Effects of a 3-year intervention: The Copenhagen School Child Intervention Study

INTRODUCTION: This study assessed short and long term effects of a 3-year controlled school-based physical activity (PA) intervention on fatness, cardiorespiratory fitness (VO2peak) and cardiovascular disease (CVD) risk factors in children. METHODS: The study involved 18 schools (10 intervention and 8 controls) and included a follow-up 4 years after the end of intervention. The analyses included 696, 6-7 yrs old children at baseline, 612 at post-intervention (age 9.5 yrs) and 441 at follow-up (age 13.4 yrs). The intervention consisted of a doubling of the amount of physical education (from 90 to 180 min/week), training of PE-teachers, and upgrading of physical education and playing facilities. Anthropometrics and systolic blood pressure (SBP) were measured. VO2peak was directly measured and PA assessed using accelerometry. Fasting blood samples were analyzed for CVD risk factors. A composite risk score was computed from z-scores of SBP, triglycerides, ratio of total cholesterol to high-density lipoproteins cholesterol, homeostatic model assessment (HOMA-score), skinfolds, and inverse VO2peak. RESULTS: The HOMA-score of intervention group boys had a smaller increase from baseline to post-intervention compared to control boys (p = 0.004). From baseline to follow-up intervention group boys had a smaller increase in SBP compared to control boys (p=0.010). There were no other significant differences between groups. CONCLUSION: This 3-years school-based PA intervention caused positive changes in SBP and HOMA-score in boys, but not in PA, VO2peak, fatness and the other measured CVD risk factors. Our results indicate that a doubling of physical education and providing training and equipment may not be sufficient to induce mayor improvements in CVD risk factors in a normal population.