By: Mark Masters
Do you LEAD an active lifestyle or a sedentary one? The question is simple, but the answer may not be as obvious as you think. Let’s say, for example, you’re a busy bloke who works 60 hours a week at a desk job but who still manages to find time for five 45-minute bouts of exercise. Most experts would label you as active. But Dr Marc Hamilton has another name for you: couch potato. Perhaps “exercising couch potato” would be more accurate, but Hamilton, a physiologist and professor at the Pennington Biomedical Research Centre in the US, would still classify you as sedentary.
“People tend to view physical activity on a single continuum,” says Hamilton. “On the far side, you have a person who exercises a lot; on the other, a person who doesn’t exercise at all. However, they’re not necessarily polar opposites.”
Hamilton’s take, which is supported by a growing body of research, is that the amount of time you exercise and the amount of time you spend on your bum are completely separate factors for heart-disease risk. New evidence suggests, in fact, that the more hours a day you sit, the greater your likelihood of dying an earlier death regardless of how much you exercise or how lean you are. That’s right: even a sculpted six-pack can’t protect you from your chair.
But it’s not just your heart that’s at risk from too much sitting; your hips, spine and shoulders could also suffer. In fact, it’s not a leap to say that a chair-potato lifestyle can ruin you from head to toe.
Statistically speaking, more Australians than ever take part in regular physical activity – 8.2 million in 2009, up from 7.1 in 2007, according to the latest Exercise, Recreation and Sport Survey. But at the same time, we’re becoming more sedentary at home and in the workplace, with the landmark 2009 Stand Up Australia study finding office workers spend on average 76 per cent of their day sitting.
MH Staff attempting to battle the sedentary slide
Now consider how much we sit today compared with, say, 160 years ago. In a revealing study, Dutch researchers at Maastricht University created a sort of historical theme park and recruited actors to play mid-19th-century Australian settlers for a week. The men did everything from chop wood to forage for food, and the scientists compared their activity levels with those of modern office workers. The result: the actors’ exercise levels were the equivalent of walking 5-12 kilometres more a day than the deskbound men. That kind of activity is perhaps even more needed in today’s fast-food world than it was in the 1800s, but not just because it boosts kilojoule burn.
A 2010 study in the Journal of Applied Physiology found that when healthy men limited their number of footsteps by 85 per cent for two weeks, they experienced a 17 per cent decrease in insulin sensitivity, raising their diabetes risk. “We’ve done a lot to keep people alive longer, but that doesn’t mean we’re healthier,” says Hamilton.
While Australians are living longer than ever – men can expect to live to an average of 79 years – rates of obesity are soaring, and it’s estimated more than two-thirds of Australian men are above their healthy weight. Rates of type 2 diabetes, which is closely linked to weight, diet and exercise levels, have markedly increased, too – about a million Australians have the disease.
Make no mistake: “Regularly exercising is not the same as being active,” says Dr Peter Katzmarzyk, Hamilton’s colleague at Pennington. Katzmarzyk is referring to the difference between official exercise activity, such as running, cycling or lifting weights, and so-called non-exercise activity, like walking to your car, mowing the lawn or simply standing. “A person may hit the gym every day, but if he’s sitting a good deal of the rest of the time, he’s probably not leading an overall active life,” says Katzmarzyk.
You might dismiss this as scientific semantics, but energy expenditure statistics support Katzmarzyk’s notion. In a 2007 report, University of Missouri scientists said that people with the highest levels of non-exercise activity (but little to no actual “exercise”) burnt significantly more kilojoules a week than those who ran 55km a week but accumulated only a moderate amount of non-exercise activity.
“It can be as simple as standing more,” says Katzmarzyk. For instance, a “standing” worker – say, a sales assistant – burns about 6300kJ while on the job; a person behind a desk might expend roughly 4200kJ. That goes a long way to explaining why people gain more than seven kilograms, on average, within eight months of starting sedentary office work, according to a study from the University of North Carolina.
But kilojoules aren’t the only problem. In 2009, Katzmarzyk studied the lifestyle habits of more than 17,000 men and women and found that those who sat for almost the entire day were 54 per cent more likely to end up clutching their chests than those who sat for almost none of the time.
That’s no surprise, of course, except that it didn’t matter how much the sitters weighed or how often they exercised. “The evidence that sitting is associated with heart disease is very strong,” says Katzmarzyk.
“We see it in people who smoke and people who don’t. We see it in people who are regular exercisers and those who aren’t. Sitting is an independent risk factor.”
This isn’t actually a new discovery. In a study by The London Hospital published in 1953, scientists examined two groups of London Transport workers: bus drivers and bus conductors. At first glance, the two occupations appeared to be pretty similar. But while the bus drivers were more likely to sit down for their entire day, the conductors were running up and down the stairs and aisles of the double-decker buses. As it turned out, the bus drivers were almost twice as likely to die of heart disease as the conductors were.
