首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 31 毫秒
1.
High intensity exercise is associated with production of energy by both aerobic and anaerobic metabolism. Conditioning by repeated exercise increases the maximal rate of aerobic metabolism, aerobic capacity, of horses, but whether the maximal amount of energy provided by anaerobic metabolism, anaerobic capacity, can be increased by conditioning of horses is unknown. We, therefore, examined the effects of 10 weeks of regular (4-5 days/week) high intensity (92+/-3 % VO2max) exercise on accumulated oxygen deficit of 8 Standardbred horses that had been confined to box stalls for 12 weeks. Exercise conditioning resulted in increases of 17% in VO2max (P<0.001), 11% in the speed at which VO2max was achieved (P = 0.019) and 9% in the speed at 115% of VO2max (P = 0.003). During a high speed exercise test at 115% VO2max, sprint duration was 25% longer (P = 0.047), oxygen demand was 36% greater (P<0.001), oxygen consumption was 38% greater (P<0.001) and accumulated oxygen deficit was 27% higher (P = 0.040) than values before conditioning. VLa4 was 33% higher (P<0.05) after conditioning. There was no effect of conditioning on blood lactate concentration at the speed producing VO2max or at the end of the high speed exercise test. The rate of increase in muscle lactate concentration was greater (P = 0.006) in horses before conditioning. Muscle glycogen concentrations before exercise were 17% higher (P<0.05) after conditioning. Exercise resulted in nearly identical (P = 0.938) reductions in muscle glycogen concentrations before and after conditioning. There was no detectable effect of conditioning on muscle buffering capacity. These results are consistent with a conditioning-induced increase in both aerobic and anaerobic capacity of horses demonstrating that anaerobic capacity of horses can be increased by an appropriate conditioning programme that includes regular, high intensity exercise. Furthermore, increases in anaerobic capacity are not reflected in blood lactate concentrations measured during intense, exhaustive exercise or during recovery from such exercise.  相似文献   

2.
The aim of this study was to investigate the effects of reduced muscle glycogen concentration on some physiological and metabolic responses during moderate intensity treadmill exercise in horses. Six Thoroughbred geldings were randomly allocated to 2 treatments (protocols A and B) or control in a 3 x 3 replicated Latin square design. In protocol A, horses performed low intensity exercise while horses in protocol B performed short bursts of high intensity exercise. Protocol A was designed to induce glycogen depletion mainly of slow twitch muscle fibers while protocol B aimed to deplete mainly fast twitch muscle fibers. Horses in the control group did not undergo exercise prior to the exercise test. Five hours after glycogen depletion, horses performed treadmill exercise at 60% VO2max at a treadmill slope of 10% until fatigue (20-30 min). The induced glycogen depletion prior to exercise had no significant effect on plasma glucose, insulin, or lactate concentrations during the exercise test, and there was no effect on glycogen utilization rate, although respiratory exchange ratios were lower in the glycogen-depleted groups. The VO2, heart rate and central blood temperature did not vary significantly between the protocols A and B and control throughout the exercise test. It was concluded that 20-30% depletion of glycogen concentration in the middle gluteal muscle resulted in a shift towards fat metabolism, but does not significantly affect heart rate, oxygen uptake, or concentrations of plasma glucose and lactate during moderate intensity exercise.  相似文献   

3.
In a crossover study, either a placebo paste or N,N-dimethylglycine was administered orally at a dose rate of 1.2 mg/kg twice daily for five days to six thoroughbred horses, with bodyweights ranging from 424 to 492 kg. Using previously determined regression equations for oxygen uptake (VO2) against speed for each horse, a standardised exercise test was given with speeds equivalent to fixed percentages of the maximum oxygen uptake (VO2max). The test consisted of two minutes at speeds equivalent to approximately 40 per cent and 50 per cent VO2max, and one minute at speeds that produced approximately 60, 70, 80, 90 and 100 per cent VO2max. During the last five seconds of each exercise stage, the values of VO2, carbon dioxide production (VCO2), heart rate, arterial blood and plasma lactate concentrations, arterial blood gases and pH were measured. Before and immediately after the exercise test, muscle biopsies were collected from the middle gluteal muscle to determine the muscle lactate concentrations. The administration of N,N-dimethylglycine produced no significant differences in any of the measured values, and it is concluded that the compound has no beneficial effects on cardiorespiratory function or lactate production in the exercising horse.  相似文献   

