Long term impact of one daily unit of physical exercise at school on cardiovascular risk factors in school children.

Background: Obesity and physical inactivity in children correlate with the presence of cardiovascular risk factors. The aim of this prospective, randomised, interventional study was to examine the long term impact of additional physical exercise lessons at school on fitness and cardiovascular risk factors.

Methods: We randomly assigned 366 5th and 6th grade students class-wise into an intervention group that participated in one-daily physical exercise unit at school and a control group, participating in conventional school sports twice a week. The intervention duration was 4 years. At baseline and yearly follow-up, anthropometric measurements, body coordination tests, spiroergometry, questionnaires and blood samples were performed.

Results: A total of 236 children qualified for analysis of the intervention effect after 4 years. At the beginning students of the intervention and control groups had similar values for fitness assessed by peak oxygen uptake. Peak oxygen uptake was significantly better in the intervention group at first and second follow-up. After 4 years we found no difference in fitness any longer. Students in the intervention group were more likely to have healthy body mass index percentiles in comparison to the control group (within 10th to 90th percentile: intervention 86.4%, control 78.2%, P = 0.13).

Conclusion: Over a period of 1-2 years, additional physical exercise lessons at school resulted in an improvement of fitness. However, long-term follow-up failed to demonstrate ongoing improvement of performance in the intervention compared with the control group. Nevertheless, the intervention group had lower rates of body mass index above the 90th percentile throughout the entire follow-up. Therefore more physical exercise units at school seem justified.