How Much Sedentary Time is Needed to Increase CVD Risk?

Higher sedentary times are associated with increased risk of cardiovascular disease (CVD), according to a new study.

It is well understood that a lack of physical activity increases the risk of CVD, but the specific dose-response association has not been studied.
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To study the categorical and quantitative dose-response association between sedentary behavior and CVD risk, the researchers searched online databases for studies that assessed sedentary times in relation to incident CVD that were published before July 6, 2015.

The researchers evaluated 9 prospective cohort studies that included 720,425 participants aged 18 years and older and 25,769 cardiovascular events with a median 11-year follow-up.

A categorical analysis showed that participants who were sedentary for a median 12.5 hours per day (highest sedentary time) had an increased risk for CVD compared with those who were sedentary for about 2.5 hours per day (lowest sedentary time). Those who were sedentary for about 7.5 hours per day (intermediate sedentary time) had no apparent risk.

However, after performing a continuous analysis, the researchers found a nonsignificant increased risk for those who were sedentary for more than 6.8 hours per day and a significant increased risk for those who were sedentary more than 10 hours per day.

“The association between sedentary time and the risk for CVD is nonlinear with an increased risk only at very high levels,” the researchers concluded. “These findings could have implications for guideline recommendations regarding the risks related to sedentary behavior.”

—Amanda Balbi

Reference:

Pandey A, Salahuddin U, Garg S, et al. Continuous dose-response association between sedentary time and risk for cardiovascular disease: a meta-analysis [published online July 13, 2016]. JAMA Cardiol. doi: 10.1001/jamacardio.2016.1567.