Targeting sedentary time or moderate- and vigorous-intensity activity: independent relations with adiposity in a population-based sample of 10-y-old British children

Background: It is unclear whether subcomponents of physical activity (PA) are associated with adiposity independent of time spent while sedentary. Objective: The objective was to examine associations between objectively measured PA and its subcomponents [ie, time spent at light-intensity PA, moderate-intensity PA (MPA), vigorous-intensity PA (VPA), and moderate-plus-vigorous- intensity PA (MVPA)], independent of sedentary time, and self-reported leisure screen time (television and electronic game use) with indexes of adiposity in a population-based sample of British children. Design: A cross-sectional study was conducted in 1862 UK children aged 9-10 y. PA and sedentary activity were measured by accelerometry, and indicators of adiposity were waist circumference, body mass index (BMI), and fat mass index calculated from bioimpedance measurements. Screen time was assessed by self-report. We examined the associations between PA subcomponents and adiposity by multilevel linear models adjusted for birth weight, maternal BMI, energy intake, and sleep duration. Results: Objectively measured sedentary time was positively associated with waist circumference (P = 0.04) and fat mass index (P = 0.05), independent of age and sex. However, this association was attenuated after adjustment for MVPA and other covariates. VPA (all P < 0.0001), combined MVPA (all P < 0.01), and total activity (counts/min) (all P < 0.001) were all inversely associated with each of the adiposity indexes, independent of sedentary time and other important covariates. Associations were weaker for MPA: P = 0.05, 0.87, and 0.1 for waist circumference, BMI, and fat mass index, respectively. Conclusions: Time spent in VPA appears to be more strongly associated with adiposity than sedentary time. Interventions may therefore need to incorporate higher intensity-based activities to curb the growing obesity epidemic. Am J Clin Nutr 2009; 90: 1185-92.