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Lactate is known as the end product of anaerobic glycolysis, a pathway that is of key importance during high intensity exercise. Instead of being a waste product lactate is now regarded as a valuable substrate that significantly contributes to the energy production of heart, non-contracting muscles and even brain. The recent cloning of monocarboxyl...
Context in source publication
Context 1
... delay acidification and thus to extend the time to exhaustion, lactate anions and protons can be exported from the muscle into interstitial space and blood plasma (Fig 4). Only the un- protonated form of lactic acid can freely diffuse through plasma membrane, because the phos- pholipid bilayer of the biological membranes prevents the passage of protons and lactate an- ions (Juel 1997). ...
Citations
... There is an obvious need for pH-buffering in the exercising Standardbred horse, because during high-intensity exercise lactic acid is produced by the skeletal muscle, resulting in high muscle and plasma lactate levels (> 70 mmol/kg and > 30 mmol/L, respectively 19 ), as well as lowered plasma pH during exercise at the lactate threshold 20 . The importance of lactate and proton removal from muscle has been studied 21 and in Standardbred horses efficient (monocarboxylate) transporters have been identified in both muscle and red blood cells 22 . While transport of lactate into red blood cells is a passive means (sink) to increase the muscle-plasma concentration gradient, oxidation of lactate in the liver and inactive muscles is more efficient 22 . ...
... The importance of lactate and proton removal from muscle has been studied 21 and in Standardbred horses efficient (monocarboxylate) transporters have been identified in both muscle and red blood cells 22 . While transport of lactate into red blood cells is a passive means (sink) to increase the muscle-plasma concentration gradient, oxidation of lactate in the liver and inactive muscles is more efficient 22 . Lactate is oxidized to pyruvate, which can be metabolized through the tricarboxylic acid cycle or converted to glucose through gluconeogenesis. ...
The plasma metabolomic profile of elite harness horses subjected to different training programmes was explored. All horses had the same training programme from 1.5 until 2 years of age and then high-intensity training was introduced, with horses divided into high and low training groups. Morning blood samples were collected at 1.5, 2, 2.5 and 3.5 years of age. The plasma was analysed using targeted absolute quantitative analysis and a combination of tandem mass spectrometry, flow-injection analysis and liquid chromatography. Differences between the two training groups were observed at 2 years of age, when 161 metabolites and sums and ratios were lower (e.g. ceramide and several triglycerides) and 51 were higher (e.g. aconitic acid, anserine, sum of PUFA cholesteryl esters and solely ketogenic AAs) in High compared with low horses. The metabolites aconitic acid, anserine, leucine, HArg synthesis and sum of solely ketogenic AAs increased over time, while beta alanine synthesis, ceramides and indole decreased. Therefore high-intensity training promoted adaptations linked to aerobic energy production and amino acid metabolism, and potentially also affected pH-buffering and vascular and insulin responses.
... XXXII, rcfcv-e32129, 1 -6 5 de 6 entrenamiento que estos equinos realizan en las clases de salto y competencias. Diferentes autores [2,4,5,13,18,22,23] concluyen que caballos en buen estado físico tienen menores niveles de LAC y de FC, ya que su metabolismo aeróbico es eficiente, tienen una mejor tasa de eliminación del lactato producido por el músculo, el cual mejora su capacidad, y por el contrario, un equino que es expuesto a una alta intensidad con un bajo estado físico presenta niveles más altos de lactato, ya que su aporte de oxígeno es insuficiente; estos equinos poco entrenados pueden llegar a obtener LAC de 30 mmol·L -1 por lo que se produce un cambio del pH sanguíneo, como consecuencia de la falla en el aclaramiento del lactato acumulado, llevando a la acidemia, fatiga muscular y miopatía [16,25]. ...
