Scott Kelly’s body endured another surprise in space


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– They called it the “perfect nature versus nurture” experiment: Astronaut Scott Kelly was sent to the International Space Station for nearly a year, while his identical twin, astronaut and now Senator Mark Kelly, remained on Earth. When Scott Kelly returned home in March 2016, scientists compared his DNA and body composition to that of his twin and found that Scott was 2 inches taller than him and had a lower body mass, among other changes (the most of whom have since) reversed). Now, according to a study published Monday in the journal Circulation, heralded another big change: Kelly’s heart mass dropped from 6.7 ounces to 4.9 ounces during his cosmos journey, or about 27%, although the astronaut did not appear to suffer any major repercussions from it. “He did remarkably well for a year,” study co-author Benjamin D. Levine, a professor of internal medicine at the University of Texas Southwestern Medical Center, told the report. New York Times.

CNN Explainer: When humans deal with Earth’s gravity, the heart has to work harder to pump blood. However, in zero gravity, the heart doesn’t have to work as hard and therefore atrophies. Levine tells the Times that Kelly’s heart did so without becoming “dysfunctional.” The study also looked at Benoit Lecomte, an endurance swimmer who attempted to cross the Pacific in 2018. The buoyancy of the water and Lecomte’s near-constant horizontal state during his five-plus-month swim produced conditions similar to Kelly’s weightlessness, and his heart shrunk in size almost as fast. Although Kelly finished well, she also exercised quite a bit while in space using exercise equipment, probably preventing her heart from getting weaker. Scientists’ concern is that astronauts on future missions could be prevented from exercising due to injury, illness or broken equipment and suffer more serious effects. NASA is funding more heart research involving astronauts on long- and short-haul voyages. (Read more discovery stories).

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