title: Effect of high-intensity intermittent training on lactate and H+ release from human skeletal muscle.
abstract: The study investigated the effect of training on lactate and H+ release from human skeletal muscle during one-legged knee-extensor exercise. Six subjects were tested after 7-8 wk of training (fifteen 1-min bouts at approximately 150% of thigh maximal O2 uptake per day). Blood samples, blood flow, and muscle biopsies were obtained during and after a 30-W exercise bout and an incremental test to exhaustion of both trained (T) and untrained (UT) legs. Blood flow was 16% higher in the T than in the UT leg. In the 30-W test, venous lactate and lactate release were lower in the T compared with the UT leg. In the incremental test, time to fatigue was 10.6 +/- 0.7 and 8.2 +/- 0.7 min, respectively, in the T and UT legs (P < 0.05). At exhaustion, venous blood lactate was 10.7 +/- 0.4 and 8.0 +/- 0.9 mmol/l in T and UT legs (P < 0.05), respectively, and lactate release was 19.4 +/- 3.6 and 10.6 +/- 2.0 mmol/min (P < 0.05). H+ release at exhaustion was higher in the T than in the UT leg. Muscle lactate content was 59.0 +/- 15.1 and 96.5 +/- 14.5 mmol/kg dry wt in the T and UT legs, and muscle pH was 6.82 +/- 0.05 and 6.69 +/- 0.04 in the T and UT legs (P = 0.06). The membrane contents of the monocarboxylate transporters MCT1 and MCT4 and the Na+/H+ exchanger were 115 +/- 5 (P < 0.05), 111 +/- 11, and 116 +/- 6% (P < 0.05), respectively, in the T compared with the UT leg. The reason for the training-induced increase in peak lactate and H+ release during exercise is a combination of an increased density of the lactate and H+ transporting systems, an improved blood flow and blood flow distribution, and an increased systemic lactate and H+ clearance.
authors.affiliation: Copenhagen Muscle Research Centre, August Krogh Institute, University of Copenhagen, DK-2100 Copenhagen, Denmark. cjuel@aki.ku.dk
authors.forename: Carsten
authors.initials: C
authors.lastname: Juel
authors.forename: Christina
authors.initials: C
authors.lastname: Klarskov
authors.forename: Jens Jung
authors.initials: JJ
authors.lastname: Nielsen
authors.forename: Peter
authors.initials: P
authors.lastname: Krustrup
authors.forename: Magni
authors.initials: M
authors.lastname: Mohr
authors.forename: Jens
authors.initials: J
authors.lastname: Bangsbo
mesh_terms: D000328:Adult; D001769:Blood / Q000378:metabolism; D006801:Humans; D006859:Hydrogen / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000097:blood / Q000378:metabolism*; D007866:Leg / Q000098:blood supply; D008297:Male; D027501:Monocarboxylic Acid Transporters / Q000378:metabolism; D009124:Muscle Proteins / Q000378:metabolism; D018482:Muscle, Skeletal / Q000378:metabolism*; D010806:Physical Education and Training; D012039:Regional Blood Flow; D017923:Sodium-Hydrogen Exchangers / Q000378:metabolism; D027981:Symporters / Q000378:metabolism; D000099233:Monocarboxylate Transport Protein 1
chemical_list: D006859:Hydrogen; D019344:Lactic Acid; D027501:Monocarboxylic Acid Transporters; D009124:Muscle Proteins; D017923:Sodium-Hydrogen Exchangers; D027981:Symporters; D000099233:Monocarboxylate Transport Protein 1; C406962:SLC16A4 protein, human; C069139:growth factor-activatable Na-H exchanger NHE-1