Adiposity And Cardiovascular Health And The Reallocation Of Waking Activities In Preschool Children With Overweight

Abstract

Physical activity and sedentary behaviors differentially relate to health outcomes in children. Isotemporal substitution provides opportunities to evaluate the relation of hypothetical time replacement scenarios across intensity categories with health. Few isotemporal studies have been conducted among preschool-aged youth and ethnically diverse populations. PURPOSE: To examine the relation of reallocation of waking activity behaviors on 1) adiposity and 2) cardiovascular health indicators among preschool-aged youth (ages 2-5 years) with overweight participating in Texas Childhood Obesity Research Demonstration (TX CORD), a low-income, majority Hispanic cohort. METHODS: Participants wore an ActiGraph wGT3X-BT monitor (waist) and attended health assessments. Valid wear time was defined as ≥10 hours between 06:00-22:59 hours on ≥3 days (≥1 weekend). Adiposity measures were percentage of the 95th percentile (%BMIp95), fat mass, fat mass index, waist circumference, and waist-to-hip ratio. Cardiovascular measures were resting systolic (SBP) and diastolic (DBP) blood pressure, and heart rate. Covariates included age, sex, ethnicity, and socioeconomic status. Isotemporal substitution modeling was employed to address the study purpose. RESULTS: Complete data were available for 131 children (Mean age = 4.3±1.1, 53% female, 87% Hispanic, 31% ≤49% income to poverty ratio). For boys, reallocating 15 minutes of sedentary, light, or moderate intensity activity to vigorous intensity activity was significantly associated with beneficial reductions in all adiposity indicators; for girls, these relations were statistically null. For boys and girls, reallocating 15 minutes of sedentary (-5.0 SBP, -3.7 DBP), light (-4.3 SBP, -3.2 DBP), or moderate intensity activity (-7.3 SBP, -5.5 DBP) to vigorous intensity activity was significantly associated with favorable cardiovascular indicators. CONCLUSIONS: Substituting vigorous for lower intensity physical activity is associated with several favorable adiposity and cardiovascular health outcomes among preschool children with overweight and obesity. Teaching caregivers how to engage young children in vigorous intensity is needed, especially as overweight children spend more time sedentary and less time in higher intensity activities.