The zero-gravity guide to aging well

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"I'd be the last one to go up in space!" says Joy Hill with a laugh.

At 86, that's likely true, unless the requirements for an astronaut suddenly become a petite, cheerful grandmother with a life well-lived. "I don't think about space stuff at all," she says.

But it turns out that astronauts have plenty in common with seniors such as Ms. Hill.

Fit and robust people blast into space and return six months later a much frailer version of their Earth-bound selves. They are prone to dizziness. Their muscles are thinner and weaker. Their bone density has decreased by up to 12 per cent - around eight times faster than it would on Earth.

Scientists say it's like aging at warp speed.

"Astronauts actually do get older, faster," says Richard Hughson, a University of Waterloo researcher who is working with the Canadian Space Agency and NASA to understand why astronauts are coming back with drastically lowered cardiovascular fitness.

And by studying how the bodies of astronauts change, scientists are gaining a better understanding of why humans deteriorate faster in space.

They're also discovering how regular exercise can help slow that process down - even here on Earth.

When Canadian astronaut Bob Thirsk returns from the International Space Station this fall, he'll bring with him data that will conclude a seven-year study led by Dr. Hughson and his team.

The 55-year-old running enthusiast is the seventh and final human guinea pig in a complex experiment designed to show exactly how an astronaut's cardiovascular fitness declines in space.

The findings will add to several other studies that have looked at physical markers such as bone density and muscle mass. Even though some astronauts exercise up to two hours a day on a treadmill, they lose up to 2 per cent of their bone density a month. Their muscles thin, and fat globules begin to appear in the muscle fibres after certain periods.

Part of the reason for the physical decline is already clear, Dr. Hughson says. When you're living in zero gravity for long periods of time, it's a lot harder to stay in shape because everything is so easy when you're weightless. Want to zip across the room? Push off a wall. Move a 100-pound weight? Lift a finger. Without gravity, even your heart doesn't have to work that hard to pump blood around your body.

Dr. Hughson's suspicion - being tested by monitoring astronauts' heart rates and blood flow in their chests, veins and heads - is that regular exercise is key to preventing the rapid physical decline. "What we hope to do is slow down that process," he said.

His results won't be published for another year or so, but the message has not been lost in space. Indeed, it's already being spread on terra firma.

Dr. Hughson, a former world-class distance runner, is keen to get the word to seniors, who might benefit the most.

Earlier this week, he presented his research to about 50 residents living at the Village of Riverside Glen, a seniors residence in Guelph. A few dozed off. Others took notes.

One elegantly dressed woman had a question: "So does that mean, if you have large muscles, you can cope better?"

Short answer, Dr. Hughson said, is yes. If you exercise - even if it only means going for a walk - you can decrease your chance of falls and dizziness, and remain mobile for longer. Physical activity may also improve cognitive abilities by increasing blood flow to the brain.

It's the type of message that more people need to hear as our population rapidly ages, said Mike Sharratt, executive director of the Schlegel-University of Waterloo Research Institute for Aging. "Up to 50 per cent of that loss in aerobic capacity is due to sedentary living," he said. "Think about the loss of dignity or quality of life if the person can't get up off the toilet on their own."

The Canadian Space Agency has created its own national incentive program for non-astronauts. Participants in the Get Fit for Space Challenge count the number of steps they take each day, aiming to complete 354 kilometres - the distance to the International Space Station. The residents at the Village of Riverside Glen have been taking part since June.

"So far today I've gone 3,365 steps and I'm going for a walk now," Ms. Hill said. During her walks, she often crosses paths with another keen participant: her friend, Art Stovel. He's been a walker all his life, he says, but he picked up the pace after he retired from raising livestock. At age 90, it shows: he's maintained a graceful gait - and a sharp wit.

After the presentation, the facility's staff kinesiologist, Meghan McCutcheon, pointed out that the group had collectively taken enough steps to get to the space station.

"You think we'll make it back?" said Mr. Stovel, his eyes twinkling.