Sedentary behaviour and a lack of whole-body movement are independent predictors of increased mortality and increased incidence of obesity, diabetes, heart disease and cancer, regardless of level of physical exercise, according to an article published online Feb. 4 in the British Journal of Sports Medicine.
Elin Ekblom-Bak, of the Karolinska University Hospital in Stockholm, Sweden, and colleagues argue that sedentary behaviour has become an erroneous synonym for lack of exercise, when it should be defined as muscular inactivity, and that a new paradigm of inactivity physiology has emerged.
There are four tenets underlying the new paradigm —
- that prolonged sitting is an independent risk factor for disease;
- that sedentary behaviour is a distinct type of behaviour, not an absence of exercise;
- that the body responds differently to prolonged sitting and physical exercise; and
- that long periods of sedentary behaviour exacerbate the disease risk associated with lack of physical activity, the researchers argue.
“We are dealing with two distinct behaviours and their effects: (1) the benefits of regular moderate- to vigorous-intensity physical exercise and (2) the risks of too much sitting and limited non-exercise everyday life activity,” the authors write. “If found to be true, the clinical importance and implication of this new paradigm is extensive. In the future, the focus in clinical practice and guidelines should not only be to promote and prescribe exercise, but also to encourage people to maintain their intermittent levels of non-exercise daily activities.”
Resource: British Journal of Sports Medicine http://bjsm.bmj.com/content/44/12/834
“The robotic lifestyle of just incorporating 30 minutes of physical activity into your day,” and spending the other 23.5 hours idle, “does not produce the healthy profile we’re looking for,” said
Mark Tremblay, Director of healthy active living and obesity research at the Children’s Hospital of Eastern Ontario Research Institute. While much research has focused on the benefits of physical activity, little attention was paid to what people do the rest of the day. Researchers are just beginning to dissect our daily routines to learn how movement, and lack of it, affects our health. Being healthy is not just about increasing physical activity, but also decreasing inactivity. People can take small steps in their daily lives to, well, take more steps. Our culture of “let’s sit down and talk about it” needs to become one of “let’s walk and talk about it.” Tremblay said.
AN IDLE BODY
Tremblay says, an obvious drawback to sitting is that you aren’t moving, so the number of calories you burn will be lower than if you were, say, standing up or walking, and sitting makes it easy to eat. “It’s much more difficult to eat if you’re playing tennis,” a sedentary lifestyle can also have less visible effects. Sitting takes a load off your skeleton and muscles and over time, this may weaken them. Studies on humans and animals also suggest being idle can lead to harmful changes in your metabolism, prompting higher blood fat levels and lower levels of “good” cholesterol.
In addition, if you don’t use your muscles after a meal, they don’t take up sugar from the blood as they should, said Frank Booth, a professor of physiology at the University of Missouri-Columbia. This means most of the sugar from your meal will stay in your blood. Over time, this may put you at risk for high blood glucose levels, a precursor to Type 2 diabetes, Booth said.
A 2010 study of more than 120,000 people in Australia found that the more time people spent sitting, the more likely they were to die of any cause over the study period. Another study, published in January, found that people who spent more than 4 hours sitting in front of a TV or computer each day were 125 percent more likely to have heart problems over a 4-year period. And in both of those studies, the amount people exercised made no difference.
Some preliminary evidence suggests sedentary behaviour may have an impact on our mental health as well as our physical health. Studies of children have found less sedentary kids have better academic scores and higher self-esteem. And researchers need to find out if the type of activity you do while sitting makes a difference. Studies suggest tasks that require a high level of cognitive engagement, such as reading or playing a board game or a musical instrument, have less adverse health outcomes. While it’s not clear why this might be, he noted there’s less opportunity to snack if your hands are occupied. Tremblay said.
Other work suggests a link between inactivity and depression in adults. However, more rigorous studies need to be done to validate the link. For instance, it’s not known whether adults who exercise for 30 minutes a day, but sit down for the rest of the time, would also be at greater risk of depression, Booth said.
CAN YOU GET RID OF YOUR CHAIR?
Revising our culture of sitting may be difficult. “We fundamentally go to what’s easiest and most convenient. But the rules may not allow them to get out and do it.” Tremblay said a message of “sit less” may be more palatable to some than one of “move more.” “This is a softer sell — something they can build into their lifestyle.”
“You can tell someone that they need to not sit all day. What we need to do is introduce inconvenience.” People might not have control over whether they can have a standing desk at their office and might not be able to walk or bike to work if they live too far away, or in a bad neighbourhood. Booth said.
To decrease your chair time, Tremblay recommends you look at your day and ask yourself: “Is it necessary to sit?” “Could you bike or walk to work? When you’re at work, are there opportunities to stand?” If you can’t get a standing desk, you might make a reminder to yourself to get up and move every 15 minutes or so. “There are a variety of things that can be done,” Tremblay said. “First and foremost is we need to bring this to people’s attention.”
So, did you hit the gym today? If so, you probably feel like you deserve a pat on the back. But your efforts may be in vain if you spend the rest of the day sitting down. This growing body of research suggests sitting down for most of the day can be lethal. It has been linked to an increased risk of heart disease, Type 2 diabetes and death from ANY cause. And a daily jog may do little to negate the deleterious effects of too much time in a chair.
AUTHOR BIO: Rachel Rettner
Rachael Rettner has been with Live Science since 2010. She has a Masters degree in journalism from New York University’s Science, Health and Environmental Reporting Program. She also holds a Bachelor of Science in molecular biology and a Master of Science in biology from the University of California, San Diego. This story was provided by MyHealthNewsDaily, sister site to LiveScience. Follow My Health News Daily staff writer Rachael Rettner on [email protected]