Physical activity and academic achievement across the curriculum: Results from a 3-year cluster-randomized trial (A+PAAC)

17 elementary schools cluster-randomized (9 intervention / 8 control); 584 children analysed (316 intervention, 268 control), grades 2-3 at baseline

Elementary schoolchildren in eastern Kansas, USA, followed from grades 2-3 through 3 academic years

Cluster RCT with school as unit of randomization. Classroom teachers trained to deliver ordinary academic lessons using moderate-to-vigorous physical activity (target >=100 min/week; delivered dose 55 min/week). Outcome was the Wechsler Individual Achievement Test-Third Edition (WIAT-III) — an independent standardized battery, not researcher-designed — administered at baseline and each spring for 3 years. Linear mixed models adjusted for baseline WIAT-III differences (intervention schools started significantly higher), ethnicity, family income and cardiovascular fitness. Weaknesses: only 17 clusters, baseline imbalance requiring statistical adjustment, and roughly half the intended activity dose delivered.

The longest school physical-activity RCT with standardized achievement outcomes, and it is null. Both groups improved over 3 years, but the group x time interactions were non-significant for math, reading and spelling. The authors state A+PAAC "neither diminished or improved academic achievement". The secondary point matters for practice: schools bought an extra 55 min/week of MVPA at zero cost to academic instruction time or results — a health argument, not an achievement argument.

Randomization at school level removes genetic confounding of the treatment contrast. Baseline achievement differed between arms, which is a selection artifact of randomizing only 17 clusters, not of heredity; adjustment handles it imperfectly but the null is not the kind of result confounding manufactures.