Sedentary behavior, even among those who are physically active, is associated with greater risk for CVD, diabetes, impaired insulin sensitivity and all-cause mortality, according to a new scientific statement from the American Heart Association.
“The state of the science right now is we don't know how much is too much,” Deborah Rohm Young, PhD, director of behavioral research at Kaiser Permanente Southern California in Pasadena and chair of the new scientific statement, told Cardiology Today. “But, we do know the evidence is highly suggestive that too much sitting or being sedentary is associated with increased CV morbidity and mortality.”
Sedentary behaviors, such as sitting, reclining or laying down while awake and reading, watching television or working on the computer, translate to a mean energy expenditure that is ≤ 1.5 metabolic equivalents (METs). Light housework or leisurely walking translates to a mean energy expenditure of about 2.5 METs and moderate to physical activity translates to ≥ 3 METs, according to the statement. Existing evidence suggests that U.S. adults spend 6 to 8 hours of their day in sedentary time and older adults spent up to 9.6 hours a day in sedentary time, according to Young.
“Even those who are the most physically active and the most sedentary still have increased risk compared to those who are physically active and not very sedentary,” Young said. “That’s what makes this so interesting: There are clearly different mechanisms [involved]. Sedentary behavior is not a lack of physical activity; it’s something different.”
The statement recommends at least 30 minutes of moderate to vigorous physical activity per day to achieve the AHA’s weekly recommendation of 150 minutes of moderate exercise or 75 minutes of vigorous exercise. The goal is to encourage more consistent activity, according to Young.
However, according to the authors, moderate to vigorous physical activity does not cancel out the impact of sedentary time. Even physically active people who spend much of their time being sedentary appear to have increased risk for CVD, according to the statement. The authors acknowledge that is it unclear whether people should replace prolonged sedentary behavior with simple movement or moderate to vigorous physical activity.
“Given the current state of the science on sedentary behavior and in the absence of sufficient data to recommend quantitative guidelines, it is appropriate to promote the advisory, ‘Sit less, move more,’” the authors wrote. – by Dave Quaile
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Deborah Rohm Young, PhD, can be reached at email@example.com.
Disclosure: Young reports no relevant financial disclosures. Please see the full study for a list of the other authors’ relevant financial disclosures.