Gender differences in physical activity, sedentary behavior, and their relation to body composition in active Brazilian adolescents.
BACKGROUND
Body weight and composition are determined by genotype, environment, and energy balance. Physical activity or sedentary behavior have different associations with body weight, fat mass, and fat-free mass, a relationship that is not clear in adolescents. The aim of this study was to test the associations between gender, physical activity, sedentary behavior, and body composition in physically active adolescents.


METHODS
Weight, height, and skinfold thickness were measured in 326 physically active boys and girls age 11 to 15 years. All subjects answered a questionnaire assessing their usual daily activities for the last month. Time spent on each activity was used to estimate the physical activity level (PAL).


RESULTS
PAL was associated with body composition after adjustment for age and maturation, with differences between genders. For boys, PAL was positively and significantly associated with body mass index (BMI) and fat-free mass index (beta=0.14 and 0.15, respectively). For girls, PAL was negatively and significantly associated with BMI and fat mass index (beta=-0.11 and -0.75, respectively). Sedentary behavior, expressed by hours of TV, videogame, and computer use, was not associated with any body-composition outcome for either gender.


CONCLUSIONS
The accumulated amount of physical activity, but not of sedentary behavior, was related to body composition in active adolescents.
Nogueira
Julia Aparecida Devide
JA
College of Physical Education, Department of Nutrition, University of Brasília, Brazil.
Macedo da Costa
Teresa Helena
TH
D000293:Adolescent; D000294:Adolescent Behavior; D001823:Body Composition; D001827:Body Height; D001835:Body Weight; D001938:Brazil / Q000453:epidemiology; D002648:Child; D002652:Child Behavior; D005260:Female; D006801:Humans; D007899:Leisure Activities; D016014:Linear Models; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D012737:Sex Factors; D012885:Skinfold Thickness; D011795:Surveys and Questionnaires