ABSTRACT
Sedentary behavior is now recognized as a discrete component of the 24-hour activity cycle. Acutely, replacing sedentary behavior results in modest (e.g., with standing) to moderate (e.g., using a treadmill desk) increases in energy expenditure. Prolonged sedentary behavior engenders acute, adverse metabolic and cardiovascular responses, but activity breaks and, to a lesser extent, standing may attenuate these adverse responses. Clinical trials have reduced sedentary behavior primarily by increasing standing, but most observe null effects on weight and modest effects on body composition, metabolic, and musculoskeletal outcomes. Preliminary data suggest that populations with preexisting dysglycemia or obesity may benefit more from sedentary behavior reduction, replacing sedentary behavior with more ambulatory activity (rather than standing) may be more beneficial, and that reduction in sedentary behavior could augment standard lifestyle interventions. While current guidelines generally recommend reducing sedentary behavior, the consensus remains elusive due to the low quality of available evidence regarding specific targets, best replacement activities, and sedentary behavior breaks. Environmental strategies such as sit–stand desks appear most effective for reducing sedentary behavior, but future research on the feasibility and effects of reducing sedentary behavior by comparing standing and more intense activity replacement within a 24-hour activity framework is critically needed.
