The “11 for Health in Denmark” intervention in 10- to 12-year-old Danish girls and boys and its effects on well-being—A large-scale cluster RCT

Background: The present study investigates the well-being effects for 10- to 12-year-old children who participated in the school-based intervention “11 for Health in Denmark,” which comprises physical activity (PA) and health education. Subgroup analyses were carried out for boys and girls. Method: Three thousand sixty-one children were randomly assigned to an intervention group (IG) or a control group (CG) by 5:1 cluster randomization by school. 2533 children (mean age 11.5 ± 0.4; 49.7% boys) were assigned to IG and 528 children (mean age 11.4 ± 0.5; 50.8% boys) were assigned to CG. IG participated in the “11 for Health in Denmark” 11-week program, consisting of 2 × 45 min per week of football drills, small-sided games, and health education. CG did not participate in any intervention and continued with their regular education. Before and after the intervention period, both groups answered a shortened version of the multidimensional well-being questionnaire KIDSCREEN-27. Results: The “11 for Health in Denmark” intervention program had a positive effect on physical well-being in girls (IG: 48.6 ± 8.5 to 50.2 ± 9.3), whereas the improvement was not significant in boys. The program also had a positive impact on well-being scores for peers and social support (IG: 50.2 ± 10.2 to 50.8 ± 10.1), though when analyzed separately in the subgroups of boys and girls the changes were not significant. No between-group differences were found for psychological well-being or school environment. Conclusion: The intervention program had a positive between-group effect on physical well-being in girls, whereas the change was not significant in boys. The overall scores for peers and social support improved during the intervention period, but no subgroup differences were found.