bluuebunny/crossref_metadata_2025_split huggingface dataset:
Plasma lactate and uric acid responses to racing in pacing Standardbreds and relationships with performance
Authors: EVANS D. L. , PRIDDLE T. L. , DAVIE A. J. 
Published: June 2010

SummaryRelationships 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 min postrace and the number of race wins (r = 0.29, P = 0.04), number of race placings (1st, 2nd or 3rd; r = 0.34, P = 0.02) and lifetime earnings (r = 0.29, P = 0.04). Net lactate was correlated with the number of race placings (r = 0.31, P = 0.03). There were no significant correlations between performance indices and plasma uric acid concentrations in races of 1760 m. For races over 2160 m, correlations were found between plasma uric acid concentration at 8 min postrace and the number of race wins (r = 0.37, P = 0.06, 95% confidence limits 0‐0.65). As well, there was a significant correlation between uric acid concentration at 8 min postrace and lifetime earnings (r = 0.35, P = 0.07, 95% confidence limits 0.06‐0.64). Only 10–15% of the variability in retrospective career performance in pacing Standardbreds can be explained by these metabolic markers of the muscle anaerobic response to racing. Plasma lactate and uric acid responses to maximal exercise are unlikely to be useful for evaluating racing performance in pacing Standardbreds in univariate analysis.
Effect of frusemide on bodyweight loss and recovery in racing Standardbreds
Authors: COLEMAN R. J. , ST LAWRENCE A. C. , LAWRENCE L. M. , ROBERTS A. M. 
Published: June 2010

SummaryThis study was conducted to compare bodyweight (bwt) loss and recovery in Standardbred horses receiving frusemide compared to controls. Thirty Standardbred horses from 7 training stables that were racing at the Red Mile in Lexington, Kentucky, during the spring 2001 pari‐mutuel meeting were studied. Fourteen horses (FRU) received frusemide (250 mg/horse i.v.) 4 h prior to racing, while 16 horses (NFRU) did not received frusemide. Horses were weighed on the morning of race day, prior to warm‐up, after racing and the next day. Changes in bwt were calculated as percentage increase or decrease from initial bwt. Prior to warm‐up, FRU horses had a mean bwt reduction of 1.30 ± 0.63%, (P<0.01), compared to a 0.19 ± 0.63% increase for the NFRU horses. FRU horses had a greater (P<0.03) postrace bwt loss (3.55 ± 0.55%) than the NFRU horses (2.71 ± 0.66%). On the morning after racing, bwt was still below initial values by 0.90 ± 0.55 and 1.24 ± 0.35% for the FRU and the NFRU horses, respectively. While frusemide administration increased the postrace weight loss in racing Standardbreds, it did not affect short‐term bwt recovery. Further research is required into management strategies required to allow horses to replenish fluids and electrolytes safely following strenuous exercise.
Effects of weight carrying, exercise and a myo‐anabolic supplement on growth and muscle
Authors: O'CONNOR C. I. , NIELSEN B. D. , SCHOTT H. C. , CLAYTON H. M. 
Published: June 2010

SummaryWeight training is commonly used by human athletes to increase strength and fitness. This study was performed to examine the effect of weight‐carrying and nutritional supplementation on muscle development and growth in yourn horses. This study examined the effect of weight‐carrying and nutritional supplementation on muscle development and growth. Seventeen horses were divided into 3 groups: controls exercised in a free‐flow exercise, a weight group that performed the same exercise, carrying progressively increasing weight up to 45 kg, and a weight‐supplement group, that also received a myo‐anabolic supplement. Horses were accustomed to handling for 30 days then baseline measurements of weight, body condition score, wither height, hip height, forearm and gaskin circumferences, and cross‐sectional area of the longissimus dorsi were taken. Horses were stalled for 108 days then conditioned for 78 days. At the end of conditioning, all measurements were taken again. Supplemented weight‐carrying horses increased their lean body tissue, as indicated by greater bodyweight (P<0.05) combined with decreased body condition score (P<0.01). Greater increases in wither height (P = 0.09) and hip height (P<0.01) were seen in weight‐carrying horses, probably the result of increased muscle tone. Supplemented weight‐carrying horses increased forearm (P<0.01) and gaskin circumferences (P<0.05). It is believed that weight‐carrying, when combined with additional dietary protein, enabled greater muscle anabolism. Additional research into the potential additive effect of resistance training and diet are warrented.
Changes in skeletal muscle GLUT4 content and muscle membrane glucose transport following 6 weeks of exercise training
Authors: McCUTCHEON L. J. , GEOR R. J. , HINCHCLIFF K. W. 
Published: June 2010

