Sociodemographic differences in patterns of sedentary and physically active behavior in older children and adolescents.

UNLABELLED: Numerous studies have found that involvement in moderate-intensity and strenuous activity has positive effects on health. This study considered the prevalence of different aspects of physical activity and sedentary behavior in 11-16-y-olds based on a representative national survey of 3270 Icelandic primary schoolchildren (91% response rate). All-day sedentary behavior was extremely rare (< 1%), and the vast majority (91%) were physically active (> or = 3 times per week) during school or leisure time, thanks largely to school physical education. Only 39% were physically active (> or = 3 times per week) during leisure time, and only 29% engaged in regular (> or = 3 times per week) leisure time strenuous exercise. Girls were more sedentary, less leisure time physically active, and less involved in leisure time strenuous exercise. Sedentary behavior increased and physically active behavior decreased with age, especially after early adolescence. However, there were no age differences in strenuous leisure time exercise. Upper-class students were less sedentary and more physically active during leisure time than working-class students. Finally, rural students were more sedentary during leisure time, and less physically active than students from urban areas. An interaction was found between age and residence when predicting leisure time physical activity, indicating that the inverse age-activity relationship in urban areas is partly reversed in rural areas.
CONCLUSION: Compulsory school physical education frequently failed to translate into voluntary physical involvement. Sociodemographic differences in physical activity were greater during leisure time, than during school and leisure time combined.