Effects of a three-year intervention: the Copenhagen School Child Intervention Study

Abstract

Introduction: This study assessed short-term and long-term effects of a 3-yr controlled school-based physical activity (PA) intervention on fatness, cardiorespiratory fitness (VO(2peak)) and CVD risk factors in children.

Methods: The study involved 18 schools (10 intervention and 8 controls) and included a follow-up 4 yr after the end of intervention. The analyses included 696, 6- to 7-yr-old children at baseline, 612 postintervention (age 9.5 yr) and 441 at follow-up (age 13.4 yr). The intervention consisted of a doubling of the amount of physical education (PE; from 90 to 180 min·wk(-1)), training of PE teachers, and upgrading of PE and playing facilities. Anthropometrics and systolic blood pressure (SBP) were measured. VO(2peak) was directly measured, and PA was assessed using accelerometry. Fasting blood samples were analyzed for CVD risk factors. A composite risk score was computed from z-scores of SBP, triglycerides, total cholesterol-to-HDL cholesterol ratio, homeostatic model assessment (HOMA score), skinfolds, and inverse VO(2peak).

Results: The HOMA score of the intervention group boys had a smaller increase from baseline to postintervention compared with control boys (P = 0.004). From baseline to follow-up intervention group boys had a smaller increase in SBP compared with control boys (P = 0.010). There were no other significant differences between groups.

Conclusions: This 3-yr school-based PA intervention caused positive changes in SBP and HOMA score in boys but not in girls, and no effects were seen in PA, VO(2peak), fatness, and the other measured CVD risk factors. Our results indicate that a doubling of PE and providing training and equipment may not be sufficient to induce major improvements in CVD risk factors in a normal population.