SummaryThis study examined changes in skeletal muscle GLUT4 content glucose transport in isolated muscle membranes (GT) from horses before and 2 min after standardised submaximal exercise tests (SET) prior to and after completion of 6 weeks of training. Seven horses, age 3–9 years, body mass mean ± s.e. 530 ± 19 kg, and sedentary for at least 4 months, completed 6 weeks of training on a treadmill. An initial SET (UT) was performed on a 4° incline at a speed equivalent to 55% of pretraining V̇02maxand was repeated post‐training at the same absolute workload (ABS). A third SET (REL) was performed at 55% of post‐training V̇02max.There was no significant pre‐ to postexercise change in GLUT4 content before or after training. Following training, total GLUT4 content was increased 2‐ or 3‐fold in pre‐exercise biopsies (pre UT: 0.30 ± 0.05; pre ABS: 1.05 ± 0.32; pre REL: 1.34 ± 0.28 arbitrary units) (P<0.05) with similar increases in postexercise GLUT4 content (P<0.05) (post UT: 0.33 ± 0.06; post ABS: 1.19 ± 0.44; post REL: 1.43 ± 0.31). GT increased 2.5‐ to 6‐fold in postexercise muscle membrane vesicles in UT over a range of glucose concentrations. After training (ABS and REL), there was a 25–50% attenuation (P<0.05) in membrane GT in response to exercise in ABS and REL. These finding indicate that moderate intensity exercise training increased middle gluteal muscle GLUT4 content, but this change was not reflected in an increase in muscle membrane glucose transport activity in postexercise muscle samples.
Pro‐ and macroglycogenolysis in skeletal muscle during maximal treadmill exercise
Authors: BRÖJER J. , JONASSON R. , SCHUBACK K. , ESSÉN‐GUSTAVSSON B. 
Published: June 2010

SummaryThe 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 increase in muscle lactate. Free muscle glucose increased immediately postexercise and a further increase was noted 15 min later. There was a significant decrease (P<0.05) in proglycogen (57.1 ± 22.2 mmol/kg dw) and macroglycogen (63.0 ± 65.5 mmol/kg dw) during exercise. The proglycogen concentration tended to increase 15 min after exercise (19.9 ± 27.3 mmol/kg dw; P= 0.06). The results from this study demonstrate that both proglycogen and macroglycogen contribute equally to glycogenolysis during intense exercise and suggest that glycogen resynthesis starts in the proglycogen pool.
Inhibition of articular cartilage degradation by glucosamine‐HCl and chondroitin sulphate
Authors: ORTH M. W. , PETERS T. L. , HAWKINS J. N. 
Published: June 2010

