Psychosocial factors affecting physical activity behaviors of adolescents in Manisa: The theory of planned behavior model

Aim: To investigate the frequency of physical activity behavior among adolescents in the city center of Manisa and to explain the causality of physical activity behavior using the theory of planned behavior (TPB) model based on structural equation modeling. Material and Method: We investigated the causality of physical activity behavior in adolescents by considering both linear and structural approaches. The dependent variable of our study was assessed with the "Physical Activity Questionnaire for Adolescents (PAQ-A)" scale, and analyses were conducted with a total of 1003 students. Descriptive analyses were illustrated for both approaches. Additionally, univariate and multivariate (logistic regression) analyses were conducted for the "linear approach" and structural equation models were established for stratified structural equation models (10 models) based on the Planned Behavior Theory model and considering the gender and economic status of the participants. In all analyses, type 1 error was set to 0.05. Results: The prevalence of physical activity among adolescents in Manisa was 25.2% (18.3% in girls, 34.2% in boys). Our results confirm the hypothesis that attitudes of adolescents — except for poor male adolescents — (β min-max: 0.39-0.46) and perceived behavioral control (β min-max: 0.27-0.39) predict "intention," while intention (β min-max: 0.39-0.46) predicts physical activity "behavior." We showed that barriers significantly reduce physical activity behavior, especially in wealthy male adolescents (β: -0.12), and peer support significantly increases physical activity behavior in adolescents in all models (β min-max: 0.21-0.28) except for poor female adolescents. With the combined model of TPB and SCT (Social Cognitive Theory), we were able to explain approximately 60.0% of physical activity intention variance and approximately 45.0% of physical activity behavior variance. In addition, the lowest values of these two variance percentages were calculated (54.0% and 28.0%) among poor female adolescents. Conclusion: The theory of planned behavior can be used to understand physical activity behavior in adolescents in Türkiye, and one in every four adolescents is still not physically active at the recommended and sufficient level. As shown in previous studies, female adolescents, those who are in poorer groups, and those who feel less peer support are at increased risk of physical inactivity. In particular, we remark that we are still unable to explain poor female adolescents' physical activity behavior fully. The fact that peer support was statistically significant in both logistic regression and structural equation models suggests that novel intervention programs that will be planned by taking into account peer support regarding adolescents' attitudes towards physical activity may have a higher success rate. Our findings show that programs or interventions designed to increase adolescents' physical activity behaviors should promote more open, large green spaces and parental and especially peer support rather than facilities and infrastructure that require large expenditures. Keywords: adolescent health, physical activity, theory of planned behavior, social cognitive theory