Development and Validation of the Adult Sedentary Behavior Reduction Intention Questionnaire based on the Theory of Planned Behavior

Background Sedentary behavior is gradually becoming the mainstream trend in people’s lifestyles, with a significant increase observed worldwide and across all age groups. The measure of adults’ intention to reduce sedentary behavior provides a significant reference for the intervention strategies. However, the measurement tool is lacking. Given that the Theory of Planned Behavior (TPB) serves as a robust psychosocial theory framework, widely applied in predicting various health behaviors, this study aims to extend this theory into the realm of sedentary behavior by developing and validating a questionnaire to evaluate adult intentions of reducing their sedentary behavior. Methods A preliminary item pool for the questionnaire was created through a literature review, followed by two rounds of Delphi expert consultation and a small-sample pilot study, resulting in the initial version of the questionnaire. A total of 316 adults with an average daily sedentary behavior duration of ≥6 hours were involved in the survey to determine its psychometric properties using reliability analysis, content validation, and confirmatory factor analysis. Results An initial version of the questionnaire with four dimensions (behavioral intention, subjective norms, attitudes, and perceived behavioral control) and 16 items was obtained. Subsequent psychometric property validation results showed that the overall Cronbach’s α coefficient for the questionnaire was 0.967, with Cronbach’s α coefficients for each dimension ranging from 0.911 to 0.950. The item-level content validity index (I-CVI) ranged from 0.813 to 1. The adjusted model indices were c 2 /df = 2.931, GFI = 0.906, AGFI = 0.857, IFI = 0.976, NFI = 0.965, TLI = 0.968, CFI = 0.976, and RMSEA = 0.078, all of which met the fitting criteria. Conclusions A theory-driven instrument is suitable for its use with Chinese adults to assess their level of intentions and the factors affecting the sedentary behavior, which provides the basis for future intervention studies.