bluuebunny/crossref_metadata_2025_split huggingface dataset:
Plasma, red cell and whole blood lactate concentrations during prolonged treadmill exercise at Vla4
Authors: PERSSON S. G. B. , ESSÉN‐GUSTAVSSON BIRGITTA , FUNKQUIST P. , ROMERO L. BLANCO 
Published: June 2010

SummaryThe purposes of this study were to test whether a relatively steady state with respect to the blood lactate pool can prevail during a prolonged exercise test (PET) at Vla4, to study the kinetics of the flux of lactate between plasma and cells in relation to lactate concentration [LA] and haematocrit and to test the interrelationships between plasma [PLA], whole blood [BLA] and erythrocyte lactate [ELA]. The study used 7 Standardbred trotters. In the PET they ran at their respective pre‐established Vla4 for 12 min. Before, every 2 min during and 0, 2, 5, 10 and 15 min after exercise, [PLA] and [BLA] as well as packed cell volume (PCV) were determined. [ELA] was calculated from [PLA], [BLA] and PCV. Heart rate was monitored continuously and remained at a relatively steady state of approximately 200 beats/min throughout the PET.Lactate concentrations increased exponentially during PET, [PLA] more rapidly than [BLA] and [ELA]. The diverging curves during exercise and converging declining curves after exercise suggested a delay in attainment of an equilibrium between plasma and cells. The close relationship between [PLA] and [BLA] (r = 0.98) allows derivations from regression equations. As the [LA] accumulation over time is exponential, it is likely that the increase during the first 2 min at any speed up to that causing a [BLA] of 4 mmol/l is marginal and insignificant and a submaximal incremental exercise test using 2 min step intervals could still be used for determination of Vla4.
Changes in haemostasis in endurance horses: detection by highly sensitive ELISA‐tests
Authors: MONREAL L. , ANGLES ANNA M. , MONREAL M. , ESPADA YVONNE , MONASTERIO J. 
Published: June 2010

SummaryExercise induced variations in coagulation and fibrinolytic activities were evaluated in 25 endurance horses competing in a 80 km ride. Venous blood samples were collected before exercise, after 40 km and 30 min after 80 km. Haematological parameters, fibrinogen, clotting times (aPTT and PT) and the main inhibitors (AT‐III and α2‐antiplasmin) activities were determined. Furthermore, we assessed thrombin‐antithrombin complexes (TAT) as a marker of coagulation activity; and fibrinogen degradation products (FgDP) and fibrin degradation products D‐dimers (FbDP) as markers of fibrinolytic activity using immunoenzymatic tests. Significant changes in all haemostatic parameters were found after endurance exercise. A significant (P < 0.001) increase of TAT values was found when comparing pre‐race (mean ± s.d. 2.28 ± 0.9), at 40 km (3.45 ± 1.2) and 30 min after 80 km (4.0 ± 1.9 ng/ml). Values of FgDP before, at 40 km and after 80 km showed a significant (P < 0.0001) decrease (mean ± s.d. 445.0 ± 144.4, 210.0 ± 111.1 and 177.7 ± 77.2 ng/ml) and the values of FbDP showed a slight but significant (P < 0.001) increase (mean ± s.d. 875.4 ± 230.9, 1062.0 ± 310.0 and 737.2 ± 305.3 ng/ml). These changes confirm a hypercoagulable state, a marked hypofibrinogenolysis and a slight hyperfibrinolysis during endurance exercise. No significant differences were found between the results from horses that finished (n / 19) and those eliminated because of fatigue (n = 6).
Factors that influence vertical velocity during take off over a water jump
Authors: COLBORNE G. R. , CLAYTON HILARY M. , LANOVAZ J. 
Published: June 2010

