bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of substituting starch with fat on the acid‐base and mineral status of female horses
Authors: ZEYNER A. , KIRBACH H. , FÜRLL M. 
Published: June 2010

SummaryFeeding a high‐fat diet may have potential advantages by maintaining pH homeostasis during intense exercise; conversely, effects including elevated PCV and increased plasma concentration of total protein may indicate effects detrimental to performance by reducing perfusion of tissues and organs. Six horses were used to determine the effects of an replacement of starch (diet ‘0.00’) with 0.33, 0.67, 1.00 and 1.33 g soybean oil/kg bwt/day (diets ‘0.33’, ‘0.67’, ‘1.00’ and ‘1.33’) on venous and renal acid‐base status and fractional clearance (FC) of electrolytes in a postprandial state but prior to exercise. Venous blood and urine were sampled for 3 days at the end of the 28 day periods, in each case 3 h postprandially. Throughout the study, the horses put on weight by 35 kg (P<0.05). From diet ‘0.00’ to ‘0.67’, blood pH decreased (P<0.05) and carbon dioxide tension increased (P<0.05). Simultaneously, the base and net acid‐base concentration in the urine rose (P<0.05) but diuresis decreased (P<0.05) and, therefore, the daily excretion of bases and net acid‐bases was only unsystematically affected. From diet ‘0.00’ to ‘1.33’, the FC of magnesium and chloride fell (P<0.05). These results suggested that the exchange of starch with up to moderate amounts of fat affects the venous and renal acid‐base status of resting horses. The decrease in urine volume is most striking. Further research is needed to investigate the importance of these effects for sporting performance.
Effects of ageing and training on maximal heart rate and V̇O2max
Authors: BETROS C. L. , MCKEEVER K. H. , KEARNS C. F. , MALINOWSKI K. 
Published: June 2010

SummaryThe purpose of this study was to test the hypotheses that ageing would result in a decline in maximal heart rate (HRmax) and maximal aerobic capacity (V̇O2max) and, secondarily, that those effects would be reversible with training. Eighteen, healthy, unfit Standardbred mares representing 3 age groups: young (Y = mean ± s.e. 6.8 ± 0.4 years, n = 6); middle‐aged (MA = 15.2 ± 0.4 years, n = 6); and old (O = 27.0 ± 0.2 years, n = 6) were used. HRmax, V̇O2maxand oxygen pulse at V̇O2max(OPmax) and the velocities producing HRmax(V̇HRmax) and V̇O2max(VV̇O2max) were measured during pretraining and post‐training incremental exercise tests (GXT). During training, mares exercised 3 days/week (Weeks 1–8) and 4 days/week (Weeks 9–12) at a submaximal intensity (∼60% HRmax) for ∼30 min/day. There were no differences (P>0.05) between Y and MA, before (218 ± 2 vs. 213 ± 3 beats/min; 116 ± 3 vs. 109 ± 3 ml/kg bwt/min; 0.55 ± 0.01 vs. 0.52 ± 0.02 ml/kg/beat; 9.0 ± 0.3 vs. 9.3 ± 0.2 m/s; 8.8 ± 0.2 vs. 8.8 ± 0.2 m/s) or after training (224 ± 2 vs. 218 ± 2 beats/min; 131 ± 3 vs. 120 ± 2 ml/kg bwt/min; 0.58 ± 0.01 vs. 0.55 ± 0.01 ml/kg/beat; 10.5 ± 0.2 vs. 9.5 ± 0.1 m/s; 10.6 ± 0.2 vs. 9.5 ± 0.1 m/s) for HRmax, V̇O2max, OPmax, V̇HRmaxor VV̇O2max, respectively. Old horses had lower HRmax, V̇O2maxand OPmaxand reached them at lower velocities compared to Y and MA (P<0.05), both before (193 ± 3 beats/min; 83.2 ± 2.0 ml/kg bwt/min; 0.43 ± 0.01 ml/kg/beat; 7.8 ± 0.1 m/s; 7.2 ± 0.1 m/s) and after training (198 ± 2 beats/min; 95 ± 2 ml/kg bwt/min; 0.48 ± 0.01 ml/kg/beat; 8.2 ± 0.2 m/s; 8.0 ± 0.2 m/s). Training did not alter HRmaxin any age group (P>0.05) but did cause increases in V̇O2max, OPmaxand VV̇O2maxfor all groups (P<0.05). Interestingly, training increased VHRmaxonly in Y (P<0.05). These data demonstrate that there is a reduction in HRmax, V̇O2max, OPmax, VHRmaxand VV̇O2maxin old horses, and that training can partially reverse some effects of ageing.
Heart rate and blood lactate responses during exercise in preparation for eventing competition
Authors: SERRANO M. G. , EVANS D. L. , HODGSON J. L. 
Published: June 2010

