Theory of Planned Behavior in Predicting Physical Activity among Portuguese Older Adults with Osteoarthritis

ABSTRACT The purpose of this study is to investigate the explanatory value of the theory of planned behavior (TPB) to predict the intentions of physical activity in older adults with lower-extremity osteoarthritis. This is a cross-sectional study with a sample of 41 older adults (50+ years) with lower-extremity osteoarthritis. The instruments used were as follows: International Physical Activity Questionnaire, Knee Injury and Osteoarthritis Outcome Score, Hip disability and Osteoarthritis Outcome Score and TPB exercise scale. The Western Ontario and McMaster Osteoarthritis Index scores were calculated and used in the statistical analysis. Results revealed that attitudes and perceived behavioral control were statistically significant predictors of physical activity intentions. Attitudes and perceived behavioral control accounted for 46% of the variance in physical activity intentions. Subjective norms did not evidence a significant effect. Knowledge of the predictors of physical activity intentions can guide researchers and clinicians in the development of interventions that are tailored to the personal characteristics and needs of older adults with chronic diseases.