Associations Between Childcare Physical Activity and Sedentary Time and Early Childhood Developmental Outcomes: A Compositional and Isotemporal Substitution Analysis.

Background: Physical activity and sedentary time are independently associated with health and developmental outcomes in preschool children. However, the integrated nature of these behaviours on early life outcomes, particularly during childcare hours, is currently understudied. As such, the aim of this study was to examine the association between preschool children's physical activity and sedentary time during childcare and various developmental outcomes (psychosocial, cognitive and fundamental movement skills).

Methods: A total of 107 preschool children (M_age: 41 ± 6 months) recruited from London, Canada, wore ActiGraph wGT3X-BT accelerometers during childcare hours to measure their sedentary time, light intensity physical activity (LPA) and moderate-to-vigorous intensity physical activity (MVPA). Developmental outcomes, including psychosocial health (internalising, externalising, prosocial behaviour), indicators of cognitive development (memory, inhibitory control) and fundamental movement skills (locomotor control, object control, total fundamental movement), were assessed using validated tools. Compositional regression and isotemporal substitution models were estimated to examine how movement compositions in childcare were associated with developmental outcomes.

Results: Engaging in more MVPA relative to LPA and sedentary time was associated with fewer internalising symptoms and better total fundamental movement skills and object control skills, whilst spending more time in LPA relative to MVPA and sedentary time was associated with more internalising symptoms and worse object control skills. Isotemporal substitution models suggested that theoretically increasing sedentary time or engaging in MVPA at the expense of time engaging in LPA during childcare is associated with lower internalising symptoms.

Conclusion: The findings of this study provide preliminary evidence that engaging in MVPA during childcare, at the expense of time in LPA or sedentary time, is associated with children's fundamental movement skills and psychosocial development. Further longitudinal research is required, with larger samples of young children, to assess the mechanisms through which childcare movement behaviour compositions may interact with developmental outcomes, including contextualising both sedentary time and LPA.

Trial registration: ClinicalTrials.gov identifier: NCT05359536.