SummaryHorses competing in the team competition at the 1992 Olympic games were videotaped as they attempted to jump a 4.5 m wide water jump. The video images were digitised to provide kinematic and centre of gravity (CG) data from 18 horses: 12 horses that cleared the water jump (Group 1) and 6 horses that failed to clear the tape on the landing side (Group 2). Univariate ANOVA revealed significant between‐group differences in horizontal distance jumped (Group 1: 5.79 m ± 0.37, Group 2: 5.03 m ± 0.34; F=0.001), inclination of the trunk segment to the horizontal at lift off of the leading hindlimb (Group 1: 21.4° ± 2.5, Group 2: 16.9° ± 4.1; F=0.011) and horizontal distance of the leading hind hoof from the horse's CG at lift off (Group 1:1.11 m ± 0.12, Group 2: 1.30 m ± 0.06; F=0.004). Pearson correlation coefficients revealed that 3 variables were highly correlated with vertical velocity at lift off: distance of the leading hind hoof from the CG at impact (r=‐0.53, P<0.05) and lift off (r=‐0.76, P<0.001) and trunk angle at lift off (r=0.70, P<0.001). Distance of the leading hind hoof from the CG at lift off and trunk angle at lift off were also significantly correlated with horizontal distance jumped (r=‐0.56, P<0.01; r/0.67, P<0.01 respectively). Stepwise multiple linear regression with vertical velocity as the dependent variable selected 3 of the 7 investigated independent variables: trunk angle, distance of the leading hindlimb from CG at lift off and distance of the leading hind hoof from the approach side of the water (r2=0.799). The position of the hindlimbs through their take off phase relative to the CG of the horse and the trunk angle at lift off are important variables in the take off over a water jump.
Kinematics of induced reversible hind and fore hoof lamenesses in horses at the trot
Authors: DEUEL N. R. , SCHAMHARDT H. C. , MERKENS H. W. 
Published: June 2010

SummaryThis study determined differences in hoof motion patterns of the trot between mild fore hoof lameness, mild hind hoof lameness and sound control conditions. Six sound Dutch Warmblood mares were shod with 4 steel shoes to which were welded 2 nuts inside the medial and lateral branches of the 2 right shoes. Into each nut was seated a vertical bolt which could be adjusted to alter pressure upon the hoof sole, producing transitory lamenesses of variable magnitude. Treatments were a sound control condition; a mild fore hoof lameness; a mild hind hoof lameness and another sound control following either lameness treatment. Videotapes (60 Hz) were taken from a camera aimed perpendicularly to the line of horse motion, with a metrestick taped as a reference distance. Horses were hand led at the trot for 6 trials under each treatment. A split‐plot in time model was used in an analysis of covariance, allowing treatment comparisons on an equivalent‐velocity basis. Velocities averaged 3.413 ± 0.027 m/s (mean ± s.e.); stride lengths 2.172 ± 0.017 m and stride durations 0.638 ± 0.004 s. Horses slowed and shortened their strides during lameness treatments without changing stride duration. Changes in the motion patterns of all 4 hooves occurred during fore and hind hoof lamenesses, reflecting a redistribution of weightbearing onto the 3 sound limbs. Several hoof kinematic variables measured in this study differed between mild hind and fore lamenesses but fewer variables differentiated mild lamenesses from sound conditions. The information gained from this study will be important in developing objective image‐based equine lameness diagnostic techniques.
Gait evaluation of race trotters using an accelerometric device
Authors: BARREY E. , AUVINET B. , COUROUCÉ ANNE 
Published: June 2010

SummarySome basic stride characteristics of race trotters were measured by means of an accelerometric device during a locomotor test in order to find stride parameters, predictive for race performance. Twenty‐four horses of various racing abilities were tested on the same flat racetrack. They were allocated to 3 groups according to their performance indices. The locomotor test consisted of 3 stages at increasing speeds and the third stage was performed at maximum individual speed. Basic stride variables were extracted from the acceleration data using specific procedures including built‐in functions of a data analysis programme. Some significant relationships were found between stride characteristics measured at maximum individual speed and race performances obtained during the year. The maximum speed and stride length were positively correlated (r=0.60 and 0.45, P<0.05) with the performance index. The maximum stride frequency was negatively correlated with the best time (r/‐0.46, P<0.05). The maximum speed, stride frequency, contribution of stride frequency to the speed and stride length were greater in the high performance group than in the other groups (P<0.05). The symmetry and regularity of the trot were not significantly related to the performance. A good performer should have a high maximum speed which is mainly produced by a high stride frequency greater than 2.40 strides/s. The accelerometric device was efficient for testing trotters and could be used to predict potential performance.
Muscle and blood metabolic responses to intense exercise during acute hypoxia and hyperoxia
Authors: ESSÉN‐GUSTAVSSON BIRGITTA , NYMAN G. , WAGNER P. D. 
Published: June 2010

