How space weakens human body – CSN News

To most of us the idea of floating through outer space and looking down on Earth is like a distant dream.

But the experience of astronauts Suni Williams, Butch Wilmore and others who returned recently from an unexpected nine month stay aboard International Space Station (ISS) has serious physical effects.

“Space is the most extreme environment that humans have ever experienced,” Prof Damian Bailey says, a physiology specialist at the University of South Wales. “We just haven’t evolved the ability to deal with it.”

Effects of zero gravity on human body

Weightlessness may feel exhilarating at first – like an extended holiday, according to British astronaut Tim Peake – but the lack of gravity causes the body to quickly lose strength and resilience.

Space is a place where you don’t need to be upright or hold your weight. This causes a rapid loss in muscle mass. Prof Bailey says: “It is a simple matter of using it or losing it.”

Impact of space on heart, muscles and bones

While it may seem effortless to float inside the ISS, your body slowly deteriorates. Even your blood vessels and heart are weaker over time because they no longer need to fight against Earth’s pull. It is the same with bones. They become brittle, and lose density as they are not under constant pressure.

Astronauts in space lose around 1 per cent of their muscle and bone mass every month, leading experts to liken it to ‘accelerated ageing.’ Astronauts need help to walk and stand when they return home. Williams and Wilmore needed assistance getting out of the capsule onto stretchers.

That’s why astronauts go into space in peak physical condition and stick to a strict exercise routine while aboard the ISS – including two hours a day of treadmill running, cycling, and weight training.

As Dr Helen Sharman, first Briton to travel into space, explains recovery is not a quick fix. “It can take months to regain muscle mass and years for bones to rebuild – and even then, some changes to the bone structure may be permanent.”

Space affects more than muscles.

Microgravity’s effects don’t just affect muscles and bones. Spaceflight reshapes the body in surprising ways, from shifting fluids upwards – giving astronauts the classic ‘puffy face’ look – to altering their gut microbiome.

Perhaps more concerning is the pressure this causes inside the skull, leading to changes in the optic nerve and retina, and contributing to the mysterious ‘spaceflight-associated neuro-ocular syndrome.’ Astronauts can experience blurred or long-term vision damage.

Balance is a separate issue. Microgravity affects the vestibular, an inner-ear system that is responsible for spatial orientation. Astronauts can feel disoriented in space, and even when they return to solid ground.

Peake acknowledges that “the first two or three day back on Earth could be punishing.” You feel weak, dizzy and unsteady while your body is trying to adapt.

For Williams and Wilmore, the road to full recovery has just begun – but their story is a reminder that life in space is far from effortless.