[Sociocultural factors and physical activity level in early adolescence]

To describe the level of physical activity in adolescents born in 1993 in the city of Pelotas, Brazil, and to evaluate the effect of sociocultural variables on those levels.

A combined ethno-epidemiological methodology was employed. In the epidemiological study, 4 452 adolescents born in 1993 were interviewed. Physical activity level was evaluated by means of a questionnaire. Adolescents with fewer than 300 minutes of physical activity per week were classified as sedentary. The ethnographic study included 69 adolescents randomly selected from among all cohort participants. On average, three in-depth interviews were carried out (about one every 6 months), with mothers and adolescents being interviewed separately.

The prevalence of a sedentary lifestyle was 48.7% (95%CI: 46.5 to 50.8) in boys and 67.5% (95%CI: 65.6 to 69.5) in girls (P < 0.001). The independent variable presenting the strongest association with physical activity level was the weekly frequency with which the adolescent met friends outside of school. The ethnographic study showed that boys have more social and family support to engage in physical activities in adolescence, but that many parents associate poor school performance with the amount of time spent outside the home.

This study suggests that physical activity is often viewed as competing with family values in adolescence. This perspective should be explored in future studies and discussed with families so that physical activity may be adopted as a cultural norm.