Co-existence of physical activity and sedentary behavior among children and adolescents in Shanghai, China: do gender and age matter?

<bold>Background: </bold>There is limited evidence for the prevalence of the co-existence of physical activity (PA) and sedentary behavior (SED), and its correlates among children and adolescents. This study has two aims: 1) to investigate the prevalence of PA and SED, and their co-existence, and 2) to examine the associations between PA or SED, or both with gender and age among children and adolescents in Shanghai, China.<bold>Methods: </bold>Using a cross-sectional study design (conducted from September to December 2014), 50,090 children and adolescents (10-18 years old, 50.4% boys) were included in this study. A self-reporting questionnaire was used to measure participants' sociodemographic characteristics, PA, and SED. Descriptive statistics were used to describe sample characteristics, the prevalence of PA and SED, and their co-existence. A Generalized Linear Model was conducted to explore the associations between the prevalence of PA and SED, and their co-existence with gender and age separately.<bold>Results: </bold>Of the children and adolescents studied, only 18.4% met the guidelines for PA, 25.5% met the guidelines for SED, and 5.7% met the guidelines for both. Boys were more physically active (aOR = 1.43, 95% CI: 1.36-1.50), and girls were less sedentary (aOR = 1.29, 95%CI: 1.24-1.34). The prevalence of PA, SED, or both all declined as age increased (p < 0.001). Stratified analysis by gender revealed greater declining trends of meeting the PA or SED guidelines, or both in girls (all p < 0.005).<bold>Conclusion: </bold>Very few children and adolescents showed active lifestyles, and this was significantly related to age. Effective interventions aiming to promote PA and concurrently to limited SED among children and adolescents should be implemented as early as possible. [ABSTRACT FROM AUTHOR]