Local and systemic effects on blood lactate concentration during exercise with small and large muscle groups

To evaluate the relationship between lactate release and [lac]art and to investigate the influence of the catecholamines on the lactate release, 14 healthy men [age 25±3 (SE) year] were studied by superimposing cycle on forearm exercise, both at 65% of their maximal power reached in respective incremental tests. Handgrip exercise was performed for 30 min at 65% of peak power. In addition, between the tenth and the 22nd minute, cycling with the same intensity was superimposed. The increase in venous lactate concentration ([lac]ven) (rest: 1.3±0.4 mmol.l-1; 3rd min: 3.9±0.8 mmol.l-1) begins with the forearm exercise, whereas arterial lactate concentration ([lac]art) remains almost unchanged. Once cycling has been added to forearm exercise (COMB), [lac]art increases with a concomitant increase in [lac]ven (12th min: [lac]art, 3.2±1.3 mmol.l-1; [lac]ven, 5.7±2.2 mmol.l-1). A correlation between oxygen tension (PvO2) and [lac]ven cannot be detected. There is a significant correlation between [lac]art and norepinephrine ([NE]) (y=0.25x+1.2; r=0.815; p=0.01) but no correlation between lactate release and epinephrine ([EPI]) at moderate intensity. Our main conclusion is that lactate release from exercising muscles at moderate intensities is neither dependent on PvO2 nor on [EPI] in the blood