Plasma catecholamine and nephrine responses to brief intermittent maximal intensity exercise

Catecholamines (noradrenaline, NA; adrenaline, AD; dopamine, DA) influence the metabolic and cardiovascular responses to exercise. However, changes in catecholamine metabolism during exercise are unclear. Plasma normetanephrine (NMET), metanephrine (MET) and catecholamine responses to a laboratory-based model of games-type exercise were examined. Twelve healthy men completed a resting control trial and a trial consisting of ten 6 s cycle ergometer sprints interspersed with 30 s recovery, in randomised order. Resting and post-sprint venous blood samples were taken. Plasma NA and AD increased after each sprint but DA was unaltered. Plasma nephrines increased significantly from sprint 4 onwards with peak NMET increasing 60% to 0.76 ± 0.19 nmol l⁻¹ and MET 230% to 0.37 ± 0.16 nmol l⁻¹ from resting values (P < 0.05). The results demonstrate increased catecholamine metabolism via elevated catechol-O-methyl transferase activity during intermittent sprinting. The results may aid regulation of the metabolic and cardiovascular responses to exercise by maintaining tissue adrenoceptor sensitivity to circulating catecholamines.