Objectives: This study was designed to explore the determinants of physical fitness in European children aged 6-11 years, cross-sectionally and longitudinally.
Methods: There were sufficient data on 4903 children (50.6 % girls) on measured physical fitness (cardio-respiratory, muscular strength, flexibility, balance, and speed) and possible determinants related to child characteristics, child lifestyle and parental factors. Multivariate and mixed linear regression models were conducted.
Results: Age, sex, children's BMI and physical activity were independent and strong determinants of children's fitness. Significant but small effects were found for low maternal BMI, high psychosocial well-being and fruit and vegetable intake as protective determinants. Sleep duration, breakfast intake, parental age and education and paternal BMI did not have a consistently significant effect on physical fitness. The role of determinants depended on children's sex and the specific PF component. Longitudinal analyses especially highlighted the importance of child's BMI as physical fitness determinant, independent of physical activity.
Conclusions: BMI together with physical activity, diet and psychosocial factors are modifiable targets to enhance physical fitness. This calls for policy approaches that combine these factors in a systematic way.
Keywords: Body mass index; Children; IDEFICS; Lifestyle; Parental determinants; Physical fitness.