SummaryThe 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 rate during exercise was 138 ± 17 beats/min and mean blood lactate concentration after exercise was 1.0 ± 0.6 mmol/l. These values were compared to heart rates and blood lactate concentrations recorded during and after a CCI*** Cross Country course using unpairedttests (unequal variances) and 99.9% confidence interval analysis. Mean heart rates during and blood lactate concentrations after the competition were 195 ± 8 beats/min and 10.2 ± 4.2 mmol/l. The 99.9% confidence intervals were 183–207 beats/min and 7.7–12.6 mmol/l. Heart rates and blood lactate concentrations recorded during exercise sessions were significantly lower than competition values (P<0.001) and lay outside 99.9% confidence intervals for most horses. Only one horse achieved heart rates and blood lactate concentrations during exercise sessions that were similar to those occurring in competition. The intensity of exercise during normal training sessions was much lower than during competition, suggesting that many event horses are not appropriately trained.
Ribose supplementation in maximally exercising Thoroughbreds
Authors: KAVAZIS A. N. , SOBOTA J. S. , KIVIPELTO J. , PORTER M. B. , COLAHAN P. T. , OTT E. A. 
Published: June 2010

SummaryA diverse group of studies, which are equine exclusive, indicate that ribose administered to myocardial and skeletal muscle tissue stimulates ATP production and recovery. This study investigated the effects of ribose supplementation on blood and muscle metabolites and performance in Thoroughbred geldings performing a maximal treadmill standardised exercise test (SET). In Experiment 1, 6 conditioned Thoroughbred geldings performed a baseline SET and horses were assigned to one of 2 experimental treatment groups, placebo or ribose, based on Vo2max. The placebo treatment group received 0.07 g glucose/kg bodyweight (bwt) and ribose treatment group received 0.07 g ribose/kg bwt top dressed on the feed twice daily. Following a 2 week treatment period, a second SET was performed. After a one‐week washout period, the horses switched treatment groups. Following another 2 week treatment period, a third SET was performed. Blood ammonia‐N was lower in the ribose treatment group at 15 min (P = 0.06) and 30 min (P = 0.02) postexercise. Plasma lactic acid was lower in the ribose treatment group at 30 min postexercise (P = 0.07). In Experiment 2, 1 h before a SET, 2 horses received 31 water (control) and 3 horses 250 g of ribose dissolved in 31 water (single ribose dose) via a nasogastric tube. Following a 2 week washout period, the horses switched treatment groups and another SET was performed. There were no differences in blood ammonia‐N, plasma lactic acid or glucose between treatment groups. No differences in performance were detected between treatment groups in either experiment. In conclusion, the results from Experiment 1 show a trend that daily ribose supplementation may be beneficial during recovery from exercise. However, a single dose of ribose 1 h before exercise revealed no effect on the variables measured. Because moderate to intense daily exercise can cause a decrease in total adenine nucleotide (TAN) pool with no meaningful recovery even after 72 h rest, future experiments should be designed to futher elucidate the effects of ribose supplementation on TAN metabolism in horses exercising at high intensity.
Induction of heat shock protein 72 mRNA in skeletal muscle by exercise and training
Authors: PÖSÖ A. R. , EKLUND‐UUSITALO S. , HYYPPÄ S. , PIRILÄ E. 
Published: June 2010

SummaryIn 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 varied between 7.2 and 10.2 mmol/I. Training increased HSP72 mRNA, as indicated by increases in samples taken at rest (A<B<C). Exercise also tended to increase HSP72 mRNA transiently but, 23 h later, values had returned to pre‐exercise levels. HSP72 mRNA was expressed in all muscle fibres. After exercise, HSP72 mRNA correlated positively with the peak concentration of blood lactate, but not with indicators of energy status. Therefore, acidosis rather than energy depletion was the major inducer of HSP72 expression after moderate intensity exercise. Because HSP72 may protect cells against stress, knowledge about their expression may help in planning optimal trainng regimes.
Influence of trotting and supplemental weight on metacarpal bone development
Authors: NIELSEN B. D. , O'CONNOR C. I. , ROSENSTEIN D. S. , SCHOTT H. C. , CLAYTON H. M. 
Published: June 2010

