Astronauts while outside the ISS. (NASA)
Hitekno.com – The Journal of Circulation publishes research the latest on March 29th that revealed the flight to outer space and swimming long distances can shrink the size of the heart.
Both of these activities reduce the gravitational pressure on the heart, so it doesn’t have to work as hard as possible to pump blood around the body.
The heart is made up of muscles and just like any other muscle function in the human body, if it is not used it shrinks.
The researchers analyzed health data from Scott Kelly, astronaut who has retired, on the International Space Station from 2015 to 2016.
In addition, health data from Benoît Lecomte, an elite swimmer, who swam as far as 2,821 kilometers across the Pacific Ocean in 2018.
Lecomte swam for 159 days between 5 June and 11 November 2018, taking a rest of seven days and 32 days due to unfavorable weather. He reportedly swam an average of about 5.8 hours per day.
Meanwhile, Kelly spends 340 days in space and works out a few hours a day, six days a week biking and using the treadmill.
Doctors then analyzed the two men’s hearts before, during and after the trip.
Researchers found that during a year in space, Kelly lost about 0.74 grams of heart mass per week in her left ventricle, the heart’s main pumping chamber.
Meanwhile, Lecomte while swimming across the Pacific lost 0.72 times the heart mass in a week in his left ventricle.
The experts also found that when Kelly and Lecomte first started traveling, both had an initial decrease in left ventricular diameter.
In comparison, the average heart rate is around 280 to 340 grams in men and 230 to 280 grams in women.
Overall, Kelly experienced 19 to 27 percent loss of left ventricular mass during a year in space and Lecomte experienced a 20 to 25 percent loss in five months while swimming.
In other words, despite exercising in a weightless environment, both men’s hearts shrank during space trips or swimming.
This finding surprised experts because high-intensity swimming exercise for one to three hours a day was previously found to be associated with an increase in left ventricular size and mass.
“Both the impact of gravity and the adaptive response to exercise play a role, and we were surprised that even low-intensity exercise for very long periods of time did not prevent heart muscle shrinkage,” says Dr. Benjamin Levine, professor of internal medicine at UT Southwestern Medical Center, is quoted from Live Science, Friday (2/4/2021).
But after the journey, the hearts of the two men returned to normal sizes.
Researchers are still planning to examine magnetic resonance imaging (MRI) scans of Lecomte’s heart from before and after swimming, to better understand whether the long-term effects of a weightless environment can be completely reversed. (Suara.com/Lintang Siltya Utami)
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