scholarly journals Sporting myths: the REAL role of lactate during exercise

2007 ◽  
Vol 19 (5) ◽  
Author(s):  
T Mann
Keyword(s):  
Lactate Concentration ◽  
Lactate Production ◽  
Blood Lactate Concentration ◽  
Endurance Performance ◽  
Post Exercise ◽  
Early Exercise ◽  
Important Intermediate ◽  
Lactate Formation ◽  
Exercise Muscle

Background. Lactate or, as it was customarily known, ‘lactic acid’ was one of the first molecules to attract the attention of early exercise scientists, mainly because blood lactate concentration could be measured and was shown to increase with increasing exercise intensity. This connection resulted in lactate being associated with numerous other events associated with high-intensity exercise including muscle cramps, fatigue, acidosis and post-exercise muscle soreness. Nobel prize-winning research by AV Hill and Otto Meyerhof provided a rational explanation linking lactate to anaerobiosis and acidosis, which resulted in this relationship being widely accepted as fact. It was only following isotopic tracer studies of George Brooks and others that the true role of lactate during rest and exercise was revealed. Conclusions. Lactate is now acknowledged as an important intermediate of carbohydrate metabolism, taken up from the blood by tissues such as skeletal and cardiac muscle as a substrate for oxidation. Furthermore, lactate formation consumes a proton, thereby buffering against muscle acidosis. For this reason, lactate production forms an essential aid to endurance performance rather than a hindrance.

scholarly journals Sporting myths: the REAL role of lactate during exercise

2016 ◽  
Vol 19 (5) ◽  
Author(s):  
T Mann
Keyword(s):  
Lactate Concentration ◽  
Lactate Production ◽  
Blood Lactate Concentration ◽  
Endurance Performance ◽  
Post Exercise ◽  
Early Exercise ◽  
Important Intermediate ◽  
Lactate Formation ◽  
Exercise Muscle

Background. Lactate or, as it was customarily known, ‘lactic acid’ was one of the first molecules to attract the attention of early exercise scientists, mainly because blood lactate concentration could be measured and was shown to increase with increasing exercise intensity. This connection resulted in lactate being associated with numerous other events associated with high-intensity exercise including muscle cramps, fatigue, acidosis and post-exercise muscle soreness. Nobel prize-winning research by AV Hill and Otto Meyerhof provided a rational explanation linking lactate to anaerobiosis and acidosis, which resulted in this relationship being widely accepted as fact. It was only following isotopic tracer studies of George Brooks and others that the true role of lactate during rest and exercise was revealed. Conclusions. Lactate is now acknowledged as an important intermediate of carbohydrate metabolism, taken up from the blood by tissues such as skeletal and cardiac muscle as a substrate for oxidation. Furthermore, lactate formation consumes a proton, thereby buffering against muscle acidosis. For this reason, lactate production forms an essential aid to endurance performance rather than a hindrance.

Estimating energy expenditure for brief bouts of exercise with acute recovery

2006 ◽  
Vol 31 (2) ◽  
pp. 144-149 ◽  
Author(s):  
Christopher B Scott
Keyword(s):  
Energy Expenditure ◽  
Total Energy ◽  
Blood Lactate ◽  
Lactate Concentration ◽  
Lactate Production ◽  
Blood Lactate Concentration ◽  
Total Energy Expenditure ◽  
Post Exercise ◽  
Anaerobic Energy ◽  
Substrate Level

Four indirect estimations of energy expenditure were examined, (i) O2 debt, (ii) O2 deficit, (iii) blood lactate concentration, and (iv) excess CO2 production during and after 6 exercise durations (2, 4, 10, 15, 30, and 75 s) performed at 3 different intensities (50%, 100%, and 200% of VO2 max). Analysis of variance (ANOVA) was used to determine if significant differences existed among these 4 estimations of anaerobic energy expenditure and among 4 estimations of total energy expenditure (that included exercise O2 uptake and excess post-exercise oxygen consumption, or EPOC, measurements). The data indicate that estimations of anaerobic energy expenditure often differed for brief (2, 4, and 10 s) bouts of exercise, but this did not extend to total energy expenditure. At the higher exercise intensities with the longest durations O2 deficit, blood lactate concentration, and excess CO2 estimates of anaerobic and total energy expenditure revealed high variability; however, they were not statistically different. Moreover, they all differed significantly from the O2 debt interpretation (p < 0.05). It is concluded that as the contribution of rapid substrate-level ATP turnover with lactate production becomes larger, the greatest error in quantifying total energy expenditure is suggested to occur not with the method of estimation, but with the omission of a reasonable estimate of anaerobic energy expenditure.Key words: O2 deficit, lactate, O2 debt, EPOC, anaerobic energy expenditure.

