Men and women react differently to long exposure to the zero gravity of space, with a resulting difference in health concerns, a study group has found.

For the past 3 years, six working groups set up by NASA and the National Space Biomedical Research Institute have been analyzing how the health of astronauts, both male and female, is affected by long-term spaceflight.

The groups, in investigating and summarizing the current state of knowledge of spaceflight's effects on human, focused on musculoskeletal, cardiovascular, sensorimotor, immunological, reproductive and behavioral consequences of spaceflight adaptation by men and women.

In anticipation of future long-duration spaceflights, the study will give insights into health and safety consideration for astronauts, with particular attention on differences impacting each sex.

Differences arising in the different sexes in natural Earth-bound environments and those triggered by long exposure to space flight were examined.

For example, the researchers said, while females experience less hearing loss in advancing age -- a health effect seen on Earth -- and don't display significant evidence of visual impairments after exposure to microgravity -- a health effect seen in space -- men experience more deficits in each of these areas.

Differences such as these can be taken into account as planners configure missions for the unique physiological responses of male and female astronauts.

Some other differences have been also been noted.

  • Orthostatic Intolerance, the inability to stand for long periods without fainting, has been more prevalent upon returning from space in female astronauts than has been seen in male counterparts.
  • Visual impairment, a result of anatomical ocular changes, have been seen in 82 percent of male astronauts as compared to just 62 percent in women astronauts.
  • In long-term exposure to microgravity, such as aboard the International Space Station, female astronauts have experienced a higher incidence of space motion sickness compared with men, and yet more men than women show symptoms of motion-sickness upon the return to Earth.

The researchers are quick to note that in terms of psychological or behavioral responses to space flight there is no evidence of differences between the sexes.

Taking gravity out the equation of how sex and gender factors influence major components of the human body introduces an entirely new factor to be taken into consideration, researcher say.

"Fortunately, we have the International Space Station," says Dr. Marshall Porterfield, Director of Space Life and Physical Sciences Research at NASA Headquarters.

"[The] Station provides us with years of biological data on male and female astronauts, and many of them continue to participate in ground-based studies to evaluate the lasting effects of spaceflight," he says.

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