bluuebunny/crossref_metadata_2025_split huggingface dataset:
Blood hydrogen ion and lactate concentrations during strenuous exercise in the horse
Authors: KRONFELD D. S. , FERRANTE PAMELA L. , TAYLOR LYNN E. , CUSTALOW S. ELIZABETH 
Published: June 2010

SummaryExceptional findings in horses, such as metabolic alkalosis during exercise and an apparent absence of a distinct lactate threshold, led us to apply Stewart's acid‐base system and to develop a new statistical model for investigating lactate threshold. The lactate threshold was clearly demonstrated by an incremental exercise test using up to 14 steps. Lactate threshold was increased by training and by fat adaptation (prolonged interval training and a 10% corn oil diet). Fat adaptation appears to facilitate the metabolic regulation of glycolysis, sparing glucose and glycogen at work of low intensity, but promoting lactate production when power is needed for high intensity exercise. The blood lactate response to exercise was enhanced by fat adaptation and by oral supplementation of sodium bicarbonate. The synergistic effect of the combination suggested that inclusion of fat may enhance the advantage of a diet with a high cation‐anion balance. The lower CO2production of fat‐adapted horses could be of benefit under hot and humid conditions, especially in horses with reduced pulmonary function.During repeated sprints, central venous [H+] increased (acidosis) but arterial [H+] decreased (alkalosis). These changes were consistent with concurrent changes in venous and arterial PCO2but not [SID]. Arterial PO2remained constant. These findings suggest that increasing ventilation to maintain arterial PO2incidentally reduced PCO2, hence arterial [H+]. In terms of homeostatic priorities, regulation of respiration took precedence over regulation of acid‐base status.
Sweat composition: comparison of collection methods and effects of exercise intensity
Authors: McCUTCHEON LAURA J. , GEOR R. J. , HARE MARTHA J. , KINGSTON JANENE K. , STAEMPFLI H. R. 
Published: June 2010

SummaryThe objectives of this study were to compare sweat collection techniques and determine effect of low and high intensity exercise on the composition and osmolality of equine sweat in exercise trained Thoroughbred horses. Sweat collection sites included the neck and thorax, bilaterally and behind the girth ventrally. Sweat was collected in cotton gauze, either exposed to the air or contained within a plastic pouch, from sealed pouches, with or without application of vaseline to the skin, and as it dripped off the skin behind the girth (free catch). There were differences in the ionic composition of sweat collected by different techniques during and after low (50% V̇O2max) and after high (90% V̇O2max) intensity exercise. These changes were most consistent where collection technique minimised evaporative losses. With regard to collection method, ionic concentrations and osmolality were lowest in samples obtained from sealed pouches without vaseline on the skin. In samples obtained from cotton gauze and by free catch, osmolality, [Na] and [Cl] were significantly increased when compared with sweat collected from sealed pouches. In samples collected from sealed pouches during low intensity exercise, osmolality increased 11%, [Na] and [Cl] increased 26% and 9%, respectively and [K] decreased 14%. Osmolality and the concentrations of these ions did not change during recovery. In contrast, osmolality increased by 12% in the first 5 min following high intensity exercise. After both intensities of exercise, there was a significant decrease in the concentration of protein in sweat collected by all methods. Results indicate that collection technique had a marked effect on composition of sweat as demonstrated by increased osmolality and increased concentrations of Na and Cl in sweat collected in cotton gauze and by free catch.
Weight loss, water loss and cation balance during the endurance test of a 3‐day event
Authors: ANDREWS F. M. , RALSTON SARAH L. , WILLIAMSON LISA H. , MAYKUTH PATRICIA L. , WHITE SUSAN L. , PROVENZA MELANIE 
Published: June 2010

