As a self-employed writer working from home, Ben has the luxury of a regular exercise schedule. Every morning, he goes out at about 9:15 for a five- or six-mile run or walk. The rest of the day and into the evening, he spends at his desk. His family, friends and even his doctor think of Ben as being “very active,” but he is well aware that he is sedentary more than 20 hours every day.
Although it may not seem fair, Ben’s sitting puts him at increased risk of dying from heart disease or any cause. Sitting, according to several recent studies, is an independent risk factor for heart disease–even among those who exercise dutifully.
A study that followed 4,512 middle-aged Scottish men for about four years found that those who sat four or more hours in front of a TV, video game or computer screen were more than twice as likely to have a heart attack and 50 percent more likely to die from any cause compared with those who spent two hours or less in front of a screen [Journal of the American College of Cardiology, January 18, 2011]. And apparently this increased risk was true for those who exercised regularly as well as those who didn’t.
Other studies have had similar results. Men spending long hours in front of a screen or behind the wheel on the expressway were more likely to die of heart disease even if they exercised. And fit and active children who watched television regularly had higher blood pressure than those who were limited in their TV viewing, regardless of weight or sports activity.
The message is clear: good cardiovascular health requires not only regular exercise but avoidance of prolonged sitting and inactivity.
What Are the Reasons?
Several possible reasons have been proposed. Laboratory studies have found that sedentary animals have reduced activity of lipoprotein lipase, an enzyme that breaks down circulating blood fats and makes them available to muscles for energy. This in turn leads to higher levels of fats and triglycerides in the blood, increasing the risk of heart disease.
In the Scottish study, levels of C-reactive protein (CRP) were about twice as high in subjects with four hours of screen time compared to those with two hours or less. CRP is a marker of low-grade inflammation and a risk factor for heart disease.
Exercise apparently has no effect on lipoprotein lipase and may tend to increase inflammation in muscle tissues.
One major benefit of regular exercise is the effect it has on controlling blood glucose and making muscle cells more receptive to the effects of insulin. Prolonged sedentary behavior, on the other hand, may have an even greater negative effect.
A University of Missouri study looked at healthy, active young adults who were asked, for the sake of the study, to stop moving around so much–to drive rather than walk to the corner store, to take the elevator rather than the stairs, to order delivery rather than carry-out pizza.
The subjects reduced their average daily step counts on the pedometer from 13,000 to 4,300 while eating exactly the same meals and snacks. During these three days of inactivity, their blood sugar spiked significantly immediately after meals–26 percent higher than on days when they were active. And each of these days, the spike in blood sugar grew more exaggerated. Blood sugar spikes are associated with an increased risk of both heart disease and type 2 diabetes.
For the salesman or construction worker who spends all day moving around but can’t find the time or energy to exercise, these studies offer hope. Even though these individuals may never get their heart rates into a training range, they use energy almost constantly every day.
Harvey B. Simon, M.D., author of the book, The No Sweat Exercise Plan, rejects the arbitrary distinction between exercise and activity and looks for “the broad spectrum of activities that contribute to health.”
A number of studies have demonstrated that moderate walking, gardening and house work have significant health benefits. Men who climbed at least 55 flights of stairs a week had a 33 percent lower death rate, according to a study of more than 10,000 Harvard graduates. Walking to work for 21 minutes or longer resulted in a 29 percent lower risk of hypertension for about 6,000 Japanese subjects.
Dr. Simon uses the term cardiometabolic exercise (CME) “to emphasize the health benefits of everything from moderate activity to aerobic training, from washing the car to hitting the elliptical.” For general health and gradual weight loss, Dr. Simon recommends a goal of at least 150 points a day or 1,000 a week. Using his system, you can rack up 200 CME points for mowing the lawn with a hand mower, 145 points for pushing a power mower. Thirty minutes of dusting at a moderate pace equals 75 CME points.
Another way of measuring your activity is with a pedometer. Set a goal of 10,000 steps a day, and this can be accomplished through one long or several shorter walks.
Most would agree that Ben and others who work out enthusiastically should continue what they’re doing. Regular, moderately vigorous physical activity may be the most important thing you can do to protect yourself against heart disease, cancer, stroke and diabetes. It regulates blood sugar, tones muscles, keeps blood vessels supple and helps control weight. But it’s also important to keep moving at other times, even when you’re injured or taking the afternoon or weekend off.
Since you’ve already had a vigorous workout, these movements should be designed to relax and recover rather than stress the cardiovascular system. Take the stairs rather than the elevator if you wish. But if that means charging up four or five flights, you might want to reconsider and save your energy for tomorrow’s gym workout.
If you have a desk job, there are a few things you can do to avoid prolonged sitting. Walk around the room while you’re talking on the phone. Stroll down the hall to talk to a colleague rather than sending an email. Take frequent breaks to visit the copier, the water fountain and the toilet. Even standing from time to time helps.
If you’ve done aerobic work at the health club, you can use your down time at home doing stretches or yoga while watching TV. The muscles you use during your workout will appreciate the activity, and your heart will benefit by avoiding the health risks of too much sitting.
REFERENCES:
“Couch potatoes beware: too much time spent watching TV is harmful to heart health,” Science Daily, January 10, 2011.
“Get moving? Where do I start? American Heart Association.
“Get moving!” Journal of Midwifery and Women’s Health, 2003;48(6).
Donald Hensrud, M.D., “Get moving and improve your health,” MayoClinic.com, June 3, 2011.
Janis Kelly, “Rheumatologists urged to get arthritics moving,” Medscape Medical News, April 20, 2006.
Roni Caryn Rabin, “The hazards of the couch,” New York Times, January 12, 2011.
Gretchen Reynolds, “Why it’s so important to keep moving,” New York Times, February 29, 2012.
“Steps to get you moving,” Women’sHealth.gov, last updated June 17, 2008.
Harvey Simon, M.D., “Moderate exercise: no pain, big gains,” Medscape Medical Feature March 28, 2006.
08/08/2012
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