Las constantes fisiológicas y los diferentes cálculos que se pueden extrapolar a partir de las concentraciones de lactato en sangre, ofrecen información acerca de la salud y del rendimiento deportivo que puede llegar a alcanzar un caballo como deportista de élite. El objetivo del presente trabajo consistió en evaluar el rendimiento deportivo en caballos de salto para la raza Silla Argentino mediante la concentración de lactato en plasma (LAC), y la frecuencia cardiaca (FC), en una banda caminadora comercial a diferentes inclinaciones. Se evaluaron quince caballos de la Escuela de Equitación Policial, ubicada en Bogotá, Colombia. Las muestras de sangre y FC se tomaron en reposo, antes (inclinación 0 %) y durante la prueba (inclinaciones a 5,5; 10,5 y 15,5 %), y al enfriamiento. Los resultados mostraron un valor basal para la LAC y FC de 0,43 ± 0,15 mmol·litros-1 (mmol·L-1) y de 36 ± 10 latidos por minutos (lpm), respectivamente. Se evidenció una correlación positiva entre estos parámetros a medida que se incrementaba el porcentaje de inclinación de la banda caminadora. Para las diferentes medias en la LAC no se evidenciaron diferencias significativas (P>0,05), no siendo así para la mayoría de comparaciones entre las medias referentes a la FC (P<0,05). Se determinó que el umbral aeróbico para la población analizada se inicia a una elevación de 10,5 % en la banda caminadora a una FC media de 71 lpm. En conclusión, los caballos de la raza Silla Argentino de salto analizados pueden mantener o mejorar el rendimiento deportivo con las condiciones establecidas por la banda caminadora en velocidad e inclinaciones mejorando el umbral aeróbico.
... In the case of the gastrocnemius muscle for example, the initial increase of T2 � and T2 relaxation times was much more prominent in comparison to the other muscles. One possible explanation is, that its (predominantly) fasttwitch muscle fibres are mainly dependent on anaerobic respiration, which is associated with reduced oxygen consumption, lactate accumulation and ultimately a decrease of the pH-value [40][41][42][43]. While at the beginning of muscular activity perfusion as well as oxygen supply of all muscles increase [44], it can be assumed that the reduced oxygen consumption leads to a higher proportion of oxyhemoglobin and thus to a stronger increase in T2 � times in the gastrocnemius muscle compared to muscles with a lower proportion of fast-twitch fibres. ...
Objectives
Previous studies on T2* and T2 relaxation time of the muscles have shown that exercise leads to an initial increase, presumably representing different intramuscular physiological processes such as increase in intracellular volume or blood oxygenation level dependent effects with a subsequent decrease after cessation of exercise. Their behaviour during prolonged exercise is still unknown but could provide important information for example about the pathophysiology of overuse injuries. The aim of this study was to evaluate the temporal course of T2* and T2 relaxation time in extrinsic foot muscles during prolonged exercise and determine the optimal mapping technique.
Methods
Ten participants had to run a total of 75 minutes at their individual highest possible running speed, with interleaved MR scans at baseline and after 2.5, 5, 10, 15, 45 and 75 minutes. The examined extrinsic foot muscles were manually segmented, and relaxation time were analysed regarding its respective time course.
Results
T2* and T2 relaxation time showed an initial increase, followed by a plateau phase between 2.5 and 15 minutes and a subsequent decrease. For the T2* relaxation time, this pattern was also apparent, but less pronounced, with more muscles not reaching significance (p<0.05) when comparing different time points.
Conclusions
T2* and T2 relaxation time showed a similar course with an initial rapid increase, a plateau phase and a subsequent decrease under prolonged exercise. Moderate but long-term muscular activity appears to have a weaker effect on T2* relaxation time than on T2 relaxation time.
... In another study in camels, lactate concentration decreased, but not significantly, after transportation for a 5-h round-trip journey (Tharwat et al. 2013b). Lactate is known as the end product of anaerobic glycolysis, a pathway that is of key importance during normal metabolic and athletic events (Pösö, 2002). Lactate accumulation occurs when the balance between production and consumption is breached. ...
... Instead of being regarded as a waste product, LA is now seen as a valuable substrate that contributes significantly to the energy production of the heart, muscles and even the brain. It may be used as fuel by many organ systems including the heart, liver and kidneys (Pösö, 2002;Tennent-Brown 2012). Therefore, the decreased serum concentration of LA could be due to its consumption by the muscles during training. ...