SummaryThe use of weight‐training to alter bone strength has not been investigated in horses. Recognising that bone responds to loading, we studied the effect of carrying weight on bone development during training. Seventeen horses were divided into 3 groups: controls exercised counterclockwise in a free‐flow exerciser; the weight group performed the same exercise carrying progressively increasing weight up to 45 kg and the weight supplement group also received a myo‐anabolic supplement. Radiographic equivalence measure of bone mineral content of zones of the third metacarpi (MCIII) was determined on 4 occasions: baseline (Day 108), pre‐conditioning following 108 days stall confinement (Day 0), mid‐conditioning (Day 39) and end‐conditioning (Day 78). Stall confinement resulted in loss of mineral in lateral and medial cortices of both MCIII. During conditioning, weight‐carrying increased mineral deposition in lateral and medial cortices of MCIII of the left (inside) leg compared with controls. In the right leg, controls had lower mineral content of the lateral cortex at Day 39 than weight‐carrying horses but no differences between treatments were recorded at Day 78. Markers of bone metabolism did not change from baseline to pre‐conditioning, but increased from Day 0 to 39 and 78 for all groups. This study demonstrates the benefits to bone mineral deposition in the third metacarpi of carrying weight when trained at low speeds and re‐emphasises the potential for bone loss when not given sufficient exercise.
Do regional variations in flexor tendons predispose to site‐specific injuries?
Authors: BIRCH H. L. , SMITH T. J. , POULTON C. , PEIFFER D. , GOODSHIP A. E. 
Published: June 2010

SummaryPartial rupture occurs most often to the superficial digital flexor tendon (SDFT) of the forelimb at the mid‐metacarpal level. In this study, we tested the hypothesis that the mid‐metacarpal region of the SDFT has the smallest cross sectional area (CSA) and a similar collagen content to other regions and, therefore, represents a weak point in the tendon. The SDFT was collected from the forelimbs of 9 horses. Each tendon was marked at 7 different levels from the origin of the accessory ligament to the phalangeal region. The CSA, water content and collagen content was measured at each level.The mid‐metacarpal level had a significantly smaller CSA than the most proximal and distal levels measured and a significantly higher dry matter content than proximal levels. However, the total amount of collagen present in the mid‐metacarpal section was not significantly less than other regions except for the most distal sections. The results of this study suggest that the mid‐metacarpal region of the SDFT, although smaller in CSA, is not significantly weaker than the proximal end andmanica flexoriaregion of the tendon. Therefore, other factors such as hypoxia and/or hyperthermia may be responsible for site‐specific tendon lesions in the SDFT.
Three‐dimensional kinematics of the tarsal joint at the trot
Authors: LANOVAZ J. L. , KHUMSAP S. , CLAYTON H. M. , STICK J. A. , BROWN J. 
Published: June 2010

SummaryThe tarsal joint is a common site of injury for many sport horses. Understanding the biomechanics of this complex joint begins with developing a clear picture of the kinematics during normal locomotion. This study describes the 3D kinematics of the tarsal joint by measuring the motion of the tibia and third metatarsus in 4 sound Quarter Horses with targets attached directly to the bones via steel pins. The objective was to determine if the tarsus had significant motion outside the tarsocrural joint. Two Steinmann pins were inserted into the lateral side of the right hindlimb and marker triads were fixed to the end of each pin. 3D motion of the bones was recorded as each subject trotted in hand. Three rotations were expressed using an attitude vector based on the finite helical angle method. Three translations were calculated as the motion of the tibia relative to the third metatarsus. Angular and translation data were mostly coupled with flexion angle. Internal/external rotation during stance and translations during swing showed evidence of noncoupled motion. Although the majority of tarsal motion occurs in the tarsocrural joint, there is evidence that translations and rotations occur in other locations within the tarsal joint and that some of these are related to the tarsal joint ‘snapping’ phenomenon.This research provides a set of reference 3D kinematics which will aid in the study of the aetiology and mechanical effects of tarsal joint lameness.
Modelling the oxygen cost of transport in competitions over ground of variable slope
Authors: SCHROTER R. C. , MARLIN D. J. 
Published: June 2010

