Background: Physical activity (PA) rates decline among most high school female students, and due to cultural restrictions, the reduction of physical activity might be exacerbated in female Iranian adolescents. 

Objective: To determine the effects of the physical activity education theory-based intervention to promote activity among adolescent girls.

Methods: This randomized clinical trial was conducted at public high schools in Tehran, Iran, from September 2015 to July 2016 on 578 girls. The subjects were assigned randomly to two groups of experiment and control (n=289 per group). All participants in the experimental group received an educational program based on a modified TPB. Measures were assessed before and 6 months after the experiment. The data were analyzed using SPSS version 23. We used descriptive statistics, multilevel analysis, Likelihood Ratio (LR) test, P-value less than 0.05 were considered statistically significant.

Results: Five hundred and seventy-eight participants with a mean age of 14.26±0.96 years were studied in two groups of experiment (n=289) and control (n=289). Moreover, adjusted for the baseline values, the mean of the scores of the knowledge (84.1±13.6), attitude (31.2±13.6), subjective norm (40.4±11.1), behavioral intention (34.3±14.7), perceived behavioral control (38.4±11.6), perceived parental control (42.9±14.2), behavioral (42.6±17.1) was significantly higher in the experiment group compared with the control group (p<0.001).

Conclusions: The results of this study implicate that theory based educational intervention is considered to be more effective in improving physical activity in adolescents. This result can be used to increase adolescent’s health promotion.

Trial registration: The trial was registered at the Iranian Registry of Clinical Trials (IRST) with the identification number: IRCT2015070623089N2.

Funding: The authors received no financial support for the research from Kermanshah University of Medical Sciences.


Keywords: Theory-based intervention, Adolescents, Physical activity, TPB
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