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Early origins of adolescent physical activity behaviour:a prospective birth cohort study

Objectives: To examine the effects of early social, anthropometric and behavioural variables on physical activity levels in adolescence.Design: Prospective birth cohort study. Setting: Population based cohort in Pelotas, Southern Brazil.Participants: 4155 adolescents aged 10-12 years belonging to a 1993 birth cohort study, corresponding to a follow-up rate of 87.5%.Main outcome measures: Sedentary lifestyle, defined as <300 minutes of physical activity per week.Results: The prevalence of sedentary lifestyle was 58.2% (95%CI 56.7 to 59.7). Female sex, high family income, high maternal schooling, and low birth order were risk factors for sedentary lifestyle in adolescence. Neither weight gain variables (0-1, 1-4, 4-11 years) nor overweight at 1 or 4 years were significantly associated with physical activity. Maternal report of the child’s physical activity at 4 years was related to sedentary lifestyle at 10-12 years.Conclusions: Our data suggest that physical activity in adolescence is partly programmed in early life. High birth order may lead to greater intensity of play in childhood, an effect that persists until adolescence. Tracking of physical activity from 4 to 10-12 years was evident. The absence of an effect of early weight gain suggests that growth acceleration may increase the risk of chronic disease by other mechanisms than through physical activity levels. The lower frequency of sedentary lifestyles among the poor may be explained by active transportation to and from school, and by nonstructured sports practice.  A systematic review of physical activity in adolescents:health benefits and measurement approaches

AbstractBackground: Physical activity (PA) in adolescence may contribute to the development of healthy adult lifestyles, helping reduce chronic disease incidence. However, definition of the optimal amount of PA in adolescence requires addressing a number of scientific challenges. This paper reviews the evidence on short- and long-term health effects of adolescent PA. Current techniques for measuring PA in adolescents are reviewed and their use quantified on the basis of the recent literature.Methods: Systematic reviews of the literature were undertaken, based primarily on the Medline/Pubmed database. Relevant studies were identified by examination of titles, abstracts and full papers, according to inclusion criteria defined a priori.Results: A conceptual framework is proposed to outline how adolescent PA may contribute to adult health, including the following pathways: A) tracking of PA from adolescence to adulthood; B) direct influence of adolescent PA on adult morbidity; C) role of PA in treating adolescent morbidity; D) short-term benefits of PA in adolescence on health. The literature reviews showed consistent evidence supporting pathway “A�, although the magnitude of the association appears to be moderate. Thus, there is an indirect effect on all health benefits resulting from adult PA. Regarding pathways “BD�, adolescent PA seems to provide both short- and long-term benefits on selected health outcomes – including bone density, breast cancer, mental health, asthma, cystic fibrosis - but there is no consistent association with cardiovascular disease risk factors. Studies using direct PA measurement tend to demonstrate greater health benefits than those using questionnaires. However, the latter were used in almost all large-scale

Prevalência de sedentarismo e fatores associados emadolescentes de 10-12 anos de idade

RESUMO A atividade física (AF) na adolescência acarreta vários benefícios à saúde, seja por um efeito direto sobre a morbidade na própria adolescência, seja por um efeito mediado pelo nível de AF na idade adulta. Avaliou-se a prevalência de sedentarismo e fatores associados em 4451 adolescentes de 10-12 anos de idade, participantes do Estudo de Coorte de Nascimentos de 1993 em Pelotas. Sedentarismo foi definido como <300 minutos por semana de AF. As perdas de acompanhamento desde o nascimento totalizaram 12,5%. A prevalência de sedentarismo foi de 58,2% (IC95% 56,7–59,7). Na análise multivariável, o sedentarismo se associou positivamente ao sexo feminino, ao nível socioeconômico, a ter mãe inativa e ao tempo diário assistindo televisão. O sedentarismo se associou negativamente com o tempo diário de uso de vídeo game. Adolescentes de nível econômico baixo apresentaram maior frequência de deslocamento ativo para a escola. Estratégias efetivas de combate ao sedentarismo na adolescência são necessárias devido a sua alta prevalência e sua associação com inatividade física na idade adulta.Palavras-chave: atividade física, inatividade física, aptidão física, sedentarismo, adolescentes, exercício.

Who, when, and how much? Epidemiology of walking in a middle-income country. Pedro C. Hallal, MSc, Mario R. Azevedo, MSc, Felipe F. Reichert, MSc, Fernando V. Siqueira, MSc, Cora L.P. Araújo, PhD, Cesar G. Victora, PhDBackground: Physical inactivity is one of the leading causes of morbidity and mortality worldwide. Walking, an inexpensive and accessible activity, is protective against unhealthy outcomes. Little data on walking practices are available outside developed countries. This study estimated the prevalence and correlates of compliance with physical activity recommendations through leisure-time and all-domain (combined leisure time, commuting, and work-related) walking in individuals aged _20 years in a southern Brazilian city.Methods: Data from two population-based surveys carried out in 2002 and 2003 in Pelotas, Rio Grande do Sul, were compared and analyzed in 2004. Multistage sampling procedures were undertaken in both surveys. Compliance with physical activity recommendations was defined as _150 minutes/week of walking during the previous week, although other cut-off points were estimated. The International Physical Activity Questionnaire was used in both studies.Results: Samples comprised 3182 (2002 study) and 3100 (2003 study) individuals. Nonresponse rates were 5.6% and 3.5%, respectively. Both prevalence and correlates of leisure-time and all-domains walking were markedly different. Compliance with physical activity guidelines (_150 minutes/week) through walking was 40.6% (all domains) and 15.0% (leisure time). Poor and uneducated participants had a lower likelihood of walking than higher-income and more educated people, particularly in leisure time. Walkers were also more likely to practice other vigorous and moderate-intensity activities.Conclusions: Although the results derive from a single Brazilian city, they are likely to be relevant to similar environments/locales in middle-income countries, where the obesity epidemic is rapidly increasing. Due to the low levels of walking detected, particularly during leisure time, healthcare professionals are encouraged to recommend walking to their patients. (Am J Prev Med 2005;28(2):156–161) © 2005 American Journal of Preventive Medicine