Astronauts are at the high risk of rapid bone loss, according to research paper presented at the American College of Rheumatology Annual Scientific Meeting in Atlanta.

Exposure to long duration of weightlessness or microgravity in spaceflights makes them prone to long term bone degeneration. Researchers studied 28 US crew members and assessed their bone mineral density, indicator bone strength.

The study included 24 men and four women in the age group of 36 to 53 years who spent 95 to 215 days in space. All members had their BMD measured both before and immediately after their return within 33 days. Their BMD was measured again between six and 18 months of return from space.

The BMD of the crew members measured immediately after return was markedly lower than would have been predicted. However, researchers also noted after roughly 12 months of their return from space that BMD of several persons were still lower than would have been predicted even the crew members had not spent the long-duration in the space flight.

Researchers have thus concluded that exposure to microgravity may have a long-term bad impact on the bone health of crew members. Shreyasee Amin, MD, MPH; associate professor at the Mayo Clinic and lead investigator in the study said, "Our results complement the work of others and show that even after one year following return from space, the BMD at some sites—particularly the hip—will not have completely recovered for some crew members,”.

"Ideally, we need to identify better strategies to prevent the bone loss that occurs during space flight so that we can keep the bones of those serving on long-duration space missions healthy and strong for the long-term," she added.