Commentary by Sheri R. Colberg, PhD, FACSM
Are you sitting down? Chances are pretty good that you are, given that Americans spend a sizable amount of time on their tushes. On average, we clock 13 sedentary hours a day, according to the American Diabetes Association (ADA). Factor in seven or eight hours of shuteye, and you’re looking at 20 to 21 hours a day that you’re not moving much at all.
Unless you’re lucky enough to live within walking or biking distance of work, your daily sitting drill might go something like this: Each morning, you sit on a train, bus or in your car and head to work. Once at the office, you plop down at your desk for an 8-hour or longer stretch, with minimal breaks. The reverse commute entails more sitting. You get home and sit down to dinner. Then you might check a few emails (sit), get your Facebook fix (sit), and cue up the latest episode of Game of Thrones (sit). Time for bed! Repeat the next day, and day after this, and … sound familiar?
If right about now you're thinking 'But I'm blowing it out on the treadmill every morning" or 'I walk every evening with my dog,' here's the harsh reality: Regular exercisers who spend most of the rest of their day being sedentary face health risks, too. Exercise does lower your risk for many diseases, including heart disease, diabetes, depression and stroke. But what researchers are learning is that a body that’s not in motion most of the time pays a price health-wise.
According to a study published in The American College of Sports Medicine’s (ACSM) journal Exercise and Sport Sciences Review, those who did 2.5 total hours of moderate to vigorous exercise each week, and then sat for long periods at their desks, experienced what exercise physiologists call Active Couch Potato phenomenon. Essentially, being physically active on a regular basis for brief blocks of time doesn’t mean you won’t also experience the negative side effects of prolonged sitting.
"The effects might not be to the degree to what the non-exerciser experiences," says Sheri R. Colberg, PhD, FACSM, an exercise physiologist and professor of exercise science at Old Dominion University in Norfolk, VA, "but they will experience some negative effect."
As if we needed more depressing news on why sitting is so bad for us: In a study being published in the June 2015 issue of Diabetologia, the medical journal for European Association for the Study of Diabetes, researchers compared the impact that lifestyle—specifically being sedentary compared with being active—has on a person's risk for developing diabetes. What they found after tracking 3,232 overweight participants for a little more than three years, and after accounting for sex, age and other leisure physical activity: For every hour of TV that a person watched their risk of developing diabetes increased by 3.4 percent.
Meanwhile, the researchers in the ACSM study also reported negative effects of prolonged sitting, included an increase in waist circumference, blood pressure, bad cholesterol, and 2-hour plasma glucose levels. Women also saw an uptick in their triglycerides, bad cholesterol and fasting plasma glucose. These negative effects develop over time, with their likelihood increasing as the sedentary habits persist.
When you have several of these factors occurring together, it’s called metabolic syndrome, also known as “sitting disease.” The American Heart Association says 34 percent of adults already have metabolic syndrome, putting them at increased risk for stroke, heart disease and diabetes.
But the short-term effects of sitting kick in sooner than you probably think. “Sitting for twenty minutes radically slows down our metabolism," says Colberg. “When we don’t use our muscles, we don’t use our energy which means most of it goes into storage mode.” Colberg adds: “If you fill the tank with carbohydrates, but you’re never using the muscles, the tank stays full. So the next time you eat, the carbohydrates have nowhere to go because the tank is still full. So the carbs get stored as fat."
Colberg makes a case for adding or maintaining as much lean muscle mass as you can, because the more muscle you have “the bigger your storage tank for carbohydrates.”
On a positive note, taking simple steps to reduce the amount of time you spend being inactive lowers your risk of diabetes, and can help reverse the disease or reduce the need for medication. Are you ready to get moving more? Check out this strength-training workout from Fitness Expert Nikki Glor that's designed to add lean muscle mass. And don't miss these eight expert-approved tips for how you can move more throughout your day.