SummaryThis study provides an objective method for estimating the oxygen consumption of horses while running on variable slopes so that realistic comparisons may be made of the locomotory transport cost involved in 3‐day events, particularly the Speed and Endurance Test, at sites of differing terrain. A knowledge of the work profile over a particular course would enable competitors to plan speed and interval times appropriately along its length. We have developed a semi‐empirical, but mechanistically based, model to calculate the oxygen cost of transport [COTpath in ml O2/kg/m path] for running on the flat, up or down a slope of given gradient (from −0.3 to +0.3). The model is then used to calculate the overall effort of running on a number of 3‐day event courses of differing standard; the model does not assess the energetic cost of jumping. The cost of transport over the range of gradient of −0.3 to +0.3 was modelled using the following equations:On the flat or uphill: COTpath = 0.123 + 1.561(gradient) Downhill:COTpath = 0.123 + 1.591(gradient) + 9.762(gradient)2 + 14.0(gradient)3
Gas exchange during intense exercise in Standardbreds with earlierRhodococcus equipneumonia
Authors: FUNKQUIST P. , DEMMERS S. , HEDENSTIERNA G. , WAERN M. JENSEN , NYMAN G. 
Published: June 2010

SummaryIt is not known if pulmonary function and gas exchange during exercise are altered after pyogranulomatous pneumonia caused byRhodococcus equiinfection in the foal. The aim was to evaluate whether pulmonary gas exchange during high intensity exercise was altered in mature Standardbreds with a history ofR. equipneumonia as foals. In 7 foals,R. equipneumonia was confirmed and treated. At age 3 years, when these horses were subjected to professional training, an inclined treadmill exercise test including 4 speeds was performed. Samples were collected when a steady state in V̇O2was obtained. Red cell volume, heart rate, respiratory rate, and systemic and pulmonary mean arterial pressures were measured and cardiac output calculated. Oxygen and carbon dioxide tensions in arterial and mixed venous blood were analysed. The alveolar ventilation and the alveolar‐arterial oxygen tension difference were determined. Pulmonary gas exchange was assessed and the ventilation‐perfusion distribution, VA/Q, was estimated by the multiple inert gas elimination technique. Ventilation‐perfusion mismatch and shunt were determined and diffusion limitation calculated. The gas exchange in Standardbred trotters previously infected withR. equiand successfully treated was not compromised during intense treadmill exercise compared with reference values for healthy, fit Standardbreds.We conclude that adult Standardbreds trotters with diagnosedR. equipneumonia as foals, can achieve an adequate gas exchange at a workload close to V̇O2peak.
Effects of different volumes of autologous blood instilled into the airways of horses on pulmonary function during treadmill exercise
Authors: KINGSTON J. K. , BAYLY W. M. , SIDES R. H. 
Published: June 2010

SummaryExercise‐induced pulmonary haemorrhage has been associated with reduced performance in racing horses. However, it is unclear what volume of blood loss into the lungs impairs performance. The purpose of the present study was to determine the minimal volume of autologous blood instilled into the airways that significantly affects performance and pulmonary function in exercising horses. Six Thoroughbred horses performed 2 exercise bouts on each of 4 treatment test days. Each exercise bout consisted of a 2 min warm‐up at 4 m/s followed by running at a speed equivalent to 115% V̇O2max, until fatigued. For the first run of each testing day there was no treatment (baseline run). Prior to the second run either there was no treatment (control) or 100, 50 or 25 ml of autologous blood was instilled into the airways on the right hand side. During each test, arterial and mixed venous blood was sampled, and V̇O2, VCO2and breathing mechanics measured. The results of this study indicate that unilateral instillation of 100 ml of blood or less into the airways of horses does not significantly affect pulmonary function, breathing mechanics or performance during supramaximal exercise. The results of this study may be helpful in determining the significance of exercise‐induced pulmonary haemorrhage on racing performance.
Structural and oxidative enzyme characteristics of the diaphragm
Authors: POOLE D. C. , PETRISKO R. N. , ANDERSON L. , FEDDE M. R. , ERICKSON H. H. 
Published: June 2010