4.
The aim of the experiment was to study the relationship between plasma lactate and allantoin accumulation in horses undergoing five exercises differing in intensity and length. Twenty-five adult trotter horses were used (18 males, two castrated, and five females), housed in three training centers. The horses were assigned to five groups: slow trot, over 2000 m (Group 1); slow trot over 1600 m (Group 2); fast trot over 1600 m (Group 3); fast trot over 2000 m (Group 4); fast trot over 2400 m (Group 5). Plasma was obtained from blood sampled at rest, at the end of the bout of exercise and after 15 and 45 minutes from the end of the bout of exercise and analyzed for glucose, lactate, uric acid, free fatty acids (FFA) and allantoin concentrations. Accumulations of plasma lactate and allantoin (mmol/sec) were calculated as difference between end of exercise and rest and between 45 minutes sample and rest, respectively.Ranking the intensity of exercise using the lactate concentrations at the end of exercise, the level of exertion was highest for Group 3 horses and lowest for Group 5 horses (20.9 and 2.8 mmol/l, respectively). At the end of exercise, glucose concentrations were much higher for horses undertaking the more intensive exercise (Groups 3 and 4 compared to Group 2). FFA concentrations were highest at the end of exercise for Groups 2 and 3 and after 15 minutes for Groups 4 and 5. Plasma uric acid and allantoin concentrations peaked 15 and 45 minutes from the end of exercise, respectively, independently of exercise intensity. The relationship between accumulation of plasma allantoin (y, dependent variables) and lactate (x, independent variable) was non-linear: y=0.15−2.61*x+68.3*x2 (r2=0.900; se=0.19). This suggests that allantoin accumulation could be used together with plasma lactate to calibrate the workload to muscle conditions to prevent muscle injury.  相似文献   

5.
OBJECTIVE: To compare effects of low and high intensity warm-up exercise on oxygen consumption (VO2) and carbon dioxide production (VCO2) in horses. ANIMALS: 6 moderately conditioned adult Standard-breds. PROCEDURES: Horses ran for 2 minutes at 115% of maximum oxygen consumption (VO2max), 5 minutes after each of the following periods: no warm-up (NoWU); 10 minutes at 50% of VO2max (LoWU); or 7 minutes at 50% VO2max followed by 45-second intervals at 80, 90, and 100% VO2max (HiWU). Oxygen consumption and VCO2 were measured during exercise, and kinetics of VO2 and VCO2 were calculated. Accumulated O2 deficit was also calculated. RESULTS: For both warm-up trials, the time constant for the rapid exponential increase in VO2 was 30% lower than for NoWU. Similarly, the rate of increase in VCO2 was 23% faster in LoWU and HiWU than in NoWU. Peak values for VO2 achieved during the high-speed test were not significantly different among trials (LoWU, 150.2 +/- 3.2 ml/kg/min; HiWU, 151.2 +/- 4.2 ml/kg/min; NoWU, 145.1 +/- 4.1 ml/kg/min). However, accumulated O2 deficit (ml of O2 equivalents/kg) was significantly lower during LoWU (65.3 +/- 5.1) and HiWU (63.4 +/- 3.9) than during NoWU (82.1 +/- 7.3). CONCLUSIONS AND CLINICAL RELEVANCE: Both the low- and high-intensity warm-up, completed 5 minutes before the start of high-intensity exercise, accelerated the kinetics of VO2 and VCO2 and decreased accumulated O2 deficit during 2 minutes of intense exertion in horses that were moderately conditioned.  相似文献   

