Definition, measurement, and health risks associated with sedentary behavior.

PURPOSE AND METHODS: Although evidence is accumulating that sedentary behavior (SB), independent of moderate-to-vigorous intensity physical activity (MVPA), is associated with cardiometabolic and aging outcomes in adults, several gaps present opportunities for future research. This article reports on the "Research Evidence on Sedentary Behavior" session of the Sedentary Behavior: Identifying Research Priorities workshop, sponsored by the National Heart, Lung, and Blood Institute and the National Institute on Aging, which aimed to identify priorities in SB research. RESULTS AND
CONCLUSIONS: A consensus definition of SB has not yet been established, although agreement exists that SB is not simply all behaviors other than MVPA. The two most common definitions are as follows: one based solely on intensity (<1.5 metabolic equivalents [METs]) and another which combines low intensity (≤1.5 METs) with a seated or reclining posture. Thus, for the definition of SB, evaluation of whether or not to include a postural component is a research priority. SB assessment methodologies include self-report and objective measurement, each offering distinct information. Therefore, evaluation, standardization, and comparison across self-report and objective assessment methods are needed. Specific priorities include the development and validation of novel devices capable of assessing posture and standardization of research practices for SB assessment by accelerometry. The prospective evidence that SB relates to health outcomes is limited in that SB is almost exclusively measured by self-report. The lack of longitudinal studies with objectively measured SB was recognized as a major research gap, making examination of the association between objectively measured SB and adverse health outcomes in longitudinal studies a research priority. Specifically, studies with repeated measures of SB, evaluating dose-response relationships, with inclusion of more diverse populations are needed.