bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kinematic response to a 70 day training period in trotting Dutch Warmbloods
Authors: BACK W. , HARTMAN W. , SCHAMHARDT H. C. , BRUIN G. , BARNEVELD A. 
Published: June 2010

SummaryTo study the influence of training on the equine locomotor apparatus, the kinematics of 24 almost two‐and‐a‐half‐year‐old Dutch Warmbloods were recorded on a treadmill at the trot (4 m/s) using a modified CODA‐3 apparatus before and after a period of 70 days. In that period, 12 horses of the group were trained for dressage and jumping, while the other 12 were sent to pasture day and night. After 70 days, the hindlimb of the trained horses showed a decreased stance duration, less limb flexion and it reached its maximal protraction earlier in the stride. The stride duration remained the same in the trained horses, while the protraction and retraction range of the forelimb decreased in this group. In the pastured group, however, the horses increased their total range of forelimb movement in the sagittal plane and had a longer swing and stride duration. These results indicate that the definition of ‘training’ is rather relative. The response in the trained group was in agreement with the observation that the majority of horses from this group were trotting with impulsion ‘on the bit’. The pastured group was trotting in a more relaxed way with a longer stride duration and thus a lower stride frequency. In conclusion, this study proved that horses show different responses in their locomotor apparatus depending on the ‘training’ regime received. Using modern gait analysis equipment these differences could be evaluated objectively.
Kinematics of the distal forelimb during the stance phase in the fast trotting Standardbred
Authors: JOHNSTON C. , ROEPSTORFF L. , DREVEMO S. , RONÉUS N. 
Published: June 2010

SummaryFast‐trotting Standardbred horses were filmed along a straight on an oval dirt track. Five consecutive stance phases were analysed to describe the plantar kinematics of the distal forelimb. Rapid changes in the geometry of the distal forelimb occurred during the early stance phase. The hoof segment was initially compressed vertically and moved in the direction of the horse. In general, the angular displacement of the fetlock joint was a smooth curve with 2 specific deviations in the early stance phase. The deviations are suggested to be related to the braking of the hoof and activation of the flexor muscles of the distal forelimb. A rotational dissociation occurred between the antebrachial and metacarpal segments due to a delay in braking caused by the carpus which preceded the maximal overextension of the carpus. The early stance phase changes in the distal forelimb suggest rapid changes in the internal forces of the limb and should be of importance to the orthopaedic health of Standardbred trotters.
Simple airflow direction and footfall sensors for use in equine exercise studies
Authors: YOUNG S. , STÄMPFLI H. , GEOR R. , McCUTCHEON LAURA J. , PRINGLE J. 
Published: June 2010

SummaryTwo durable, inexpensive and non‐invasive sensors for detecting airflow direction and footfall in exercising horses were developed. The airflow sensor measured temperature of the gas at the nostrils using a copper/constantan thermocouple. The response time of the thermocouple unit, the time for the signal to change from 10% to 90% of its final value, was 260 ms in forced air. The tip of the thermocouple was held just inside the false nostril by a small wire frame. The sensor did not interfere with placement of face masks and the addition of the mounting frame slightly decreased response time of the sensor to 208 ms. The footfall sensor was a simple accelerometer, using the contact arm of an electrical relay as a spring/mass unit. Bending of the metal strip was recorded using a strain gauge. The response of the accelerometer was highly under‐damped when attached to a rigid surface (resonant frequency 117 Hz, quality factor (Q) 171) but attaching it to the hoof with adhesive foam increased the damping considerably. Both sensors were used in a study of Standardbred horses exercising maximally on a treadmill. Air temperature at the nostril changed from ambient on inspiration to about 35°C on expiration and each leading hoof strike produced a burst of signal from the accelerometer. The sensors may be useful in studies that examine respiration, stride rate and respiratory‐locomotor coupling in exercising horses.
Effects of post exercise activity on recovery from maximal exercise
Authors: LOVELL D. K. , ROSE R. J. 
Published: June 2010

