Abstract

The purpose of the study was to compare the responses of blood lactate and urine cortisol concentration to different forms of physical exercise under natural swimming training and laboratory conditions, and to evaluate the effectiveness of training. Schoolchildren (14 girls and 16 boys aged 11-12 years) of classes with an extended programme of swimming training were studied in two stages. Stage I covered all the children and consisted in 90 min swimming training and a laboratory test. Stage II dealt with a group of 4 girls and 4 boys, selected by the coach according to the subjects progress and performance, who participated in controlled swimming training (5 x 400 m with 1 min intervals). Blood lactate concentration was determined prior to and after training and after the laboratory test, using the Barker and Summerson method modified by Stroem. Urine cortisol was determined with the Murphy radiocompetition method modified by Barcikowski and Stupnicki, both prior (60 min) to and (immediately) after training, and after 60 min rest. The results permit the following conclusions: postexercise responses of lactic acid concentration, observed during training, depended on the training load applied; decreased urine cortisol concentration in most children (17 out of 30 subjects) after 90 min swimming training would suggest low intensity of the exercise; during controlled training (5 x 400 m) urine cortisol level increase was found after swimming in 5 children, suggesting that the exercise was sufficient for stimulation of adrenal cortex and increased hormone secretion; a relationship between performance, post-exercise urine cortisol and blood lactate concentrations was observed. Verf.-Referat