SummaryBodyweights (BW) of 39 horses, competing in a 3‐day event, were measured the evening before the endurance test (BW1), afterphase D(BW2) and the next morning before stadium jumping (BW3). Plasma sodium concentration [Na1] was measured the evening before and afterphase Cof the endurance test [Na2]. Total body water (TBW1) was calculated using the formula (BW1 (kg) × 0.66 l/kg) and water loss (WL) was calculated as [(BW1– BWx) X 0.9]. Cation balance (CB), the exchangeable cation concentration, was calculated using the formula [(TBW1(1) X Na1) ‐ (TBW2(1)] X Na2). The decrease in BW and TBW averaged 17.4 ± 1.0 kg and 15.6 ± 0.8 litres respectively (mean ± s.e.m.) during the endurance test and remained decreased 9.2 ± 1.0 kg (BW) and 8.3 ± 1.0 litres (TBW) for 18 to 24 h after competition. Plasma sodium concentration afterphase Cof the endurance test (141.2 ± 0.3 mmol/l) was greater than resting values (138.8 ± 0.2 mmol/l), resulting in a net decrease in CB (‐1601.1 ± 171.7 mmol). Significant water and electrolyte losses occur in horses competing in the endurance test of a 3‐day event and these fluid losses persist for 18–24 h after this phase of competition.
Effects of sodium bicarbonate on acid‐base status and exercise capacity
Authors: LLOYD D. R. , ROSE R. J. 
Published: June 2010

SummaryThe first experiment examined the effects of 0.5 g/kg bwt and 1.0 g/kg bwt doses of sodium bicarbonate in 2 litres of water, administered by nasogastric tube, on venous blood bicarbonate concentration [HCO3−] in 12 Thoroughbred horses. The mean ± s.e. increase in [HCO3−] was 7.6 ± 0.4 mmol/l after the 0.5 g/kg dose and 10.1 ± 0.3 mmol/l after 1.0 g/kg. In a second experiment, the performance effects of sodium bicarbonate (1.0 g/kg bwt) and associated post exercise venous [HCO3−] were examined in horses given a high speed exercise test. Seven Thoroughbred horses received sodium bicarbonate (1.0 g/kg bwt) and venous [HCO3−] was measured after intense exercise (115% V̇O2max) on a treadmill. Blood bicarbonate concentrations were significantly higher in the treated horses for 3 h after exercise. The administration of sodium bicarbonate did not affect the run time to fatigue. We concluded that sodium bicarbonate (0.5 and 1.0 g/kg bwt) produced significant metabolic alkalosis, which persisted for up to 20 h after bicarbonate administration; and that post race sampling may allow detection of horses that have received sodium bicarbonate.
The long term effects of feeding fat to 2‐year‐old Thoroughbreds in training
Authors: PAGAN J. D. , BURGER I. , JACKSON S. G. 
Published: June 2010

SummaryA study to evaluate the long term effects of feeding a fat supplemented diet during medium intensity, aerobic training was conducted over 7 months using 12, 2‐year‐old Thoroughbreds. The control group (n=6) was fed grass hay and a fortified sweet feed (CON) and the other group (FAT)(n=6) received hay, sweet feed, a supplement pellet and 400 ml of soybean oil that supplied about 12% of the DE intake of the FAT group. After 2, 4 and 7 months, the horses performed 2 standardised exercise tests (SETs) on a high speed treadmill. The first test (STEP) consisted of sequential steps of 800 m at speeds of about 4, 8, 9, 10 and 11 m/s. V200and VLA4increased with training, but were not different between treatment groups. During the last STEP, insulin was higher post feeding in the CON horses. Blood glucose was lower at the end of the STEP in CON horses. The second test (SET30) consisted of 30 min of trotting at about 4 m/s. Cortisol was elevated during exercise in the CON horses during the last SET30. T4was unaffected by diet or exercise. Consuming a fat supplemented diet altered the insulin response after feeding and this may have prevented a fall in blood glucose during strenuous exercise. Feeding a fat supplemented diet to 2‐year‐old. Thoroughbreds during training did not change red or white blood cell numbers or liver function as measured by serum levels of AST, γGT and SDH. Fat supplemented diets can be fed safely for extended periods of time to horses in training.
Glucose infusion increases maximal duration of prolonged treadmill exercise in Standardbred horses
Authors: FARRIS J. W. , HINCHCLIFF K. W. , McKEEVER K. H. , LAMB D. R. 
Published: June 2010

