Laurent Messonnier

Lactate kinetics at the lactate threshold in trained and untrained men

To understand the meaning of the lactate threshold (LT) and to test the hypothesis that endurance training augments lactate kinetics [i.e., rates of appearance and disposal (Ra and Rd, respectively, mg·kg(-1)·min(-1)) and metabolic clearance rate (MCR, ml·kg(-1)·min(-1))], we studied six untrained (UT) and six trained (T) subjects during 60-min exercise bouts at power outputs (PO) eliciting the LT. Trained subjects performed two additional exercise bouts at a PO 10% lower (LT-10%), one of which involved a lactate clamp (LC) to match blood lactate concentration ([lactate]b) to that achieved during the LT trial. At LT, lactate Ra was higher in T (24.1 ± 2.7) than in UT (14.6 ± 2.4; P < 0.05) subjects, but Ra was not different between UT and T when relative exercise intensities were matched (UT-LT vs. T-LT-10%, 67% Vo2max). At LT, MCR in T (62.5 ± 5.0) subjects was 34% higher than in UT (46.5 ± 7.0; P < 0.05), and a reduction in PO resulted in a significant increase in MCR by 46% (LT-10%, 91.5 ± 14.9, P < 0.05). At matched relative exercise intensities (67% Vo2max), MCR in T subjects was 97% higher than in UT (P < 0.05). During the LC trial, MCR in T subjects was 64% higher than in UT (P < 0.05), in whom %Vo2max and [lactate]b were similar. We conclude that 1) lactate MCR reaches an apex below the LT, 2) LT corresponds to a limitation in MCR, and 3) endurance training augments capacities for lactate production, disposal and clearance.

Effects of compression stockings during exercise and recovery on blood lactate kinetics

This study aimed to investigate if wearing compression stockings (CS) during exercise and recovery could affect lactate profile in sportsmen. Eight young healthy trained male subjects performed two maximal exercise tests on a cycle ergometer on two different occasions performed randomly: CS during both exercise and recovery, and no CS. Blood lactate concentration was taken during exercise and at 0, 3, 5, 10, 15, 30 and 60xa0min post-exercise. The individual blood lactate recovery curves were fitted to a biexponential time function:

Cardioventilatory changes induced by mentally imaged rowing

{text{La}}_{(t)} = {text{La}}_{(0)} + A_{ 1} ( 1- {text{e}}^{{ - gamma_{1} t}} ) + A_{ 2} ( 1- {text{e}}^{{ - gamma_{2} t}} )

Are the effects of training on fat metabolism involved in the improvement of performance during high-intensity exercise?

, where γ1 and γ2 denote the abilities to exchange lactate between the previously active muscles and the blood and to remove lactate from the organism, respectively. A significantly higher blood lactate value at the end of the maximal exercise was found (12.1xa0±xa00.5 vs. 10.8xa0±xa00.5xa0mmolxa0l−1) wearing CS as compared to no CS (Pxa0<xa00.05). Lower γ1 and higher γ2 values were observed with CS during recovery, as compared to no CS. It was concluded that CS during graded exercise leads to a significant higher blood lactate value at exhaustion. Since lactate exchanges were expected to be decreased during exercise due to CS, this result was likely attributable to a higher lactate accumulation related to a greater overall contribution of anaerobic glycolysis. Although the lactate removal ability was significantly improved when wearing CS during recovery, its efficacy in promoting blood lactate clearance after high-intensity exercise is limited.

Effects of training in normoxia and normobaric hypoxia on time to exhaustion at the maximum rate of oxygen uptake

To assess whether the ability to demonstrate a plateau in oxygen consumption

Muscle MCT4 Content Is Correlated with the Lactate Removal Ability during Recovery Following All-Out Supramaximal Exercise in Highly-Trained Rowers

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