To make sure you never miss out on your favourite NEW stories, we're happy to send you some reminders

Click 'OK' then 'Allow' to enable notifications

Not now

Astronaut’s Heart Shrinks By Almost A Third After A Year In Space

Emily Brown


Astronaut's Heart Shrinks By Almost A Third After Year In SpacePA Images

A scientific study has revealed that astronaut Scott Kelly’s heart shrank by almost a third during the months he spent on the International Space Station. 

Kelly set off on March 27, 2015, for his historic 340-day mission aboard the International Space Station, during which time he exercised six days a week with the help of a treadmill, a stationary bicycle and a resistance machine.


After returning on March 2, 2016, scientists looked at the impact the mission had on Kelly’s heart, with the results published in the journal Circulation on Monday, March 29, this year.

PA ImagesPA Images

Due to the lack of gravity in space, the human body typically undergoes a number of transformations including a swollen head, shrivelled legs and bones that become more brittle. In the study, scientists revealed that Kelly’s time in space had caused the largest chamber of his heart to shrink in mass from 6.7 ounces to 4.9 ounces, a decline of about 27%.

Dr. Benjamin D. Levine, the senior author of the study and a professor of internal medicine at the University of Texas Southwestern Medical Center and Texas Health Presbyterian Dallas, said the change did not appear to have any negative effects on Kelly, The New York Times reports.


He said the astronaut did ‘remarkably well over one year’, explaining: ‘His heart adapted to the reduced gravity. It didn’t become dysfunctional, the excess capacity didn’t get reduced to a critical level. He remained reasonably fit. His heart shrank and atrophied kind of as you’d expect from going into space.’


Kelly has said that he pushed himself when it came to exercising in space and that he lifted more weight than he did at home, but his work did not prevent the shrinkage. Due to the lack of gravity, his heart did not have to pump as hard and lost some of its fitness from less strenuous use.

Though the astronaut is still healthy, the results of his mission may be a cause for concern for future missions to Mars. Levine said astronauts would ‘probably be okay’, based on knowledge of the experience of Kelly and other astronauts, but problems may arise if an astronaut became injured, sick or could not exercise.


If those on the mission ended up with weaker hearts from months of space travel, they could become lightheaded and faint when stepping foot on Mars.

PA ImagesPA Images

After his return from space, Kelly has said he doesn’t have ‘any [physical] symptoms from being in space’, adding: ‘Today, if you let me, I’d go do it all over again.’

In an effort to stay informed about the effects of space travel, NASA has provided financing to study the heart health of the next 10 astronauts who spend a year in space.


If you have a story you want to tell, send it to UNILAD via [email protected]

Topics: Science, Astronaut, heart, International Space Station, NASA, Now, Space


The New York Times and 1 other
  1. The New York Times

    Note to Future Space Travelers: Prepare for a Shrinking Heart

  2. Circulation

    Cardiac Effects of Repeated Weightlessness During Extreme Duration Swimming Compared With Spaceflight

Emily Brown
More like this

Chosen for YouChosen for You


Guilty defendant casually walks out of courtroom to freedom when nobody is looking

20 minutes ago

Most Read StoriesMost Read

Spider-Man: Across the Spider-Verse fans think Gwen might be transgender

4 hours ago