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Glenn D. Braunstein, M.D. Headshot

Are You Sitting Down? That Inactivity May Impair Your Health

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The good news is you kept that New Year's resolution and have hit the gym five days a week for 30 minutes of exercise, just as the experts recommend. Unfortunately, you're also spending much of your day sitting -- stuck in traffic, slumped before a computer screen or slouching on a couch, rooting for a favorite sports team or reality show contestant on TV. That sitting around may be a factor that puts you at risk for a number of serious diseases and even premature death.

A growing body of scientific study, "inactivity research," shows that prolonged sitting can lead to serious health problems, regardless of whether you exercise and are at fighting weight. We're not just talking secretarial spread or lower back pain. Excessive sitting, sometimes called "sitting disease," recently also has been linked to breast and colon cancer, high cholesterol and sleep apnea. That's in addition to the obvious sedentary-induced ailments, such as obesity, type 2 diabetes, heart disease, blood clots and skeletal issues, like back and neck problems.

Sitting is no worse than lying sprawled on the sofa watching The Biggest Loser. But on average, adults spend more than half their waking hours in lassitude, primarily prolonged sitting. The rest of their time is spent in light-intensity physical activity; just 4 percent to 5 percent of the day is spent in moderate to vigorous physical activity. And it's not just adults glued to their chairs. According to a recent study by the Kaiser Family Foundation, children spend an average of more than seven hours a day potted like plants at school and in front of the TV, computer or video games.

Bodies Built to Move

Our bodies are built to move and when they don't, our metabolic system goes into storage mode. Triglycerides rise and high-density lipoprotein ("good cholesterol") drops. Insulin resistance, fasting plasma glucose (blood sugar), resting blood pressure and leptins (one of the hormones that regulate appetite and energy) also are affected. These all are biomarkers of obesity, heart disease and other chronic illnesses. When your calf muscles don't contract, which helps blood to circulate, blood clots can form. Prolonged sitting can make you feel lethargic, which perpetuates more inactivity. That vicious cycle further promotes the risk of obesity, type 2 diabetes and even depression. In short, sitting for long periods may take years off your life.

Three major studies all recently reached that conclusion. Among these, the American Cancer Society analyzed survey responses from 123,216 individuals (53,440 men and 69,776 women) who had no history of cancer, heart attack, stroke, or emphysema-other lung disease; they all were enrolled in the American Cancer Society's Cancer Prevention II study in 1992. Researchers examined the time they spent sitting and physical activity relative to mortality, between 1993 and 2006. Their findings: greater time spent sitting was associated with a significantly higher risk of mortality, especially in women. Women who sat more than six hours a day were 37 percent more likely to die during the time period, compared to those who sat fewer than three hours a day. Men who sat more than six hours a day were 18 percent more likely to die than those who sat fewer than three hours, even after adjusting for physical activity level. Associations were stronger for death from cardiovascular disease than from cancer. A lack of physical activity made matters worse. Women and men who both sat more and were less physically were 94 percent and 48 percent more likely, respectively, to die compared with those who reported sitting the least and being most active.

Similarly, in a 2009 study of more than 17,000 Canadians ages 18 to 90, researchers at the Pennington Biomedical Research Center found that time spent sitting was associated with increased risk of all-cause and cardiovascular disease mortality, independent of physical activity levels. Those who sat the most were roughly 50 percent more likely to die during the follow-up period than individuals who sat the least, even after controlling for age, smoking, and physical activity levels. Further analyses suggested that the relationship between sitting time and mortality also was unaffected by body weight. In short, all things being equal, people who sit more are at a higher risk of death than those who don't.

Those findings echo a study in Australia in which each hour of daily television viewing (a proxy of sedentary time) was found to increase by 11 percent the risk of all-cause mortality regardless of age, sex, waist circumference, and physical activity level.

On your feet yet?

Risk of Cancer

If not, consider that prolonged sitting has been linked specifically to an increase in colon and breast cancers, again even among people who exercise daily, according to the American Institute for Cancer Research in Washington, D.C. This reinforces earlier results reported by researchers in Australia. In that 2005-2007 study, researchers reported that participants who spent 10 or more years in sedentary occupations had almost twice the risk of distal colon cancer than those who did not spend any time in such work.

You also may add sleep apnea to the list of potential hazards of being anchored to that chair. That is the finding of researchers at the University of Toronto Center for Sleep Medicine, who studied 23 non-obese men suspected of having the condition. Prolonged sitting causes fluids to gather in the legs. When we lie down, the fluid moves from the legs to the upper body and could reach the neck, causing upper airway constriction. Researchers also discovered that the circumference of the legs and neck changed overnight.

What's the Solution?

Short of trading in that desk job for a more active career, say as a dance instructor or pro athlete, what to do? One option: trade in just your desk. Switch to furnishings that allow you to both sit and stand or one attached to a treadmill? Yes, these exist. The Georgia Poison Center in Atlanta is among the enterprises that have installed adjustable desks that allow employees -- who sit for most of the day answering phone calls -- to stand up when they choose. Meanwhile, SALO, a Minneapolis human resources firm and Kentucky-based health care giant, Humana, both offer some treadmill desks for employees. As the name hints, these desks, attached to treadmills, let workers walk at a slow pace while completing office tasks.

Even some school rooms are going chair-less. Some early elementary classes, such as those at Community Christian School, in Pease, Minn., and Chardon's Gurney Elementary in northern Ohio, have swapped traditional chairs for exercise balls, which allow students to move without making noise and disturbing others.

If new furniture isn't in the cards, you still may break up your sitting time. Try these tips from the American Institute for Cancer Research: Set a timer on your computer to remind you every hour that it's time to move. Dash down the hall or deliver a message in person instead of by email. If possible, stand up and walk around during phone calls and meetings. Keep light hand-weights in your office to use while reading email or talking on the phone.

Breaking up sitting with just two minutes of light walking every 20 minutes was shown to improve glucose and insulin levels in overweight or obese participants ages 45 to 65. In fact, just by standing, you burn three times as many calories as you do sitting. Muscle contractions, including the ones required for standing, reactivate the processes that breakdown fats and sugars.

Even baby steps -- taking the stairs instead of the elevator or walking to the filing cabinet rather than rolling your chair to it -- make a difference and the natural inclination to fold these sorts of movements into daily life may be an innate predisposition of the thin. Still, we all can benefit by adopting their more active lifestyle. So don't accept this health ill sitting down. Get up, stand up and move!