SummaryThree horses performed exercise on a treadmill under normoxic conditions (F1O2–0.21) and during exposure to acute hypoxia (F1O2–0.17) and hyperoxia (F1O2–0.35) achieved by addition of nitrogen and oxygen to inspired air by means by an open flow system. The gases were added after the horses had walked and trotted at 2 submaximal speeds (2 and 4 m/s for 7–15 min). Thereafter, the treadmill speed was increased in 3 steps to attain near maximal oxygen uptake within 5–8 min (8–10.5 m/s for normoxia and hyperoxia and 7–10 m/s for hypoxia). Heart rate and oxygen uptake were recorded continuously. By use of indwelling catheters in the pulmonary and carotid arteries, blood samples were drawn at rest and immediately after exercise. Muscle biopsies (m.gluteus) were taken before and immediately after exercise. In all horses, at the end of exercise, heart rates were lower and oxygen uptake, arterial and venous PO2, haemoglobin saturation and oxygen content were higher following hyperoxia than following hypoxia. At the end of exercise, all horses had lower concentrations of lactate, ammonia and potassium in plasma and lower lactate in muscle after hyperoxia than after hypoxia and normoxia. Concentrations of ATP were higher and of G‐6‐P lower after hyperoxia than after normoxia. Significant correlations were observed between post exercise concentrations of lactate and ammonia (r=0.80) and between lactate and potassium (r=0.96) in plasma. There was also a correlation between muscle and plasma lactate (r=0.92). Post exercise ATP concentrations were correlated with IMP (r=0.85), ammonia (r=0.94) and potassium (r=0.84) concentrations in plasma. The results indicate that acute hypoxia and hyperoxia during intense exercise influence the production and/or removal of lactate.
Lactate response to maximal exercise on the track: relation to muscle characteristics and kinematic variables
Authors: RONÉUS N. , ESSÉN‐GUSTAVSSON BIRGITTA , JOHNSTON C. , DREVEMO S. , PERSSON S. 
Published: June 2010

SummaryFourteen 2‐year‐old Standardbred trotters, born, raised and trained at the same establishment performed maximal exercise on a track over a distance of 1000 m. Blood samples for plasma lactate (PLA) analyses were obtained from the jugular vein immediately after exercise. Muscle biopsies from m. gluteus medius were taken and analysed for fibre type composition (I, IIA, IIB) and enzyme activities representing oxidative (citrate synthase (CS), 3‐OH‐ acyl‐CoA dehydrogenase (HAD)) and glycolytic (lactate dehydrogenase (LDH)) capacity. Stance time (ST), stride length (SL) and velocity were determined from high speed films (250 frames/s). Simple linear regression analysis was used to describe relationships between lactate response, muscle characteristics and basic kinematic variables. Significant positive correlations were found between PLA/IIB and negative correlations between ST/IIB, SL/PLA, ST/PLA. No relationships were observed between CS, LDH or HAD and PLA, IIB or the kinematic parameters. The results indicate that young Standardbred trotters with a low percentage of type IIB fibres perform maximal trotting with a low lactate production and long stride length and stance time.
ATP content of single muscle fibres of gluteus medius sampled at rest
Authors: HARRIS D. B. , HARRIS R. C. 
Published: June 2010

SummaryATP distribution at rest was studied in 11 Thoroughbred horses, 8 of which had been admitted for clinical post mortem examination. A biopsy of the middle gluteal muscle was obtained from 6 horses immediately after death, following which a larger piece was taken by dissection from the same area. From the other 2 horses, only cut sections were obtained. The risk of damage to fibres dissected from the inner portion of the cut samples was considered less than for fibres from biopsies. From a separate 3 standing horses, a single biopsy of the middle gluteal muscle was taken at rest. Following freeze‐drying, single fibres were dissected, weighed and analysed for ATP by luminometry. Fibre type was determined by staining for myosin ATPase. Variance in ATP content due to weighing error (se), analytical precision (sp) and the variability in content within a fibre (SDf) were determined in 16 fibres. Total variance (SDt) in ATP content was estimated both for cut sections and biopsies. Data were analysed by ANOVA using an hierarchical model to estimate the specific variance within (s̀wf) and between (s̀bf) fibres. ATP distribution was the same in cut sections and biopsy samples. The mean content of all fibres at rest was 20.14 mmol/kg dm. Values for se, sp, SDf and SDt were 0.49, 0.61, 1.61 and, 3.38 (cut sections) 4.28 (biopsies) mmol/kg dm, respectively; s̀wf was 1.53 mmol/kg and s̀bf 2.91 and 3.92 mmol/kg dm in cut sections and biopsy samples, respectively. ATP contents did not differ between fibre types. We conclude that most of the variance observed in measurements of single fibre ATP contents is due to variance between and within fibres rather than to the imprecision of the procedures used.
Capillaries of muscle in red cell hypervolaemic versus normovolaemic Standardbred horses
Authors: KARLSTRÖM KRISHNA , ESSÉN‐GUSTAVSSON BIRGITTA , PERSSON S. G. B. 
Published: June 2010

