Cardiorespiratory fitness and TV viewing in relation to metabolic risk factors in Portuguese adolescents

Background: The purpose of this study was to examine whether adolescents who have high levels of cardiorespiratory fitness (CRF) co-existing with low levels of television (TV) viewing present a better metabolic risk profile compared to their low fit and high TV viewing counterparts. Subjects and methods: A total of 372 students (aged 12-15 years old) comprised the sample of this study. Anthropometric data (body mass index and waist circumference) was collected. CRF was calculated based upon the 20 metres shuttle run test. A questionnaire was used to estimate weekly TV viewing. Information about biological maturity and parental education was collected. Participants were then categorized into one of four category profiles according to the scores they achieved: low TV-Fit; high TV-Fit; low TV-Unfit and high TV-Unfit. Metabolic risk score (MRS) was calculated based on the sum of the Z-scores of all the metabolic variables analysed. Results: Logistic regression analyses indicated that the high TV-Unfit group was almost 3-times more likely to be assigned to the high MRS group (OR 2.85, 95% CI 1.08-7.50) compared to their low TV-Fit group counterparts. Conclusions: The data showed that the high TV-Unfit group was associated with an increased metabolic risk in adolescents after adjustment for gender, age, biological maturity and parental education.