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Topic:Lactate
Lactate is a byproduct of anaerobic metabolism, produced when glucose is broken down for energy in the absence of sufficient oxygen. In horses, lactate levels can increase during intense physical exertion, such as racing or other high-performance activities. Elevated lactate concentrations are often associated with muscle fatigue and can provide insights into a horse's exercise physiology and conditioning status. Monitoring lactate levels can aid in assessing the horse's fitness, recovery, and adaptation to training. This page compiles peer-reviewed research studies and scholarly articles that explore the production, regulation, and implications of lactate in equine exercise physiology and performance.
Reliability of cardiorespiratory measurements with a new ergospirometer during intense treadmill exercise in Thoroughbred horses. This study investigated the reliability of measurements with a new equine ergospirometer (Quadflow). Heart rate and blood lactate responses during exercise in horses wearing the Quadflow and an open flow mask were also compared. The mean percentage error of the oxygen uptake measurements was 8.2% (range 2.1-12.5%). Percent error for peak expiratory flow rates ranged from 6.1% to 9.4 %, and for minute ventilation from 2.5% to 7.4%. The coefficients of variation of the means of four measurements in two horses exercising continuously at 9.0 m/s were <5% for variables related to pulmonary venti...
Whole blood, plasma viscosity, and erythrocyte aggregation as a determining factor of competitiveness in standard bred trotters. In situations where capillary perfusion in skeletal muscles is limited, changes in blood flow play an important role. Especially alterations in intrinsic erythrocyte factors like red cell aggregation and deformability would increase blood flow resistance. In our study we investigated whether whole blood and plasma viscosity influence exercise tolerance during submaximal training and whether a difference can be realized between trained and untrained standardbred trotters. Venous blood from 42 healthy adult trotters (20 horses at the beginning of their training and 22 well trained horses) was in...
Arterial lactate concentration, hospital survival, sepsis and SIRS in critically ill neonatal foals. Blood lactate concentration has been shown to be a useful clinical indicator in human patients, but has not been formally investigated in critically ill foals. Objective: To investigate the association of blood lactate with hospital survival, markers of cardiovascular status, metabolic acid base status, sepsis and systemic inflammatory response syndrome (SIRS). Methods: A database containing clinical, haematological, plasma biochemical and hospital outcome data on neonatal foals referred to an intensive care unit in 2000-2001 was analysed. Seventy-two foals for which arterial lactate was measu...
Comparison of 4 blood storage methods in a protocol for equine pre-operative autologous donation. To compare viability of equine whole blood stored by 4 different methods, and to establish optimal storage protocols for an equine autologous blood donation program. Methods: In vitro study of stored equine whole blood. Animals- Six healthy adult horses. Methods: Blood from each horse was collected into 4 different containers: glass bottles containing acid-citrate-dextrose solution (ACD), plastic bags containing ACD, citrate-phosphate-dextrose (CPD), and CPD with supplemental adenine (CPDA-1). Blood was stored for 5 weeks and sampled at 2-day intervals. Standard hematologic and biochemical var...
Comparison of the effects of fructose and glucose supplementation on metabolic responses in resting and exercising horses. The aim of this study was to compare the effects of two different carbohydrate sources (fructose and glucose) on the metabolic responses in resting and exercising horses. The following regimes were fed in randomized order to five trained horses at rest and immediately before or during exercise. The resting regime comprised 0.6 kg grass meal pellets (control) or 0.6 kg grass meal pellets supplemented with either 50% glucose or 50% fructose. The exercise regime comprised 0.3 kg grass meal (control) or 0.6 kg grass meal pellets supplemented with either 50% glucose or 50% fructose fed immediately ...
Metabolism of MDCK cells during cell growth and influenza virus production in large-scale microcarrier culture. The production of equine influenza in Madin-Darby canine kidney (MDCK) cells in large-scale microcarrier culture is described with detailed on- and off-line analytical data during cell growth and virus replication. Metabolite concentration profiles for glucose, glutamine, lactate and ammonium are shown. Lactate and ammonium concentrations were always below inhibiting levels. Concentration profiles for essential and non-essential amino acids of the cell culture medium are discussed. During cell growth proline was released into the medium with a significant rate while two amino acids, serine and...
Effects on plasma endotoxin and eicosanoid concentrations and serum cytokine activities in horses competing in a 48-, 83-, or 159-km endurance ride under similar terrain and weather conditions. To determine plasma endotoxin concentration in horses competing in a 48-, 83-, or 159-km endurance race and its importance with regard to physical, hematologic, or serum and plasma biochemical variables. Methods: 3 horses. Methods: Weight and rectal temperature measurements and blood samples were obtained before, during, and after exercise. Blood samples were analyzed for plasma endotoxin concentration; serum antiendotoxin antibody titers; thromboxane B2 (TxB2) and 6-keto-prostaglandin F1alpha (PGF1alpha) concentrations; tumor necrosis factor alpha (TNFalpha) and interleukin-6 (IL-6) activitie...