Lactate efflux from exercising human skeletal muscle: role of intracellular P O 2

1998 ◽  
Vol 85 (2) ◽  
pp. 627-634 ◽  
Author(s):  
Russell S. Richardson ◽  
Elizabeth A. Noyszewski ◽  
John S. Leigh ◽  
Peter D. Wagner
Keyword(s):  
Lactate Concentration ◽  
Work Rate ◽  
Incremental Exercise ◽  
Resonance Spectroscopy ◽  
Trained Subjects ◽  
Lactate Formation ◽  
Breathing Room ◽  
Direct Measures ◽  
Maximal Effort

It remains controversial whether lactate formation during progressive dynamic exercise from submaximal to maximal effort is due to muscle hypoxia. To study this question, we used direct measures of arterial and femoral venous lactate concentration, a thermodilution blood flow technique, phosphorus magnetic resonance spectroscopy (MRS), and myoglobin (Mb) saturation measured by 1H nuclear MRS in six trained subjects performing single-leg quadriceps exercise. We calculated net lactate efflux from the muscle and intracellular[Formula: see text] with subjects breathing room air and 12% O2. Data were obtained at 50, 75, 90, and 100% of quadriceps maximal O2 consumption at each fraction of inspired O2. Mb saturation was significantly lower in hypoxia than in normoxia [40 ± 3 vs. 49 ± 3% (SE)] throughout incremental exercise to maximal work rate. With the assumption of a[Formula: see text] at which 50% of Mb-binding sites are bound with O2 of 3.2 Torr, Mb-associated [Formula: see text] averaged 3.1 ± 0.3 and 2.3 ± 0.2 Torr in normoxia and hypoxia, respectively. Net blood lactate efflux was unrelated to intracellular[Formula: see text] across the range of incremental exercise to maximum ( r = 0.03 and 0.07 in normoxia and hypoxia, respectively) but linearly related to O2 consumption ( r = 0.97 and 0.99 in normoxia and hypoxia, respectively) with a greater slope in 12% O2. Net lactate efflux was also linearly related to intracellular pH ( r = 0.94 and 0.98 in normoxia and hypoxia, respectively). These data suggest that with increasing work rate, at a given fraction of inspired O2, lactate efflux is unrelated to muscle cytoplasmic [Formula: see text], yet the efflux is higher in hypoxia. Catecholamine values from comparable studies are included and indicate that lactate efflux in hypoxia may be due to systemic rather than intracellular hypoxia.

Acute anemia increases lactate production and decreases clearance during exercise

1989 ◽  
Vol 67 (2) ◽  
pp. 756-764 ◽  
Author(s):  
S. G. Gregg ◽  
R. S. Mazzeo ◽  
T. F. Budinger ◽  
G. A. Brooks
Keyword(s):  
Blood Glucose ◽  
Blood Lactate ◽  
Lactate Concentration ◽  
Lactate Production ◽  
Blood Lactate Concentration ◽  
Flow Distribution ◽  
Plasma Catecholamine ◽  
Metabolic Clearance ◽  
Sprague Dawley ◽  
Mean Values

We evaluated whether elevated blood lactate concentration during exercise in anemia is the result of elevated production or reduced clearance. Female Sprague-Dawley rats were made acutely anemic by exchange transfusion of plasma for whole blood. Hemoglobin and hematocrit were reduced 33%, to 8.6 +/- 0.4 mg/dl and 26.5 +/- 1.1%, respectively. Blood lactate kinetics were studied by primed continuous infusion of [U-14C]lactate. Blood flow distribution during rest and exercise was determined from injection of 153Gd- and 113Sn-labeled microspheres. Resting blood glucose (5.1 +/- 0.2 mM) and lactate (1.9 +/- 0.02 mM) concentrations were not different in anemic animals. However, during exercise blood glucose was lower in anemic animals (4.0 +/- 0.2 vs. 4.6 +/- 0.1 mM) and lactate was higher (6.1 +/- 0.4 vs. 2.3 +/- 0.5 mM). Blood lactate disposal rates (turnover measured with recyclable tracer, Ri) were not different at rest and averaged 136 +/- 5.8 mumol.kg-1.min-1. Ri was significantly elevated in both control (260.9 +/- 7.1 mumol.kg-1.min-1) and anemic animals (372.6 +/- 8.6) during exercise. Metabolic clearance rate (MCR = Ri/[lactate]) did not differ during rest (151 +/- 8.2 ml.kg-1.min-1); MCR was reduced more by exercise in anemic animals (64.3 +/- 3.8) than in controls (129.2 +/- 4.1). Plasma catecholamine levels were not different in resting rats, with pooled mean values of 0.45 +/- 0.1 and 0.48 +/- 0.1 ng/ml for epinephrine (E) and norepinephrine (NE), respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

An analysis of changes in blood pH following exhausting activity in the starry flounder, Platichthys stellatus

