H. Freund

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

SummaryArterial 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%

Prolonged submaximal exercise and L-carnitine in humans

\dot V_{O_2 }

Effect of exercise duration on lactate kinetics after short muscular exercise

max exercise. The velocity constants were dependent on the exercise load. They were also linearly related to each other. The time of lactate disappearance during recovery increased with the work load.

Lactate after exercise in man: II. Mathematical model

The relationships between individual performance and lactate exchange and removal abilities were studies in 12 male rowers all subjected to three measurements on a rowing ergometer. An incremental exercise carried out to determine the maximal oxygen uptake (VO2max) and the corresponding maximal aerobic power (Pamax), a 2500-m all-out test where the mean work rate (P2500) represented the individual performance, and a 6-min 90% Pamax exercise designed to assess the lactate kinetics during the following 90 min passive recovery were performed. The lactate recovery curves were fitted to the bi-exponential time function: La(t) = La(O) + A1(1-e-gamma 1.t) + A2(1-e-gamma 2.t). The velocity constants gamma 1 and gamma 2 denote the lactate exchange and removal abilities, respectively. The mean value of P2500 sustained by the rowers was 376 +/- 41W (106 +/- 5% of Pamax (P2500%). P2500 was positively correlated with gamma 2 (P < 0.05). gamma 1 and gamma 2 explained 67% of the P2500 variance. P2500% was also correlated with gamma 2 (P < 0.01). These results suggest that a better performance on the rowing ergometer is associated with improved lactate exchange and removal abilities. Furthermore, the ability to row at high relative work rates was correlated with an increased lactate removal ability. Training-induced adaptations could explain the high gamma 1 and gamma 2 displayed by the present rowers.

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

SummaryChanges in the main physiological parameters and circulating indicators of carbohydrate, protein, lipid (and ketone body) metabolism were measured in ten exercising subjects before L-carnitine (L-carn) loading, after 4 weeks of daily loading with 2 g L-carn, and 6–8 weeks after terminating L-carn administration. Measurements were made on venous blood samples collected during each experiment at fixed time intervals over an initial rest of 45 min, 60 min bicycle exercise performed near 50%

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

\dot V_{{\text{O}}_{{\text{2}} {\text{max}}} }