6.
To consider the optimal training programme for Thoroughbred horses, we examined the recruitment pattern of muscle fibres including hybrid muscle fibres in well-trained Thoroughbred horses. The horses performed exercise at three different intensities and durations; i.e., 100% VO2max for 4 min, 80% and 60% VO2max for 8 min on a treadmill with 10% incline. Muscle samples were obtained from the middle gluteal muscle before, during (4 min at 80% and 60% VO2max), and after exercise. Four muscle fibre types (types I, IIA, IIA/IIX, and IIX) were immunohistochemically identified, and optical density of periodic acid Schiff staining (OD-PAS) in each fibre type, and the glycogen content of the muscle sample, were determined by quantitative histochemical and biochemical procedures. The changes in OD-PAS showed that the recruitment of all fibre types were identical at the final time stage of each exercise bout, i.e., 4 min running at 100% VO2max, and 8 min running at 80% and 60% VO2max. The changes in OD-PAS of type IIA/IIX fibre were very similar to those of type IIX fibre. The recruitment of these fibres were obviously more facilitated by 4 min running at 100% VO2max than by 4 min running at 80% or 60% VO2max. Short duration with high intensity exercise, such as 4 min running at 100% VO2max or 8 min running at 80% or 60% VO2max, is effective to stimulate type IIX fibre and IIA/IIX fibres that have the fastest speed of contraction.  相似文献   

7.
Lactate kinetics in whole blood of horses was investigated after exercise of differing velocities and duration. The following categories of exercise were used: A: <11 m/second and >180 seconds (n=35), B: >11 m/second and <180 seconds (n=17) and C: <11 m/second and <180 s (n=10). The mean peak lactate concentration determined in horses in category A was 4.49 ± 2.21 mmol/1, in B, 16.32 ± 4.81 mmoVl and in C, 4.58 ± 1.59 mmol/l. While the maximum lactate concentrations in categories A and C were always found immediately after the exercise, the peaks in category B were measured between the first and tenth minute after exercise. Mean lactate concentrations measured at 2-minute intervals after bouts of category-B exercise tended to stabilize 3 to 10 minutes after exercise; however, mean lactate concentrations measured during the intervals before and after the peak value differed significantly. The lactate concentration returned to pre-exercise levels within 20 minutes after exercise bouts of category C, but remained above pre-exercise levels up to 60 minutes after bouts of category-A and -B exercise. It was concluded that, for an evaluation of lactate data after intensive anaerobic exercise, sequential blood sampling at 2-minute intervals for a period of up to 12 minutes after exercise is necessary. Less frequent sampling may be a reason for the often described irreproducibility of lactate concentrations in horses. After aerobic or mild anaerobic exercise, one sample is sufficient, but it has to be taken as soon as possible after exercise.  相似文献   

8.
OBJECTIVES: To determine whether i.v. administration of furosemide (250 mg) to horses before maximal exercise affected maximal oxygen consumption (VO2max), breathing mechanics, or gas exchange during exercise. ANIMALS: 7 healthy, well-conditioned Thoroughbred horses. PROCEDURES: 5 horses initially performed an incremental treadmill exercise test to determine VO2max 4 hours after i.v. administration of furosemide (250 mg i.v.) or placebo (saline [0.9% NaCl] solution). Time to fatigue and distance run were recorded. All 7 horses were then used to determine the effects of furosemide on gas exchange and breathing mechanics at 40, 60, 80, and 100% of VO2max. Horses were weighed immediately before exercise. RESULTS: Furosemide treatment significantly increased mass-specific VO2max (5.3%), but absolute VO2max was not significantly altered. In the 2 parts of the study, body weights were 2.9 and 2.5% higher when horses were given placebo than when they were given furosemide. Time and distance run at speeds > or = 11.0 m/s were significantly greater following furosemide administration. Furosemide treatment had no effect on breathing mechanics or gas exchange. CONCLUSIONS AND CLINICAL RELEVANCE: Previous studies have suggested that prerace administration of furosemide may have a positive effect on performance. Results of this study indicate that this may be attributable, in part, to an increase in mass-specific VO2max but not to improvements in breathing mechanics or gas exchange. Most of the increase in mass-specific VO2max appeared to be attributable to weight loss associated with diuresis induced by furosemide.  相似文献   