SummaryWe determined the effect of post exercise activity on recovery from maximal exercise. Five Standardbred horses were exercised on an inclined treadmill (+10% slope) for 2 min at 2.5 m/s followed by 2 min at 12.5 m/s (∼110% V̇O2max). They had one of 3 recovery regimens: standing on the treadmill (A), trotting at 4 m/s for 15 min followed by walking at 2 m/s for 15 min (B), or walking at 2 m/s for 30 min (C). Muscle biopsies from the m. gluteus medius and jugular blood for blood lactate determination were collected, before and after exercise and at 3, 5, 10, 15, 20 and 30 min recovery. Ten minutes after exercise, heart rate was significantly (P<0.05) higher with recoveries B and C than recovery A, but there were no differences at 20 or 30 min following exercise. Both muscle and rectal temperatures were significantly (P<0.01) lower with recovery A compared with recoveries B and C. The type of recovery had no influence on the rate of change of [ATP] or [G‐6‐P]. The rate of decrease in plasma and muscle [lactate] was significantly faster with recovery B than A (P<0.05). Creatine phosphate increased (P<0.05) at a faster rate with recoveries B and C than A. We conclude that ‘warm‐down’ periods enhance clearance of lactate from skeletal muscle and that lactate may be utilised as a substrate by muscle during recovery from exercise.
Effect of elevated plasma FFA on fat utilisation during low intensity exercise
Authors: ORME C. E. , HARRIS R. C. , MARLIN D. J. 
Published: June 2010

SummaryThe aim of the present study was to evaluate the capacity of the horse, during low intensity exercise, to increase the contribution of fat oxidation to energy production as a result of a pre‐exercise elevation of triglyceride derived plasma FFA. Seven Thoroughbred horses were exercised for 91 min (3.2 m/s for 60 min, 13.4 ± 2.9% V̇O2max) during 2 randomised experimental sessions (test, T and control, C). Prior to the test session, plasma FFA were elevated using a combination of a heparinoid type substance (pentosan polysulphate, 1.3 mg/kg bwt) and a triglyceride emulsion (Iverlip 20; 0.4 g/kg bwt). Mean pre‐exercise plasma FFA and triglyceride concentrations were 903.9 ± 275.0 and 810.2 ± 169.6 μmol/l for the test session and 465.5 ± 266.0 and 158.4 ± 64.5 μmol/l for the control session, respectively. Total lipase activity was significantly increased at rest after pentosan polysulphate and Iverlip administration and throughout exercise during the test session. Respiratory exchange ratio (RER) was lower in 5 out of 7 horses and plasma glucose concentration was higher in 4 of these 5 horses during the test exercise session. These results suggest that an elevation of plasma FFA concentration prior to exercise results in an increase in the utilisation of fat, during subsequent low intensity exercise, in a proportion of horses. This effect, however, is probably influenced by individual biological and metabolic variation in the response to exercise and may depend upon the individual's inherent ability to utilise fat.
Limitations to performance caused by skeletal muscle enzyme deficiencies
Authors: VALBERG STEPHANIE J. , JONES J. H. , SMITH BARBARA L. , SOMMERVILLE B. 
Published: June 2010

SummaryRecently, 2 new enzyme deficiencies of equine skeletal muscle have been identified, involving either mitochondrial respiration or glycolysis. We hypothesised that in these unique horses, maximum oxygen consumption (V̇O2max) would not be limited by oxygen transport but rather by oxygen utilisation and substrate metabolism, respectively. To test this hypothesis, an Arabian mare with Complex I deficiency (OXID) and 2 half‐sibling Quarter Horses with a polysaccharide storage myopathy (GLY1 and GLY2) were accommodated to run at maximal speed on a treadmill. These horses and 5 healthy Thoroughbred horses each performed 2 identical exercise tests consisting of 6 min submaximal exercise and 2 min at their maximal speed. The OXID horse fatigued at 6 m/s with a markedly low V̇O2max (20% of controls), a low maximum total power output (25% of controls) with a high contribution of net anaerobic power (38% compared to 24% for controls). The GLY horses developed a stiff gait and fatigued with a low V̇O2max (50–65 % of controls), a low maximum total power (50–60% of controls) but with a low contribution of net anaerobic power (18% vs. controls 24%). The rate of lactate accumulation at maximal speeds was approximately 30–50% lower than for controls. It appeared that mitochondrial oxidative capacity severely limited aerobic performance in the OXID horse and substrate limitation within the Embden Myerhof pathway limited both aerobic and anaerobic power output in the GLY horses. We conclude that in some horses, skeletal muscle oxidative or glycolytic capacity may limit maximum aerobic performance.
Carnosine and taurine contents of type I, IIA and IIB fibres in the middle gluteal muscle
Authors: DUNNETT M. , HARRIS R. C. 
Published: June 2010

