Discussion
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This study analyzed the prevalence of AST among children and adolescents and barriers perceived by parents and adolescents in a city of about 600 000 inhabitants in Germany. The prevalence of AST in our study sample (53.6%) ranges below the percentages published for Germany as a whole: 78.3% in a nationwide cohort of children and adolescents [Our data shows that more children and adolescents would engage in AST if they could choose than the number of children and adolescents who actually reported AST. This underlines the necessity of studying what external reasons deter children from AST. In our sample, the correlation between AST and age was negative but became positive when controlling for school type. The highest proportion was found at age 10, which is consistent with results of a Canadian study by Pabayo et al. [Regarding perceived barriers, significant associations were found in the domains of physical environment, safety, social and individual/family preferences. Taking too much time was a significant barrier for adolescents, but not their parents. Conversely, in a Canadian study, this was a barrier only perceived by parents [Counterintuitively, the route being too dangerous exhibited a positive correlation with AST in the model for children. However, again, this association might be attributable to worse infrastructure or a higher awareness of traffic-related dangers among parents of children who use AST out of necessity than among parents whose children use passive means of transport. Too much traffic exhibited a significant negative correlation in the self-reported model for adolescents and in the model for children, but not in the parent-reported model for adolescents. It can be assumed that the parents of adolescents are less familiar with the exact route and its characteristics due to adolescents’ higher degree of independence. Conversely, the number of barriers perceived by adolescents’ parents was a significant predictor of AST, suggesting that the number may be more decisive than any specific barrier. Previous studies have shown that traffic-calming measures can increase use of active transport to school and elsewhere [