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Exercising in space helps astronauts avoid fainting back on Earth

As exciting as it is for astronauts to brave the final frontier, spending a prolonged amount of time suspended in microgravity comes at a cost. 

In space, the lack of gravity shrinks muscle mass and bone density, and those are just some of the impacts of being in space. Returning to Earth can also be a health hazard with many astronauts fainting due to changes in blood pressure. 

A new study has found that exercising in microgravity can help astronauts decrease the risk of fainting during and after the return journey. 

Researchers from the University of Texas Southwestern Medical Center examined how exercise impacted the risk of Orthostatic hypotension for astronauts.

Orthostatic hypotension is characterized by a sharp temporary drop in blood pressure after sitting or laying down for a long time. As the blood flow rushes to the feet, it can cause dizziness and fainting. 

“One of the biggest problems since the inception of the manned space program has been that astronauts have fainted when they came down to Earth. The longer the time in a gravity-free environment space, the greater the risk appeared,” said Benjamin Levine, M.D., the senior author of the study. “This problem has bedeviled the space program for a long time, but this condition is something ordinary people often experience as well.”

Twelve astronauts, eight men and four women ages 43 to 56, participated in the study, so it was a relatively small sample size. The astronauts spent six months in space and completed up to two hours of endurance and resistance training per day. 

Each exercise regime was individualized for each participant, and the goal of the daily physical training was to protect muscle mass, strength, and heart health. 

Blood pressure was recorded before, during, and after the six months in space. When the astronauts returned to Earth, they were also given a saline infusion.

None of the astronauts got dizzy or fainted when they landed, and the research is the first to prove that routine exercises while in flight can reduce the risk of Orthostatic hypotension.

“What surprised me the most was how well the astronauts did after spending six months in space. I thought there would be frequent episodes of fainting when they returned to Earth, but they didn’t have any. It’s compelling evidence of the effectiveness of the countermeasures–the exercise regimen and fluid replenishment,” said Levine. 

The researchers plan to test if the results can be replicated with larger sample sizes and for astronauts who spend more time in space. 

The study findings were published in the journal Circulation: Journal of the American Heart Association. 

By Kay Vandette, Staff Writer 

Image Credit: Shutterstock/Andrey Armyagov

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