RESUMEN
The purpose of the study was to analyze the physical activity and the determinants of sedentary behavior in 1,268 Brazilian adolescents (638 girls, 630 boys) between the ages of 15 and 18 years, randomly selected from a relatively underdeveloped region. Data were collected from a community-based survey in the city of João Pessoa, Paraiba, Brazil. Information related to physical activity was derived on the short version of the International Physical Activity Questionnaire. The prevalence of sedentary behavior was 28.2% for girls and 19.1% for boys, whilst 28.9% of the girls and 36.7% of the boys showed high physical activity. The sedentary behavior varied by sociodemographic and environmental determinants studied. Parents' education, socioeconomic status, school's characteristics, transport to school, paid work, smoking, alcohol use, and BMI scores were significantly related to sedentary behavior for boys and girls.