Acclimating to Earth’s gravity, after months on the ISS, is an arduous journey. It’s not like simply recovering from a hard workout; you can’t sleep it off. In fact, long-term affects when returning home include shrinking muscle mass, decreased bone density and chronic vision issues—you even have to do things like relearn how to talk.

For someone like Chris Hadfield, who recently returned to Earth as part of the Expedition 35 crew, physical rehabilitation will last a few months.

“Right after I landed, I could feel the weight of my lips and tongue and I had to change how I was talking,” Hadfield said. “I hadn’t realized that I learned to talk with a weightless tongue.”

During Hadfield’s rehabilitation, NASA will begin recording data to help astronauts better cope with trips to space. Hadfield’s mission lasted five months—twelve month-long missions are currently being planned for 2015. Over the course of two months, Hadfield will endure simple balance tests, MRIs and optical coherence tomography checks.

To give you an idea of how difficult it is to assimilate to conditions on Earth, Hadfield had to wear a special G-suit just so blood pressure would go to his head. He can’t drive for 21 days, and the first few days after returning he had to sit down in the shower. Not the most glamourous of returns after being away for five months, but certainly a small price to pay as NASA continues to learn about the relationship between man and space.