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 (La₀, A₀ and NA₀), immediately at the end of the exercise (A_max and NA_max) and after 5 min recovery (La_max, A₅ and NA₅). 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.