We all dream of living the experience of space, seeing the earth from the height of the International Space Station (ISS), to experience the unique sense of lack of gravity. However, this experience, while impressive, has an impact on the human body.

The human body has evolved to function with the gravity of the earth.

Astronauts Sunni Williams and Bush Wilmore returned to Earth after being sent to the International Space Station, which was originally scheduled to last eight days, but expanded for nine months due to conditions. Now, their recovery process begins.

“Space is by far the most extreme environment that people have faced and we have just evolved to withstand extreme conditions,” says Professor Damian Bailey, who studies the physiology of the human body at the University of South Wales.

The entry into space changes the human body – and at first this is wonderful. “You feel like you’re on vacation,” says astronaut Tim Pick, who went to the ISS in 2015.

“Heart function is easier, as is the case for muscles and bones floating around the space station in this wonderful environment without gravity.”

Imagine spending weeks lying in bed and never having to get up – this is actually a technique used by scientists to investigate the effects of gravity.

Muscle strength

As for the muscles, the rule says “use them or you will lose them”.
Even the simple act of standing still uses muscle all over the body to keep the human body upright.

And this is not the case in the ISS.

Muscle strength acquires a different meaning when everything is practical without weight.

Acceleration of aging

The heart and blood vessels also have easier work as they do not have to draw blood against gravity – and begin to weaken. The bones become weaker and fragile.

There should be a balance between the cells that break down the old bones and those who make new ones.

But this balance is disturbed without feedback and resistance to gravity.

“Every month, about 1% of their bones and muscles weaken, accelerating aging,” says Professor Bailey.

And this becomes obvious upon returning to Earth.

The following video shows astronauts needing support to get out of the capsule and transferred to a stretcher.

All this is why astronauts who go in space must be in excellent physical condition.

Then, their daily routine includes two hours of exercise – a combination of runs in treadmill, bicycle and weight – to maintain as much muscle and bone health as possible.

Upon their return, Sunni and Bush will start an intensive exercise program to regain their lost function.

“It will take them a few months to build their muscle mass again,” says Dr. Helen Sarman, who was the first British to go in space.

The bone mass could take “a few years” until it recovers – but even then, there are “subtle changes in the type of bones that are restructured after returning to Earth and may never fully return to normal”.

But these only concern muscles and bones while space changes the whole body.

Even the kinds of good bacteria living in our bodies – the microbiome – change. The fluids in the body are also shifting to the microfinance.

Instead of being attracted to the feet, as on earth, the liquids move to the chest and face. The swollen face is one of the first perceived changes in the body.

But this can also lead to swelling in the brain and eye changes, including optic nerve, retina, but even in the shape of the eye.

This “space -related syndrome” can lead to blurred vision and possibly irreversible damage.

Dizziness

The microfinance also deforms the vestibule, which is responsible for how we balance and perceive the direction. In space, there is no up, down or sideways. Can lead to disorientation.

Tim Paco says that “the initial phase of stopping to feel dizzy, regaining your balance and having the power to walk normally lasts only two or three days.” “These first two or three days on earth can be truly exhaustive.”