SummaryThoroughbred racing involves periods of intense exercise above the anaerobic threshold, characterised by H+ ion accumulation in muscle. Progressive intracellular acidosis may be a primary cause of local muscle fatigue. Carnosine is quantitatively the most important buffer in equine skeletal muscle with estimated contents 3–5‐fold greater in type II compared with type I fibres. Taurine is believed to be concentrated in type I fibres. In the present study we have measured carnosine and taurine contents directly within individual fibres. Seven samples were collected from the middle gluteal muscle of 5 horses at post mortem. Fibres were dissected from freeze‐dried tissue, weighed and characterised as types I, IIA or IIB by histochemistry. Carnosine and taurine contents were determined by HPLC. Mean (± s.d.) carnosine contents of type I, IIA and IIB fibres were 24.9 ± 4.4 mmol/kg dry muscle (d.m.), 94.8 ± 6.8 mmol/kg d.m. and 104.3 ± 11.9 mmol/kg d.m. respectively. Mean (± s.d.) taurine contents of type I, IIA and IIB fibres were 54.3 ± 8.3 mmol/kg d.m., 2.8 ± 2.1 mmol/kg d.m. and 1.8 ± 1.9 mmol/kg d.m. respectively. The results agree with previous estimates. Higher carnosine contents in type II fibres emphasise the importance of carnosine to intramuscular acid‐base regulation. A specific role for taurine in type I fibres is unclear. Owing to the differential distribution in muscle fibres of carnosine and taurine, their appearance in plasma may be useful in diagnosing types I or II fibre damage.
The effect of moderate exercise on equine muscle satellite cells in vitro
Authors: GREENE ELIZABETH A. , BALCH S. G. , RAUB R. H. , GAUGHN E. 
Published: June 2010

SummaryTwelve weanling Quarter Horses were divided randomly into 2 groups; exercised (EX) and non‐exercised (NONEX). The EX horses were divided randomly into 2 groups subjected to either a 15‐day or 30‐day exercise protocol and weanlings were exercised at a brisk trot (3 m/s) on a high speed treadmill. Muscle satellite cells were obtained by surgical biopsy from the biceps femoris at the conclusion of exercise protocols. Time course studies were used to examine the main effects of exercise on proliferation and differentiation of equine satellite cells (ESC) in vitro. No differences occurred between proliferation and differentiation of cells from 15‐ or 30‐day EX and NONEX treatments. In a second experiment, the ability of serum from EX or NONEX horses to stimulate proliferation or differentiation of ESC in vitro was examined. Serum had a significant effect on both proliferation and differentiation. During Days 3 and 5 in culture, serum from EX weanling horses increased (P<0.005) total cell numbers; however, after 7 days, no differences (P>0.10) existed between serum sources. From Days 3–7, satellite cells cultured in serum from EX horses had greater (P<0.005) per cent fusion than cells cultured in serum from NONEX weanling horses. Origin of satellite cell cultures (EX or NONEX) caused no differences. A constituent seems to be present in the serum from EX that is capable of stimulating increased levels of proliferation and differentiation of ESC.
Exercise induced purine nucleotide degradation and changes in myocellular protein release
Authors: RÄSÄNEN LEENA A. 
Published: June 2010

SummaryXanthine oxidase has been claimed to produce tissue damaging oxygen free radicals during purine nucleotide degradation. The aim of this study was to evaluate whether xanthine oxidase (XO) activity is present in horse plasma and whether it is associated with the post exercise release of muscular proteins into plasma. Purine nucleotide degradation was measured as the accumulation of reaction end products, uric acid and allantoin, and activities of aspartate aminotransferase (AST), creatine kinase (CK), carbonic anhydrase (CA) and the concentration of myoglobin in plasma were measured as indicators of increased sarcolemmal permeability after a standardised submaximal exercise test (SET) on a high speed treadmill and after maximal exercise (trotting races). The activity of XO in plasma was significantly elevated up to 5 min after the SET and correlated positively with the activity of CK measured 1 h after exercise, but not with the concentrations of uric acid or allantoin. After the trotting races, concentration of myoglobin and activity of CK peaked within 4 h after exercise. No correlation was found between CK and the concentrations of uric acid and allantoin. CA activity did not change significantly in any of the samples. These findings suggest that XO, both in plasma and in endothelial cells, may contribute to the formation of free radicals and therefore to the genesis of exercise induced increase in the sarcolemmal permeability.
Effects of creatine supplementation in the Thoroughbred horse
Authors: SEWELL D. A. , HARRIS R. C. 
Published: June 2010

