What do extreme long-distance swimming and spaceflight have in common? It can shrink both hearts, according to a new study.
Reduces the pressure of both activities Gravity On the heart, it makes it so that the body does not have to work as hard to pump blood upwards. The heart is a muscle, and like other muscles in the body, if not used as much as before, it will contract.
To understand what effect weight loss has on the heart, the group of researchers analyzed the health data of retired astronaut Scott Kelly on the International Space Station between 2015 and 2016 and the health data of select endurance swimmer Benot Lecomte, who swam 1,753 miles (2,821 kilometers). ) In the Pacific Ocean in 2018.
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According to the study, between June 5 and November 11, Lecomte swam for 159 days, taking a 7-day and 32-day break due to unfavorable weather (which was a data collection limit, but for its own safety), according to the study. He swims an average of 8.8 hours per day.
Kelly spent 404040 days in space and spent several hours a day cycling, using a treadmill and doing resistance exercises. Doctors analyzed the hearts of both men before, during and after their respective journeys.
The researchers found that during their years in space, Kelly lost 0.74 grams of heart mass per week in her left ventricle in the heart’s main pumping chamber. Lecomte, during his swim in the Pacific, lost 0.72 glims of heart mass in a week in his left ventricle. The researchers also found that when Kelly and Lecomte first began their journey, both men experienced an initial drop in the diameter of their left ventricle. The average heart is about 280 to 340 grams in males and 230 to 280 grams in females. According to living science.
Overall, Kelly suffered 19% to 27% of ventricular mass damage during her year, and 20 to 25% when Lecomte swam in five months, co-author Dr. James said. University of Texas Southwestern Medical Center in Dallas Told the BBC.
In other words, despite exercising in a weightless environment (water and space), both men have contracted their hearts during the journey. That came as a surprise to scientists, as 1 to 3 hours of intense training a day has previously been found to be associated with increasing size and mass of the left ventricle. “We assumed that a longer duration of the swimming exercise would be sufficient for stimulation,” to increase the left ventricular mass, the authors wrote.
UT Senior author, professor of internal medicine at Southwestern Medical Center, Dr. Said in a statement. “Both the effect of gravity as well as the adaptive response to exercise play a role, and we were surprised that even extremely long-term low-intensity exercise does not contract the heart muscle.”
But after their journey, according to the BBC, once they returned to walk on the ground, the hearts of both men returned to their normal size. The researchers said they were still preparing to analyze Lebomte’s mammocentric resonance imaging (MRI) scans of the heart and also to see if the long-term effects of weight loss could be completely reversed.
The findings were published in the March 29 issue of the journal Rotation.
Published on Original Living Science.