The Theory of Planned Behavior as a model for understanding sedentary behavior

Objectives: Sedentary time has emerged as an independent risk factor for numerous adverse health outcomes. However, little is known about the social-cognitive correlates of sedentary behavior. The purpose of this study was to provide preliminary evidence for the factor structure and composition of sedentary derived Theory of Planned Behavior (TPB) constructs and to determine the utility of these constructs in predicting sedentary intention and sedentary time. Method: Twenty-three items were created to assess attitudes, subjective norms (SN), perceived behavioral control (PBC), and intention with respect to time spent being sedentary. Using a web-based survey, 372 adults completed a modified Sedentary Behavior Questionnaire and were then randomised to one of three TPB questionnaire packages: general, weekday, and weekend. Weekday and weekend participants completed items for work/school (less-volitional) and leisure/recreation (volitional) activities separately, resulting in five TPB models being analyzed: general, weekday work/school, weekday leisure/recreation, weekend work/school, and weekend leisure/recreation. Results: Irrespective of model, items grouped into coherent factors consistent with TPB and explained 9 -58% and 8-43% of the variance in intention and behavior, respectively. The strongest and most consistent predictor of intention and behavior were SN and intentions, respectively. Mediation analyses indicated that attitudes consistently affected sedentary time through intention. Conclusions: There is growing evidence that the TPB is a useful framework for understanding sedentarism. (C) 2015 Published by Elsevier Ltd.