The association between 24-hour movement behaviours and adiposity among Australian preschoolers: a compositional data analysis

Introduction The relationship between 24-hour movement behaviours (i.e. physical activity, sedentary behaviour and sleep) and adiposity in preschoolers remains unclear. Therefore, this study aims to investigate the associations between 24-hour movement behaviours and adiposity in preschoolers making use of compositional data-analysis (CoDA). Methods Australian preschoolers (3–5 years) from the Early Start Baseline Study wore an ActiGraph accelerometer to assess sedentary behaviour (SB), light physical activity (LPA) and moderate-to-vigorous physical activity (MVPA). Their weight and height were measured using standardizes protocols and converted to Body Mass Index (BMI) z-scores using the World Health Organisation growth references. Their parents completed a questionnaire to assess their level of education and the child’s sleep duration, age and sex. CoDA was employed to investigate the association between 24-hour movement behaviours and adiposity in R. Results This study included 174 preschoolers and their overall 24-hour movement behaviour composition was associated with BMI z-scores (F = 4.09, p = 0.008). When examining the association between each movement behaviour relative to the others and BMI z-scores, we observed a statistically significant association for MVPA (p = 0.023), but not for the other behaviours. For example, reallocating 10 min from MVPA, proportionally to the other behaviours resulted in a difference of + 0.069 in BMI z-score. Conclusion Despite the association between more time spent in MVPA and higher BMI z-scores, a healthy amount of time spent in each of the 24-hour movement behaviours should be stimulated. Future studies should address methodological challenges, use larger and more diverse samples, and consider longitudinal designs. Additionally, a focus on sex- and age-specific adiposity indicators beyond BMI z-scores could enhance understanding of these relationships.