1977 ◽  
Vol 69 (1) ◽  
pp. 173-185
Author(s):  
C. M. Wood ◽  
B. R. McMahon ◽  
D. G. McDonald
Keyword(s):  
Time Course ◽  
Recovery Period ◽  
Lactate Concentration ◽  
Blood Lactate Concentration ◽  
Respiratory Acidosis ◽  
Temporal Separation ◽  
Post Exercise ◽  
Modest Contribution ◽  
Platichthys Stellatus ◽  
Blood Ph

Exhausting activity results in a marked and immediate drop in blood pH which gradually returns to normal over the following 6h. The acidosis is caused largely by elevated Pco2 levels, which vary inversely with pH. Blood lactate concentration increases slowly, reaching a maximum at 2--4h post-exercise, and contributes significantly to the acidosis only late in the recovery period. The slow time course of lactic acid release into the blood permits temporal separation of the peak metabolic acidosis from the peak respiratory acidosis. Evidence is presented that a metabolic acid other than lactic also makes a modest contribution to the pH depression during the recovery period.

scholarly journals Changes in pulmonary function and feasibility of portable continuous laryngoscopy during maximal uphill running

2020 ◽  
Vol 6 (1) ◽  
pp. e000815
Author(s):  
Mette Engan ◽  
Ida Jansrud Hammer ◽  
Trine Stensrud ◽  
Hilde Gundersen ◽  
Elisabeth Edvardsen ◽  
...  
Keyword(s):  
Pulmonary Function ◽  
Vital Capacity ◽  
Perceived Exertion ◽  
Lactate Concentration ◽  
Blood Lactate Concentration ◽  
Forced Expiratory Volume ◽  
Video Laryngoscope ◽  
Post Exercise ◽  
Technical Performance ◽  
Exercise Induced

ObjectiveTo evaluate changes in pulmonary function and feasibility of portable continuous laryngoscopy during maximal uphill running.MethodsHealthy volunteers participated in an uphill race. Forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) were obtained before and 5 and 10 min after finishing the race. Capillary blood lactate concentration ([BLa-]) and Borg score for perceived exertion were registered immediately after the race. One participant wore a portable video-laryngoscope during the race, and the video was assessed for technical performance.ResultsTwenty adult subjects participated with a mean (SD) age of 40.2 (9.7) years. Mean (SD) race duration and post-exercise [BLa-] was 13.9 (2.3) min and 10.7 (2.1) mmol/L, respectively, and the median (range) Borg score for perceived exertion was 9 (5–10). Mean percentage change (95% CI) 5 and 10 min post-exercise in FEV1 were 6.9 (3.7 to 10.2) % and 5.9 (2.7 to 9.0) %, respectively, and in FVC 5.2 (2.3 to 8.1) % and 4.7 (1.6 to 7.9) %, respectively. The recorded video of the larynx was of good quality.ConclusionsMaximal aerobic field exercise induced bronchodilatation in the majority of the healthy non-asthmatic participants. It is feasible to perform continuous video-laryngoscopy during heavy uphill exercise.

Physiological and metabolic responses as function of the mechanical load in resistance exercise

2014 ◽  
Vol 39 (3) ◽  
pp. 345-350 ◽  
Author(s):  
Sebastian Buitrago ◽  
Nicolas Wirtz ◽  
Ulrich Flenker ◽  
Heinz Kleinöder
Keyword(s):  
Resistance Exercise ◽  
Mechanical Load ◽  
Lactate Concentration ◽  
Blood Lactate Concentration ◽  
Maximum Velocity ◽  
Linear Increase ◽  
Detectable Effect ◽  
Turnover Rates ◽  
Post Exercise ◽  
The Relationship

The present study aimed to investigate the relationship between the mechanical load during resistance exercise and the elicited physiological responses. Ten resistance-trained healthy male subjects performed 1 set of resistance exercise each at 55%, 70%, and 85% of 1 repetition maximum for as many repetitions as possible and in 4 training modes: 4-1-4-1 (4 s concentric, 1 s isometric, 4 s eccentric, and 1 s isometric successive actions), 2-1-2-1, 1-1-1-1, and explosive (maximum velocity concentric). Mean concentric power and total concentric work were determined. Oxygen uptake (V̇O2) was measured during exercise and for 30 min post exercise. Total volume of consumed oxygen (O2 consumed) and excess post-exercise oxygen consumption (EPOC) were calculated. Maximum blood lactate concentration (LAmax) was also determined. V̇O2 exhibited a linear dependency on mean concentric power. Mean concentric power did not have a detectable effect on EPOC and LAmax. An augmentation of total concentric work resulted in significant linear increase of O2 consumed and EPOC. Total concentric work caused a significant increase in LAmax. In general, a higher mechanical load induced a larger physiological response. An increase in mean concentric power elicited higher aerobic energy turnover rates. However, a higher extent of total concentric work augments total energy cost covered by oxidative and (or) glycolytic pathways.

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