RESUMO
PURPOSE: As impaired glucose metabolism may arise progressively during childhood, we sought to determine whether the introduction of specialist-taught school physical education (PE) based on sound educational principles could improve insulin resistance (IR) in elementary school children. METHODS: In this 4-yr cluster-randomized intervention study, participants were 367 boys and 341 girls (mean age = 8.1 yr, SD = 0.35) initially in grade 2 in 29 elementary schools situated in suburbs of similar socioeconomic status. In 13 schools, 100 min·wk-1 of PE, usually conducted by general classroom teachers, was replaced with two classes per week taught by visiting specialist PE teachers; the remaining schools formed the control group. Teacher and pupil behavior were recorded, and measurements in grades 2, 4, and 6 included fasting blood glucose and insulin to calculate the homeostatic model of IR, percent body fat, physical activity, fitness, and pubertal development. RESULTS: On average, the intervention PE classes included more fitness work than the control PE classes (7 vs 1 min, P < 0.001) and more moderate physical activity (17 vs 10 min, P < 0.001). With no differences at baseline, by grade 6, the intervention had lowered IR by 14% (95% confidence interval = 1%-31%) in the boys and by 9% (95% confidence interval = 5%-26%) in the girls, and the percentage of children with IR greater than 3, a cutoff point for metabolic risk, was lower in the intervention than the control group (combined, 22% vs 31%, P = 0.03; boys, 12% vs 21%, P = 0.06; girls, 32% vs 40%, P = 0.05). CONCLUSIONS: Specialist-taught primary school PE improved IR in community-based children, thereby offering a primordial preventative strategy that could be coordinated widely although a school-based approach.
