Effects of a 12-week multicomponent intervention on 24-hour movement behaviour and physical fitness in parents and their children: a mediation analysis

To determine the effect of a multicomponent intervention on the moderate-to-vigorous physical activity (MVPA) of parents and their children; secondly, to identify the modification of other components of 24-hour movement behaviour and physical fitness as a result of the intervention; thirdly, to explore how the intervention modifies the different moments of children’s MVPA by examining changes in their parents’ MVPA. This 12-week quasi-experimental pilot intervention included156 pairs of parents and children from 3rd to 6th grade (mean age 11 years). These parent-child pairs were volunteers from two private and one public school, intentionally allocated to control and intervention groups. Both groups completed questionnaires, but only the intervention group participated in the 12-week intervention. Educational infographics and videos about the benefits of regular physical activity on health were sent every Monday via parents’ email and WhatsApp, while Friday messages provided physical activity suggestions for the weekends. Also, three face-to-face sessions were held with parents and children. Pre-to-post intervention changes in MVPA, sedentary behaviour, sleep and physical fitness were compared between groups using analysis of covariance adjusted for age, sex and school. A separate mediation analysis, also adjusted for age, sex and school, tested parental MVPA as a mediator of the change in children’s MVPA at school, out of school and on weekends. The intervention significantly improved parents’ physical fitness and children’s MVPA out of school and on weekends. Still, it did not significantly change sedentary behaviour or sleep time in either parents or children. Mediation analysis revealed that parental MVPA were not established as a mediator for increased children’s MVPA out of school and on weekends. Parent-focused interventions have the potential to improve not only parents’ own physical fitness but also their children’s out-of-school and weekend MVPA. These findings extend the family-inclusive intervention literature by showing that meaningful benefits for children’s out-of-school and weekend MVPA can occur even when the targeted change in parental MVPA is not achieved, suggesting that mechanisms beyond parental MVPA itself, such as shared activity time or increased family engagement, may drive these effects and merit further investigation. Current ClinicalTrials.gov number is NCT06362655 registered on 22/03/2024.