Résumé
Movement behaviours, including moderate-to-vigorous-intensity physical activity (MVPA), light-intensity physical activity (LPA), sedentary behaviour (SB), and sleep, influence childhood adiposity. However, their collective impact on adiposity from a sex-specific perspective remains underexplored. Our research examined the sex-specific longitudinal associations of 24-h movement behaviours with body mass index (BMI) and abdominal adiposity among children.
In the Growing Up in Singapore Towards healthy Outcomes (GUSTO) cohort study, we repeatedly measured 24-h movement behaviours using wrist-worn accelerometers (ActiGraph GT3x) and assessed adiposity (BMI, abdominal circumference, and MRI-based abdominal fat volumes) at three time points (ages 5.5-6, 7.5-8, and 10-10.5 years) within the same children in a longitudinal design. Compositional multivariable linear mixed-effect modelling and isotemporal substitution were used to estimate the associations.
531 children (49.5% girls) were included in the analysis. Significant interactions between movement behaviours and sex were observed across all outcomes. In girls, higher MVPA relative to other behaviours was linked to lower BMI [-0.8 (-1.5, -0.1) kg/m²] and total abdominal adiposity [-225.5 (-451.6, -2.5) mL], while in boys, longer sleep duration was associated with lower BMI [-1.6 (-3.2, -0.1) kg/m²] and total abdominal adiposity [-624.2 (-1225.6, -31.3) mL]. The isotemporal substitution model showed that replacing 30 min of LPA/SB with MVPA reduced BMI and abdominal circumference by 1-2% and MRI-measured abdominal adiposity by 6-9% in both sexes. However, replacing LPA/SB with sleep reduced BMI and abdominal circumference by 1% and MRI-measured adiposity by 3-6% only in boys, with no changes in girls. These associations were pronounced on visceral adiposity.
This study highlights sex-specific associations of movement behaviours with adiposity in school-aged children, with stronger associations observed in MRI-derived measures compared to conventional adiposity indices. Replacing LPA/SB with MVPA reduced BMI and abdominal adiposity in both sexes, with particularly pronounced effects on visceral adiposity. However, sleep replacement benefits were observed only in boys, suggesting the need for gender-sensitive approaches in lifestyle interventions.