SummaryThe main purpose of this study was to describe the effect of glucose infusion on selected physiological variables and on the duration of treadmill exercise to fatigue. Six, 3–4 year old, clinically normal, Standardbred fillies were used in a randomised and balanced crossover design. The treatments were either an infusion of glucose (an initial bolus followed by an infusion rate adjusted during exercise to maintain glucose at approximately 9.0 mmol/l) or an infusion of a similar volume of normal saline. Saline was also infused during the first 30 min of recovery in both treatments. Treadmill speed and grade were 6.0 m/s and 2°. All horses underwent an exercise and dietary control period for 3 days prior to each treatment. A period of 7–10 days separated the treatments. Treadmill exercise duration was prolonged with glucose (89.8 min ± 15.4 s.e.m.) compared to saline (78.7 ± 12.4 min) (P<0.05). Plasma glucose concentrations were similar at rest and increased (P<0.05) above resting concentrations throughout exercise beginning at 15 min and 35 min for the glucose and saline trials, respectively. By 15 min of exercise, glucose concentrations were 8.72 ± 0.22 and 5.78 ± 0.28 mmol/l (P<0.05) for the glucose and the saline trials, respectively. Changes in haematocrit, plasma lactate, plasma total solids, plasma electrolytes, heart rate, core temperature, body weight and body water loss were similar for both treatments. An explanation for the glucose‐induced prolongation of exercise could be the availability of additional substrate during exercise.
Effect of time of feeding on metabolic response to exercise
Authors: LAWRENCE L. M. , HINTZ H. F. , SODERHOLM L. V. , WILLIAMS JANICE , ROBERTS A. M. 
Published: June 2010

SummaryFour mature horses (3 Standardbreds and 1 Thoroughbred) were used in a 4 × 4 Latin square design experiment to investigate the effect of time of concentrate feeding prior to exercise on the metabolic response to exercise. Horses were fasted overnight and then given no feed (fasted) or 1 kg corn grain 1, 3 or 5 h before exercise. Exercise consisted of a warm‐up (1600 m at 6.0 m/s) and walk (800 m) followed by a high intensity phase (400 m at increasing speed and 1600 m at 11 m/s; 2% grade). During exercise, plasma glucose decreased in horses fed 1 or 3 h before exercise (P<0.05), but increased in horses fasted before exercise (P<0.05). Plasma insulin declined (P<0.05) during exercise in horses fed 1 or 3 h before exercise but did not change in horses that were fasted or fed 5 h before exercise. For all treatments, peak plasma free fatty acids (FFA) occurred during the walk phase and FFA decreased (P<0.05) during the last 2000 m (11 m/s; 2% grade). At the onset of exercise and during much of the exercise test, plasma FFA were highest in horses that were fasted for 16 h before exercise. Plasma lactate increased during the exercise test but was not affected by treatment (P>0.05). These data indicate that time of feeding prior to exercise can affect metabolic responses of horses to exercise, which could ultimately alter performance. In addition, researchers should consider that time of feeding may affect the interpretation of data from experiments examining the effects of diet and/or training on exercising horses.
Influence of nutritional status on metabolic responses to exercise in donkeys
Authors: MUELLER PAMELA J. , RAWSON R. E. , VAN SOEST P. J. , HINTZ H. F. 
Published: June 2010

SummaryThe metabolic consequences of submaximal exercise following long term nutritional deprivation were investigated in 6 donkeys. Animals were fed all roughage diets, either adequate (Timothy hay: H) or deficient in energy and protein (wheat straw: S) in a crossover design. After 8–10 weeks of dietary adaptation, responses to 60 min of moderate intensity draft loading exercise were compared. Jugular blood was sampled at rest and during exercise for glucose, lactate and free fatty acids (FFA) concentrations, haematocrit, Cortisol and insulin levels. Heart rate (HR) was monitored electronically. Resting lactate concentration was higher in animals fed hay (H) than in animals fed straw (S); only in S animals, however, did post exercise lactate concentration (1.55 ± 0.9 mmol/l) exceed pre‐exercise lactate concentration (0.6 ± 0.1 mmol/l). Hypoglycemia occurred in all animals in early exercise but was more pronounced in S animals. Straw‐fed animals had higher FFA concentrations at rest than H animals (mean ± s.e. 433 ± 71 vs. 102 ± 9 μmol/l). Plasma FFA concentrations declined precipitously in S animals at the onset of exercise, thereafter FFA increased over resting concentrations in both diets. Cortisol concentrations were higher at all times in H animals and increased during exercise regardless of diet. Insulin was lower in S animals and decreased during exercise in both diet groups. Resting HR was lower in S than in H animals (mean ± s.e. 34 ± 2 vs. 45 ± 2 beats/min). Exercising HR was greater in S animals. These data suggest that long term undernutrition in donkeys leads to decreased carbohydrate reserves, diminished maximal aerobic capacity and endocrine alterations. Work difficulty and stress level may increase, with possible negative implications for animal health and endurance.
Effects of phenylbutazone and frusemide on urinary excretory responses to high intensity exercise
Authors: II H. C. SCHOTT , RAGLE C. A. , BAYLY W. M. 
Published: June 2010

