[Effect of physical training on the somatic development and work capacity of boys aged 10-13 years]

Working capacity was assessed for 20 healthy boys aged 13, who had been intensively trained as football players for the last three years. The control group consisted of similar age group boys who, apart from physical training classes at school, did not take part in any organized sport. On the basis of standard work load measured on a bicycle ergometer and by the gradational step tests, a more economical reaction of the circulatory and respiratory systems was observed in the trained boys in comparison with the controls. In the course of submaximal as well as maximal loads, a significantly lower heart rate was noted not only during work but also in the period of recovery. The systolic pressure after tets obtained lower values and returned more speedily to the initial level. At the maximal load and at high heart frequency up to 210 min-1, the systolic pressure, contrary to the adults, did not exceed 170 mm Hg which may be linked with the anatomo-functional character of the circulatory system . During the ergometric tests lower VO2 uptake was observed in the sport group, especially when calculated for the lean body mass. That group also showed higher values for VO2 max. at lower heart frequency. Lactic acid blood concentration at the maximal load did not show significant differences in the sport boys in comparison with the controls, but it reached lower level in comparison with the adults. Moreover, it was also stated that in the trained boys albuminuria was lower after the maximal load than in the controls. Albuminuria was diagnosed in 50 per cent of the sport boys after 90 minutes of football game, which leads to the conclusion that training is a comparatively high physical effort and the child's body needs a supplement of protein for its normal development.