9.
Two groups of previously unconditioned young adult horses participated in 6 weeks of gradually increasing exercise on an inclined plane treadmill while receiving a cornoats-hay diet with or without a commercially available dietary yeast culture preparation. Forced treadmill exercise at a workload of 11.98 j/kg/m, equivalent to a workrate of 18.34 j/sec/kg and an estimated ground speed of 5.36 m/sec, began at 5 minutes per day (2.75 Mjoules/500 kg body-weight) and was increased by 5 minutes per week to a maximum of 35 minutes per day (19.25 Mjoules/500 kg) after 6 weeks. Treadmill exercise increased venous plasma lactate concentrations in direct proportion to the duration of an exercise bout, but the increases tended to be smaller after a given amount of work as the horses became conditioned. At the end of 35 minutes of exercise, plasma lactate concentrations averaged 30.08 mg/dl in the supplemented horses and 41.29 mg/dl in the unsupplemented horses (p<.01). Plasma glucose concentrations decreased significantly and triglyceride concentrations increased significantly in both groups as exercise duration exceed 10 minutes. Changes in plasma glucose concentrations were not significantly affected by yeast culture supplementation, while the supplemented horses exhibited somewhat slower rates of increased plasma triglyceride concentrations. During the 35-minute exercise bouts, significantly lower heart rates were recorded in the supplemented horses during the first 5 and the final 10 minutes of the workouts (p<.01), suggesting an enhanced state of athletic fitness. The digestible energy required for work (Mcal/500 kg bodyweight) was calculated to be 0.454 (Mcal/Mjoule) (Mjoules of work/500 kg bodyweight) + 0.024 Mcal/500 kg bodyweight (r2=0.95), with an efficiency of converting dietary DE to work of 53% for both groups of horses. Although the exercise challenges to these horses were not severe, these results suggest that dietary yeast culture supplementation of horses entering into conditioning programs may well enhance athletic training.  相似文献   

10.
OBJECTIVE: To compare exercise-induced immune modulation in young and older horses. ANIMALS: 6 young and 6 aged horses that were vaccinated against equine influenza virus. PROCEDURE: Venous blood samples were collected for immunologic assessment before and immediately after exercise at targeted heart rates and after exercise for determination of plasma lactate and cortisol concentrations. Mononuclear cells were assayed for lymphoproliferative responses and incubated with interleukin-2 (IL-2) to induce lymphokine-activated killer (LAK) cells. Antibodies to equine influenza virus were measured. RESULTS: Older horses had significantly lower proliferative responses to mitogens than younger horses prior to exercise. Exercise caused a significant decrease in lymphoproliferative response of younger horses, but not of older horses. Activity of LAK cells increased slightly with exercise intensity in younger horses. Cortisol concentrations increased in both groups after exercise; younger horses had higher concentrations after exercise at heart rates of 180 and 200 beats/min than those of older horses. Plasma lactate concentrations increased with exercise intensity but there were no differences between older and younger horses. Older horses had lower antibody titers to equine influenza virus than younger horses. Exercise did not affect antibody titers. CONCLUSION: Although lymphoproliferative responses and antibody titers of older horses were less than those of younger horses, older horses were more resistant to exercise-induced changes in immune function, possibly because of lower cortisol concentrations. CLINICAL RELEVANCE: Stress and aging are known to affect immune function. Older horses had reduced immune function, but were more resistant to exercise-induced immune suppression than younger horses.  相似文献   

