Archive for February 16th, 2015

Sedentary Behavior and Disease Risk

February 16, 2015

Trending lately are articles on how sitting for almost the entire day can be harmful to health.  The latest issue of the Annals of Internal Medicine, reports how the bad effects of sitting can affect health and how these effects are not be “reversed” by physical activity….

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Background: The magnitude, consistency, and manner of association between sedentary time and outcomes independent of physical activity remain unclear.

Purpose: To quantify the association between sedentary time and hospitalizations, all-cause mortality, cardiovascular disease, diabetes, and cancer in adults independent of physical activity.

Data Sources: English-language studies in MEDLINE, PubMed, EMBASE, CINAHL, Cochrane Library, Web of Knowledge, and Google Scholar databases were searched through August 2014 with hand-searching of in-text citations and no publication date limitations.

Study Selection: Studies assessing sedentary behavior in adults, adjusted for physical activity and correlated to at least 1 outcome.

Data Extraction: Two independent reviewers performed data abstraction and quality assessment, and a third reviewer resolved inconsistencies.

Data Synthesis: Forty-seven articles met our eligibility criteria. Meta-analyses were performed on outcomes for cardiovascular disease and diabetes (14 studies), cancer (14 studies), and all-cause mortality (13 studies). Prospective cohort designs were used in all but 3 studies; sedentary times were quantified using self-report in all but 1 study. Significant hazard ratio (HR) associations were found with all-cause mortality (HR, 1.240 [95% CI, 1.090 to 1.410]), cardiovascular disease mortality (HR, 1.179 [CI, 1.106 to 1.257]), cardiovascular disease incidence (HR, 1.143 [CI, 1.002 to 1.729]), cancer mortality (HR, 1.173 [CI, 1.108 to 1.242]), cancer incidence (HR, 1.130 [CI, 1.053 to 1.213]), and type 2 diabetes incidence (HR, 1.910 [CI, 1.642 to 2.222]). Hazard ratios associated with sedentary time and outcomes were generally more pronounced at lower levels of physical activity than at higher levels.

Limitation: There was marked heterogeneity in research designs and the assessment of sedentary time and physical activity.

Conclusion: Prolonged sedentary time was independently associated with deleterious health outcomes regardless of physical activity.

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Take note however, that the deleterious effects of prolonged sitting time on health from watching TV, working in our office overtime,  are more pronounced among those who do little or no exercise than among those who exercise regularly.

It is therefore advised to take breaks by standing and walking few minutes for every hour of sitting.

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