Background/Purpose: Individuals with physical disabilities are more likely to develop a chronic lifestyle-related disorder because they are physically inactive (USDHHS, 2000). Understanding factors that influence physical activity participation are important for intervention design, therefore the purpose of this study was to examine the ability of the theory of planned behavior (TPB) to predict physical activity over a 4-month period in persons with physical disabilities.
Method: Participants were 190 individuals (M age = 49.8 yrs, SD = 10.3) with physical disabilities (53.7% with multiple sclerosis) who completed an online survey at two time points. At time 1, participants responded to questions that measured the TPB constructs including intention (3 items, α = .89), attitude (7 items, α = .91), subjective norm (4 items, α = .76), and perceived behavioral control (4 items, α = .84). Four months later, participants completed the 13-item physical activity scale for individuals with physical disabilities.
Analysis/Results: Based on the path analysis, the most important predictors of intention were attitude (.39), perceived behavioral control (.37), and subjective norm (.13). The only significant predictor of physical activity was intention (.28). The TPB model fit the sample data well (e.g., RMSEA < .01) and the explained variance in intention and physical activity was 57% and 11%, respectively.
Conclusions: Overall, the TPB was supported with attitude and perceived behavioral control as the strongest predictors of intention, and intention was the strongest predictor of 4-month physical activity. Interventions among this population should include behavior change strategies that target these specific constructs.