Space travel can literally shrink your heart

Originally published at: Space travel can literally shrink your heart | Boing Boing

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I wonder if this effect would be altered if they lowered the oxygen in the atmosphere mix on the station.

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I fly only Millennium Falcon or USS Enterprise for space travel, or I don’t go at all.

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among the many hazards of space travel

Just wait until Christmas comes around again!

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This is mostly due to the force it takes to pump blood up to your head under Earth’s gravity. Reducing O2 might make the heart and lungs need to speed up (and increase health risks if it was lowered a lot) but it wouldn’t change the force that the heart pumps with.

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But earthbound adaptation to low oxygen doesn’t involve a correspondingly higher heart rate over the long term. It generally involves higher volume and stronger pumps and thus a larger heart. I’m not sure I understand why that adaptation would be different in space.

I guess this is why Bezos and Musk want to go to space; they don’t actually have hearts in the first place.

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The short answer is the difference is Earth’s gravity makes pumping blood up to the brain harder requiring more forceful heart contractions. Even at lower O2 it wouldn’t take much force to pump enough blood to the brain without gravity

Don’t know what long-term low oxygen adaptation your talking about. The only real long-term low oxygen I’m familiar with on Earth is at high altitudes which means a general reduction in air pressure (not just O2). In those conditions there can me a wide mix of physiological responses depending on the person and timescale.

All of the responses are due to low systemic O2, which is unhealthy. Having a smaller heart at the ISS is not unhealthy. Intentionally reducing the oxygen to a point that astronauts would struggle to get enough unless they increase their heart contractions seems like it would create problems much worse than the one its trying to solve

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Yes, that would be the adaptation I’m talking about. Perhaps my view is limited to only looking at endurance athletes who typically adapt with larger hearts and higher red blood cell counts. I guess nobody is running marathons on the ISS.

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