Correlates Of Objectively Measured Sedentary Time And Self-reported Screen Time In Brazilian Children

Abstract

Sedentary time (SED) and self-report screen time (ST) are influenced by an array of complex and diverse factors.The purpose of this study was to examine potential correlates of objec¬tively measured SED and self-report ST in a sample of 9-11 year old Brazilian children. METHODS: This study focused on 328 Brazilian children (51.5% boys) enrolled in the International Study of Childhood-ISCOLE. An Actigraph GT3X+ accelerometer was used to monitor SED over 7 days. Body fat percentage (BF%) was measured with bioelectrical impedance and BMI (kg/m2) was calculated from measured height and weight. Questionnaires completed by the participants, their parents, and school personnel queried behavioral, family and home environment, and school environment correlates. Twenty two potential correlates of SED and ST were examined using multi-level linear regression. Variables that were moderately associated with SED and/or ST in univariate analyses p<.10 were included in the final models. Variables that remained significant in the final models p<.05 were considered correlates of SED and/or ST. Sex, ethnicity, school, number of siblings, and total annual household income were used as covariates in all multivariable models. RESULTS: Children averaged 500.06 min/day in SED (489.67 boys; 511.11 girls: p=0.005) and 3.9 hours/day in ST (4.1 boys; 3.7% girls: p=(.053). For boys and girls combined, SED was negatively associated with healthy eating score and moderate-to-vigorous physical activity (MVPA). In boys, the only significant correlate of SED was MVPA (β-1.434). In girls, significant correlate of SED were healthy eating score (β-19.301), time of travel to school (β 57.918), and MVPA (β-1.896). For boys and girls combined, ST was negatively associated with BMI and healthy eating score. In boys, the significant correlates of ST were BMI (β .019), healthy eating score (β.090) and TV in bedroom (β.201). In girls, significant correlate of ST were healthy eating score (β.184), time of travel to school (β-.230), and policies or practices on physical activity (β-.281). CONCLUSIONS: Several factors were identified as correlates of SED and/or of ST in Brazilian children; however, few correlates were common for both SED and ST, and for both boys and girls. This suggests that a single strategy to reduce SED and ST is unlikely to be effective.