Effect of interventions based on the theory of planned behavior on promoting physical activity: a systematic review

Introduction: Inadequate physical activity is the first among the ten risk factors of mortality worldwide. Adequate and regular physical activity can reduce high blood pressure, cardiovascular diseases, Cerebrovascular accidents, breast cancer, colon and depression, and falls and fracture in adults. The present research aimed to investigate the effect of interventions based on the theory of planned behavior on promoting the physical activity of different groups systematically. Methods: Seven databases including Iran medex, SID, PubMed, Web of Science, Science Direct, Scopus and Google Scholar were searched for the following key words: Theory of planned behavior OR TPB, experimental randomized controlled trial OR intervention, motor activity, physical activity, exercise. The inclusion criteria were for the results to be quantitative, interventional, and in English or Persian language. The theory of planned behavior had to be an integral part of the selected articles. Results The initial search ended up with 319 articles in different databases which were filtered according the inclusion and exclusion criteria. Finally, 14 articles were included in the research which covered the years 2003 to 2016. The majority of studies were case-control and semi-experimental. The intervention durations were 2 weeks to 3 months. The target research populations were students, elderly, housewives, and health workers. The used educational interventions were mostly lecture, panel discussion, booklet, focal groups, educational pamphlets, Q&A, and brainstorming. In the majority of investigations, attitude, perceived behavioral control, and behavioral intention were strong predictors of physical activities. Subjective norms were poor predictors in less than half of the studies. The theory-based interventions revealed to have a positive effect on promoting physical activity. Conclusion: The majority of interventions based on the theory of planned behavior were proved to promote physical activities. However, the heterogeneity of target groups makes comparing the effect of interventions on physical activities difficult. To explore the effect of the interventions in theory-oriented studies, it is recommended to extend the length of the interventions and follow-ups to properly decide on the effectiveness of the intervention. Key words: theory of planned behavior, physical activity, educational intervention