title: Tracking of physical activity during adolescence: the 1993 Pelotas Birth Cohort, Brazil.
abstract: OBJECTIVE To analyze physical activity during adolescence in participants of the 1993 Pelotas Birth Cohort Study, Brazil. METHODS Data on leisure time physical activity at 11, 15, and 18 years of age were analyzed. At each visit, a cut-off point of 300 min/week was used to classify adolescents as active or inactive. A total of 3,736 participants provided data on physical activity at each of the three age points. RESULTS A significant decline in the proportion of active adolescents was observed from 11 to 18 years of age, particularly among girls (from 32.9% to 21.7%). The proportions of girls and boys who were active at all three age points were 28.0% and 55.1%, respectively. After adjustment for sex, economic status, and skin color, participants who were active at 11 and 15 years of age were 58.0% more likely to be active at 18 years of age compared with those who were inactive at 11 and 15 years of age. CONCLUSIONS Physical activity declined during adolescence and inactivity tended to track over time. Our findings reinforce the need to promote physical activity at early stages of life, because active behavior established early tends to be maintained over time.
authors.affiliation: Universidade Federal de Pelotas, Pelotas, RS, Brasil.
authors.forename: Mario Renato
authors.initials: MR
authors.lastname: Azevedo
authors.affiliation: Universidade Federal de Pelotas, Pelotas, RS, Brasil.
authors.forename: Ana Maria
authors.initials: AM
authors.lastname: Menezes
authors.affiliation: Universidade Federal de Pelotas, Pelotas, RS, Brasil.
authors.forename: Maria Cecília
authors.initials: MC
authors.lastname: Assunção
authors.affiliation: Universidade Federal de Pelotas, Pelotas, RS, Brasil.
authors.forename: Helen
authors.initials: H
authors.lastname: Gonçalves
authors.affiliation: Universitat de Vic, EspaÃ±a.
authors.forename: Ignasi
authors.initials: I
authors.lastname: Arumi
authors.affiliation: Universidade Federal de Pelotas, Pelotas, RS, Brasil.
authors.forename: Bernardo Lessa
authors.initials: BL
authors.lastname: Horta
authors.affiliation: Universidade Federal de Pelotas, Pelotas, RS, Brasil.
authors.forename: Pedro Curi
authors.initials: PC
authors.lastname: Hallal
mesh_terms: D056044:Actigraphy / Q000706:statistics & numerical data*; D000293:Adolescent; D001938:Brazil / Q000453:epidemiology; D002648:Child; D015331:Cohort Studies; D015444:Exercise; D005260:Female; D006801:Humans; D007899:Leisure Activities; D008297:Male; D057185:Sedentary Behavior; D012737:Sex Factors; D012959:Socioeconomic Factors