Association Between 24-Hour Movement Behaviors and Adiposity in Malaysian Schoolchildren: A Compositional Isotemporal Substitution Analysis.

Background: Physical activity (PA), sedentary behavior (SB), and sleep are interrelated 24-hour movement behaviors that are important for the growth and well-being of children. This cross-sectional study examined the relationship between 24-hour movement behaviors and adiposity, and predicted changes in adiposity following compositional time reallocations in 7- to 12.9-year-old Malaysian children from the South East Asian Nutrition Surveys II Malaysia.

Methods: A total of 381 children (mean age 9.7 [1.6] y, 57% girls) provided 24-hour wrist-worn GENEActiv accelerometry data which captured time spent for sleep, SB, light PA and moderate to vigorous PA (MVPA). Indicators of adiposity were derived from anthropometry and bioelectrical impedance analysis: body-mass-index-for-age, waist circumference, waist-to-height ratio, percent body fat, and body mass index. The composition of 4-part movement behaviors was expressed as isometric log-ratio coordinates which were entered into regression models. Isotemporal substitution analysis was used to assess changes in adiposity indicators when reallocating time between movement behaviors.

Results: Relative to other movement behaviors, time spent on MVPA was significantly associated with waist circumference, waist-to-height ratio, percent body fat, and fat mass index. A 15-minute one-to-one reallocation from other movement behaviors to MVPA predicted lower body-mass-index-for-age (-0.03 to -0.11), smaller waist circumference (-0.67 to -1.28 cm), lower waist-to-height ratio (-0.004 to -0.008), percent body fat (-0.87% to -1.47%), and fat mass index (-0.23 to -0.42). Replacing SB and light PA with sleep or MVPA was associated with lower adiposity.

Conclusions: The overall composition of movement behavior was significantly associated with the adiposity of Malaysian schoolchildren. Promoting MVPA and sleep and reducing SB and light PA are important for prevention of childhood obesity.