How living in space affected Chris Hadfield’s health

TORONTO – There was some tweeting, some YouTube videos and a lot of science. After 146 days abroad in the International Space Station, Canadian astronaut Chris Hadfield is en route for planet Earth.

Space travel can wear out the human body – that’s why astronauts are limited to spending just six months orbiting about 400 kilometres above Earth.

Calcium is stripped from the bones. Muscles atrophy. And the sense of “up” and “down” is affected, at least temporarily, according to the Canadian Space Agency.

Zero gravity does a number on their bodies – it’s akin to breaking your leg and staying in bed with a cast on, said Dr. Richard Hughson, a University of Waterloo professor and principal investigator in a few Canadian Space Agency sponsored projects.

“We know that if you take away activity then muscle, bone and cardiovascular systems all start to deteriorate,” Hughson said.

“Some people come back from space really having lots of difficulty with their regulation of blood pressure and they feel dizzy easily, others come back and they feel pretty good.”

There’s something about gravity

For the most of us with two feet planted on earth, gravity keeps our blood pressure in check – it’s lower in the head than the feet, for example. Once we lie down, that blood pressure evens out.

Gravity, in short, forces our bodies to maintain enough muscle and bone mass to support our own weight.

“The key thing with space life is you take away gravity. We’re always having to use our reflexes and cardiovascular system every time we stand up or get out of bed (on Earth). If we didn’t have good reflexes to maintain our blood pressure, we’d be fainting,” Hughson explains.

But in space, those reflex systems aren’t exercised and can become complacent.

“Without that stimulus, your body deteriorates fairly quickly.”

That’s why exercise is so imperative in space. The CSA notes the astronauts’ two hours of physical activity a day isn’t just to kill time while in space.

They need to try to maintain their fitness to perform strenuous activities in space: walking, emergency procedures during landing, for example.

But exercise in space doesn’t come close to hitting the gym on Earth. It appears, two hours doesn’t do very much.

“If (Hadfield) needs to move a 100-kilogram object in space, he just pushes it with his finger and it floats away. You don’t do the same thing on Earth,” Hughson said.

“When he is moving and spinning around, the actual energy cost of that is almost like rolling around in bed. It really is a dramatic reduction in the energy expenditure,” Hughson explained.

The bones, the muscles and the veins

Bone mass takes a steep decline at a pace of about one per cent per month. Keep in mind, post-menopausal women lose bone mass at about three per cent a year – this is many times worse.

“The aging-like processes happens faster in space – the combination of bone loss, muscle mass loss and now we’re seeing arterial stiffness. Those are all aging-like processes,” Hughson said.

For Hughson’s part, the scientist is studying astronauts’ blood pressure and blood vessels while in space in two separate investigations.

With BP-Reg, Hughson is studying Hadfield’s blood pressure. Hadfield inflated cuffs to his upper legs while in space and then deflated them three minutes later, sending blood flow through his legs. It’s about as close to “standing up” in space as Hadfield can get.

Before departing, Hadfield’s blood pressure was also monitored as he stood up from a chair.

The two results will be compared – Hughson hopes his findings will help determine which astronauts will encounter steep drops in blood pressure in space, and in turn, dizziness after returning to Earth.

In VASCULAR, Hadfield is the eighth astronaut offering information on his blood vessels for Hughson’s study.

Read more about VASCULAR here.

In this case, Hadfield drew vials of blood and tested his arteries using an ultrasound. Hughson had posited nine years ago that blood vessels get stiffer with a lack of physical activity.

“Right at the moment, we don’t know if the arteries are just temporarily stiffer while they’re in space and just after they get back or if they’re stiffer for a long time,” Hughson said.

Recovery process could take months

Hughson said that the Canadian Space Agency already has a rehabilitation plan in place and a doctor monitoring his progress, dedicated to walking Hadfield back to full recovery.

Some astronauts bounce back easily, literally within 24 hours – one even balanced on one foot while touching the top of his head to prove to Hughson that he was in tip-top shape.

Meanwhile, others could be dealing with dizzy spells, nausea and lots of bed rest before they’re ready to move around like they used to.

“There is a huge variation between how individuals respond to being in space and returning to Earth.”

Either way, it could take some time before Hadfield is back to the physical shape he was in before, Hughson said.

“It is probably going to be a couple of months before he is going to be able to go out and jog the same way he did before flight. Within two months for sure,” Hughson said.

carmen.chai@globalnews.ca
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