Abstract

To establish the dynamics of endorphin levels in blood during prolonged exercise 49 healthy persons were studied: 20 qualified endurance sportsmen, 10 joggers and 19 untrained persons. During 2-h exercise on bicycle ergometer blood samples were taken by a venous catheter. Concentrations of beta-endorphins and in a part of experiments alpha-and gamma-endorphins, as well as corticotropin and cortisol were determined by radioimmunoassay. 4 common variants of dynamics of beta-endorphin level were distinguished: 1) an increase during the first 30 min followed by a decrease below initial values, 2) a biphasic increase (peak values at the 30th and 120th min), 3) increase only during the 2nd exercise, 4) decrease during the whole period of exercise. For trained persons the most common variant was the biphasic increase, for untrained persons the overall decrease. With an intensity of exercise >55 of VO2max, only a biphasic increase was observed in sportsmen. In untrained persons the distribution of all variants over the full range of exercise intensities were noticed. Obviously, in a number of untrained persons the endogenous opioid system is not enough developed to respond to exercise. Blood gamma-endorphin concentration did not change substantially, the changes of alpha-endorphin were not parallel to the alternations of beta-endorphin level. Consequently, beside the changes in endorphin output their metabolism alters. The dynamics of beta-endorphin level was in accordance with changes in corticotropin and cortisol concentrations. Verf.-Ref.