Activities of enzymes in the malate-aspartate shuttle and the isoenzyme pattern of lactate dehydrogenase in plasma and peripheral leukocytes of lactating Holstein cows and riding horses. The activities of the enzymes involved in the malate-aspartate shuttle and lactate dehydrogenase (LDH) and the pattern of the isoenzymes of LDH were determined in plasma and peripheral leukocytes of lactating Holstein cows and thoroughbred riding horses as representative herbivorous animals. In the horse plasma, LDH activities were significantly lower and AST activities were significantly higher than those in the cow plasma. The specific activities of cytosolic malate dehydrogenase (MDH), LDH and AST in the horse leukocytes were higher than those in the cows. The cytosolic ratio of MDH/LDH act...
Effects of novelty stress on neuroendocrine activities and running performance in thoroughbred horses. This study investigated the effects of novelty stress on neuroendocrine activities and running performance in Thoroughbred horses. First, to examine the neuroendocrine responses to novelty stress, we exposed horses to two types of novel environmental stimuli (audiovisual or novel field stimuli). After the stimuli, plasma concentrations of vasopressin, catecholamines and adrenocorticotropin (ACTH), as well as heart rates, were significantly increased in each experiment. Second, we investigated neuroendocrine activities during incremental exercise. Plasma concentrations of vasopressin, catechola...
Calcium homeostasis and intact plasma parathyroid hormone during exercise and training in young Standardbred horses. Physical exercise is known to affect calcium homeostasis in horses, but there is little information on the hormonal regulation of calcium metabolism during exercise. In order to evaluate the effects of exercise and training on calcium homeostasis and intact plasma parathyroid hormone, 7 untrained Standardbred horses were studied in a 6 week training programme. These horses were accustomed to running on the treadmill 3 weeks before onset of training and were exercised on a high-speed treadmill with an initial incremental standardised exercise test (SET 1: 6 incremental steps of 5 min duration e...
Biochemical markers of bone activity in young standardbred horses during different types of exercise and training. Seven untrained Standardbred horses were used in a training programme of 6 weeks to evaluate the effects of exercise and training on bone metabolism. The horses were exercised on a treadmill according to a standardized exercise test (SET 1: six incremental steps, 5 min duration each; start 5 m/s, increase 1 m/s). SET 1 was followed by a training programme of 6 weeks. In alternating order: high-speed exercise (HSE): 15 min duration, start at VLa4, continuous increase in speed every 60 s by 0.3 m/s (14 incremental steps); low-speed exercise (LSE): constant velocity at VLa2.5, duration: approxima...
Physiological measurements and upper and lower respiratory tract evaluation in French Standardbred Trotters during a standardised exercise test on the treadmill. There are a variety of reasons for poor performance in racehorses. Exercise intolerance has often been associated with subclinical respiratory abnormalities, and diagnostic aids are therefore used to enhance clinical detection. Physiological variables can also be measured in order to evaluate the metabolic reponse to exercise. This study evaluated the relationship between physiological measurements and upper airway videoendoscopy during a standardised treadmill exercise test and bronchoalveolar lavage (BAL) cytology in control horses (good racing performance, n = 14) and poor performers (n = 2...
Exercise- and metabolism-associated blood variables in Standardbreds fed either a low- or a high-fat diet. Feeding a high-fat diet increases fat utilisation and may decrease glycogen utilisation resulting in a lower lactate production during moderate exercise. The effects of fat feeding on exercise- and lipid metabolism-associated blood variables were evaluated in 6 Standardbred horses during submaximal exercise. The horses were fed a high- (11.8% fat in total dietary dry matter) or a low-fat diet (1.5% fat) in a cross-over experiment with feeding periods of 4 weeks. At the end of each feeding period, the horses were subjected to a submaximal standardised stepwise exercise test on a treadmill. Bloo...
Metabolic responses to submaximal field exercise tests and relationships with racing performance in pacing Standardbreds. This study was undertaken to invesigate the application of submaximal field tests in assessment of performance. A submaximal field exercise test consisting of 2 bouts of pacing for 1600 m, with 5 min rest or walking between runs was performed on Standardbred racehorses at 2 training centres (A and B). Performance indices were compiled for each horse: number of race starts, number of race wins, number of race placings (1, 2 or 3), and lifetime earnings. Regression analysis was conducted to describe the relationship between plasma lactate concentrations and speed for tests one, 2 and pooled resu...
