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 (P(v)O(2)) 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 P(v)O(2) nor on [EPI] in the blood.