By this point, most people are aware of the connection between being sedentary and dying earlier. If that’s not enough of a problem, it also seems that long hours sitting isn’t totally offset by activity: A study a couple of years ago found that even people who exercise, if they sit a lot otherwise, are still at greater risk of mortality. And a new study in Annals of Internal Medicine builds on the growing body of evidence against sitting, finding that being sedentary for longer chunks of time, unpunctuated by getting up and about, may be just as bad as sitting for more hours total.
“We tend to think of sedentary behavior as just the sheer volume of how much we sit around each day,” said study author Keith Diaz in a news release. “But previous studies have suggested that sedentary patterns–whether an individual accrues sedentary time through several short stretches or fewer long stretches of time–may have an impact on health.”
To tease apart this dichotomy, the team from Columbia University Medical Center and NewYork-Presbyterian looked at data from almost 8,000 people who wore activity monitors for seven days. Their health outcomes were tracked over the next four years—340 people died of various causes during this time. People spent, on average, more than three-quarters of their waking hours sitting, which is more than 12 hours of a 16-hour day.
There were a couple of interesting findings when the team correlated sitting behavior to mortality. People who sat more had a higher risk of death, which isn’t surprising. But the way that the time was broken up mattered: People who sat more but punctuated it by getting up every 30 minutes or less had a significantly lower risk of death than people who sat more but got up only every 60-90 minutes.
The authors suggest, as others have before, that people get up as much as they possibly can throughout the day. “So if you have a job or lifestyle where you have to sit for prolonged periods of time,” said Diaz, “we suggest taking a movement break every half hour. This one behavior change could reduce your risk of death, although we don’t yet know precisely how much activity is optimal.”
The study has a few limitations—for instance, the fact that it only logged people’s activity for a short period of time (seven days) and followed their health outcomes for a few years. The other issue is that reverse causation could be at play—that is, people who were less healthy to begin with may be more sedentary as a result, not a cause. Indeed, people who were more sedentary also tended to be heavier, smoke more, exercise less, and have past health problems. Though the authors tried to adjust for these variables, it’s certainly possible that the connection works in both directions.
Though the study may have limitations, it’s definitely supported by a number of past studies, which have looked both at health outcomesover the long term, and at the physiological changes in people who are asked to be sedentary in the lab for short periods. Enough work has been done in the field that it’s probably safe to say that sitting is unhealthy, for several body systems: the cardiovascular system, the immune system, the nervous system, and of course our mental health.
So we may need to remind ourselves to get up every so often, and do some jumping jacks, go talk to a coworker, do some yoga, or a take a quick walk down the block. And keep in mind that even getting up regularly is linked to mortality: It was just, as the authors say, the “least harmful pattern” of racking up sitting time.
“This study adds to the growing literature on how dangerous long periods of sitting are for our health,” said study co-author Monika Safford, “and underscores a growing awareness among clinicians and researchers that sitting really is the new smoking.”