Speed associated with plasma pH, oxygen content, total protein and urea in an 80 km race. To test the hypothesis that endurance performance may be related quantitatively to changes in blood, we measured selected blood variables then determined their reference ranges and associations with speed during an 80 km race. The plan had 46 horses in a 2 x 2 factorial design testing a potassium-free electrolyte mix and a vitamin supplement. Blood samples were collected before the race, at 21, 37, 56 and 80 km, and 20 min after finishing, for assay of haematocrit, plasma pH, pO2, pCO2, [Na+], [K+], [Ca++], [Mg++], [Cl-], lactate, glucose, urea, cortisol, alpha-tocopherol, ascorbate, creatine ...
Lactate transport in red blood cells by monocarboxylate transporters. The lactate transport activity of red blood cells (RBC) varies widely among different species; in equine RBC, the activity of the main lactate carrier, H+-monocarboxylate co-transporter (MCT), is distributed bimodally. The influence of lactate transport activity is measurable in vivo; after maximal exercise, the RBC lactate concentration in horses with high (HT) lactate transport activity is higher than in those with low (LT) activity. To study the expression of MCT in HT and LT horses, blood samples were taken from 10 horses at rest and after submaximal exercise. Blood and plasma lactate conc...
Effects of prolonged training, overtraining and detraining on skeletal muscle metabolites and enzymes. Thirteen Standardbred horses trained intensively for 34 weeks and detrained for 12 weeks to investigate the effects of training, overtraining and detraining on muscle metabolites, buffering capacity and enzyme activities (CS, HAD and LDH). After a standardised exercise test to fatigue at 10 m/s (approximately 100% VO2max), there was significant depletion of [ATP], [PCr] and muscle [glycogen] and accumulation of muscle and plasma [lactate], [NH3] and elevated muscle temperature. After training, associated with increased run time to fatigue (148%), there was reduced depletion of muscle [glycogen...
Plasma lactate and uric acid responses to racing in pacing Standardbreds and relationships with performance. Relationships between racing performance and plasma lactate and uric acid concentrations after racing were investigated in pacing Standardbred racehorses. The study was undertaken in order to better understand factors that limit racing performance. Twenty horses were tested after races of 1760 m and 28 horses after races over 2160 m. Blood samples were taken 30-60 min before and 8 and 30 min after a race. There were no significant differences between the race distances for prerace and 8 min postrace plasma lactates. Significant low correlations were obtained for plasma lactate concentration 8 ...
A lactate-guided conditioning programme to improve endurance performance. Blood lactate measurements are used widely in horses to assess athletic performance, but there are few published data on using lactate as a guide for endurance improvement. The velocity at which blood lactate concentration ([LA]) of 4 mmol/l is reached (v4) is widely used to determine fitness. In an earlier study of v4, exercise at low intensities for longer duration was more effective at improving endurance than shorter, higher intensities. However, the prescription was unchanged during the study (6 weeks). We hypothesised that, to produce greater improvement in v4 in the same time frame, it ...
Induction of heat shock protein 72 mRNA in skeletal muscle by exercise and training. In response to stress, cells synthesise heat shock proteins (HSP) to maintain protein homeostasis. To study whether exercise and training induce expression of HSP72 in the middle gluteal muscle, 10 Finnhorses performed a submaximal 60 min exercise test on a treadmill. Test A was performed after 3 months of training, and the other two tests 2 (B) and 5 (C) weeks later. Blood samples were taken during and after the tests, and biopsy samples before, immediately after and 23 h after each test. HSP72 mRNA was analysed using a digoxigenin-labelled probe. Blood lactate concentration in the 3 tests va...
Pro- and macroglycogenolysis in skeletal muscle during maximal treadmill exercise. The purpose was to investigate the degradation of proglycogen and macroglycogen in skeletal muscle during intense exercise. Ten Standardbred trotters performed a maximal treadmill exercise test comprising a warm-up period, an exercise period, starting at 7 m/s with increments of 1 m/s every 60 s until the onset of fatigue (mean +/- s.d. 246 +/- 32 s) and a walking recovery period. Muscle biopsies were taken at rest, immediately after exercise and 15 min postexercise. The exercise caused a marked anaerobic metabolism as shown by the decrease in both muscle ATP and creatine phosphate and increas...
Comparison of the metabolic responses of trained Arabians and Thoroughbreds during high- and low-intensity exercise. In order to compare the metabolic responses to exercise in 2 similarly managed breeds of horses, 5 Arabian (AR) and 5 Thoroughbred (TB) horses, fed an identical diet with a similar diet and exercise training programme for the 2 preceding months, undertook 3 treadmill (3 degree incline) trials with a minimum of 7 days between tests: 1) an incremental test (MAX) for determination of aerobic capacity, V(LA4) and lactate threshold (LT; the percentage of VO2max when plasma lactate = 4 mmol/l); 2) a single high-speed exercise test (SPR) at 115% VO2max for estimation of maximal accumulated oxygen def...
