Adrenocortical function of female endurance runners and joggers

The aim of the present study was to investigate the long-term effects of endurance exercise on the function of the adrenal cortex of 18 female runners, 12 control subjects, and 13 joggers and their 11 control subjects by measuring the serum concentrations of cortisol and dehydroepiandrosterone sulfate and the responses of cortisol to intravenous ACTH injection. All of the participants were studied over one menstrual cycle, during a light training period in the autumn and a hard training period in the spring. There were no significant between-group differences in the concentrations of cortisol in the autumn or the spring. However, the mean spring vs autumn concentrations of cortisol were significantly increased in runners during the follicular and luteal phases of the menstrual cycle. The concentrations of cortisol in the ACTH response test were also increased at 30 and 60 min in runners and all the time in joggers in spring, in relation to the respective values in the autumn. The absolute and relative rises of cortisol in response to ACTH did not differ between the groups, but the relative spring vs autumn increase of cortisol was significantly higher at 60 min in the runners and lower at 30 min in the control subjects of the joggers. There were no differences in the serum concentrations of dehydroepiandrosterone sulfate between the groups, or between spring and autumn values in any group. In conclusion, chronic endurance exercise per se did not appear to alter the function of the adrenal cortex, while an undefined spring-associated factor, possibly the high luminosity, appeared to induce an increase in cortisol secretion in female runners.