SummaryTo determine whether phenylbutazone or frusemide administration exacerbates the urinary excretory responses to high intensity exercise, 6 fully conditioned Thoroughbred mares were subjected to treadmill exercise at =120% of the V̇O2maxafter 4 treatments: 1) 4.4 mg/kg phenylbutazone i.v. 24 h prior to exercise (B); 2) 1.0 mg/kg frusemide i.v. 4 h prior to exercise (F); 3) 4.4 mg/kg phenylbutazone i.v. 24 h prior to exercise and 1.0 mg/kg frusemide i.v. 4 h prior to exercise (BF) and 4) placebo at both pre‐exercise times (C). Urine was collected for 4.5 h before exercise, during exercise and for 2 h after exercise.Urine flow (UF) and urinary sodium excretion (UNAex) increased and urine osmolality (Uosm) decreased following frusemide administration (F and BF only). UF decreased (B and C only) during exercise and subsequently increased from a pre‐exercise value of 4.3 ± 0.4 (s.e.) ml/min (n=24) to 8.4 ± 4.1, 15.0 ± 3.6, 10.3 ± 4.2 and 9.5 ± 1.6 ml/min between 25 and 40 min following exercise for B, F, BF and C, respectively. This finding was only significant for F. Similarly, UNAexincreased from a pre‐exercise value of 0.05 ± 0.02 mEq/min (n=24) to 0.53 ± 0.34, 0.68 ± 0.30, 0.61 ± 0.38 and 0.67 ± 0.25 mEq/min between 25 and 40 min following exercise for B, F, BF and C, respectively. This finding was significant for B and F but not for BF or C. Uosmdecreased following exercise in all treatment groups.Considerable within and between treatment variation in the urinary excretory responses to high intensity exercise was observed and precluded finding differences between treatment groups. To investigate this variation further, values for UF and UNAexbetween 25 and 40 min post exercise (period of greatest post exercise diuresis and natriuresis) were compared with peak plasma lactate concentration. Positive linear correlations were found for UF (r=0.65) and for UNAex(r=0.65). Thus, the magnitude of the diuresis and natriuresis which follows high intensity exercise in horses is related, in part, to work effort, as measured by plasma lactate concentration.
Exercise performance indices in normal and anabolic steroid treated trotters
Authors: HYYPPÄ S. , RÄSÄNEN L. A. , PERSSON S. G. B. , PÖSÖ A. REETA 
Published: June 2010

SummarySix adult Finnhorse trotters performed a standardised exercise test (SET) on a treadmill and a 4000 m maximal exercise test (MET) on a racetrack before, immediately and 13 weeks after a 14 week treatment with nandrolone laurate. Six other trotters served as controls. All horses were trained during the whole experiment. Blood lactate concentration, V200 VLa4 and red cell volume (CV) were determined in connection to the SET and blood lactate concentration, heart rate and performance time in the MET. All horses significantly improved their performance in the MET, but no differences were observed between the 2 groups. Nandrolone treatment caused a significant (P<0.05) increase in the CV and in the percentage of the oxidative type IIA fibres in the middle gluteal muscle. During the experiment V200 and VLa4 did not change (P>0.05) in either of the groups. The results indicate that CV was the only variable that predicted performance during the last 1000 m of the maximal test, whereas indicators of aerobic capacity, like V200 and VLa4, were of minor value. In the control group, the increase in the blood lactate concentration in the SET correlated positively with the total performance time (r=635; P<0.01) and the time of the last 1000 m (r=0.727; P<0.001) in the MET, but no correlation was found in the nandrolone group. The differences between the control and nandrolone groups suggest that both aerobic and anaerobic energy production in muscle are affected by nandrolone treatment.
Effect of dexamethasone on serum osteocalcin and metacarpal mineral content in horses
Authors: GEOR R. , WALSER MARY , KLASSEN JOAN , PIELA SUZANNE , KING VICKY , MURPHY M. 
Published: June 2010

