Sex-specific BMI, 24-hour movement behaviors, motor skills, and executive functions in Tunisian preschool children: an observational cross-sectional study

Background: Early childhood is a critical period for motor, cognitive, and behavioral development, and the rising prevalence of overweight and obesity are associated with differences in physical activity (PA), motor skills (MS), and executive functions (EF). This study aimed to examine associations between sex-specific BMI categories, 24-hour movement behaviors (MB), MS, and EF in Tunisian preschool children. Methods: A cross-sectional observational study included 112 children aged 4-5 years (50 boys, 62 girls) from urban and rural kindergartens. Anthropometric measures classified children into sex-specific BMI categories (below normal, normal, above normal). PA, sedentary behavior (SB), and sleep were objectively assessed via accelerometry over five consecutive days. EF (inhibition, working memory) and MS (functional mobility, balance, upper and lower limb strength, manual dexterity) were evaluated using standardized and validated tests. Results: Overall, BMI showed limited associations with MB, EF, and MS, but some sex-specific associations were observed. Statistically significant differences were found for upper-body strength (girls, p = 0.003), moderate intensity PA (girls, p = 0.040), and screen-based SB (boys, p = 0.049). No statistically significant differences were observed for functional mobility, balance, lower limb strength, manual dexterity, other PA measures, sleep, or EF. Anthropometric scores were higher in BMI > normal groups, most children met MVPA and sleep recommendations, but total PA compliance was low. Conclusion: This study provides novel evidence from a North African context on sex-specific associations between BMI, MB, MS, and EF in preschool children. Findings indicate limited but domain-specific functional implications of BMI and emphasize the need for longitudinal, sex-stratified studies with larger samples to clarify developmental trajectories. However, due to the cross-sectional design, these findings reflect associations only, and no causal inferences can be drawn from these results.