Physical Activity Intensity, Sedentary Time and Body Composition in Preschoolers

Aim To examine the magnitude of associations between objectively-measured PA subcomponents and sedentary time with body composition in a large free-living population cohort of preschool children.

Methods This was a cross-sectional study of 398 preschool children recruited from the Southampton Women’s Survey. PA was measured by accelerometry and body composition by Dual Energy X-ray Absorptiometry (DXA). Associations between light (LPA), moderate (MPA), vigorous (VPA), and moderate-to-vigorous (MVPA) PA intensities, sedentary time and body composition were analysed by repeated measures linear regression adjusting for age, gender, birth weight, maternal education, maternal BMI, smoking during pregnancy and sleep duration. Sedentary time and PA were also mutually adjusted for one another, to check if they were independently related to adiposity.

Results VPA was the only intensity of PA to exhibit strong inverse associations with both total adiposity (p<0.001 for percentage body fat [%BF & fat mass index [FMI]) and abdominal adiposity (p=0.002 for trunk fat mass index [TFMI]). MVPA was inversely associated with total adiposity (p=0.018 for %BF & p=0.022 for FMI), but only due to the contribution of VPA, as MPA was unrelated to fatness (p≥0.077). No associations were found between time spent sedentary and body composition (p≥0.11).

Conclusions In preschoolers, more time spent in high-intensity PA is strongly and independently associated with adiposity, to a greater extent than time spent in low-to-moderate intensity PA and time spent sedentary. The results indicate that efforts to challenge paediatric obesity may benefit from prioritising PA that is of higher intensity.