Hypokinesia, which is a consequence of modern technological development, is now one of the three biggest health risk factors. Whereas physical inactivity and obesity in adults is subject of concern, these factors in children presage an even greater public health problem because many health-related problems and life-threatening diseases begin in childhood and adolescence. It has been noted that regular physical activity modulates vascular endothelial function via an effect on basal nitric oxide (NO) production, thus leading to a significant reduction in the incidence of cardiovascular disease (1). Exercise can also increase energy expenditure and can create a negative energy balance. Conversely, scientific data regarding the effect of school-based physical activity interventions on body mass index (BMI) in children are conflicting (2, 3). Moreover, there is insufficient clinically useful scientific data on BMI in children and its possible association with motor skills. With both sexes, motor abilities improve from physical development in adolescents, and regular sports training influences fitness and motor abilities. The aim of our study was to evaluate the morphological status and physical abilities of 13-year-old children in order to investigate the relationship between sports engagement, BMI and physical abilities. The results of our study should give coaches important parameters in the selection of young athletes, as well as provide them with information that may be useful in training and programming assignments.