Mice, muscles, and Mars are all part of a new study on the physical effects of space travel. The surprising results hold promise. Someday they could prevent the harmful physical effects on astronauts—and give hope to bed- or wheelchair-confined Earthlings too.

God created the amazing human body to adapt; He created Earth to nourish and protect it. But space travel is hard on bodies, human and otherwise. The lack of gravity in space actually decreases bone and muscle mass. Zero gravity can also affect balance, coordination, strength.

Se-Jin Lee researches at Jackson Laboratory, a biomedical research institution. His research team sent 40 female black mice to the International Space Station aboard a SpaceX rocket.

Eight mice left Earth as genetically altered “mighty mice.” They had double the usual amount of muscle. The other 32 were, well, regular mousey mice.

The capsule brought the mice back in good condition. But after a month in space, not all mice remained equal.

In space, 24 of the regular mice got no treatment. They lost up to 18% of their muscle and bone mass. Eight regular mice received the mighty mice treatment while in space. The treatment blocks proteins that limit muscle growth. The treated mice returned to Earth with much larger muscles.

And the eight already ripped rodents? They splashed down with their bodybuilder physiques intact.

Upon their return, some of the ordinary mice received the mighty mice drug. Even those that had lost bulk quickly built up more muscle and bone than their untreated pals.

Lee says the findings are encouraging. The mice-in-space experiment revealed “many things we’d like to pursue,” Lee says. But he knows further research must be done. So far, what builds muscle and bone in mice hasn’t worked on people.

“We’re years away,” says Lee’s wife, Emily Germain-Lee of Connecticut Children’s Medical Center. She also worked on the mighty mice experiment. “But that’s how everything is when you go from mouse to human studies.”

Still, the Lees say further research could benefit humans with muscle problems, including those who are bedridden, elderly, or severely injured.

Scientists completed their experiment in January—just as the coronavirus was hitting the United States.

Germain-Lee sees a “silver lining of COVID.” While the world was quarantined, “We had time to write [the experiment] up very intensively and submit it for publication.”