SummaryDuring exercise, the horse can achieve oxygen uptakes and ventilations in excess of 200 ml/kg/min and 1800 I/min, respectively. Whether the diaphragm has the capacity to contribute substantially to inspiratory effort in the exercising horse is not known. To investigate the potential for the horse diaphragm to generate tension, lung displacement and sustain ventilatory function, we measured diaphragm thickness, muscle length and oxidative enzyme activity (citrate synthase) within the ventral, medial and dorsal costal and crural diaphragm. In the diaphragms of 6 mature horses (5 Thoroughbreds, one Quarter Horse; body mass (mean ± s.e.) 475 ± 14 kg, age 4 ± 1 years), the mass of the freshly‐excised diaphragm was 4.54 ± 0.19 kg of which 79% was the costal diaphragm, 17% the crural diaphragm and 4% the central tendon. The medial costal region (2.1 ± 0.1 cm) was significantly thicker (P<0.05) than either the ventral (1.4 ± 0.1 cm) or dorsal (1.2 ± 0.2 cm) costal regions and the crural diaphragm was significantly thicker (>3.2 ± 0.3 cm, P<0.05) than any costal diaphragm region. With respect to the costal diaphragm, excised muscle length was greatest (P<0.05) in the medial costal (17.2 ± 1.0 cm) than either the ventral costal (<12.6 ± 1.5 cm) or dorsal costal (<13.9 ± 1.8 cm) regions and therefore the medial region would be expected to exhibit the greatest absolute length change on inspiration. Citrate synthase activity was high throughout the diaphragm (40.8 ± 11.3 to 55.3 ± 9.7 μmol/g/min), but was not significantly different among regions. These structural characteristics and the oxidative potential of the horse diaphragm are consistent with the diaphragm providing a significant and substantial contribution to the inspiratory effort during exercise in the horse. Consequently, clinical and physiological investigations of exercise performance should not ignore the potentially crucial importance of the diaphragm.
Heart size estimated by echocardiography correlates with maximal oxygen uptake
Authors: YOUNG L. E. , MARLIN D. J. , DEATON C. , BROWN‐FELTNER H. , ROBERTS C. A. , WOOD J. L. N. 
Published: June 2010

SummaryMaximum oxygen uptake also appears to correlate to athletic performance in horses. In the Thoroughbred industry, there has long been an empirical theory that heart size is related to athletic performance, despite a lack of scientific evidence supporting this assertion. To investigate the relationship between peak oxygen consumption (V̇O2max) and cardiac size measured by echocardiography, guided M‐mode and 2‐dimensional echocardiography were performed in 17 conditioned Thoroughbreds with a range of V̇O2max from 126 to 217 ml/min/kg STPD (mean ± s.d. 158 ± 28 ml/min/kg). Horses were age 2–10 years and weighed 430–510 kg. Echocardiography was performed using a Vingmed System V echocardiograph with a 2.25 MHz phased array ultrasound transducer. All images were obtained from the right hemithorax using a short axis view of the left ventricle (LV) at the level of the chordae tendinae. All horses were free from significant regurgitation at the aortic or mitral valves. Maximal oxygen uptake was measured during a standardised incremental treadmill exercise test to fatigue. Maximal oxygen uptake was correlated significantly with LVIDd (r = 0.71; P = 0.001), MWT (r = 0.72; P = 0.001), LV mass (r = 0.78; P = 0.0002) and LV short‐axis area (r = 0.69; P = 0.003). When indices of heart size were indexed to bodyweight, the correlation between V̇O2max and indices of heart size were LVIDd (r = 0.57; P = 0.01), MWT (r = 0.44; P = 0.07), LV mass (r = 0.78; P = 0.0002) and LV short‐axis area (r = 0.69; P = 0.003). The current study suggests there is a strong relationship between V̇O2max and measurements of left ventricular size in Thoroughbred horses when individuals with a range of V̇O2max are compared.
The effect of coat clipping on thermoregulation during intense exercise in trotters
Authors: MORGAN K. , FUNKQUIST P. , NYMAN G. 
Published: June 2010

SummaryThe aim of this study was to study the physiological, especially thermoregulatory, responses during intense exercise in the clipped horse compared to the horse with winter coat. Six Standardbred trotters were studied before and after clipping. They performed an inclined incremental high intensity treadmill exercise test and were monitored during recovery. The clipped horse differed significantly (ANOVA) during exercise as compare to coated: less increase in central venous blood temperature, higher skin surface temperature, greater difference skin to ambient temperature and higher rate of nonevaporative heat loss. The clipped horse had significantly lower total cutaneous evaporative heat loss from walk to end of peak exercise and a shorter time for recovery for the respiratory rate using a paired t test. The clipped horse showed a tendency (P = 0.059) to decreased oxygen uptake during the stepwise increase in workload. We concluded that the clipped horse experienced less strain on the thermoregulatory system due to an enhanced heat loss. Some clipped horses in the study showed a more efficient power output; future studies with emphasis on respiration and oxygen demand are needed to explain this.