One in four American adults sit for more than eight hours a day, according to new federal research from investigators at the Centers for Disease Control and Prevention (CDC).
The study, which was published in JAMA, analyzed data from the National Health and Nutrition Examination Survey (NHANES), which collects health information on a representative sample of adults over 18 years old. The nearly 6,000 people who responded reported on the number of hours a day they spent sitting — at work, home and during their commutes — as well as how many hours they spent doing moderate to vigorous physical activity each week. About 25% said they spent more than eight hours a day sitting, and 44% said they did no moderate to vigorous physical activity each week. About 11% said they sat for more than eight hours a day and also did little leisure-time physical activity. Only 3% said they sat for less than four hours a day and were active.
Sitting has been called “the new smoking” when it comes to the wide-ranging health problems it can trigger. Studies show that people who spend more time sitting have higher rates of heart problems and certain cancers compared to people who spend less time sitting, and they are more likely to die early. The negative health effects are due to a combination of what sitting does to the body — it can lead to weight gain and poor circulation, which are risk factors for heart disease — as well as to the fact that people who sit more are less physically active.
The data are only the latest to quantify how prevalent sitting is in the average adult’s daily life, and they highlight the importance of finding ways to sit less in order to lower rates of obesity, heart problems and cancer. Incorporating more physical activity, even if it doesn’t completely meet the recent government recommendations of 150 minutes of moderate to vigorous exercise a week, can help to offset some of the negative health effects of sitting. “If a person does sit for eight hours a day for their job, it’s best to reduce some of that sitting time with physical activity, and every little bit of exercise helps,” says Emily Ussery, an epidemiologist in the division of nutrition, physical activity and obesity at the CDC and the lead author of the study.
Ussery says that the recent physical activity guidelines from the Department of Health and Human Services support the idea that any physical activity is better than none, and everything from more activity-friendly policies like standing desks and walking meetings, to individual, conscious efforts to simply get up periodically throughout the day and take short walks can help. “Five minutes here, 10 minutes there, all adds up and can have positive health benefits,” she says.