SummaryGlucosamine and chondroitin sulphate in many animal and human trials has improved joint health.In vitrostudies are beginning to clarify their mode of action. The objective of this research was to: 1) determine at what concentrations glucosamine‐HCl (GLN) and/or chondroitin sulphate (CS) would inhibit the cytokine‐induced catabolic response in equine articular cartilage explants and 2) to determine if a combination of the 2 was more effective at inhibiting the catabolic response than the individual compounds. Articular cartilage was obtained from carpal joints of horses (age 1–4 years). Cartilage discs (3.5 mm) were biopsied and cultured. Explants were incubated with lipopolysaccharide (LPS) in the presence of varying concentrations of GLN, CS, or both. Control treatments included explants with no LPS and LPS without GLN or CS. Media were analysed for nitric oxide (NO), prostaglandin E2(PGE2) and keratan sulphate. Cartilage was extracted for analysis of metalloproteinases (MMP). Four experiments were conducted. In all experiments, GLN at concentrations as low as 1 mg/ml decreased NO production relative to LPS stimulated cartilage without GLN over the 4 day period. In general, CS at either 0.25 or 0.5 mg/ml did not inhibit NO production. The addition of CS to GLN containing media did not further inhibit NO production. GLN at concentrations as low as 0.5 mg/ml decreased PGE2production, whereas CS did not effect on PGE2. The combination of GLN/CS decreased MMP‐9 gelatinolytic activity but had no effect on MMP‐2 activity. The combination in 2 experiments tended to decrease MMP‐13 protein concentrations and decreased keratan sulphate levels in media. Overall, the combination of GLN (1 mg/ml) and CS (0.25 mg/ml) inhibited the synthesis of several mediators of cartilage degradation. These results further support the effort to understand the role of GLN and CS in preserving articular cartilage in athletic horses.
Forelimb skeletal scintigraphy responses in previously untrained Thoroughbreds undergoing initial treadmill training
Authors: FOREMAN J. H. , KNELLER S. K. , TWARDOCK A. R. , CHAMBERS M. D. , INOUE O. J. 
Published: June 2010

SummaryScintigraphy has been used in numerous clinical settings to examine horses to determine the origin of lameness problems, but it has not been used previously to monitor prospectively the skeletal responses of a group of similarly‐trained racehorses. Our hypothesis was that in naive Thoroughbred (TB) racehorses, initial treadmill training induces increased radiopharmaceutical uptake in high‐motion joints and in the dorsal third metacarpal bone (MC3). Eight previously‐untrained TB racehorses underwent sequential skeletal scintigraphic examinations as they exercised daily for 9 weeks on an inclined treadmill. At the end of Weeks 0 (pre‐training), 3 (trotting at 4.2 m/s and initial galloping), 6 (galloping at 7.5 m/s), and 9 (sprinting 600 m at 12.5 m/s), horses received 140 mCi 99m Technetium‐methylene diphosphonate i.v. followed by a standard skeletal scintigraphic forelimb examination 2 h later. Views were graded for increased radiopharmaceutical uptake by 3 co‐investigators who were blinded to horse identification, breed, sex, date, and clinical findings. Results were compared before and after training for each skeletal location using the Mann‐Whitney Rank Sum Test with the level of significance set at P<0.05. Initial treadmill training resulted in increased radiopharmaceutical uptake in the carpus (P = 0.031), metacarpophalangeal joint (P = 0.021), proximal phalanx (P = 0.035), and distal phalanx (P = 0.003). Training did not affect dorsal MC3 radiopharmaceutical uptake (P>0.05).
Effect of training duration and exercise on blood‐borne substrates, plasma lactate and enzyme concentrations in Andalusian, Anglo‐Arabian and Arabian breeds
Authors: MUÑOZ A. , RIBER C. , SANTISTEBAN R. , LUCAS R. G. , CASTEJÓN F. M. 
Published: June 2010

SummaryMetabolic 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, were studied. They performed 3 exercise tests (ET), consisting of a warm‐up of 800 m at 0.7 km/h and 4 workloads at 15, 20, 25 and 30 km/h, at respective distances of 1250, 1670, 2080 and 2500 m, with 5 min active recovery between each workload (Experiment A). Three ETs were performed at the beginning and after 2 and 6 months of training (Experiment B). Venous blood samples were collected during the ETs and plasma glucose (GLU), free fatty acids (FFA), lactate (LA), creatine kinase (CK), lactate dehydrogenase (LDH), α‐hydroxybutyrate dehydrogenase (HBHD), aspartate aminotransferase (AST), Na+, K+ and Cl− were measured.AN horses responded to exercise with greater increases in GLU, HBHD, LDH, CK and AST compared to the other breeds. An unexpected result in Experiment A was the lack of interbreed differences in plasma peak LA concentrations, since it is commonly accepted that AA and A horses have greater athletic potential. Although the glycolytic response to exercise was reduced after 2 months of training in the AA and A horses, and after 6 months of training in the AN horses, at the end of Experiment B, AN horses produced more lactate than the other 2 breeds. Most of the adaptations linked to training were found in the AN breed. The more striking changes in plasma enzyme activities corresponded to CK in AN horses after 2 months of training. The attenuation of CK response to exercise was related to lower extrafibrilar GLU utilisation with LA formation and greater fat metabolism. The results show that plasma muscle enzyme concentrations for the diagnosis of equine myopathies must be interpreted in relation to breed and training.
Effects of prolonged training, overtraining and detraining on skeletal muscle metabolites and enzymes
Authors: McGOWAN C. M. , GOLLAND L. C. , EVANS D. L. , HODGSON D. R. , ROSE R. J. 
Published: June 2010

