This material is the copyright of the original publisher. Unauthorised copying and distribution is prohibited. Sports Med 2006; 36 (12): 1019-1030 REVIEW ARTICLE 0112-1642/06/0012-1019/$39.95/0  2006 Adis Data Information BV. All rights reserved. Adolescent Physical Activity and Health A Systematic Review Pedro C. Hallal, 1 Cesar G. Victora, 1 Mario R. Azevedo 1 and Jonathan C.K. Wells 2 1 Post-Graduate Program in Epidemiology, Federal University of Pelotas, Pelotas, Brazil 2 Childhood Nutrition Research Centre, Institute of Child Health, London, UK Contents Abstract ................................................................................... 1019 1. Health Benefits of Physical Activity (PA) During Adolescence ................................ 1020 1.1 Influence of PA During Adolescence on PA in Adulthood (Pathway A) ................... 1021 1.2 Direct Influence of PA During Adolescence on Adult Morbidity (Pathway B) .............. 1021 1.3 Influence of PA in the Treatment and Prognosis of Adolescent Morbidity (Pathway C) ..... 1025 1.4 Influence of PA During Adolescence on Adolescent Morbidity (Pathway D) .............. 1025 1.5 Other Pathways .................................................................... 1026 1.6 Possible Adverse Effects of Adolescent PA ............................................ 1027 2. Discussion .............................................................................. 1027 3. Conclusions ............................................................................ 1028 Physical activity in adolescence may contribute to the development of healthy Abstract adult lifestyles, helping reduce chronic disease incidence. However, definition of the optimal amount of physical activity in adolescence requires addressing a number of scientific challenges. This article reviews the evidence on short- and long-term health effects of adolescent physical activity. Systematic reviews of the literature were undertaken using a reference period between 2000 and 2004, 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. A conceptual framework is proposed to outline how adolescent physical activity may contribute to adult health, including the following pathways: (i) pathway A – tracking of physical activity from adolescence to adulthood; (ii) pathway B – direct influence of adolescent physical activity on adult morbidity; (iii) pathway C – role of physical activity in treating adolescent morbidity; and (iv) pathway D – short-term benefits of physical activity 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 physical activity.