Purpose: This study sought to examine sex- and age-associated variations in physical activity (PA) among Portuguese adolescents aged 10-18 yr.
Methods: A total of 12,577 males and females at the primary or secondary education level were sampled across four regions of Portugal. PA was assessed by a questionnaire, producing four different indexes: work/school (WSI), sport (SI), leisure time (LI), and total physical activity index (PAI). We examined sex and age differences by using two-way analysis of variance.
Results: Males had higher mean values of PA than did females. In both sexes, mean values for all four PA indexes increased from ages 10 to 16 yr. After age 16, females decreased their mean values, whereas males continued to increase their values (except for LI). In both sexes, the average annual rate of change for the mean values of all four PA indexes correspond to three sensitive age periods (10-13, 13-16, and 16-18 yr). Until age 16, average mean changes for females ranged from +0.7 to +1.6% per year, except for SI in the youngest group (a modest decrease). For males under 16 yr, the pattern was similar, with increases ranging from 0.4 to 1.9% per year. After age 16, females experienced decreases of 1-2.1% per year for the four PA indexes, whereas males showed an increase for three indexes and an average decrease of 1.3% per year for LI.
Conclusions: These results suggest that it is important to consider sex differences in PA levels among Portuguese adolescents. Unlike their male counterparts, Portuguese females may reduce much of their PA during late adolescence.
1Faculty of Sports, 2Institute of Biomedical Sciences Abel Salazar, ICBAS, University of Porto, Porto, PORTUGAL; 3Faculty of Sport Sciences and Physical Education, Katholieke Universiteit Leuven, Leuven, BELGIUM; 4Division of Diabetes Translation, and 5Division of Nutrition and Physical Activity, National Center for Chronic Disease Prevention and Health Promotion, Centers for Disease Control and Prevention, Atlanta, GA
Address for correspondence: André Filipe Teixeira e Seabra, Ph.D., MPH, Faculty of Sports, University of Porto, Portugal, Rua Dr. Plácido Costa, 91-4200 Porto, Portugal; E-mail: email@example.com.
Submitted for publication March 2007.
Accepted for publication August 2007.