The current literature regarding physical activity (PA) and sedentary behavior (SB) highlights the negative effect of considerable amounts of time spent in activities such as sitting, TV viewing, computer use, and some work and study activities on cardiovascular health. SB may be defined as any waking behavior characterized by an energy expenditure ≤ 1.5 metabolic equivalents while in a sitting, reclining, or lying posture.^, Thus, SB is not the absence or low level of PA, but it can coexist with it. In this sense, a recent review showed an interaction between SB and PA, providing evidence that individuals with higher time spent in SB presented a higher risk of cardiovascular mortality. However, estimates have been less consistent in individuals with higher PA levels.

The literature cites a series of possible mechanisms for SB effects, independent of PA, on metabolic and cardiovascular outcomes. One of these mechanisms is the decrease in enzymatic activity responsible for HDL production and the capture of triglycerides in the blood chain due to sustained inactivity in sitting, reclining, or lying posture. In this regard, strategies reducing the time spent in SB or interrupting sustained inactivity have been studied. Some of these approaches focus on standing up for a while or a short period of movement between periods of sitting time (breaks in SB). A meta-analysis with adults found a positive effect of breaks in SB on adiposity control and glycemia. In addition, an experimental study showed that 1-to-2–minute breaks in sedentary work activities every half an hour resulted in small-to-moderate declines in total cholesterol, triglycerides, and fasting blood glucose.

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