Plasma catecholamine and nephrine responses following 7 weeks of sprint cycle training.

The catecholamine metabolites normetanephrine (NMET) and metanephrine (MET) increase in response to acute exercise. However, changes in catecholamine 'nephrines' during sprint training are unclear. Therefore, the aim of this study was to examine the plasma nephrine and catecholamine (noradrenaline, NA; adrenaline, AD) responses to a laboratory-based cycle test before and after a 7-week period of cycle sprint training. Ten healthy men completed a 2-min cycle test at a power output equivalent to 110% of pre-training VO(2)max before and after 7 weeks of laboratory based sprint cycle training, three times per week. Resting and post-sprint venous blood samples were taken. Resting plasma nephrines and catecholamines increased significantly following exercise (P < 0.05). Post-exercise NA and NMET were reduced after training (P < 0.05) and a trend for a reduction in AD (P = 0.09) and MET (P = 0.07) was observed. The results demonstrate a reduction in exercise-induced increases in plasma nephrine concentrations following sprint training. This suggests catechol-O-methyl transferase activity is coupled to high intensity cycle exercise. These findings may aid in the understanding of catecholamine regulation during high intensity exercise and sprint training.