SummaryThirteen 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% V̇O2max), 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] and increased [NH3] and muscle temperature at fatigue. Training resulted in increased muscle buffering capacity (19%) and activities of CS (29%) and HAD (32%) and reduced glycogen utilisation (1.32 mmol/s in week 1 to 0.58 mmol/s in week 32). Plasma [lactate] at fatigue increased with training as opposed to muscle [lactate] implying enhanced ability to remove lactate from muscle. Overtraining resulted in reduced run time and associated effects in overtrained horses. While muscle [glycogen] prior to exercise was lower in overtrained horses, glycogen utilisation/s was not reduced and it may not, therefore, have caused the reduced run time. Prolonged high intensity training caused primarily aerobic adaptations and poor performance associated with overtraining may not be due to metabolic disturbances.
Oral L‐carnitine combined with training promotes changes in skeletal muscle
Authors: RIVERO J. ‐L. L. , SPORLEDER H. ‐P. , QUIROZ‐ROTHE E. , VERVUERT I. , COENEN M. , HARMEYER J. 
Published: June 2010

SummaryThe purpose of this study was to determine whether oral L‐carnitine supplementation enhances the responses of skeletal muscle to training in seven 2‐year‐old Standardbreds. Four horses were supplemented with 10 g/day L‐carnitine for 10 weeks and 3 horses served as controls. All horses were exercised regularly every second day on a treadmill for 5 weeks (training period) and housed in individual boxes for 5 additional weeks (detraining period). The training period consisted of 8 high‐ and 8 low‐speed exercises carried out in alternating sequence. Gluteus medius muscle biopsies were taken at Weeks 0 (pretraining), 5 (post‐training) and 10 (detraining). Muscular adaptations to training were observed mainly in the L‐carnitine‐supplemented horses and included an increase in the percentage of type IIA fibres (δ35%, P<0.05), atrophy of type I fibres (δ24%, P<0.01), a rise in the capillary‐to‐fibre ratio (δ40%, P<0.01) and an increase in the quantitative reaction of periodic acid Schiff stain (δ11%, P<0.05), used as an indicator of intrafibre glycogen content. After detraining, most of these adaptations reverted towards the pretraining situation. Therefore, exogenous carnitine has an additive effect on muscular responses to training and this should be favourable to improve athletic performance. Nevertheless, further studies are necessary to show whether muscle carnitine content is a limiting factor for fatty acid oxidation.
Training‐induced apoptosis in skeletal muscle
Authors: BOFFI F. M. , CITTAR J. , BALSKUS G. , MURIEL M. , DESMARAS E. 
Published: June 2010