This study was designed to investigate the effect of 8 km training on the serum concentrations of the cardiac biomarkers troponin I (cTnI) and creatine kinase myocardial band (CK-MB) in 23 healthy racing camels (Camelus dromedarius). From each camel, 2 blood samples were collected; before training (T0) and within 2 h after training (T1). Serum concentrations of cTnI and CK-MB, and hematobiochemical profiles were estimated. Compared to a value of 7.21±1.9 ×10 9 /L pre-training, neutrophils decreased significantly to 6.2±2.2 × 10 9 /L post-training (P=0.05). Similarly, haemoglobin concentration decreased from 11.1±1.1 g/dL before training to 10.3±2.0 g/dL after training (P=0.0002). The MCV showed a similar pattern where it decreased from 26.0±1.3 (fl) pre-training to 24.0±3.6 (fl) post-training (P=0.01). Other haematological variables did not show any significant changes before and after training (P>0.05). The serum activity of AST increased from 85.5±12.8 U/L before training to 91.5±8.6 U/L after training (P=0.0001). Serum concentration of TP increased also from 54.2±8.7 g/L pre-training to 59.0±3.8 g/L post-training (P=0.04). On the contrary, the serum concentration of lactic acid decreased from 3.9±0.8 (mmol/L) before training to 3.3±0.4 (mmol/L) after training (P=0.004). Other biochemical variables did not show any significant changes before and after training (P>0.05). Before training the serum concentration of cTnI was 0.03±0.03 ng/mL; a value that did not differ significantly when compared to the value of 0.04±0.02 (ng/mL) after training (P=0.60). The CK-MB value differed significantly before and after training (0.47±0.1 ng/mL before training vs 0.48±0.8 ng/mL after training; P=0.004). In conclusion, the cardiac biomarker cTnI did not change significantly after training compared to baseline levels, a result that disagrees with values in camels after race. However, the CK-MB increased significantly after training compared to pre-training serum concentrations.
... Presence of high levels of lactate in the bloodstream, indicates as a parameter of direct correlation with the physical conditioning of horses, as excess of it and the slow return to baseline levels, may indicate fatigue and muscle wasting (PÖSO, 2002, BESSA, et al. 2018. ...
... El cotransportador de lactato-protón y lactato-sodio en la membrana plasmática b) Cotransporte de lactato-sodio al citosol y transporte de lactato a la mitocondria en células consumidoras de lactato. Figura modificada de Poso69 . ...
Lactate is considered to be a waste metabolite produced during muscle fatigue. In contrast with this simplistic point of view, in this review we provide evidence of the multiple and complex functions of this metabolite. We show that: 1) lactate is the final product of the glycolysis regardless the oxygen concentration in the cell 2) lactate is part of two types of shuttle, one that functions in the intermembrane space of the mitochondrion, and another intercellular, which is responsible for feeding lactate to certain cell types, such as neurons or heart muscle, 3) in sperm,lactate is transported directly to the mitochondrial matrix and there it is oxidized to produce pyruvate and NADH, 4) in the liver, lactate participates in the oxidation of ethanol through the generation of hydrogen peroxide, 5) Depending on the cell line, lactate can function as anti-inflammatory agent (endocrine) and/or a regulator of gene expression. Keywords: Lactic fermentation; hypoxia; muscle fatigue; gene regulator
... It is well known that the lactic acid level is used in practice to evaluate the fitness of racehorses and used as an indicator of racing performance (Harkins et al., 1993;Lindner, 2000). The changes in the rate of the LA production by muscles, reflect the degree at which anaerobic glycolysis contributes to the total energy production (Pösö, 2002) and the decline in blood lactate concentration reflects the cessation of exercise in chronic tendinitis horses due to the tendon injury. The lower values of icteric index reported in tendinitis than the normal horses may be attributed to the.interference with biochemistry assays due to haemolysis, icterus or lipaemia (HIL) which is a common problem in clinical laboratory practice which is measured by icteric index (Simundic et al., 2009;Adiga, 2016;Farrell et al., 2016). ...
