Muscles need the tension imposed by gravity to stay in shape. Spending a lot of time away from this gravitational earth voltage can totally damage them. Running on a vertical carousel can help exercise the legs and arms of astronauts by simulating the level of gravity on the ground.
At a press conference prior to his first zero-gravity experience in 2007, theoretical physicist Stephen Hawking stated the desire of his flight to encourage public interest in space exploration. He pointed out that with humanity's increasing risk of eliminating itself here on Earth, humans need to colonize space. Since then, Stephen Hawking argues that we have to achieve this in less than two centuries or we are doomed to extinction. It was undoubtedly encouraged by the announcement by President Barack Obama last April of a new initiative to send people to Mars.
To function properly, we need gravity. Without it, the environment is, in various ways, less demanding on the human body, and this is observed upon return to Earth. For example, astronauts returning from the Apollo missions were clearly weakened. And this is nothing compared to the effects of a trip to Mars.
One of the first organs to be affected is the heart, which shrinks practically a quarter after a week into orbit. The atrophy of the heart leads to a decrease in blood pressure and the amount of blood expelled by this muscular organ.💪