SummaryThe objectives of this study were to determine the effect of 1) dexamethasone (DEX) on serum osteocalcin concentration (OC) in untrained and trained horses and 2) DEX, administered weekly, on serum OC and metacarpal bone mineral content in horses during training. Inexperiment 1, the baseline concentrations of OC and endogenous Cortisol (COR) were determined every 2 h during a 24 h period. Inexperiment 2, DEX (0.2 mg/kg bwt i.v.) was administered before and after 6 weeks of exercise training. Inexperiment 3, horses received either 0.2 mg/kg bwt i.v. DEX (n=5) or saline (n=5) i.v. on a weekly basis for 8 weeks, with the horses exercising 5 times per week. Metacarpal mineral content was measured weekly on each forelimb by photon absorptiometry. Inexperiment 1, serum COR concentration fluctuated between mean (± s.e.) 82 ± 4 (0800 h) and 22 ± 2 (2000 h) ng/ml, but significant variations in serum OC were not detected. Inexperiment 2, serum OC was decreased between 6 and 36 h after DEX treatment both pre‐ and post training. Inexperiment 3, serum OC was not different at any sampling time during any 7 day period after saline administration. In contrast, each week after DEX, serum OC was decreased between 6 and 48 h. However, differences in serum OC (P=0.055) and bone mineral content (P=0.055) between treatment and control groups were not detected over the 8‐week period. It was concluded that dexamethasone administered weekly to horses in exercise training altered the pattern of serum osteocalcin, but there was no change in metacarpal bone mineral content.
Urinary Cortisol excretion in the resting and exercising horse
Authors: TOUTAIN P. L. , LASSOURD V. , POPOT M. A. , LAROUTE V. , ALVINERIE M. , BONNAIRE Y. 
Published: June 2010

SummaryThe aim of this study was to document the 24 h urinary Cortisol concentrations during a rest day and a day that included prolonged exercise. The influence of exercise on disposition (plasma, urine) of a dose of Cortisol (1 mg/kg) was also assessed. Six adult saddle horses were used. In one experiment, urinary Cortisol elimination rates were measured during rest and prolonged exercise (56 km, 12 km/h) corresponding to about 50% of the V̇O2max. In another experiment, horses received, according to a crossover design, an intravenous (i.v.) bolus administration of Cortisol (1 mg/kg) either at rest or during the same prolonged exercise.The urine Cortisol concentration was lower than 100 ng/ml in the control resting horse. It was increased by exercise but the maximal concentration was lower than 300 ng/ml and returned to control values by 10 h after the end of exercise. After 1 mg/kg Cortisol i.v. Cortisol clearance was decreased by exercise (552 ± 143 vs. 452 ± 59 ml/kg/h, mean ± s.d.), but the difference was not significant The peaks of urinary Cortisol ranged from 760 to 21,967 ng/ml and occurred 0.8 to 6.9 h after Cortisol administration depending on the time of the first urination after administration. The return to values below 100 ng/ml was observed after 21 h in all horses. The 1000 ng/ml threshold for Cortisol control in urine after i.v. Cortisol (1 mg/kg) is specific (conservative) but of low sensitivity.
Heart rate and lactate concentration during two different cross country events
Authors: WHITE SUSAN L. , WILLIAMSON LISA H. , MAYKUTH PATRICIA , COLE S. , ANDREWS F. 
Published: June 2010

SummaryThe exercise intensity of horses competing in the cross country phase of an advanced horse trial (Group 1; n=17) and an advanced 3‐day combined training event (Group 2; n=7) over a similar course on the same day was investigated. Environmental conditions during the trial were cool. Heart rates were continuously recorded at 5 s intervals by a heart rate monitor. Mean ± s.d. heart rates for Group 1 and Group 2 were 167.7 ± 24.0 beats/min and 171.4 ± 19.2 beats/min, respectively, (P>0.05). Plasma lactate concentrations were determined at rest, within 60 s post exercise and 10 min post exercise. Mean lactate concentrations were highest immediately post exercise (Group 1=15.18 ± 5.79 mmol/l; Group 2=19.10 ± 4.22 mmol/l) and had declined significantly in 10 min (Group 1=11.15 ± 6.56 mmol/l; Group 2=16.06 ± 6.11 mmol/l). Lactate concentrations were not significantly different between groups at each time period. We concluded that the work effort for the cross country phase was not different between advanced horse trial and 3‐day competitions for horses competing under similar conditions during non stressful environmental conditions.