Guess what? Your job really might be killing you.
Especially if, like the majority of the population, it requires you to sit immobilized in front of a computer for eight or so hours a day.
Sitting is the new smoking, experts say. That may sound alarmist, but a growing number of scientists and medical experts believe the analogy is not at all far-fetched.
Recent research indicates that bouts of sitting -not just in front of the TV, but at work and at school -cause serious physiological responses related to chronic disease and premature death. The most serious of these is the effects on glucose tolerance and blood lipids: As you sit, the activity of lipoprotein lipase, the enzyme that allows muscles to draw fat circulating in the blood and burn it off, drops precipitously.
Even more alarmingly, this deadly physiological reaction affects the lean and the overweight alike.
That hour in the gym once a day doesn't counteract the effects of prolonged sitting -the average Canadian is immobile 9.5 hours a day.
"Think about it: An hour of exercise is only 1/24th of your day," said Dr. Mark Tremblay, director of the Children's Hospital of Eastern Ontario Research Institute in Ottawa.
The equation is simple, Tremblay said in a phone interview: You sit down, your body stops working.
"I've got a headset, I am walking while we're talking," he said.
"We have evolved to move. I probably spent 1,000 hours a year playing catch with my brother when I was growing up. It was sometimes fun, sometimes monotonous, but we were moving."
Tremblay is also an advocate of standing desks -standing is an activity that requires a whole host of physiological actions -and even desks with slow treadmills or pedals underneath.
Your employer, or Grade 3 teacher, who expects to see you sitting, and not moving, for three hours before lunch and about four hours after, may not like it, but it's important to stand up, and take short breaks and walks.
Just as with smoking, researchers like Tremblay are hoping that public policy will get onside and begin to influence large-scale behavioural changes in schools, workplaces and at home.
Tremblay, a leading international researcher on sedentary behaviour, said the science around obesity just hasn't added up. Even with an increased focus on getting kids into organized sports, obesity rates keep soaring. We need more than heartpounding bouts of cardio. We need regular, constant light to moderate activity in order to keep the metabolism functioning. Tremblay has studied and compared the physical activity profiles of old order Amish, Mennonite and contemporary children.
The Amish and Mennonite children and adults were leaner and fitter, and provide useful models, said Tremblay, not just because they spend less prolonged sedentary time, but because they tend to accumulate small amounts of physical activity intermittently throughout the day.
Studies show that adults and kids who incorporate small, light activities into their day, break up their bouts of sitting with frequent small breaks, whether it's to stand and stretch, walk across the room, jump up and down or buzz to the water cooler (or in the case of an Amish woman, Tremblay said, go out to the garden, bend, pull out a few carrots and stand up again) have better metabolic profiles.
"An alarm should go off in your head every 15 minutes to ensure you move; better yet, set your iPhone," he advised.
Health institutions, like Vancouver General Hospital, and many government offices are already working to make changes, bringing in standing desks, for example.
"We try to make as many meetings as we can walking meetings," explained Maureen Ashe, an assistant professor in the department of family practice at the University of B.C., and an investigator at the Centre for Hip Health and Mobility near VGH.
When she gets to work, she flicks a hand under her desk and pulls it up to about the height of her lower ribs.
You won't catch her sitting down.
Increasing light activity in her own life has become something of a healthy obsession. At home, she and her husband have started washing the dishes by hand. They switched to a push mower. At work she stands at her desk, walks to a printer that's slightly farther away, takes the stairs.
Making stairways into attractive architectural features is just one way to change employee patterns, she said.
When she's working on something intense, she sets her iPhone timer to make sure she's moving around.
She wears a pedometer daily, and works with older adults to measure their sedentary patterns using an accelerometer.
The device straps around the waist and records an objective measure of the intensity of a person's movement output and sitting-to-standing transitions. At the end of a seven-day period, she can evaluate when and where a person can add a boost of light activity. "Sometimes it's just as simple as every hour, stand up."
She pointed out that we've engineered energy expenditure out of our lives. Tremblay agreed.
What his data show, however, is that the movement we need for health isn't necessarily gym time.
We've become too reliant socially on structure in which to become active -a bike path, a sports stadium, a rink-and we've become obsessed with safety.
"Imagine if everyone was out in the morning, walking to school, biking?" he asked.
The argument that it's not safe for kids to walk to school, or to bike where there are no bike paths, falls apart if we all start to do it, he pointed out.
It's about taking supports away -our chairs, our desks, our edifices of comfort -and allowing our bodies to do what they are meant to do.
"Instead of building more structures," he mused, "why can't we turn the arrow back?"