11.
OBJECTIVE: To evaluate changes in plasma ionized calcium (Ca2+) and parathyroid hormone (PTH) concentrations in horses competing in endurance rides. DESIGN: Longitudinal clinical study. ANIMALS: 28 horses. PROCEDURE: Venous blood samples were obtained from horses before and after racing 80 km. Plasma pH and concentrations of Ca2+, PTH, inorganic phosphorus, albumin, lactate, and magnesium were measured. RESULTS: Overall, a significant decrease in mean (+/- SD) plasma Ca2+ concentration (from 6.44 +/- 0.42 to 5.64 +/- 0.42 mg/dl) and a significant increase in plasma PTH concentration (from 49.9 +/- 30.1 to 148.1 +/- 183.0 pg/ml) were found after exercise. Exercise also resulted in significant increases in plasma inorganic phosphorus, albumin, and lactate concentrations. No changes in plasma magnesium concentration or pH were detected after exercise. Plasma PTH concentration was not increased after exercise in 8 horses; in these horses, plasma PTH concentration decreased from 58.2 +/- 26.3 to 27.4 +/- 22.4 pg/ml, although plasma Ca2+ concentration was also decreased. CONCLUSIONS AND CLINICAL RELEVANCE: Plasma Ca2+ concentration was decreased after racing for 80 km, compared with values obtained before racing. In most horses, an increase in plasma PTH concentration that was commensurate with the decrease in plasma Ca2+ was detected; however, some horses had decreased plasma PTH concentrations.  相似文献   

12.
The purpose of this study was to examine the effects of an external nasal strip (NS), frusemide (FR) and a combination of the 2 treatments (NS + FR) on exercise-induced pulmonary haemorrhage (EIPH) in Thoroughbred horses. It was hypothesised that both the NS and FR would attenuate EIPH as assessed by red blood cell count in bronchoalveolar lavage fluid. In random order, 8 horses completed each of 4 sprint exercise tests on a treadmill: 1) NS; 2) FR (0.5 mg/kg bwt i.v., 4 h pre-exercise); 3) NS + FR; and 4) control (C; no treatment). After a 5 min warm-up (4.5 m/s), horses completed 2 min running at 120% maximum oxygen consumption (VO2max) with the treadmill set at 3 degrees incline. Mean +/- s.d. running speed was 14.2+/-0.2 m/s. In the FR and NS + FR trials, horses carried weight equal to that lost as a result of frusemide administration. During exercise at 120% Vo2max, oxygen consumption (Vo2) and carbon dioxide production (Vco2) were measured at 15 s intervals. Plasma lactate concentration was measured in samples collected before exercise, at the end of the sprint and after 5 min cool-down at the trot. Thirty minutes after the run, bronchoalveolar lavage (BAL) was performed and the red cell count in the fluid quantified. Vo2 and Vco2 were significantly lower in NS and NS + FR trials than in the C and FR trials at the end of the sprint exercise protocol. However, plasma lactate concentrations did not differ among treatments. Compared with the C trial (61.1+/-30.5 x 10(6) red blood cells/ml BAL fluid), pulmonary haemorrhage was significantly (P<0.05) decreased in both the NS (15.9+/-4.0 x 106 RBC/ml) and FR (12.2+/-5.8 x 10(6) RBC/ml) trials. EIPH in the NS + FR trial (7.9+/-1.0 x 10(6) RBC/ml) was further diminished (P<0.05) compared to the NS trial, but not different from the FR trial. We conclude that both the external nasal strip and frusemide attenuate pulmonary haemorrhage in Thoroughbred horses during high-speed sprint exercise. The external nasal strip appears to lower the metabolic cost of supramaximal exertion in horses. Given the purported ergogenic effects of frusemide, the external nasal strip is a valuable alternative for the attenuation of EIPH.  相似文献   

13.
To answer the question of whether horse height, cannon bone circumference, and loin width can be used as indicators of weight-carrying ability in light horses, eight mature horses underwent a submaximal mounted standard exercise test under four conditions: carrying 15, 20, 25, or 30% of their body weight. Heart rate was monitored, plasma lactate concentration was determined in jugular blood samples pre-exercise, immediately post-exercise, and 10 minutes post-exercise, with serum creatine kinase activity determined at the same times as plasma lactate concentrations, with additional samples collected at 24 hours and 48 hours post-exercise. Muscle soreness and muscle tightness scores were determined using a subjective scoring system 24 hours before and 24 hours after exercise. Heart rates remained significantly higher when the horses carried 25 and 30% of their body weight. Plasma lactate concentrations immediately and 10 minutes after exercise differed when horses carried 30% of their body weight compared with 15, 20, and 25% weight carriage. Horses tended to have a greater change in muscle soreness and muscle tightness when carrying 25% of their body weight, and a significant change in soreness and tightness scores was found in horses carrying 30% of their body weight. Loin width and cannon bone circumference were found to be negatively correlated to the changes in muscle soreness and tightness scores. In conclusion, the data suggest that horses with wider loin and thicker cannon bone circumference became less sore when carrying heavier weight loads.  相似文献   

