The American Heart Association (AHA) has issued a science advisory examining the association between greater time spent in sedentary behavior and all-cause and cardiovascular morbidity and mortality in adults. This advisory reviews the current evidence on sedentary behavior in terms of assessment methods, population prevalence, determinants, associations with cardiovascular disease incidence and mortality, potential underlying mechanisms, and interventions. While the evidence is currently insufficient on which to base specific public health recommendations regarding the appropriate limit to the amount of sedentary behavior required to maximize CVD health benefits, the review did find the following:
• There is no “gold standard” for sedentary behavior assessment; self-report measures provide information on the behavioral context that is not available from objective measures.
• Prevalence of sedentary behavior differs depending on the assessment tool; however, it is estimated that adults spend 6 to 8 hours per day in sedentary behavior, including sitting, TV viewing, screen time, and computer use. The prevalence is greater for older adults.
• There is cross-sectional evidence that psychological well-being could be inversely associated with sedentary behavior, but prospective studies are needed to understand the directionality of potential associations.
• There might be a significant genetic component contributing to sedentary behavior in individuals; however, no specific loci have been convincingly identified and replicated.
• Prospective evidence is accumulating that sedentary behavior could be a risk factor for CVD and diabetes mellitus morbidity and mortality and for all-cause mortality. The degree to which this is independent of the effects of moderate to vigorous physical activity (MVPA) needs further study.
The advisory also includes recommendations for future research, including the importance of interventions to determine whether reductions in sedentary time can reduce the risk of CVD and diabetes mellitus.
Young DR, Hivert MF, Alhassan S, et al. Sedentary behavior and cardiovascular morbidity and mortality: A science advisory from the American Heart Association. [Published online ahead of print August 15, 2016]. Circulation. doi:10.1161/CIR.0000000000000440.
Increasing research supports that sedentary behavior should be viewed as a separate and additional risk factor for chronic disease development, specifically the development of coronary artery disease and type 2 diabetes. In addition, there are data linking increased sedentary time with increased total mortality. Sedentary behavior or the time spent sitting, acts distinctly from a lack of moderate to vigorous physical activity (MVPA). An example of this is what has been dubbed the “exercising couch potato,” which describes individuals who regularly exercise but spend the rest of their day sitting, and it appears that exercise does not in itself offset the risk that accrues with increasing sedentary time.1 It appears that two aspects of activity, exercise and sedentary time, both influence risk in a separate and additive manner. From a practical point-of-view, short periodic breaks during otherwise prolonged periods of sedentary time make sense and some studies have shown positive effects on biomarkers from even brief 3-minute periods of activity every half-hour.2 —Neil Skolnik, MD
1. Schmid D, Ricci C, Leitzmann MF. Associations of objectively assessed physical activity and sedentary time with all-cause mortality in US adults: The NHANES Study. PLoS One. 2015;10(3):e0119591. doi:10.1371/journal.pone.0119591.
2. Dempsey P, Larsen RN, Sethi P, et al. Benefits for type 2 diabetes of interrupting prolonged sitting with brief bouts of light walking or simple resistance activities. Diabetes Care. 2016;39(6):964-72. doi:10.2337/dc15-2336.
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