Urinary excretion of catecholamines, 17-hydroxycorticosteroids and concentration of certain blood parameters during progressive endurance conditioning

Abstract

The urinary excretion of noradrenaline and adrenaline, 17-0HCS, the concentration of hemoglobin, hematocrite, the concentration of plasma lactic acid, K⁺, Na⁺ and blood glucose, in 22 male students were determined both before and after a periodic, submaximal exercise on a bicycle ergometer. The measurements were repeated three tinies during a nine-week endurance conditioning where eleven of tile subjects participated. Except for the decreased heart rate during exercise (p < .001) and increased VO₂ max. (p < .001) the endurance conditioning resulted in a significantly decreased concentration of the average plasma lactic acid in the trained subjects during the most anaerobic phases of exercise (p < .025). During the loading both the noradrenaline and adrenaline increased significantly (p < .001) as compared with the situation of relative rest before the exercise. During loading the respective urinary excretion of 17-OHCS did not change significantly. The training did not result in any significant difference between the trained and untrained groups in the urinary excretion of the adrenal hormones and the sympathetic transmitter, noradrenaline. Beside the increased concentration of plasma lactic acid during the exercise periods (p < 001), temporary increases and decreases in the concentrations of blood hemoglobin and hematocrite values were found after the heaviest and 1ightest anaerobic phases of loading respectively (p < .05 - .001). After the period of endurance conditioning the trained and untrained groups differed significantly in the response of hemoglobin after the first phases of exercise (p < .025 - .05). The fluctuation was then found only in the untrained group. No significant difference in hematocrite values due to the conditioning was found. Since the second loading phase of the exercise period the concentration of K⁺ in plas111a increased significantly (p < .05 - .001). The respective lowered rations of Na⁺/K⁺ were found (p < .05 - .001) but not change in the Na⁺ concentrations. No significant effect of conditioning on these ionic concentrations were noted.