RESUMO
Low level physical activity is a risk factor for several chronic diseases and evidences suggest that the level of physical activity is decreasing. Reversing the trend depends on a behavior change by most people. However, the association between various psychosocial determinants and physical activity are not well understood. The aim of this study was to predict the stages of change in physical activity behavior of QUMS students by Pender's model. This cross-sectional survey was carried out at Qazvin University of Medical Science in 2008. A total sample of 222 students completed a self-report questionnaire consisting of an exercise change. A test-retest method was applied to determine the reliability while the Cronbach's Alpha used to confirm internal consistency. Face and content validity were confirmed in this study. Also, ANOVA and Path analysis were performed to determine the association between these constructs and stage of physical activity behavior change. More than half of students were in inactive stage and exercised for 41.62 minutes a week on average. Exercise self-efficacy, perceived barriers, and perceived benefits were found to be significant predictors of the stage of exercise behavior change among medical students. Only self-efficacy and stages of change [P<0.001] could directly predict the significant variance of physical activity while other constructs from Pander's model indirectly influenced the physical activity behavior through mediating stages of change construct. Perceived benefits [P<0.001] directly and perceived barriers inversely [P<0.001] were predictor of stage of exercise behavior. Perceived health status could indirectly influence the stage of change via perceived benefit. Our results indicated that the change in stage of readiness for exercise is probably dependent on the student's perceptions of exercise self-efficacy, benefits and barriers as well as the perceived health status to engage in physical activity. Furthermore, the results of this study made moderate support for the health promotion model constructs to predict physical activity and exercise stage of change