Too much time spent in a chair could shorten our lives, even if we exercise, according to a study that uses objective measures to find the links between lengthy sitting time and death among middle-aged and older adults.

More hopefully, the study also suggests that we might be able to take steps to reduce our risks by taking steps every half-hour or so.

Most of us almost certainly have heard by now that being seated and unmoving all day is unhealthy. Many past epidemiological studies have noted that the longer people sit on a daily basis, the likelier they are to develop various diseases, including obesity, diabetes and heart disease. They also are at heightened risk for premature death.

This association between sitting and ill health generally remains, the past science shows, whether people exercise or not.

But most of these studies have relied on people’s memories of how they spent their time on any given day, and our recall about such matters tends to be notoriously unreliable. The studies also usually have focused on the total number of hours that someone sits each day. Some scientists have begun to wonder whether our patterns of sitting — how long we sit at a stretch and whether, when, and how often we stand up and move — might also have health implications. And they have questioned whether gender, race or weight might alter how sitting affects us.

So for the new study, which was published this week in Annals of Internal Medicine, scientists from Columbia University in New York City and many other institutions turned to an extensive database of existing health information about tens of thousands of Caucasian and African-American men and women 45 or older who were part of a study of stroke risk.

The participants had undergone a battery of health tests and about 8,000 of them also had worn accelerometers for a week to track their daily movements.

Accelerometers are, of course, an objective measure of how much and often someone sits, exercises or otherwise moves about. They do not hedge about those hours you spent sprawled on the couch binge-watching “30 Rock.”

The scientists pulled the records for the accelerometer group.

They then stratified these participants into various groups, depending on how many hours per day each person had sat, as well as how long each of the bouts of sitting had continued, uninterrupted — 10 minutes? 30 minutes? 60 minutes? more? — and how much time, if any, they had spent exercising (mostly with walks).

Finally, they checked these records against mortality registries, looking for deaths that had occurred within about four years of the participants having worn the accelerometers and completed other health tests.

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Source: New York Times