[A review of the literature on sedentary behavior]

Sedentary behavior (such as sitting, watching TV, and driving) is characterized by little physical movement and low energy expenditure (≤1.5 metabolic equivalents). Previous studies have shown associations between sedentary behavior and adverse outcomes, including cancer, cardiovascular disease, and death. This study is a narrative review that aims to summarize the assessment tools for sedentary behavior as well as the association between sedentary behavior and adverse health outcomes. Additionally, guidelines for future research on sedentary behavior are discussed.Sedentary behavior is assessed using subjective methods such as questionnaire responses or objective methods such as accelerometer readings. Although questionnaire methods have low validity, they allow researchers to collect information regarding the purpose or occasion of physical activity at a low cost. Accelerometers are expensive but collect precise information on the duration of sedentary behavior. Sedentary behavior is a risk factor for the incidence of cardiovascular diseases and cancer and associated mortality. The association between sedentary behavior and some diseases such as cancer type have been reported. Previous studies have found a dose-response relationship between sedentary time and adverse outcomes. Research on the associations between sedentary behavior and the subtypes of stroke, heart disease, and orthopedic diseases is insufficient; further studies are needed to clarify these associations. Recently, sedentary behavior has been the focus of guidelines in some countries because of increasing evidence on its adverse consequences. Intervention studies have shown that taking breaks and replacing sedentary behavior with vigorous or high-intensity physical activity benefit the health of participants. Future studies are needed to examine the cutoff values of sitting time that reduce the risk of morbidity for each disease and the health effects of interventions that shorten sitting time.