Gretchen Reynolds on the science of fitness.
Using a standing desk at the office may adversely influence how much time you spend lounging in a chair at home, according to a new study of sedentary behavior. The findings subtly underscore that, when it comes to health habits and exercise, we humans have a surprising capacity to be our own worst enemies.
There is virtually unanimous scientific agreement that uninterrupted sitting is bad for us. Sitting for long stretches of time has been linked to markedly increased risks for obesity, diabetes and other metabolic disorders, heart disease and premature death.
But it can be difficult not to sit, especially for those of us who work in offices. Past studies of deskbound workers have shown that most of us sit for about 10 hours or more every day, with the majority of that chair time occurring at work.
Such statistics account for the growing popularity of sit-stand workstations, which allow people to stand up for at least part of their workday. In experiments, workers who receive sit-stand desks generally reduce the amount of time that they spend seated during office hours, at least in the short term, and often report feeling more energetic and productive.
But the ripple effect these desks have on people’s lives has not been studied. It might seem as if standing up in one arena, when we know that doing so is healthy, should inspire us to stand up in others.
But the human body and brain are funny. They often, and rather insidiously, undermine some of our best efforts to be healthier, in an attempt to maintain our physiological status quo. The result can be that we do not benefit as much as we’d hoped from changes to our lifestyles. When we slash calories to lose weight, for instance, our bodies often lower our metabolic rate, and our weight doesn’t budge much.
Similarly, studies of people who begin or greatly intensify an exercise program have shown that these exercisers often start sitting more during the hours when they are not working out, so that their overall daily energy expenditure doesn’t increase substantially and the number of hours that they spend sitting grows.
Whether a relatively low-key intervention, however, such as providing people with sit-stand workstations would likewise cause physiological compensations away from the office remained unknown.
So for the new study, which was published last month in Medicine & Science in Sports & Exercise, researchers from Loughborough University in England and Victoria University in Australia recruited 40 healthy but sedentary university office workers and had them wear two types of activity monitors for 14 days. One of the monitors carefully tracked changes in posture that reveal how much someone is sitting or standing. The other monitor tracked steps and other physical activity.
Then the researchers provided all of their volunteers with sit-stand workstations and asked them to don the monitors after a week of using the new desks, after six weeks and after three months. In each instance, the volunteers wore the monitors at work and at home for a week at a time.
Then the researchers examined how people’s daily activity patterns changed after they began using the sit-stand desks. And they did change. Before receiving the new desks, most of the workers had spent about 10 hours each day in a chair either at the office or at home and less than five hours standing up.
After a week with the new desks, the workers were standing for almost 6.5 hours in total each day — between work and home — and sitting for less than 8.5 hours.
That shift lingered throughout the three-month study period, although there was some chair-time rebound. After six weeks, the workers were standing for about six hours a day, and after three months, their daily standing time had fallen to about 5.5 hours and their sitting time had climbed back to a little over nine hours.
What’s particularly interesting and revelatory about those numbers, though, is just where they were doing that sitting and standing. When the researchers looked closely at the volunteers’ daily activity patterns, they found that while the workers were sitting less at the office, they were spending more time seated at home than they had been at the start of the experiment.
“It appears that participants were compensating for sitting less at work by sitting more and moving less after work,” said Stacy Clemes, a professor of exercise science at Loughborough University who conducted the study with Maedeh Mansoubi, a graduate student, and other colleagues.
The net effect of giving people sit-stand desks, in other words, was to decrease the total amount of time they sat each day but nudge them toward sitting more at home.
These dynamics were evident and accelerated throughout the three months of the study. Whether they would alter for better or worse after a longer period with sit-stand desks remains unknown, although Dr. Clemes and her colleagues are studying that issue.
For now, she said, the message of this experiment is that someone wishing to sit less should “consciously think” about his or her behavior throughout the day, especially away from the office.
“Stand up and walk around during TV commercials,” she said. Although, to avoid undermining your other health intentions, perhaps don’t walk to the refrigerator.