Earth’s gravity was undoubtedly a factor in the way human muscles evolved. The heart, for example, has to be strong enough to pump blood upward from the feet, where it would otherwise collect.
In low gravity, however, such muscles do not have to work so hard.
Since muscles must be exercised to remain healthy, and as preparations for extended missions are underway, scientists are concerned about the effect living in space can have on the human body.
Kelly’s heart shrank by an average of 0.74 grams per week during the year he spent in space, although the muscle continued to perform well.
The senior author of the letter is Dr. Benjamin Levine. Of Kelly’s heart, Dr. Levine says:
The research, published in the journal Circulation, compares the changes to Kelly’s heart size with an unexpected yet similar change in the heart size of an athlete who attempted to swim across the Pacific Ocean.
Tracking the human heart in space
Dr. Levine’s experience with space and cardiological health extends back to the 1980s, when he implanted the first catheter in an astronaut, which allowed NASA to monitor heart pressure while in space.
Kelly was in space between March 27, 2015, and March 1, 2016. The loss in left-ventricle mass he experienced was the equivalent of three-tenths of an ounce per week.
Kelly’s heart mass decreased in spite of a rigorous regimen of cycling, treadmill, or resistance work 6 days per week.
Dr. Levine recently completed a study of 13 astronauts who had been aboard the International Space Station for 6 months. The effects of the time spent in space varied from person to person.
Dr. Levine found that the astronauts who were the fittest at launch lost heart muscle during their missions, whereas the less fit flyers gained heart mass while in space.
“It all depended on how much work the astronaut’s heart did in space relative to how much it regularly did on the ground,” he says.
Content created and supplied by: Martin_Churu (via Opera News )