SummaryThe present study was undertaken to examine the absorption of creatine (Cr) by the horse and, if so, whether this results in an uptake of Cr into muscle. The timecourse for the appearance of a single dose of creatine monohydrate (Cr.H2O), given by nasogastric intubation, in plasma was investigated in 4 horses. Individual resting plasma [Cr] ranged from 8 μmol/1 to 103 μmol/1. Mean post intubation plasma concentrations showed a modest increase reaching a peak after 6 h. At various times post intubation the change from rest was statistically significant. The effect of 13 days feeding of 0.15g/kg body mass/day of Cr.H2O on muscle [TCr] was studied in 4 horses. Supplementation had no effect upon muscle [TCr] (pre‐ vs. post supplementation: 104 ± 4 vs. 98 ± 14 mmol/kg dry muscle). There was no change either in the resting muscle [ATP] (pre‐ vs. post supplementation: 21.2 ± 1.0 vs. 20.2 ± 1.9 mmol/kg dry muscle) or the [TCr]/[ATP] ratio.
Effect of conditioning and exercise type on serum creatine kinase and aspartate aminotransferase activity
Authors: SICILIANO P. D. , LAWRENCE L. M. , DANIELSEN KRISTIN , POWELL DEBRA M. , THOMPSON K. N. 
Published: June 2010

SummaryIn the first study, 5 mature, unconditioned, Thoroughbred geldings performed an initial submaximal exercise test (UC) prior to any conditioning and a final test (C) following 8 weeks conditioning. Serum creatine kinase (CK) and aspartate aminotransferase (AST) activity were measured before and for 72 h after exercise. Plasma lactate concentration [La−] was used as an indicator of exercise conditioning. Serum CK and AST activity remained increased above pre‐exercise levels from 0–24 h and 0–8 h post exercise, respectively. There was a time by conditioning interaction for AST, CK and plasma [La−] resulting in an attenuated response of each variable following exercise test C as compared to following exercise test UC. These results indicate that submaximal exercise can elevate serum AST and CK and that conditioning can attenuate these changes.A second study using 8 mature Thoroughbred horses was conducted to evaluate the effect of 2 different types of exercise, short term high intensity (STHI) and repeated submaximal exercise (RS) on serum AST and CK activities. Serum AST and CK activities during the post exercise period were higher in response to the RS test compared to the STHI test.
Effects of NaCI supplementation before exercise on metabolism of water and electrolytes
Authors: COENEN M. , MEYER H. , STEINBRENNER B. 
Published: June 2010

SummaryFour horses were exercised for 2 h on a treadmill at up to 200 m/min 4 h after feeding. The trial included 3 treatments, control (A) and electrolyte supplementation provided either in the diet at the morning feeding (B) or 1 h before start of exercise (C). The horses were fed 2 meals/day of hay and concentrate (6.5 g dry matter, 13.8 mg Na, 66.6 mg K and 54.2 mg Cl/kg bwt per meal). The supplement was a mixture of grass meal (47.6%), sugar beet syrup (33.3%) and NaCl (19.1%); additional intake: Na 79.7, K 15.5 and Cl 165.6 mg/kg bwt. Hourly urine and blood samples were taken.Water intake and renal water excretion were significantly influenced by supplementary feeding (intake: A 35.5, B 49.9, C 55.6 ml/kg bwt/12 h; excretion: A 9.47, B 15.34, C 7.92 ml/kg bwt/12 h). The urinary Na and Cl excretion was significantly higher in treatment B (Na 24, Cl 55 mg/kg bwt/12 h) and C (Na 12, Cl 44 mg/kg bwt/12 h) as compared to A (Na 5, