Should we target increased physical activity or less sedentary behavior in the battle against cardiovascular disease...

Physical inactivity is a well-established risk factor for cardiovascular disease (CVD) incidence and mortality. In the last decade, there is also emerging evidence of the role of sedentary behaviors (sitting) as a risk factor for CVD. Therefore, there is increasing interest in understanding the independent and joint effects of physical activity and sedentary behavior on CVD risk. Higher levels of moderate-to-vigorous physical activity and less time spent in sedentary behavior are associated with a decreased risk of CVD. There is also preliminary evidence that higher levels of light-intensity physical activity are associated with lower all-cause mortality rates; however, the cardio-protective effects of light-intensity physical activity are yet to be determined. The results from several studies have demonstrated that the effects of sedentary behavior on CVD risk is more pronounced among individuals who are physically inactive, compared to those who are more active. Further, high levels (60-75 min per day) of moderate-to-vigorous physical activity appear to eliminate the increased risk of CVD associated with excessive sedentary behavior. Replacing sedentary behavior with any intensity of physical activity will produce health benefits; however, the greatest benefits occur when replacing sedentary behavior with moderate-to-vigorous intensity physical activity.