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Literature review reveals no improvement in BMI from school-based physical activity intervention

Tuesday, October 14 2008 | Comments

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What's This? By Patrice LaVigne

School-based physical activity interventions may not improve body mass index (BMI), according to a new analysis.

Dr. Kevin Harris from the Department of Pediatrics at the British Columbia Children's Hospital in Vancouver, Canada, and his colleagues conducted an electronic literature search for randomized controlled trials and controlled clinical studies published through September 2008 on the efficacy of school-based exercise interventions. Additionally, Dr. Harris' team hand-searched journals from January 2003 through September 2008 for trials that met the analysis criteria.

The team identified 18 unique articles evaluating studies involving 13,003 children (primarily elementary school age) with duration of 6 months to 3 years. The studies assessed a range of physical activity interventions administered during the school day and some that involved a co-intervention (e.g., diet). All studies compared the intervention participants with control students.

According to the summary estimate of the difference in mean change in BMI for the intervention and control groups across the studies, Dr. Harris noted that BMI did not improve with the interventions (decrease of 0.05 kg/m2; 95% CI, -0.19-0.10). Even in extensive sensitivity analyses, there were no significant effects of the interventions on BMI.

"We believe that childhood obesity is the most significant problem that we face today in pediatrics," Dr. Harris said.

He noted that although there are many proven health benefits from school-based physical activity, such as improved aerobic capacity and lower blood pressure levels, the review revealed no improvement in BMI from school-based physical activity interventions. He stressed that other outcomes need to be measured, such as diet and exercise levels outside of school, as no one has agreed on these. With BMI being the most frequently reported, it has become the best available outcome measure.

"Nonetheless, the school setting remains an important location for future interventions, and we believe that interventions that aim to improve diet and limit access to unhealthy foods warrant further investigation," Dr. Harris concluded. (Abstract 300.)

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