What does space do to heart health?

You asked: What does space do to heart health?

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NASA’s Insight landing has stirred up a lot of questions about space. How far does it go? Is there life out there? When will space travel become available to everyone? To get back down to earth – so to speak – many are left wondering what the effects of space travel are on people’s health. NASA and other researchers have been wondering the same thing and luckily for us, there are some answers.

Research seems to sum up the effects of space on heart health from 2 main differentiating factors that people get in space: 1) zero gravity; 2) increased radiation.

  1. In zero gravity conditions, there isn’t so much a sense of directionality when it comes to blood flow. Your body loses its sense of blood flow with respect to where your feet are and where your head is. It’s been described that under these conditions, the heart muscle becomes weaker. The shape of the heart becomes more round as opposed to conical and doesn’t pump as hard. Just like any other self-respecting muscle, when it doesn’t have to work as hard, it gets weaker. The issue is when people come back to Earth from being in space and now their heart has to pump against gravity in its weakened state. As far as scientists can tell, the heart does go back to “normal” after re-equilibrating with gravity, but in the short-term, space travelers can experience low blood pressure with standing, dizziness, and even passing out because their body’s can’t regulate their blood pressure as well to keep blood pumping to the brain.

  2. Radiation comes into play once astronauts get past a magnetic shield that protects those on Earth from a grand majority of these harmful cosmic rays. To give you an idea, radiation is measured in units called millisieverts (mSv) and the farther away from Earth you get, the more ambient radiation you’re exposed to. For example, a typical plane flight exposes you to about 0.003 mSv per hour. Astronauts are exposed to anywhere from 50 up to 2,000 mSv of potentially harmful radiation. While it’s not clearly defined how much is too much, researchers have shown that space Apollo astronauts (who were exposed to such doses of radiation) did have significantly higher rates of cardiovascular disease later in life. In fact, they were about 5 times as likely to die of heart disease than those who hadn’t been to space. The reason is thought to be that radiation causes inflammation and damage to blood vessels and can lead to extensive atherosclerosis in a shorter period of time than would normally happen for those living on Earth.

Before you sign up for a weekend lunar vacation, be sure to stay grounded as to the risks. As space travel becomes more common, there will likely be much more information about what the risk really is.


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