Sustained noradrenaline sulphate response in long-distance runners and untrained subjects up to 2 h after exhausting exercise

Summary We investigated the response of plasma and platelet free catecholamine (CA]) and sulphated catecholamine (CA-S]) concentrations after an incremental treadmill test to exhaustion and during recovery. In triathletes (n = 9) plasma and platelet CA] and CA-S] were measured before, immediately after and 0.5 and 24 h after exercise. In long-distance runners (n = 9) and in controls (n = 10) plasma CA] and CA-S] were determined 2 h instead of 24 h after exercise. Platelet CA] and CA-S] remained unchanged throughout the study. Plasma CA] increased after exercise in all groups (P<0.05) and returned to pre-exercise values within 0.5 h of recovery. Plasma sulphoconjugated noradrenaline concentration (NA-S]) was elevated after exercise in the triathletes, long-distance runners and in controls 9.96 (SEM 0.84) nmol·1^–1, 11.8 (SEM 1.19) nmol·1^–1, 9.53 (SEM 1.10) nmol·l^–1, respectively;P<0.05] compared with resting values 7.13 (SEM 1.04) nmol·l^–1, 6.19 (SEM 0.56) nmol·l^–1, 6.76 (SEM 0.67) nmol·1^–1, respectively] and remained elevated after 0.5 h of recovery 9.94 (SEM1.14) nmol·l^–1, 10.96 (SEM 0.80) nmol·l^–1, 8.95 (SEM 0.99) nmol·l^–1, respectively;P<0.05]. In the long-distance runners and controls plasma NA-S] remained elevated during 2 h of recovery 9.96 (SEM 0.76) nmol·l^–1, 9.03 (SEM 0.88) nmol·l^–1, respectively]. These results would indicate that plasma NA-S] increases after sympathetic nervous system activation by an exhausting incremental exercise test and remain elevated up to 2 h after exercise.