A year ago, Lisa Annelouise Rentz, 41, an arts administrator and writer in Beaufort, S.C., made a simple but life-changing switch. "I heard that sitting is unhealthy, and after years of back pain, I decided to just stand up," she says. "I haven't used my 1950s rolling desk chair since."
Instead of vegging at her desk all day, accumulating aches and pains, Rentz now uses a multitude of small movements to wear a path between the various work "stations" she created in her home office—the desk with her phone, the antique sideboard where her laptop sits, the table where she spreads out projects. "After a few months I didn't feel tired at all and now I feel discernibly stronger," she says.
A burgeoning body of research suggests that Rentz may be gaining more than strength by getting up and moving. She's also developing protection from a variety of health risks. In study after study, sitting for long hours at a desk, behind the wheel, or in an easy chair has been linked to such ills as heart disease, cancer, type 2 diabetes, and premature death, even among those who exercise regularly. "The body is a perpetual motion machine," says Joan Vernikos, former director of NASA's Life Sciences Division and author of the recently released book Sitting Kills, Moving Heals. "We weren't designed to sit."
A large recent Australian study makes the point. Researchers showed that adults who sat 11 hours or more a day had a 40 percent increased risk of dying during the next three years compared to those who sat for less than four hours a day. "This was after taking in account the individuals' exercise levels, weight, and general health," says lead author Hidde van der Ploeg, a senior research fellow at the University of Sydney's School of Public Health.
Similar data come from the American Cancer Society. Combing the records of more than 120,000 Americans, researchers found that women who sat more than six hours a day were at a 37 percent increased risk of an early death, compared to women who sat less than three hours. Men were at a 17 percent increased risk. The association held even among those who did regular workouts. And a 2010 study led by the University of South Carolina's Arnold School of Public Health showed that men who reported more than 23 hours a week of sedentary activity had a 64 percent greater risk of dying from heart disease than those who reported less than 11 hours per week.
Activity breaks. Small wonder that more people, like Rentz, are breaking the sitting habit. Some are using desks that incorporate a treadmill or stationary bicycle, setting their computer's alarm to sound every hour or so as a signal to take an activity break, or wearing pedometers to motivate themselves to move more. Companies have instituted walking meetings, started employee dart leagues, and outfitted offices with sit-stand desks, all designed to increase employees' motions throughout the day. At Beneficial Blends, a Tampa-based company that markets coconut oil, employees take a 10-to-15-minute walk at 3 p.m. every day. "It keeps us sharp," says company founder Erin Meagher. "We talk through company strategies, brainstorm, and walk and talk off frustrations. Then we come back and are more productive than we would have been just stewing at our desks and staring at computer screens."
Robert Perez, 50, a public relations executive in Orlando, took up his employer's offer of a standing workstation a few months ago and now stands or walks about his office five hours a day. "The toughest part was trading in my comfy, high-back leather chair," he says. But increased stamina and weight loss have made him a convert to the concept.
Such efforts can produce other benefits and boost the bottom line. After Replacements Ltd., a retailer selling china, crystal, and silver in Greensboro, N.C., introduced regular activity breaks into employees' routines several years ago, morale went up and complaints of musculoskeletal disorders went down among those who participated. Companies can also reap savings in healthcare costs. "For every person we help prevent get diabetes, we save the company $10,000 per year ... every year," says James Levine, a professor of medicine at the Mayo Clinic in Rochester, Minn., who has studied the effects of inactivity and who helped create an early treadmill desk.
How sitting hurts. When people sit or lie for hours at a time, the muscles—particularly the large ones in the leg and back—go dormant, setting off some dangerous metabolic consequences. "Sitting shuts down electrical activity in the legs," says Toni Yancey, a professor of health services at UCLA's Fielding School of Public Health. "It makes the body less sensitive to insulin, causes calorie-burning to plummet, and slows the breakdown of dangerous blood fats, lowering 'good' HDL cholesterol."
In fact, just one day of inactivity reduced insulin action in a small group of men and women by about 40 percent in a 2011 study from the Department of Kinesiology at the University of Massachusetts–Amherst and the Pennington Biomedical Research Center in Baton Rouge, La. Vernikos likens hours of continuous or uninterrupted sitting to the weightlessness that astronauts experience in space. "The absence of gravity even for a few days accelerates astronauts' degeneration, inducing harmful changes we typically associate with aging," she says.
The human body evolved to function with the constant downward pull of gravity. Without it, the heart shrinks, blood volume plunges, muscles atrophy, fat replaces muscle, and bone mass decreases. Even the immune system is weakened, with wounds taking longer to heal and infections more likely. When astronauts return to Earth, however, gravity helps them rebound by stimulating the bones, muscles, and other body systems. The more you work against gravity, the greater these systems respond. The key to optimal functioning, Vernikos says, is making as much use of gravity as possible. "That means increasing the number of small, low-intensity movements you make throughout the day as you go about the business of living," she says. "Humans today use much less gravity than our ancestors did throughout history."
Research bears out Vernikos's advice. A 2008 study from the Cancer Prevention Research Centre at the University of Queensland in Brisbane, Australia, showed that people who took the most breaks from sedentary time had on average a smaller waist size, a lower body mass index, and reduced triglycerides, a particularly unhealthy type of blood fat. The latest study shows that interrupting sitting time with two-minute bouts of walking every 20 minutes significantly improves glucose metabolism. "Importantly, walking at a light pace and walking at a moderate pace yielded almost identical responses," says lead author David Dunstan, associate professor at the Baker IDI Heart and Diabetes Institute in Melbourne, Australia. "That suggests that the frequency of physical movement is the most important consideration, not the intensity of the movement." Standing up to take a stretch, getting a drink of water, or marching in place for a few minutes all count toward better health.
But don't ditch your running shoes or gym membership, experts say. Standard exercise guidelines—30 minutes a day of moderate to vigorous exercise, five times a week—still apply. Indeed, this prescription has been shown to lower blood pressure, improve cholesterol levels and metabolism, and lower the risk of some cancers. "The goal is to minimize sitting, especially continuous sitting, and follow a regular exercise program," says Timothy Church, an investigator at the Pennington Biomedical Research Center.
That's borne out by the recent American Cancer Society research. While sitting time increased risk of early death, irrespective of exercise levels, both being physically inactive and spending too much time sitting was far worse, says ACS researcher Alpa Patel. "Women who were the least active and spent the most time sitting were 94 percent more likely to die early compared to women who were the most active and sat the least," she says. "For men there was a 48 percent increased risk." The bottom line, Church says: "A fitness program and movement throughout the day are both important—it's all good."