[Effects of daily physical exercise at school on cardiovascular risk--results of a 2-year cluster-randomized study]

Abstract

Background and objective: It was the aim of this study to measure the effects over two years of daily sport activity during the school-day on their physical fitness (primary endpoint), motor coordination and blood pressure (secondary endpoints).

Methods: A total of 232 children from eleven different 6 (th) grade classes were enrolled after informed parental consent. Their mean age was 11.1 ± 0.6 years. Six classes were randomly assigned for intervention (n=141), five as control (n=91). Those of the intervention cohort undertook, for five days weekly during the school year one hour of regulated sport exercise, including 15 min of endurance training. The pupils of the control group undertook customary sport activity (two hours a week). Anthropometric data were recorded and maximal oxygen uptake measured in each pupil, as well as blood pressure and motor coordination at the beginning and at the end of each of the two years of the study. The data were analyzed using the cluster randomization method.

Results: Maximal oxygen uptake (VO (2)max) had improved among the intervention group after two years, compared with the controls (3.12 m/kg/min, 95% confindence interval [CI] 0.06-6.19), while improvement in motor coordination just failed to reach statistical significance (3.06, 95% CI -0.17-6.29). There was no significant difference in systolic and diastolic blood pressure, but a downward trend in the prevalence of overweight and obesity from 12.1% to 7.8% in the intervention group.

Conclusion: The results indicate that daily physical exercise during school hours should be given greater importance. But it will require a long-term trial to determine whether promotion of increased physical activity at school influences the prevalence of cardiovascular risk factors when the pupils reach adulthood.

Trial registration: ClinicalTrials.gov NCT00176371.