Physical activity to prevent obesity in young children: cluster randomised controlled trial.

Objective: To assess whether a physical activity intervention reduces body mass index in young children.

Design: Cluster randomised controlled single blinded trial over 12 months.

Setting: Thirty six nurseries in Glasgow, Scotland.

Participants: 545 children in their preschool year, mean age 4.2 years (SD 0.2) at baseline.

Intervention: Enhanced physical activity programme in nursery (three 30 minute sessions a week over 24 weeks) plus home based health education aimed at increasing physical activity through play and reducing sedentary behaviour.

Main Outcome Measure: Body mass index, expressed as a standard deviation score relative to UK 1990 reference data. Secondary measures were objectively measured physical activity and sedentary behaviour; fundamental movement skills; and evaluation of the process.

Results: Group allocation had no significant effect on the primary outcome measure at six and 12 months or on measures of physical activity and sedentary behaviour by accelerometry. Children in the intervention group had significantly higher performance in movement skills tests than control children at six month follow-up (P=0.0027; 95% confidence interval 0.3 to 1.3) after adjustment for sex and baseline performance.

Conclusions: Physical activity can significantly improve motor skills but did not reduce body mass index in young children in this trial.

Trial Registration: Current Controlled Trials ISRCTN36363490.