Objectives. The purpose of this study was to evaluate the effect of a school-based intervention program to reduce overweight
and improve fi tness in primary school children. Methods. A cluster randomized controlled design was used over one school
year with schools as unit of randomization. In total 20 schools and 2,622 children aged 6 – 12 years (grades 3 – 8) from
multi-ethnic, low income inner-city neighbourhoods in Rotterdam, Netherlands, participated. The intervention, named
Lekker Fit! (Enjoy being fi t!) was a multi-component intervention based on behavioural and ecological models. Main
components of the intervention are the implementation of three physical education (PE) sessions a week by a professional
PE teacher, additional sport and play activities outside school hours and an educational program. Main primary outcome
measures were weight status, body mass index (BMI), waist circumference and fi tness (20 m shuttle run). Results. Signifi -
cant positive intervention effects were found for percentage overweight children (OR 0.53; 95% CI 0.36 – 0.78), waist
circumference ( 1.29 cm; 95% CI 2.16 to 0.42 cm) and 20 m shuttle run (0.57 laps; 95% CI 0.13 – 1.01 laps) among
pupils of grades 3 – 5 (6 – 9-year olds). The prevalence of overweight in grades 3 – 5 increased by 4.3% in the control group
and by 1.3% in the intervention group. No signifi cant effects were found for BMI or for grades 6 – 8 (9 – 12-year olds).
Conclusions. Our results provide evidence for the effectiveness of the multi-component intervention Lekker Fit! among pupils
of grades 3 – 5 and adds to the growing body of evidence that school-based programs with a focus on PA are most effective
in reducing childhood obesity.[ISRCTN84383524]
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