Sedentary Behaviour and Cardiovascular Disease

Abstract

Sedentary behaviour is ubiquitous in high income countries and increasingly so in low-to-middle income countries also. Despite substantial research progress achieved in the past decade, our understanding of the influence of sedentary behaviour on cardiovascular health and cardiovascular disease occurrence is still in its infancy. Multiple methodological issues such as poor measurement, unmeasured confounding, inconsistent definition, paucity of prospective study designs, incomplete understanding of key sedentary behaviour indicators such as television viewing, and large heterogeneity between studies hinder a confident translation of available research into quantitative sedentary behaviour public health and clinical guidelines for primary prevention of cardiovascular disease. In young people, the overwhelming majority of the evidence examining the links between objectively assessed sedentary behaviour and surrogate markers of cardiovascular health is cross-sectional, and the few prospective studies point towards no association. The best available epidemiologic evidence on sitting time in adults suggests that the risk for incident cardiovascular disease is elevated at 10 h/day and over. The association between sedentary time and cardiovascular disease appears to be modified by physical activity; equivalents of approximately 1 h of moderate intensity activity per day appear to largely offset cardiovascular events risk. But such an amount of daily physical activity may be beyond the reach of large parts of the population and therefore the public health relevance of sitting for cardiovascular health remains high. Although causality between sitting and cardiovascular disease is not established, there is scope for developing and testing sitting-reducing interventions targeting the most physically inactive population groups and those who are likely to be resistant or unable to increase physical activity of moderate-to-vigorous intensity. Existing sedentary behaviour-reducing interventions have reported modest effects and as such, the assumption that decreasing sitting time in the population will be easier than effectively promoting physical activity may need further scrutiny. Further research efforts are warranted for optimizing the definition and measurement of sedentary behaviour, for understating better its independent cardiovascular effects and mechanisms of action, and for developing effective interventions with broad reach.