SummaryApoptosis or programmed cell death is a genetically controlled response of cells to commit suicide and is associated with DNA fragmentation or laddering. The common inducers of apoptosis include Ca2+i and oxygen free radicals/oxidative stress, which are also implicated in the pathogenesis of exercise‐induced myopathies. To examine training‐induced apoptosis, Thoroughbred horses were subjected to 3 months training programme on a treadmill. At the end of the training programme venous blood samples were taken for a creatine kinase (CK) assay. In addition, muscle biopsy samples were obtained for a membrane lipid peroxidation measurement by malondialdehyde (MDA) assay and for apoptosis detection. Apoptosis was studied by visualising the apoptotic myocytes on the paraffin sections by the modified TUNEL method. DNA laddering was evaluated by subjecting the DNA obtained from the biopsies to 1.5% agarose gel electrophoresis. There was a significant increase (P<0.05) of protein‐bound MDA, and a nonsignificant trend (P = 0.14) for the control group to have higher levels of CK compared to the trained group. Under light microscopy, percentage of the TUNEL positive cells was higher (P<0.001) in the training group. This result was corroborated with the findings of DNA fragmentation by gel electrophoresis, which showed higher ladders of DNA band at the same group. In conclusion, these results clearly demonstrate that there is training‐induced apoptosis in skeletal muscle. It is probable that apoptosis allows the work/recovery/rebound/supercompensation cycle, when unaccustomed muscle cells activate programmed cell death and are replaced by new and stronger cells, which is the mechanism for training‐induced increases in fitness.
Plasma carnosine concentration: diurnal variation and effects of age, exercise and muscle damage
Authors: DUNNETT M. , HARRIS R. C. , DUNNETT C. E. , HARRIS P. A. 
Published: June 2010

SummaryThis study was undertaken as part of a larger investigation into carnosine metabolism and function in the Thoroughbred horse. More specifically, we wished to evaluate plasma carnosine concentration as a potential indicator of muscle carnosine status. In contrast to man, carnosine is present in equine plasma where its presence is consistent with the absence of plasma carnosinase. A significant effect of age on plasma carnosine concentration in resting Thoroughbred horses was observed. Values in horses age 3 years and older were 11.3–14.1 μmol/***l, whereas concentrations in foals and yearlings were 3.9‐8.7 μmol/l (P<0.001). Lower values in young horses may reflect lower skeletal muscle carnosine concentrations. There was no significant within‐day variation in plasma carnosine concentration in fed and fasted horses (P>0.05). Intense exercise resulted in a small significant increase (P<0.05) in plasma carnosine concentration (pre‐exercise, 10.3 ± 1.0 μmol/l; postexercise, 12.4 ± 4.4 μmol/l). Greater increases were observed (57.6–702.3 μmol/l) following onset of exercise‐induced rhadomyolysis (ERS). An apparent relationship was observed between elevated plasma carnosine and increased plasma creatine kinase (CK) and aspartate transaminase (AST) activities. Plasma carnosine concentrations did not reflect the severity of the condition as determined by clinical examination. In conclusion, elevated plasma carnosine levels are observed following exercise induced muscle damage, with the greatest elevations occurring during episodes of external rhabdomylosis syndrome. Plasma carnosine measurements could provide an alternative clinical indicator of muscle damage; and in conjunction with plasma taurine measurements may be indicative of selective type 1 or type 2 muscle fibre damage. However, given the complexity of the analytical technique, its applications would probably be confined to specialist referral or research centres.
Effects of trotting speed on muscle activity and kinematics in saddlehorses
Authors: ROBERT C. , VALETTE J. ‐P. , POURCELOT P. , AUDIGIÉ F. , DENOIX J. ‐M. 
Published: June 2010

SummaryA thorough knowledge of the horse's back and limb movements at different speeds is important in the design of training programmes and the prevention of speed‐related injuries. The objective of this study was to investigate changes in muscle activity and kinematics of the trot with increased speed. To evaluate these effects, 4 Saddlehorses were recorded while trotting on a horizontal treadmill at speeds ranging from 3.5–6.0 m/s. The 3‐D trajectories of skin markers on the left side of the horse and the dorsal midline of the trunk were established. Electrical activity was obtained simultaneously from 6 muscles using surface electrodes. Ten consecutive strides were analysed for each horse at each of the 5 velocity steps.The increase in speed resulted in a decrease in stride and stance phase duration, increased muscle activity and range of motion of the limbs, but a decrease in back movements. During the stance phase, the limbs appeared more loaded, which resulted in more flexion of the joints and higher excentric muscle activity. During the swing phase, the higher concentric activity of the muscles was responsible for an increased shortening of the limbs.Understanding the effects of speed on equine locomotion is a prerequisite for the development of training programmes.