Increased Sedentary Time Ups Risk for CVD, Diabetes, and Death, the AHA Says


Evidence is mounting that sedentary behavior can increase the risks of cardiovascular disease and diabetes morbidity and mortality, as well as death from any cause, according to a new scientific statement from the American Heart Association (AHA) published online earlier this week in Circulation.

“There has been a plethora of articles in the past 5 to 10 years examining the association of sedentary time of disease outcomes,” statement chair Deborah Rohm Young, PhD (Kaiser Permanente Southern California, Pasadena, CA), told TCTMD in an email. “We wanted to ascertain the strength of the evidence.”

The AHA advisory committee reviewed the current data available on sedentary behavior, looking at assessment methods, population prevalence, determinants, and the association with cardiovascular disease incidence and mortality.

Sedentary behavior was defined as “any waking behavior characterized by an energy expenditure 1.5 metabolic equivalents (METs) while in a sitting or reclining posture.” Common examples of sedentary behavior include watching television, computer use, or other “screen time.” Light housework or slow, leisurely walking requires approximately 2.5 METs, while moderate to vigorous physical activity typically requires 3.0 or more METs.

Using data from economic, occupational, and time use surveys, the researchers found that adults spend an average of 6 to 8 hours per day being sedentary, with that amount increasing in adults 60 years and older. In 1960, about 15% of occupations were considered sedentary compared with more than 20% in 2008. Interestingly, even those adults who spend more time doing moderate to vigorous physical activity had similar amounts of sedentary time, suggesting that physical activity does not displace sedentary time.

Although the AHA document states that too much sedentary time could be a risk factor for cardiovascular disease, diabetes morbidity and mortality, and all-cause mortality, it also cautions that the evidence, while suggestive, is not yet conclusive. More studies are needed looking at the link between sedentary behavior and these risks, as well as the impact of physical activity.

To TCTMD, Young said there is currently not enough evidence for the AHA to make any specific recommendations on the amount of daily sitting time; however, a key point for physicians to share with patients is to sit less and move more. “The message physicians should continue is to encourage their patients to engage in at least 30 minutes of moderate to vigorous physical activity,” she said. “Also, patients should move throughout the day when they’re able.”

Carl “Chip” Lavie, MD (John Ochsner Heart and Vascular Institute, New Orleans, LA), who was not involved in crafting the AHA statement, praised the work and called it an excellent resource.

“I believe that most are aware that lack of physical activity and low cardiorespiratory fitness are bad things associated with more cardiovascular disease and higher mortality,” Lavie wrote in an email to TCTMD. “This document also highlights the adverse consequences of sedentary behavior such as prolonged sitting.”

In fact, he said, a person who exercises daily but then sits for 10 to 12 hours will largely negate the benefits of exercise.  

“The ideal situation would be to increase physical activity, at least 30 minutes of moderate or 15 minutes of vigorous activity most days, and also reduce sitting (at least under 9 to 10 hours, even better under 8 hours and, ideally, under 6 hours per day),” Lavie said. “This can be accomplished by getting up frequently, doing some work and even TV watching while standing or walking, in addition to increasing regular physical activity.”


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Sources
  • Young DR, Hivert MF, Alhassan S, et al. Sedentary behavior and cardiovascular morbidity and mortality: a science advisory from the American Heart Association. Circulation. 2016;Epub ahead of print.

Disclosures
  • Young reports no relevant conflicts of interest.
  • Lavie is the author of the book The Obesity Paradox.

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