14.
The purpose of this, trial was to determine the effect of hyperkalemic periodic paralysis (HYPP) on exercise tolerance in Quarter Horses. Five HYPP affected and five nonaffected horses were matched for age, size, gender and reproductive status. HYPP status was diagnosed by DNA analysis and potassium chloride challenge testing. Plasma lactate concentration and heart rate were used as indicators of work intensity. Serum potassium concentrations were also monitored. Two exercise experiments were conducted, the first being forty-five minutes of slow, aerobic exercise (hacking) and the other being moderate, partially anaerobic exercise (galloping). Post-exercise the horses were cooled out by randomly assigning them to either forty minutes, of standing still or forty minutes of walking. Heart rates of HYPP affected and unaffected horses were not significantly different during exercise or recovery. Plasma lactate concentrations changed slightly following slow exercise and were significantly higher for HYPP affected horses (P=0.01).At the end of exercise, values were 1.4±0.2 mmol/L and 1.0±0.1 mmol/L for HYPP affected and unaffected horses, respectively. Following moderate exercise, plasma lactate concentrations were much greater, and the difference (P<0.001) between affected and unaffected horses was more marked: immediately following exercise concentrations were 10.6±1.8 and 6.2±1.0 mmol/L in affected and unaffected horses, respectively. The higher post-exercise plasma lactate concentrations in affected horses indicates increased anaerobic muscle metabolism. Serum potassium concentrations rose following exercise and significantly higher values were seen in horses that were walked rather than stood still post-exercise.Hyperkalemic periodic paralysis (HYPP) is a dominant autosomal genetic defect occurring in American Quarter Horses and related breeds. 1–5 The condition is widely geographically distributed and has been estimated to affect 0.4% of all Quarter Horses.6 Signs include sporadic attacks of muscle fasciculation, muscle spasm, sweating and weakness. Oral administration of potassium chloride produces a more severe hyperkalemia in HYPP affected horses and induces clinical attacks.1 Electromyography reveals widespread continuous, spontaneous, muscle contraction.2 Some people believe that HYPP affected horses are suitable for riding7; others have expressed doubts about the safety of this practice and the exercise tolerance of affected horses. HYPP affected horses have an unstable muscle membrane potential causing random muscle fiber contractions,2,8 which could antagonize purposeful movement. This, in combination with increases in extracellular potassium concentration occurring during exercise,9–11 may cause affected horses to stumble or collapse while being ridden, posing a danger to both horse and rider. In HYPP affected people, potassium concentration rises approximately one to two hours after exercise during which time HYPP attacks can occur.9,10 For these reasons, the exercise tolerance of HYPP affected horses and the effects of exercise on spontaneous HYPP attacks deserves investigation.We standardized the exercise test and chose heart rate and plasma lactate concentrations as indicatoors, of exercise tolerance and energy metabolism.12 Heart rate is the major determinant of oxygen delivery to muscle and the rate rises with exercise intensity until it reaches a plateau at high velocities.13,14 Several lines of investigation indicate that plasma lactate concentrations reflect muscle work. Lactate release from resting muscle is minimal but large amounts are released during strenuous exercise.15–17 Lactate release increases with increasing muscle work.16,18 During exercise, muscle oxygen consumption increases until eventually a plateau is reached after which no further increase in oxygen consumption in response to increased work loads is possible.18 At this point the mitochondrial electron chain transport system is operating at its maximal possible rate, energy production can only be supplemented by the use of inefficient anerobic glycolytic metabolism and the muscle starts to release lactate. If the concentrations of plasma lactate are high, the muscles are depending on anaerobic metabolism and are working closer to exhaustion16,18–21The objectives of this experiment were twofold. One was to determine if HYPP adversely affects exercise performance. The second was to study the effects of cooling out, by either standing still or walking, on serum potassium and plasma lactate concentrations.  相似文献   

