Development and validation of the physical activity behavior scale for older adults based on the theory of planned behavior

Regular physical activity is crucial for the health of older adults. While existing tools can accurately measure activity levels, they fail to reveal the underlying psychological motivations behind this behavior. Based on the Theory of Planned Behavior, this study developed and validated a scale to evaluate the psychological factors influencing physical activity among older Chinese adults. The initial scale was developed based on the Theory of Planned Behavior through a literature analysis, consultation with experts, and a preliminary survey. A cross-sectional study was conducted with 451 Chinese older adults who were selected using convenience sampling. Item analysis and exploratory factor analysis (EFA) were performed on data from 152 participants to refine the scale. Then, confirmatory factor analysis (CFA) was conducted with the remaining 299 participants to validate the scale’s structure. The scale’s reliability was evaluated by measuring its internal consistency and test-retest reliability. The final scale comprises 19 items across four dimensions: behavioral attitude (6 items), subjective norm (3 items), perceived behavioral control (5 items), and behavioral intention (5 items). Exploratory factor analysis (EFA) revealed the Kaiser-Meyer-Olkin (KMO) measure was 0.837, and Bartlett’s test of sphericity was significant (χ² = 1559.016, df = 171, p < 0.001), with the cumulative variance explained reaching 69.26%. Confirmatory factor analysis (CFA) confirmed a good model fit (χ²/df = 1.713, RMSEA = 0.049, SRMR = 0.039, TLI = 0.963, and CFI = 0.968). For reliability, the overall Cronbach’s α was 0.939, with dimension values ranging from 0.872 to 0.884, and the test-retest reliability was 0.940. The scale demonstrated excellent content validity (S-CVI/Ave = 0.915). In conclusion, the scale demonstrates good reliability and validity for use in related research and practice. The Physical Activity Behavior Scale for Older Adults is a reliable and valid tool for assessing the psychological determinants of physical activity in this population.