Six months to a year of inactivity is equivalent to 10-15 years of skeletal and muscle aging, with significant difficulty in recovery.

“The best, you know, way to explain it to people is to say, put somebody up in space because there's no gravity that's effectively disuse because you can't really generate any force with your muscles. And we know that, you know, six months or a year standing up at the space station is about 10 to 15 years of skeletal and muscle aging. And it's tough to get back.”