Hamadan University of Medical Sciences Journal of Research in Health Sciences 2228-7795 15 4 2015 12 30 Predictors of Physical Activity among Adolescent Girl Students Based on the Social Cognitive Theory 223 227 EN Monasadat Ardestani Shamsaddin Niknami Alireza Hidarnia Ebrahim Hajizadeh Journal Article 2015 06 06 Background: The importance of increasing adolescence girl’s level of physical activity is recognized as a priority for having a healthy lifestyle. However, adolescent girls especially Iranian, are at high risk for physical inactivity. Social Cognitive Theory (SCT) is a successful theory to explain physical activity behavior. The aim of this study was to determine the predictors of physical activity based on the SCT. Methods: This cross-sectional study was conducted among 400 adolescent girls (15-16 yr old) in Tehran, Iran (2013). The participants were randomly chosen with multistage sampling. The SCT constructs consisted of self-efficacy, self-regulation, social support, outcome expectancy, and self-efficacy to overcoming impediments. Statistical analysis was carried out applying SPSS: 16, LISREL 8.8. Stepwise regression was used to test predictors of behavior. Pearson correlation was assessed. Results: Self efficacy to overcoming impediments was the main construct to predict physical activity (Beta=0.37). Other determinants were self-efficacy (Beta=0.29), family support (beta=0.14), outcome expectancy (beta=0.13), friend support (beta=0.12), and self-regulation (beta=0.11), respectively. In general, the SCT questionnaire determined 0.85 variation of physical activity behavior. All of the constructs had direct significant relation to physical activity behavior (P<0.001). Conclusions: The constructs of SCT provide a suitable framework to perform promoting physical activity programs and self-efficacy to overcoming impediments and self-efficacy are the best predictors of physical activity in adolescent girls.