15.
OBJECTIVE: 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. ANIMAL: 3 horses. PROCEDURE: 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) activities; WBC, plasma protein, lactate, serum electrolyte, and calcium concentrations; PCV; and creatine kinase activity. RESULTS: Detection of plasma endotoxin increased during exercise for horses competing at all distances but occurred more frequently in the 48- and 83-km groups. Plasma lactate concentration was significantly greater when endotoxin was concurrently detected. Endotoxin in plasma was not significantly associated with success of race completion. Plasma TxB2 and PGF1alpha concentrations and serum IL-6 activity significantly increased with exercise. Horses that had an excellent fitness level (as perceived by their owners) had greater decreases in serum antiendotoxin antibody titers during exercise than did horses perceived as less fit. In horses with better finish times, TxB2 and PGF1alpha concentrations were significantly greater and TNFalpha activity was significantly less than that of slower horses. CONCLUSIONS AND CLINICAL RELEVANCE: Endotoxemia developed during endurance racing, but was significantly correlated with increased plasma lactate concentration and not with other variables indicative of endotoxemia. Plasma TxB2 and PGF1alpha concentrations and serum TNFalpha activity may be associated with performance success.  相似文献   

16.
OBJECTIVE: To determine the effects of 3 rations (low grain, fat, high grain) on plasma creatine kinase (CK) activity and lactate concentration in Thoroughbred horses with recurrent exertional rhabdomyolysis (RER). ANIMALS: 5 Thoroughbreds with RER and 3 healthy Thoroughbreds (control horses). PROCEDURES: Rations were formulated to meet (low-grain and fat rations) or exceed (high-grain ration) daily energy requirements. Each ration was fed to horses in a crossover design for 3 weeks. Horses were exercised on a treadmill Monday through Friday; maximum speed on Monday and Friday was 11 m/s (6% slope), on Tuesday and Thursday was 9 m/s, and on Wednesday was 4.5 m/s. Plasma CK activity and lactate concentration were determined before and after exercise. RESULTS: Horses with RER fed the high-grain ration had significantly greater CK activity and change in CK activity 4 hours after exercise, compared with those fed the low-grain ration. Horses with RER exercised at the trot or canter had significantly greater increases in CK activity, compared with those exercised at the gallop. Plasma lactate concentrations after exercise were similar in control and affected horses. Lactate concentration and CK activity were not correlated in horses with RER. CONCLUSIONS AND CLINICAL RELEVANCE: Rations high in grain and formulated to exceed daily energy requirements may increase episodes of rhabdomyolysis in thoroughbred horses susceptible to RER.  相似文献   

17.
Six Standardbred (STB) mares (11+/-2 years, 521+/-77 kg; means+/-SD) performed an exercise trial (EX) where they underwent an incremental exercise test (GXT) as well as a parallel control trial (CON) to test the hypothesis that short-term, high intensity exercise would alter plasma concentrations of glucose, leptin, adiponectin, ghrelin, insulin and cortisol. Plasma samples were taken before (0 min), during (last 10s at 6, 8m/s, and the velocity eliciting VO(2max)), and after exercise (2, 10, 30, 60 min; 12 and 24h post-GXT). A second set of blood samples was collected before and after an afternoon meal given at 1515 h (at 1500, 1514, 1530, and 1545 h). Data were analyzed using ANOVA for repeated measures and Tukey's test. During the GXT, there were no changes (P>0.05) in the plasma concentrations of glucose, leptin, adiponectin or ghrelin. However, there was a 29% increase (P<0.05) in mean plasma cortisol concentration and a 35% decrease (P<0.05) in mean plasma insulin concentration. Substantial increases (P<0.05) in the mean plasma concentrations of glucose and cortisol of 36% and 102%, respectively, were seen in the EX trial during the first 60 min post-GXT. Plasma leptin concentration, measured at the 24h post-GXT time point, was 20% lower (P<0.05) during the EX trial compared with the parallel time point in the standing control (CON) trial. Plasma ghrelin concentration was 37% lower (P<0.05) in the EX trial compared with CON before and after the afternoon meal, but was 43% higher (P<0.05) 12h post-GXT. There were no differences between EX and CON for plasma concentrations of insulin or adiponectin during recovery. It was concluded that short-term high intensity exercise alters plasma leptin and ghrelin concentrations in STB mares post-exercise, which may signal the exercised animals to alter energy intake.  相似文献   

