Crew-1 astronauts to undergo strength rehabilitation upon return to Earth

The SpaceX Crew-1 astronauts will undergo at least three months of strength rehabilitation when they return to Earth.

The four astronauts have been aboard the International Space Station for six months and are due to return home soon.

Embry-Riddle Aeronautical Associate Professor of Special Operations Dr. Erik Seedhouse said it will take some time before the astronauts’ bodies adjust to being back on Earth. He said they will feel different from the moment they take their first step.

RELATED: SpaceX Crew-1 astronauts return to Earth delayed for second time due to weather

"It's a little bit like waking up from a deep sleep. You have to rush somewhere, so you feel a little bit a little bit unsteady… that’s the sensation," he described.

He said the feeling is partly due to the inner ear, which helps with balance, being adjusted to microgravity zero G for six months. He said it should wear off in a few days. Dr. Seedhouse said 60-65 percent of astronauts also will not be able to walk in a straight line immediately after returning from space and they will not be able to drive for three weeks.

"They're basically like invalids because they've lost between 20 and 25% of their muscle mass, despite doing all the exercise," said Dr. Seedhouse. "They lose a lot of the muscles that help you balance… Power spinal muscles that are going up and down the spine helps you maintain an upright posture when you walk around but they’ve lost about 30 percent of those. Also, have muscles that goes up and down the leg abductor and the other two muscles that help you walk again in a straight line."

Dr. Seedhouse says each astronaut will have a strength rehabilitation coach and a personalized exercise program that will help them regain their strength. The programs are six days a week for about three months.

"It's about two hours (per day), mostly resistance training. They'll do range of motion training flexibility training very, very gradual, to begin with."

Dr. Seedhouse said the biggest issue will be bone loss. He said the astronauts have been losing bone mass 10 times faster than someone with osteoporosis and it takes an average of three to five years to build it back.

"After six months in space you've lost about 7 percent of your total bone mass, which means you have an increased risk of fracture two or three times higher, when you come back to Earth."

Dr. Seedhouse said NASA and SpaceX will be studying the impacts of long-term space travel on the Crew-1 astronauts as they work towards a mission on Mars.