Tendon injury is the most important veterinary reason for wastage of thoroughbred racehorses. Clinical diagnosis of tendon injuries is confirmed by a combination of clinical, ultrasonographic or post mortem examination of the injured limb. In addition, measurement of hematological and biochemical blood parameters are an important tool that aid health assessment and decision-making in diagnosis, treatment and follow-up of the injured tendon. Therefore, the lack of information or misinterpretation of these parameters may affect the accuracy of disease diagnosis and then lead to poor treatment. The present study was conducted to evaluate the levels of some hematological and biochemical parameter in the blood of thoroughbred horses affected by chronic tendinitis and compared with normal horses. Blood samples were collected from 15 healthy thoroughbred horses (8 stallions and 7 mares) and 21 tendinitis thoroughbred horses (11 stallions and 10 mares); and the levels of 18 blood parameters were determined. The tendinitis horses had higher number of erythrocytes and thrombocytes, higher values of packed cell volume (PCV) and mean corpuscular volume (MCV); lower enzyme activity of creatine kinase (CK), lower values of lactic acid (LA), icteric index and mean corpuscular hemoglobin concentration (MCHC) and lower numbers of band neutrophils than the normal horses. The chronic tendinitis mares had higher number of thrombocytes and lower values of lactate dehydrogenase (LDH) enzyme activity, lactic acid, plasma proteins, MCHC and lower numbers of white blood cells (WBC) than the normal mares. The chronic tendinitis stallions had higher levels of lactic acid, plasma proteins, MCV, and higher numbers of erythrocytes and lower values of icteric jaundice, MCHC, band neutrophils than the normal horses. No significant differences were reported when tendinitis mares were compared with tendinitis males. However, normal mares showed higher levels of plasma proteins than normal stallions. The results obtained by this study can be used as useful index to diagnose and treat chronic tendinitis in horses.
... During low intensity exercise, the energy demands are primarily met by aerobic metabolism and the LAC produced within the muscle cells can be directly metabolised. When the rate of LAC production exceeds the metabolising capacity of the muscle cells, lactic acid molecules accumulate within the exercising muscle cells and diffuse into the blood where they are removed and oxidised by other tissues such as nonworking muscles and liver (Pösö, 2002). As long as the LAC production within exercising muscles do not exceed the oxidative capacity of the whole system, an equilibrium between blood LAC accumulation and blood LAC elimination leads to a steady state blood LAC concentration which, in humans, usually occurs between approximately 2 and 8 mmol/l (Billat et al., 2003). ...
... Another factor that needs to be considered when interpreting post-exercise LAC concentrations is the sample material that has been used. Plasma LAC concentrations are usually approximately 1.5 times greater than that of whole blood, however, the ratio between plasma and whole blood LAC concentrations depends on the LAC transport activity of the red blood cells and varies greatly between horses (Pösö, 2002;Rainger et al., 1995). Comparisons between whole blood and plasma LAC concentrations are therefore barely possible. ...
... Comparisons between whole blood and plasma LAC concentrations are therefore barely possible. The variable rate of LAC uptake into the red blood cells suggests that whole blood concentrations are more comparable between horses than plasma concentrations (McGowan, 2008;Pösö, 2002). ...
The objective of this retrospective study was to evaluate the physiological demands of cross-country competitions at different levels. Heart rates (HR) and post exercise blood lactate concentrations (LAC) measured between 2010 and 2019 in response to 1,463 cross-country competitions (437 at 2-star, 703 at 3-star, 313 at 4-star and 10 at 5-star level) in 294 horses were analysed. The effect of competition level, mean velocity, height profile, total distance, number of jumping efforts, climate, age, sex, percentage of Thoroughbred blood and performance level on HR, LAC, HR recovery and LAC disappearance rates was evaluated by Linear Mixed Effects Models. Mean HR and LAC significantly increased from 2-star to 4-star level (P<0.001). Each 30 m/min increase in mean velocity was associated with a 3 beats/min increase in HR (P<0.001) and a 41% increase in LAC (P<0.001) and each 30 m increase in cumulative elevation with a 2 beats/min increase in HR (P<0.001) and a 32% increase in LAC (P<0.001). Each 20 m increase in mean distance per jumping effort was associated with a 1 beat/min decrease in HR (P<0.01) and a 13% decrease in LAC (P<0.001). Compared to Warmbloods, horses with 75% Thoroughbred blood had 4 beats/min lower HRs (P<0.05) and 34% lower LAC values (P<0.001). Each 5 years increase in age was associated with a 4 beats/min decrease in HR (P<0.001, only in mares) and an 11% decrease in LAC (P<0.01). The HRs during the first 3 minutes of recovery were higher at warmer and more humid conditions (P<0.05). The rate of LAC disappearance was higher in horses with higher percentages of Thoroughbred blood (P<0.05).
