The aim of this study was to investigate the locomotor capacity of children during the performance of different lower extremity tasks with increasing difficulty. Two subject groups of children (aged 6-8 and 9-12 years) and adult controls performed several motor tasks from the Zürich Neuromotor Assessment (ZNA) test, as well as a unilateral and bilateral obstacle stepping test during treadmill walking. Performance of ZNA items, changes in foot clearance, and obstacle hits were assessed. Correlations between children's age, ZNA and obstacle measures were calculated. Performance of all motor tasks improved with increasing age. All three groups improved foot clearance during unilateral obstacle stepping, while the younger children achieved a poorer performance level. During bilateral obstacle stepping, only the adult controls and the 9-12 years old children's group further improved foot clearance, while no further improvement occurred in the 6-8 years old children's group. A relationship between items of ZNA and bilateral obstacle stepping was found. It is concluded that children in the mid-childhood range are able to significantly improve performance of a high-precision locomotor task. However, children below 9 years of age have a poorer motor performance compared to older children and adults that becomes more pronounced with increasing complexity of the task. Finally, ZNA tests can improve the prediction of complex adaptive locomotor behaviour compared to calendar age alone.