Effects of mild forelimb lameness on exercise performance. Mild lameness is considered a performance-limiting problem that may escape detection until it worsens, and is considered the primary reason for reduced racing performance. The kinematics changes associated with a lame horse at the trot have been demonstrated previously, but the metabolic cost of these alterations in their gait have not been demonstrated. Six fit Thoroughbred horses with an established VO2max participated in 4 trials using a randomised cross-over design study, separated by 10-14 days. The horses were tested with one of 4 trial conditions: lead forelimb lameness (LL); off-lead f...
Potassium and lactate uptake by noncontracting tissue during strenuous exercise. Efflux of potassium (K+) and lactate (lac-) from active skeletal muscle during high intensity exercise leads to increased plasma [K+] and [lac-] in venous and arterial blood. The exercise-induced increases in these ions in human athletes is ameliorated, in part, by uptake by noncontracting tissue, reflected by an increase in the arteriovenous difference across these tissues from rest to exercise. To test the hypothesis that these ions are taken up by noncontracting tissue in strenuously exercising horses, plasma [K+] and [lac-] were measured in blood samples collected simultaneously from the c...
Age-related changes and inheritance of lactate transport activity in red blood cells. In red blood cell membranes, the activity of the main lactate carrier, H+-monocarboxylate co-transporter (MCT), varies interindividually and its distribution is bimodal. To show the repeatability of MCT activity, 2 to 5 blood samples were taken, at an interval of approximately 1 year, from 51 Standardbred horses, age 2 weeks-8 years, for a total of 128 observations. The horses could be divided into low (LT) and high (HT) lactate transport activity groups. Age significantly affected (P<0.05) MCT activity such that activity was highest in foals, reached a nadir at 2-3 years, and tended to inc...
Evaluation of the i-STAT hand-held chemical analyser during treadmill and endurance exercise. This study examined the accuracy and precision of a hand-held, chemical analyser, i-STAT, in measuring selected blood constituents which may be of use in the diagnosis and management of metabolic disorders found in exercising horses. Venous blood samples were taken from 3 Thoroughbred geldings, fit and trained to exercise on a treadmill, both before and after exercise at a speed sufficient to elicit VO2max. The samples were analysed both with the i-STAT and with in-house analysers to compare the values of pH, partial pressure of oxygen (PO2), partial pressure of carbon dioxide (PCO2), bicarbon...
Effect of training duration and exercise on blood-borne substrates, plasma lactate and enzyme concentrations in Andalusian, Anglo-Arabian and Arabian breeds. Metabolic responses to exercise differ between Andalusian horses and other breeds, although changes in plasma muscle enzymes have not been reported and most useful information is obtained from animals subjected to different training programmes. The objectives of this study were to 1) describe the changes in plasma enzymes during exercise in different horse breeds in relation to other biochemical parameters (Experiment A) and 2) assess the effect of training duration on these measures (Experiment B). Twenty stallions, 9 Andalusian (AN), 7 Arabian (A) and 4 Anglo-Arabian (AA), age 5-10 years, we...
Effect of molassed sugar beet pulp on nutrient utilisation and metabolic parameters during exercise. The aim of this study was to investigate the effect of partly replacing oats with molassed sugar beet pulp in a traditional hay/oat diet on nutrient utilisation and metabolic parameters in exercising horses. In a change-over experiment, 4 Standardbred geldings were fed a hay and oat-based diet (Oat diet) and a hay and oat-based diet where oats was partially replaced with molassed sugar beet pulp (MSBP diet). Each experimental period was 21 days during which total collection of faeces and urine was made and an exercise test (ET) performed. The crude fat digestibility was lower on the MSBP diet ...
Relationship between markers of blood oxidant status and physiological variables in healthy and heaves-affected horses after exercise. Exercise-induced oxidative stress is investigated as a potential performance-limiting factor in human sports medicine. Therefore, the present study aimed to assess whether physiological variables that change with exercise intensity were correlated with blood oxidant markers in healthy and heaves-affected horses. Seven healthy horses, 8 heaves-affected in remission and 7 heaves-affected in crisis performed a standardised exercise test (SET) of stepwise increasing intensity. Variables monitored during exercise were heart rate (HR), venous plasma lactate (LA), packed cell volume (PCV) and arteria...
Heart rate and blood lactate responses during exercise in preparation for eventing competition. The aim of this study was to investigate the heart rate and blood lactate responses to exercise in event horses in normal training, and to compare them to those encountered in eventing competition. It was hypothesised that the responses during exercise in the course of training for CCI*** events would be significantly different from those of the Cross-Country day. Heart rates and blood lactate concentrations were measured in 13 elite event horses after intense exercise sessions conducted during the late stages of preparation for CCI*** or CCI**** 3-day-event competition. Mean +/- s.d. heart ra...
