A multiple regression model for blood lactate removal in man.

After exercise the lactate (La) removal from blood occurs significantly faster during moderate exercise than at rest. However, under both conditions there are considerable inter-individual differences in La removal. These differences in man may depend on the slow-twitch (ST) fiber content of muscle (X1), the La concentration in blood (X2), and the intensity of the recovery exercise (X3). Therefore, multiple regression models were obtained to describe La removal rates with these variables. In 10 women La concentrations were increased via a 6 min bicycle ergometer ride (87% VO2max) and blood La concentrations were measured every 5 min during 20 min resting and active recovery periods (29--49% VO2max). For resting recovery only the initial La concentration after the 6 min exercise provided a significant description for La removal in 8 subjects (P = 0.03). However, for the active recovery a highly significant description for La removal was obtained: La removal rate (mM/1 . min) = 0.773 x 10-2X1 + 0.321 x 10-1X2 - 0.120 x 10-1X3 + 0.202 (R = 0.91; P = 0.01). The statistical independence (P greater than 0.010) of each of these variables in the model suggests that each is contributing uniquely to the total removal rate of La observed during an active recovery period. The relationship between La removal and %ST fibers may be related to the metabolic and anatomical features of these fibers, the La concentration probably reflects the significance of the mass action effect of La, and the intensity of exercise reflects the role of the muscle's metabolic rate. The present results illustrate that the removal of blood lactate is influenced by the interactive effects of the intensity of the recovery exercise, blood lactate concentration and the ST fiber content of muscle.