Effects of training on lactate production and removal during progressive exercise in humans.
To determine whether the reduced blood lactate concentrations [La] during submaximal exercise in humans after endurance training result from a decreased rate of lactate appearance (Ra) or an increased rate of lactate metabolic clearance (MCR), interrelationships among blood [La], lactate Ra, and lactate MCR were investigated in eight untrained men during progressive exercise before and after a 9-wk endurance training program. Radioisotope dilution measurements of L-[U-14C]lactate revealed that the slower rise in blood [La] with increasing O2 uptake (VO2) after training was due to a reduced lactate Ra at the lower work rates [VO2 less than 2.27 l/min, less than 60% maximum VO2 (VO2max); P less than 0.01]. At power outputs closer to maximum, peak lactate Ra values before (215 +/- 28 mumol.min-1.kg-1) and after training (244 +/- 12 mumol.min-1.kg-1) became similar. In contrast, submaximal (less than 75% VO2max) and peak lactate MCR values were higher after than before training (40 +/- 3 vs. 31 +/- 4 ml.min-1.kg-1, P less than 0.05). Thus the lower blood [La] values during exercise after training in this study were caused by a diminished lactate Ra at low absolute and relative work rates and an elevated MCR at higher absolute and all relative work rates during exercise.
MacRae
H S
HS
Department of Physiology, University of Cape Town Medical School, Observatory, Republic of South Africa.
Dennis
S C
SC
Bosch
A N
AN
Noakes
T D
TD
D000328:Adult; D050260:Carbohydrate Metabolism; D015444:Exercise / Q000502:physiology*; D006801:Humans; D007700:Kinetics; D007773:Lactates / Q000097:blood*; D019344:Lactic Acid; D008297:Male; D010084:Oxidation-Reduction; D010101:Oxygen Consumption; D010806:Physical Education and Training; D010807:Physical Endurance / Q000502:physiology
D007773:Lactates; D019344:Lactic Acid