NASA astronauts, Barry 'Butch' Wilmore and Sunita 'Suni' Williams, who have been stuck in space for over nine months, will reportedly undergo intense rehabilitation once they return to Earth.

Doctors told Daily Mail the duo wouldn't be able to walk unaided due to their prolonged exposure to low gravity. Once they land on March 19 or 20, they’ll be carried out on stretchers for immediate medical check-ups.

Dr Vinay Gupta, a pulmonologist and Air Force veteran, told Daily Mail that Williams and Wilmore could need up to six weeks of rehabilitation to rebuild their strength through guided exercise and a tailored diet. He added that their rehab will start immediately upon landing, focusing first on walking, flexibility, and muscle strength.

During their extended stay, they were also exposed to high levels of space radiation — equivalent to a year’s exposure on Earth in just one week — increasing risks of cancer, bone loss, and heart issues.

"If I was their physician, I would think about a more proactive strategy for cancer screening. We want to take a different approach here, given their unique exposure history," said Gupta, as Williams and Wilmor's eight-day mission stretched into nine months due to Boeing's Starliner's technical issues.

Despite daily workouts, low gravity causes muscle and bone loss. "Astronauts who spend long periods in low gravity lose musculature, they lose bone density," biomedical engineer Dr John Jaquish told Daily Mail.

Astronauts can lose up to 20% of muscle mass within just five days in low gravity, while weight-bearing bones lose 1% to 1.5% density per month, NASA says. Research shows astronauts aged 30 to 50 lose about half their strength after six months in space, increasing the risk of fractures and osteoporosis.

To counter this, they train intensively before launch and exercise regularly on the ISS — but "the reality is, they’re effectively getting a fraction of the sort of exercise that we all take for granted just by walking in (Earth's) gravity," said Dr Gupta.