Secular trends in physical fitness and obesity in Danish 9-year-old girls and boys: Odense School Child Study and Danish substudy of the European Youth Heart Study

Introduction: Low physical fitness and obesity have been shown to be associated with cardiovascular disease (CVD) risk. Obesity is on the increase in many countries, but little is known about physical fitness trends. Monitoring of changes in fitness and obesity in the population is important for preventive strategies, and the aim of this study was to analyse the secular trends in fitness and body composition in Danish children. Materials and methods: Two representative population studies were conducted 12 years apart on 9-year-old children in the same location: the Odense School Child Study in 1985-86 and the European Youth Heart Study in 1997-98. In both studies, physical fitness was determined by a maximal cycle ergometer test, and obesity was assessed by skinfolds. Results: Boys had a lower physical fitness and were fatter in 1997-98 than in 1985-86. In addition, an increased polarization is emerging, with the difference between the fit and the unfit and the difference between the lean and the fat being greater in 1997-98 than in 1985-86. In girls, a similar polarization was found, but no overall change in fitness or obesity. Conclusion: The negative trend and increased polarization for physical fitness and obesity in Danish children suggest a future generation with a higher degree of CVD risk.