Lactate release, concentration in blood, and apparent distribution volume after intense bicycling

To study the release of lactate from muscle and its relationship to the blo od lactate concentration during and after intense bicycling, young men cycl ed at 5.5 W kg(-1) body mass for 2 min to exhaustion or stopped after 1 min (nonexhaustive ride). The leg's release of lactate during and after each r ide was taken from the measured blood flow and lactate concentrations in ar terial and femoral-venous blood. Muscle biopsies were taken in separate exp eriments and analyzed for lactate. During the bicycling, 6 to 10% of the la ctate produced was released to the blood. During exercise and for the first few minutes after, the rate of lactate release did not differ between 2 mi n exhaustive and 1 min nonexhaustive bicycling, The integrated release (exe rcise plus recovery) for the I min bicycling was 60 to 80% of the correspon ding value of the 2 min exhaustive bicycling. in the late recovery, the blo od lactate concentration was 3 to 5 times higher after 2 min exhaustive bic ycling than after the 1 min nonexhaustive bicycling, There was thus a misma tch between the amount of lactate released and measured concentration in bl ood, reflecting a smaller distribution volume after the exhaustive bicyclin g. The blood lactate concentration may therefore not be a good measure of t he lactate production and anaerobic energy release during bicycling.