E-19 Free Communication/Slide - Physical Activity and Obesity: MAY 29, 2009 8:00 AM - 10:00 AM ROOM: 4C3
Changes in Body Mass Index during Adolescence: Associations with Physical Activity, Fitness and Sedentary Behaviors
PURPOSE: The aim of this study was to analyze whether Physical Activity Index (PAI), Physical Fitness (PF), Screen Time (ST) (TV watch and Computer use), Socio Economic Status (SES) and Commuting to School (CS) made a significant contribution to longitudinal changes of Body Mass Index (BMI), in children and adolescents
METHODS: This is a longitudinal study carried out in a middle and high school over a period of 3 years, from 2005 to 2008 academic years. 345 students (147 boys=42.6%) were followed with starting ages of 11 to 19 yr-old. Students were invited to perform tests from Fitnessgram battery for strength (curl-ups, push-up), flexibility (sit and reach right and left) and Cardiorespiratory (20m-shuttle run). Fitness variables were categorized in "Healthy Zone" and "Under Healthy Zone"; PAI in Inactive and Active; SES, in Low, Medium and High education, and CS in active and Passive. Excluding Fitness tests, all variables were evaluated using a standard questionnaire. BMI was used as dependent variable in a Linear Mixed Model. BMI was centered for all analysis meaning that we subtracted the age-and-sex-specific cut points for overweight.
RESULTS: From 2005 to 2008, overweight varied respectively, 25.5%, 31.9% and 25.7% in boys and 19.7%, 22.3% and 22% in girls. Results indicate that a change of Cardiorespiratory from Under HZ to Healthy Zone is a significant (p=0.001) contributor to decrease of BMI over time. PAI, ST, and CS were not associated with the changes in BMI. Low education of the mother was positively associated with BMI (p=0.043).
CONCLUSION: This study confirms a strong protective effect of cardiorespiratory fitness on the development of obesity, since it was the single predictor in 3 years longitudinal changes of BMI. Therefore increasing Fitness levels in youth can result in a positive impact on the prevalence of obesity.
This study was Supported by the Portuguese Foundation of Science and Technology: SFRH/BD/23128/2005