SummaryCapillary supply in the gluteus medius of red cell hypervolaemic and normovolaemic horses was investigated. Muscle biopsies were taken from 2 groups of 4–9‐year‐old stallions: 10 normovolaemic (NV, CV/bwt=78.1 ml/kg) and 10 hypervolaemic (HV, CV/bwt=112.6 ml/kg). The muscle biopsies were analysed for fibre type composition, fibre areas, capillary supply and enzyme activities. There were no differences between groups for fibre type composition, fibre areas or enzyme activities. Hypervolaemic horses were found to have a significantly lower capillary density (HV: 587 ± 62; NV: 661 ± 57 cap mm−2), capillarisation in relation to mean fibre area (HV: 1.59 ± 0.19, NV: 1.77 ± 0.16 μnr2 10−3) and especially capillarisation of type I fibres (HV: 1.87 ± 0.24; NV: 2.15 ± 0.26 μm−2 10−3). The lower capillarisation of hypervolaemic horses could be one factor affecting their racing performance.
Isolating equine sarcoplasmic reticulum: its function during high intensity repeated sprints
Authors: WILSON J. A. , KRONFELD D. S. , GAY L. , WILSON T. M. 
Published: June 2010

SummaryA method has been developed for isolating equine sarcoplasmic reticulum (SR) and measuring calcium uptake by modifying methods previously established in rat and rabbit muscle tissue. Excisional biopsies were used to obtain muscle samples from the gluteal muscles of 10 Quarter Horses. Sarcoplasmic reticulum vesicles were isolated through homogenisation and differential centrifugation. Calcium uptake into the vesicles was monitored spectrophotometrically using a calcium probe, antipyrylazo III. An enzyme linked optical assay was employed to assess Mg++ ‐stimulated, Ca++ ‐stimulated and total ATPase activity in the isolated SR vesicles. The present results provide a system for obtaining SR microsomes and measuring calcium uptake in the isolated vesicles in a relatively short period of time. High intensity sprinting decreased calcium uptake and Ca‐ATPase activity of SR vesicles in horses.
Frusemide
Authors: HINCHCLIFF K. W. , McKEEVER K. H. 
Published: June 2010

SummaryFrusemide is administered to large numbers of North American racehorses because of its putative prophylactic effect on exercise induced pulmonary haemorrhage (EIPH). Two issues central to the use of frusemide in performance horses remain to be resolved: 1) Does frusemide reduce the incidence or severity of EIPH? and 2) does frusemide alter athletic performance or the capacity for muscular work, separate from any effect on EIPH? These issues are discussed, as is the reasoning that EIPH is, at least in part, a consequence of exertion induced high vascular transmural pressures and that reduction of these pressures by frusemide is the mechanism by which frusemide reduces the incidence or severity of EIPH. It is concluded that, on balance, it appears unlikely that frusemide reduces the incidence of EIPH, although it may reduce the severity of haemorrhage. The evidence that frusemide is ergogenic is evaluated and a potential mechanism for an effect of frusemide on athletic capacity, the frusemide induced reduction in body weight, is discussed.
Interrelationships between fluid, electrolyte and acid‐base balance during maximal exercise
Authors: CARLSON G. P. 
Published: June 2010

