Brian Johnson explains how gravity strengthens the human body by maintaining muscle mass, bone density, and heart and lung strength. Astronauts in space lose these gains quickly without gravity's constant pressure. Standing and sitting alone keep your body resilient.
When astronauts go into space, they just deteriorate. They lose muscle mass, they lose bone density. Their lungs become less powerful, their heart becomes less powerful just because there's no gravity. The fact that gravity is pulling on your body all day, every day, is making you stronger. Your bones are stronger, your muscles are stronger. Your heart is stronger. Your lungs are stronger. And just removing that little obstacle of gravity, the human body starts to deteriorate. By standing up and sitting down, you are helping gravity help your body get strong and helping your blood flow move around.
