Work rate-dependent lactate kinetics after exercise in humans.

Arterial blood lactate concentrations were measured on 19 subjects before, during, and after a 3-min bicycle exercise at several work rates, and the concentrations during the recovery phases were fitted to a biexponential time function consisting of a rapidly increasing and a slowly decreasing component. Highly significant correlations with the work rate of the exercise preceding the recovery were found for all the parameters of the fitted equation. The two velocity constants show inverse linear relationships, whereas the other parameters vary according to a definite power function.

Lactate after exercise in man: IV. Physiological observations and model predictions.

Following earlier papers that established the mathematical form of the time dependence of lactate concentrations during recovery from several types of exercise, and that set up a two-compartment model predicting the same time dependences, the present work applies the model to obtain parameters of specific physiological processes. Satisfactory agreement between predictions of the model and our experiment and literature data is obtained in the cases were comparisons can be made, as in the muscular lactate time evolution measured from biopsy samples, in blood flows through the active muscle at the end of exercise or at rest and their evolution during recovery, as well as in the volume of the active muscle compartment. The model prediction that lactate efflux from the muscles to the blood can reduce to zero during recovery is verified experimentally.

Lactate after exercise in man: III. Properties of the compartment model.

Lactate movements during recovery following muscular exercise in man were studied by means of a two-compartment model. Mathematical discussion of the literal expressions obtained allows one to represent parameters concerning lactate exchange, utilization, and production in the previously working muscles and in the remaining lactate distribution space. It also shows that bi-exponential time courses predicted for muscular and blood lactate concentrations as well as for rates of lactate uptake, release, and utilization can denote several morphologies.

Lactate after exercise in Man: II. Mathematical model.

A mathematical model of lactate kinetics after exercise has been constructed from the application of the mass conservation law and the following assumptions: 1. The total lactate distribution space is composed of two compartments, i.e.

Lactate after exercise in man: I. Evolution kinetics in arterial blood.

Arterial and venous blood lactate concentrations were measured at 10 or 30 s time intervals before, during, and after several types of muscular exercise on an ergocycle in a sitting or supine position. Arterial blood lactate concentration curves over the recovery period were found to fit a biexponential time function including a rapidly increasing and a slowly decreasing component, even during active recovery at approximately 40% VO2 max exercise. The velocity constants were dependent on the exercise load.