A more recent interpretation of that study, published in 2004, found that none of the participants ever exercised. But the two groups did sit for different amounts of time. The analysis revealed that even after the scientists accounted for differences in waist size – an indicator of belly fat – the bus drivers were still more likely to die before the conductors. So the bus drivers were at higher risk not simply because their sedentary jobs made them resemble Homer Simpson, but also because all that sitting truly was making them unhealthy.
Hamilton came to call this area of science “inactivity physiology” while he was conducting studies to determine how exercise affects an enzyme called lipoprotein lipase (LPL). Found in humans as well as mice, LPL’s main responsibility is to break down fat in the bloodstream to use as energy. If a mouse (or a human) doesn’t have this enzyme, or if the enzyme doesn’t work in their leg muscles, the fat is stored instead of burnt as fuel.
Hamilton discovered that when the rodents were forced to lie down for most of their waking hours, LPL activity in their leg muscles plummeted. But when they simply stood around most of the time, the gene was 10 times more active. That’s when he added an exercise session to the lab-rat routine and found that exercise had no effect on LPL. He believes the finding also applies to people.
“Humans sit too much, so you have to treat the problem specifically,” says Hamilton. “The cure for too much sitting isn’t more exercise. Exercise is good, of course, but the average person could never do enough to counteract the effect of hours and hours of chair time.
“We know there’s a gene in the body that causes heart disease, but it doesn’t respond to exercise no matter how often or how hard you work out. And yet the activity of the gene becomes worse from sitting – or rather, the complete and utter lack of contractile activity in your muscles. So the more non-exercise activity you do, the more total time you spend on your feet and out of your chair. That’s the real cure.”
“Your body adapts to what you do most often,” says personal trainer and certified strength and conditioning specialist Bill Hartman. “So if you sit in a chair all day, you’ll essentially become better adapted to sitting in a chair.”
The trouble is, that makes you less adept at standing, walking, running and jumping, all of which a truly healthy human should be able to do with proficiency. “Older folks have a harder time moving around than younger people do,” says Hartman. “That’s not simply because of age; it’s because what you do consistently from day to day manifests itself over time, for both good and bad.”
Do you sit all day at a desk? You’re courting muscle stiffness, poor balance and mobility, and lower-back, neck and hip pain. But to understand why, you’ll need a quick lesson on fascia, the tough connective tissue that covers all your muscles. While fascia is pliable, it tends to “set” in the position your muscles are in most often. So if you sit most of the time, your fascia adapts to that specific position.
Now think about where your hips and thighs are in relation to your torso while you’re sitting. They’re bent, which causes the muscles on the front of your thighs, known as hip flexors, to contract slightly, or shorten. The more you sit, the more the fascia will keep your hip flexors shortened.
“If you’ve ever seen a guy walk with a forward lean, it’s often because of shortened hip flexors,” says Hartman. “The muscles don’t stretch as they naturally should. As a result, he’s not walking tall and straight because his fascia has adapted more to sitting than standing.”
This same effect can be seen in other areas of your body. For instance, if you spend a lot of time with your shoulders and upper back slumped over a keyboard, this eventually becomes your normal posture. “That’s not just an issue in terms of how you look,” says Hartman. “It frequently leads to chronic neck and shoulder pain.”
Also, people who frequently cross their legs a certain way can experience hip imbalances. “This makes your entire lower body less stable, which decreases your agility and athletic performance and increases your risk for injuries,” says Hartman. Add all this up, and a person who sits a lot is less efficient not only at exercising, but also at simply moving from, say, the couch to the fridge.
There’s yet another problem with all that sitting. “If you spend too much time in a chair, your glute muscles will actually ‘forget’ how to fire,” says Hartman. This phenomenon is aptly nicknamed “gluteal amnesia”.
A basic anatomy reminder: your glutes are your body’s largest muscle group. So if they aren’t functioning properly, you won’t be able to squat or dead lift as much weight and you won’t burn as much fat. After all, muscles burn kilojoules. And that makes your glutes a powerful furnace for fat – a furnace that’s probably been switched off if you spend most of the day on your arse.
It gets worse. Weak glutes as well as tight hip flexors cause your pelvis to tilt forward. This puts stress on your lumbar spine, resulting in lower-back pain. It also pushes your belly out, which gives you a protruding gut, even if you don’t have a shred of excess fat.
“The changes to your muscles and posture from sitting are so small that you won’t notice them at first,” says Hartman. “But as you reach your thirties, forties, fifties and beyond, they’ll gradually become worse and a lot harder to fix.”
So what’s a desk jockey to do? Hamilton’s advice: think in terms of two spectrums of activity. One represents the activities you do that are considered regular exercise. The other denotes the amount of time you spend sitting versus the time you spend on your feet. “Then every day, make the small choices that will help move you in the right direction on that sitting-versus-standing spectrum,” he says. “Stand while you’re talking on the phone. It all adds up and it all matters.”
Of course, there’s a problem with all of this: it kills all your lame excuses for not exercising (no time for the gym, fungus on the changing-room floor, an episode of Entourage you haven’t seen). Now we have to redefine “workout” to include every waking moment of our days. But there’s a big pay-off: more of those days to enjoy in the future. So get up off your chair and start non-exercising.