18.
OBJECTIVE: To evaluate plasma epinephrine and norepinephrine concentrations and serum cortisol concentration in horses with colic and assess the relationship of these variables with clinical signs, routinely measured clinicopathologic variables, and outcome in affected horses. DESIGN: Prospective observational study. ANIMALS: 35 horses with colic. PROCEDURE: Blood samples were collected within 30 minutes of arrival at the veterinary hospital from horses referred because of colic. Plasma and serum samples were analyzed for cortisol, epinephrine, norepinephrine, lactate, and electrolyte concentrations and acid-base variables. Heart rate at admission and outcome (survival or nonsurvival) were recorded. Univariate logistic regression was used to calculate crude (unadjusted) odds ratios and 95% confidence intervals. RESULTS: Of the 35 horses with colic, 26 survived. Higher plasma epinephrine, plasma lactate, and serum cortisol concentrations were significantly associated with increased risk of nonsurvival, but plasma norepinephrine concentration was not associated with outcome. Plasma epinephrine concentration was significantly correlated with heart rate (r = 0.68), plasma lactate concentration (r = 0.87), blood pH (r = -0.83), anion gap (r = 0.74), and base excess (r = -0.81). CONCLUSIONS AND CLINICAL RELEVANCE: The risk of death appears to be greater in colic-affected horses with high circulating concentrations of epinephrine and cortisol. The correlation of epinephrine with other biochemical markers of illness severity and with heart rate indicates that the degree of sympathetic activation in horses with colic can be inferred from routinely measured variables.  相似文献   

19.
The effects of single bouts of moderate (30 to 40 per cent VO(2)max) and high (115 per cent VO(2)max) intensity exercise on equine peripheral blood leucocyte function were evaluated by determining neutrophil phagocytosis and oxidative burst activity before and after treadmill exercise and training. Prior to all exercise tests, the possible effect of diurnal variation was evaluated in samples obtained from four resting horses. Subsequently eight horses underwent moderate and high intensity exercise protocols and then commenced a 17-week training period. High intensity exercise tests were repeated in week 10, after 7 weeks of endurance training, and in week 17, after a further 6 weeks of high intensity training. Time of sampling had a significant effect on neutrophil function for resting, untrained horses. Prior to training, moderate intensity exercise was associated with improved neutrophil phagocytosis and oxidative burst activity. High intensity exercise was associated with transient impairment of these responses. A similar reduction was not demonstrable following high intensity exercise in weeks 10 or 17 of training. Neutrophil function in week 17 was suppressed at all sampling times relative to results obtained in week 10, suggesting that high intensity training may have been associated with a general reduction in neutrophil function.  相似文献   

20.
Because exercise fatigue has been associated with the accumulation of lactic acid, factors that influence lactate metabolism during exercise can potentially enhance performance. The objective of this study was to examine the effects of supplemental betaine on eight mature Thoroughbred horses before and after 8 wk of conditioning. The effects of betaine were tested in two cross-over design experiments, allowing each horse to receive both the control and betaine treatments at each fitness level. Ingestion of 80 mg of betaine/kg of BW for 14 d before exercise testing did not alter plasma lactate, glucose, free fatty acids (FFA), or triglyceride concentrations during exercise in the untrained or trained horses. A time x treatment interaction (P < .05) was observed for plasma lactate in untrained horses during recovery from exercise, and plasma lactate concentrations were lower (P < .05) at 60 min after exercise when untrained horses received betaine. Plasma FFA concentrations were lower (P < .05) before exercise and at 720 min after exercise when untrained horses received betaine. These data indicate that betaine may influence lactate metabolism following exercise in untrained horses; however, betaine does not seem beneficial for trained horses.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号