Effect of the intensity of training on catecholamine responses to supramaximal exercise in endurance-trained men

In this study we investigated whether plasma catecholamine responses to the Wingate test are affected by the intensity of training in endurance-trained subjects. To do this we compared plasma adrenaline (A) and noradrenaline (NA) concentrations in response to a Wingate test in three different groups: specialist middle-distance runners (MDR) in 800-m and 1,500-m races, specialist long-distance runners (LDR) 5,000-m and 10,000-m races, and untrained subjects (UT). The maximal power (W-max) and the mean power (W) were determined from the Wingate test. Blood lactate (La), plasma A and NA concentrations were analysed at rest (La-0, A(0) and NA(0)), immediately at the end of the exercise (A(max) and NA(max)) and after 5 min recovery (La-max, A(5) and NA(5)). The ratio A(max)/NA(max) was considered as an index of the adrenal medulla responsiveness to the sympathetic nervous activity. At the end of the test, W-max and W were similar in the three groups but La-max was significantly greater in MDR compared to LDR and UT [15.2 (2.2) mmol l(-1), 11.7 (3.1) mmol l(-1), 11.6 (1.6) mmol l(-1), respectively, for MDR, LDR and UT; mean (SD)]. Concerning the plasma catecholamine concentrations in response to exercise, MDR and LDR A(max) values [3.73 (1.53) nmol l(-1), 3.47 (0.74) nmol l(-1), respectively, for MDR and LDR] were significantly greater than those of UT [1.48 (0.32) nmol l(-1)] who also exhibited the lowest NA(max) values [11.09 (6.58) nmol l(-1)] compared to MDR and LDR [20.43 (3.51) nmol l(-1); 15.85 (4.88) nmol l(-1), respectively, for MDR and LDR]. However, no significant differences were observed between the two trained groups either for A(max) or NA(max.) These results suggest that long-term endurance training can enhance plasma catecholamine concentrations in response to supramaximal exercise. However, as there were no significant differences between MDR and LDR A(max) and NA(max) values, the effect of the intensity of training remains to be clarified.