Abstract

The basic problem by interpretation of exercise testing results in children is determination of actual (biological) state of subjects. Body composition (BC) may be used as a criterion of the actual biological state of children - state of development. Dependence between frequently used indicators of aerobic fitness (VO2max • kg-1, calculated total work (CTW), and maximal power output (MPO)), and body composition (BC) (percent body fat (BF), free fat mass (FFM), body cell mass (BCM) and extracellular mass/body cell mass(ECM/BCM)) were studied in a group of 1647 Czech children (883 boys and 764 girls) in age from 6 to 14 years. The physical performance variables were assessed by incremental treadmill test with constant slope of 5 percent. The age dependent initial speed was increased by 1 km • h-1 till subjective exhaustion. Body composition was determined by whole body bioimpedance measurements using a modified prediction equation for children. Percent of body fat was negatively correlated with VO2max • kg-1, and calculated total work (CTW). Both free fat mass and body cell mass were positively related with calculated total work, maximal power output, and VO2max • kg-1. ECM/BCM relationship was negatively related to VO2max • kg-1 and calculated total work. In conclusion, the body composition is an important determinant of physical performance in laboratory (treadmill exercise tests) and in field (running and/or walking tests). The observed variables of body composition significantly influent the variables which may characterise the aerobic fitness. The results further demonstrate that when oxygen consumption is not feasible, the physical performance characteristics together with parameters of body composition seem to be a good predictor of aerobic fitness; this may be very helpful in large population studies. Zusammenfassung (geändert)