SummaryExercise at maximal intensity results in marked, but transient alterations in plasma electrolyte concentration and acid‐base balance. Compartmental fluid shifts contribute to the increased haematocrit, plasma protein and electrolyte concentrations. Elevations in plasma sodium and potassium concentrations relative to chloride tend to ameliorate the impact of lactate accumulation on anion‐cation balance. Lactate accumulation is associated with the development of a profound metabolic acidosis, but there are physiologically important differences between the mixed venous and arterial acid‐base values. Arterial blood is characterised by a moderate hypoxaemia, marked acidosis, modest increase in the partial pressure of carbon dioxide (PCO2) and a marked decrease in bicarbonate. Mixed venous blood pH is lower than arterial and is associated with a profound increase in PCO2 with a slight increase in bicarbonate. It is estimated that over 70% of the CO2 produced during maximal exercise is transported as bicarbonate in the venous circulation. This is largely a function of the carbonic anhydrase‐dependent chloride shift in which erythrocytes participate in CO2 transport from the tissues to the lungs. The chloride shift is responsible for the mixed venous‐arterial differences in plasma chloride concentration. The compartmental fluid shifts as well as the alterations in plasma electrolyte concentration and acid‐base balance are part of the integrated physiological response to the energy generating metabolic events associated with maximal exercise.
Respiratory adjustments in unacclimatised horses exercised under hot, humid conditions
Authors: ART TATIANA , LEKEUX P. 
Published: June 2010

SummaryThe purpose of this study was to investigate the effect of a hot and humid environment on the pattern of breathing and the gas exchange in heavily exercising horses. Five healthy fit Standardbred horses were investigated twice at 8 day intervals, once in temperate conditions (TC) (ambient temperature: 15°C; relative humidity: 55%) and once in hot and humid conditions (HHC) (ambient temperature: 30°C; relative humidity: 75%). The standardised treadmill exercise test consisted of 8 min warm‐up and 8 min exercise (1 min at 1.7, 4, 7, 8, 9 and 10 m/s and 2 min at 4 m/s with a 6% slope). Running in HHC induced a significant decrease in peak expired minute volume (V̇E), oxygen uptake (V̇O2), V̇CO2and oxygen pulse, while RQ remained unchanged and PACO2increased. The changes in skin temperature (ST), i.e. the difference between ST at rest and at 10 m/s, was dramatically higher in HHC. The test induced changes, i.e. the differences between the values before and after the test, in Cortisol, β‐endorphins and plasma lactate (LA) values after the test were significantly higher. This study showed that performing a strenuous exercise in hot, humid conditions in unacclimatised horses induced a reduction of the aerobic capacity, i.e. decrease of the V̇O2and increase of LA production. A relative hypoventilation could be partly responsible for this observation, but all the steps of the oxygen transport from the pulmonary ventilation to the muscle metabolism could also potentially be impaired in such conditions.
Ion and water losses from body fluids during a 163 km endurance ride
Authors: LINDINGER M. I. , ECKER GAYLE L. 
Published: June 2010

SummaryThis study calculated extracellular fluid (ECF) and intracellular fluid (ICF) water losses and ECF ion losses from 39 endurance trained horses during a 163 km ride. Jugular venous blood samples and body mass (BM) were obtained pre‐ride, at 32, 80 and 163 km of the ride and at 1 h of recovery. Blood was immediately analysed for haematocrit, plasma [Na+], [Cl−], [K+], ionised [Ca++] and total solids. ECF water losses were calculated from changes in plasma total solids assuming equilibrium between plasma and remaining ECF. ECF ion losses were calculated from changes in plasma ion concentrations and ECF volume (ECFV). Results were analysed with respect to speed (GroupA, 14.7 ± 1.0 km/h, n = 12;Group B, 11.2 ± 1.0 km/h, n = 11;Group C, did not finish, n = 16) and whether or not horses were pre‐loaded with electrolytes before the ride. The majority of ECF water losses occurred by 32 km: ECFV decreased by 5.4 ± 1.7 litres in A andBand by 7.8 ± 1.6 litres inC.At 80 km, there were no further losses inAandB, while inCECFV had decreased by 10.4 ± 1.9 litres. However, total body water and therefore ICFV, decreased progressively until the finish and were only partially restored after 1 h recovery. Most ECF ion losses also occurred within the first 32 km, with losses greater inC(P < 0.05) and β (P < 0.1) than in A (Na+5.9 ± 2.1%, K+24 ± 4%, Cl−8.4 ± 1.7%, Ca++13 ± 2%). Only at 32 km did the preloaded horses (n = 21) show reduced losses of Na+, K+and Cl−. In conclusion, the majority of ECF ion and water losses occurred early in the ride (by 32 km); net loss of TBW and ICFV continued until 80 km; better performing horses (A) were able to maintain ECF ion and water balance during the ride; and in most horses fluid and ion supplementation was effectively inadequate to replace all lost water and ions.