Most US Adults Sit 6 or More Hours Per Day and Are Inactive

Ricki Lewis, PhD

November 20, 2018

One quarter of US adults sit for more than 8 hours every day, and 1 in 4 are inactive, according to results of a study published online November 20 in the Journal of the American Medical Association.

A sedentary lifestyle with little exercise is associated with elevated risks for certain chronic diseases and premature mortality. Emily N. Ussery, PhD, of the Centers for Disease Control and Prevention, and colleagues investigated the joint prevalence of time spent sitting and insufficient leisure-time physical activity among US adults. Knowing such prevalence could guide healthcare practitioners in prioritizing interventions, they write.

The researchers analyzed data from 5923 adult respondents to the 2015 - 2016 National Health and Nutrition Examination Survey.

They defined sedentary behavior in several scenarios: "sitting at work, at home, getting to and from places, or with friends, including time spent sitting at a desk, traveling in a car or bus, reading, playing cards, watching television, or using a computer," and then asked respondents to estimate the amount of time they spent sitting during a typical day. The respondents also reported the frequency and duration of moderate- and vigorous-intensity leisure-time physical activity during a typical week.

Overall, 25.7% (95% confidence interval [CI], 23.0% - 28.5%) of the respondents reported sitting for more than 8 hours per day, and 44.6% (95% CI, 40.2% - 49.0%) reported being inactive.

The largest group of respondents reported sitting for 6 to 8 hours per day and being inactive (13.9%; 95% CI, 12.1% - 16.0%). The next most common scenario was sitting for more than 8 hours per day and being inactive (11.4%; 95% CI, 10.5% - 12.4%) and sitting for 4 to fewer than 6 hours per day and being inactive (11.2%; 95% CI, 9.6% - 13.0%).

The smallest group consisted of people who sat for fewer than 4 hours per day and were sufficiently active (2.6%; 95% CI, 2.1% - 3.2%) or who sat for fewer than 4 hours per day and were insufficiently active (2.7%; 95% CI, 2.0% - 3.6%).

The researchers summarized their findings: "These data reveal a substantial prevalence of high sitting time and physical inactivity among US adults: about 1 in 4 sit for more than 8 hours a day, 4 in 10 are physically inactive, and 1 in 10 report both."

Sex did not influence sitting and/or activity level. The combination of sitting more than 8 hours a day and inactivity was more prevalent with increasing age, however.

Limitations of the investigation include self-reporting bias and not capturing physical activity of duration less than 10 minutes.

In light of the finding that sitting time and inactivity often go hand in hand and are associated with chronic disease and premature mortality, healthcare providers "can support efforts to implement programs, practices, and policies where adults live, learn, work, and play to help them sit less and spend more time being physically active," the researchers conclude.

The researchers have disclosed no relevant financial relationships.

JAMA. Published online November 20, 2018. Abstract

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