[Prevalence of sedentarism and its associated factors among urban adolescents].
To evaluate the prevalence and determinants of sedentarism among adolescents living in Pelotas, State of Rio Grande do Sul, Brazil. A cross-sectional study was carried out in Pelotas, in 2002. An anonymous, self-administered questionnaire was answered by a representative sample of 960 adolescents with ages ranging from 15 to 18 years old. Those who reported that their participation in some kind of physical activity amounted to less than 20 minutes a day with a frequency of less than 3 times a week were considered to have a sedentary lifestyle. Sociodemographic and behavioral variables were evaluated. The chi-squared test was used for comparisons between proportions. The Poisson regression was used for multivariate analysis with robust adjustment for variances. Corrections were made for study design effects. Interviews were held with 960 adolescents. Of these, 39% were classified as having a sedentary lifestyle. The prevalence of sedentarism was higher among girls than among boys (prevalence ratio of 2.45; 95% CI 2.06-2.95). The adolescents from lower social levels had the highest percentage of sedentarism (prevalence ratio of 1.35; 95% CI 1.06-1.72). There was an inverse relationship between the adolescent's and the mother's schooling and sedentarism. After adjusting for confounding factors, there was also a positive association between sedentarism and minor psychiatric disturbances, and in relation to sexual activity. Higher prevalences of sedentarism are associated with girls, low social class, low levels of schooling and being the child of a mother with a low level of schooling.