How quickly do your muscles waste in space?

Chris Smith put this question to space travel guru Richard Hollingham...

Richard - He'd be fine on a Virgin Galactic flight journey in space for, sort of, 10 minutes or so they'd be fine for that but essentially as soon as you remove gravity your muscles start wasting away. There were studies, I mean lots of studies, in humans because now humans have lived on the space station for more than a year at a time. They did a study in rats. So within 10 days the rats lost a third of their muscle mass. And that includes heart muscle. Now none of this would be a problem if you were going to stay in space forever. So if you go up to space and you live on the space station you can spend the rest of your life on the space station floating around being this idea of this extra-terrestrial human. That's absolutely fine. Trouble is when you come back to earth and you've lost that muscle particularly something damaging like heart muscle you see the astronauts getting out of capsules staggering. Normally they're lifted out of their carriage because no matter how much exercise they do on the space station, they do a lot you know, a couple of hours a day. They're still weakened. They also lose bone density as well. So you can imagine a mission to Mars and you get to Mars. You climb down the steps, fall over and break a leg. That's the sort of, these are the sort of problems so it's more when you stop rather than when you're in there that it's a problem.

Chris - Indeed, among the astronauts to whom you have spoken when you've interviewed them. What is it like when they take those first faltering steps out of the capsule and return to Earth? Do they feel exhausted? Do they absolutely hate it? And how does it take them to rehabilitate themselves after say six months on the ISIS to get back to their full fitness?

Richard -  Actually it takes a year. That's what they allow for most of them because they’re really fit. I mean every astronaut I've met they are kind of superhuman. You know they're really bright. They're really pleasant. They are really really strong. You know it's sickening but yes. So they get back to fitness pretty quick but it does I mean to get back to that full physical fitness that they go into spaces at. It can take you know up to 12 months.

Chriss - And that means for your average Joe like me then I'd be really really up the Swanny without a paddle if I if I were to. I mean I'm not superhuman.

Richard - I mean if you did your exercise every day you'd be okay. I mean you know it's shown when John Glenn had his second mission on the on the space shuttle. He was in his I think his 70s or even his even 80s. There's no there's no reason why a moderately fit person cannot go into space and stay moderately fit in space if they follow Giles’ advice about what they eat if they take exercise and they come back to Earth. They won't be quite as fit as they were when they went up but they will be fine.