or cycling), and you will be well on your way to leading a long and healthy life with strong bones and the ability to be active well into your later years.