... Sharp increase in the lactate concentration in these two events was associated with metabolic demands of high-intensity effort, predominantly anaerobic. Lactate is considered a valuable substrate, with a significant role in producing energy for the myocardium, non-contracting muscles and even the brain (PÖSÖ, 2002). After the end of physical exertion (the period when O 2 level is low), the lactate produced by the anaerobic metabolism is converted into glucose by the liver. ...
... Finally, the increase in the lactate values is expected after any type of exercise, because all the energy sources are activated (McGOWAN, 2008). However, this increase depends mainly on the intensity and duration of the physical effort (PÖSÖ, 2002). Based on these findings and the results of this study, the lactate values observed after the competition indicated that cavalcade exercise is not physically very demanding of the animals and allowed the organism to metabolize the lactate produced. ...
Acid-base and electrolyte disorders have been described in horses associated during and after exercise. The aim of the present study was to evaluate the effect of cavalcade competition on the acid-base and hydroelectrolytic balance in Mangalarga Marchador horses. For this purpose, 15 geldings, 6.2 ± 1.2 years old and clinically healthy, were distributed into three groups of five animals each. Horses were trained to take part in cavalcade competitions. Animals were submitted to cavalcade along 4km (G4), 8km (G8), and 20km (G20) at mean speeds of 15km h-1, 12km h-1, and 12km h-1, respectively. From each horse, venous blood samples were collected before exercise (T0) and immediately after (T1) cavalcade. Bicarbonate ion (HCO3-), pH, partial pressure of carbon dioxide (pCO2), partial pressure of oxygen (pO2), base excess (BE), hematocrit (Hct), sodium (Na+), potassium (K+), chloride (Cl-) and lactate were determined. The variables pH, pO2 and pCO2 were corrected in function of rectal temperature of each animal. Blood samples were analyzed for acid-base balance, as well as biochemical and electrolyte parameters using an i-STAT analyzer. Significant (P
... During maximal exercise, the plasma lactate concentration increases to over 30 mmol/L 3) . Lactate transport across the sarcolemma is mediated by protonlinked monocarboxylate transporters (MCT1 and MCT4) in mammalian skeletal muscle [4][5][6] . MCT1 facilitates the uptake of lactate into oxidative muscle fibers, whereas MCT4 facilitates the lactate efflux from glycolytic muscle fibers [7][8][9][10] . ...
We examined the muscle glycogen, and muscle and plasma lactate concentrations before and after 1 and 2 min of intensive exercise at 120% VO2max, and examined possible relationships between these indexes and protein levels of monocarboxylate transporters (MCT) in the gluteus medius muscle of Thoroughbred horses. The horses underwent 1 and 2 min of intensive exercise at the speed of 120% maximal oxygen consumption (VO2max) on a treadmill. The plasma lactate concentration increased after 1-min exercise (11.7 ± 0.8 mmol/L) and 2-min exercise (23.1 ± 1.1 mmol/L). The muscle lactate concentration increased after 1-min exercise (17.3 ± 2.1 mmol/kg) and 2-min exercise (23.6 ± 2.0 mmol/kg). While there was no significant difference in lactate accumulation in the plasma between the first minute and the second minute, lactate accumulation in muscle significantly decreased in the second minute compared with the first minute. The muscle glycogen level decreased after both 1- (42%) and 2-min (41%) exercise, but there was no difference between the levels after 1- and 2-min exercise. The muscle lactate concentration after 2-min intensive exercise positively correlated with the protein level of MCT4 (r = 0.78, p < 0.01). These results suggest that glycogen breakdown occurs in the first minute of intensive exercise, and Thoroughbred horses with higher muscle lactate production during exercise are endowed with higher expression of MCT4, that facilitates the efflux of lactate from muscle cells.
