Document Type



Two samples of preschool children were studied serially from the point of view of somatic and functional development: 246 boys and girls from 3 to 6 years. A representative cross-sectional sample of 5449 children of both sexes from Bohemia and Moravia was studied at the age of 6.4 years. Marked sexual differentiation was apparent in both samples—boys were taller, heavier, with longer measurements on the trunk and extremities, greater transverse and antero-posterior chest dimensions, greater skeletal robustieity (i.e. greater hand and wrist breadth, broader bicondylar humerus and femur and ankle breadths), greater circumferences (head, neck, chest) which were obviously due to greater lean laxly mass. Also hand grip strength, performance in 20m dash, broad jump from the spot and cricket ball throw by both hands were greater in the boys. Girls showed greater thigh and arm circumferences, and more subcutaneous fat measured by Best and Harpenden calipers on both body sites. There were no sex differences in the reaction of the cardiovascular system during a modified step test representing the standard work load. With advancing age along with increasing bodily dimensions and muscular strength, subcutaneous fat decreased in boys but did not change in girls. The economy of work of the cardiovascular system during the step test improved significantly as well as the performance in mentioned disciplines in children of both sexes.