Sympathoadrenergic Regulation of Metabolism and Cardiocirculation During and Following Running Exercises of Different Intensity and Duration

Abstract

In three different field studies running loads of 2 × 200 m and 400 m, 3 × 1000 m and 3000 m, and finally 10,000 m were performed by respective groups of sprinters, middle-, and long-distance runners. We investigated the effects of exercise on the sympathoadrenal system by determining catecholamine (CA) concentrations in the venous blood and urine [free norepinephrine (NE), epinephrine (EPI)] and the respective sulfoconjugates in plasma and various hormonal, metabolic, and cardiocirculatory parameters.

Endurance-trained athletes showed a lower heart rate (HR) and plasma renin activity (PRA) at rest in comparison with the sprinters.

The concentrations of the plasma CA reflected the intensity more than the duration of exercise. At rest and following recovery the ratio of free NE/EPI in plasma was markedly higher in the group of sprinters in comparison with the long-distance runners. During exercise, however, an opposite movement occurred resulting in a higher ratio in the latter group. The pre-start ratios of NE/EPI in urine were similar to those in plasma. The sports disciplines' specific differences in NE/EPI both at rest and during exercise suggest that the overall sympathetic activity, reflected by NE and EPI, is regulated in a quite differentiated pattern. The sulfoconju-gated CA, however, increased less clearly after the middle- and long-distance bouts than the respective free CA which caused the ratio sulfates/free CA to decline. There were strong relations between the levels of free plasma NE and EPI and that of blood lactate, which, however, rather reflects a parallelism subsequent to the highly intensive stimulation.

A close connection between the sympathoadrenal system and the renin-angiotensin-aldosterone (RAA) system in the regulation of cardiocirculation was evident. Short-term regulation seems to depend mainly on the action of EPI on the heart and the pressoric action of NE on the blood vessels and precapillary on the kidney. During recovery the HR seems to be linked mainly to the metabolic stimulation. The RAA system seems to be effective in the medium- and long-term counterregulation of plasma volume loss.

Key words

running exercise - catecholamines - energy metabolism - cardiocirculation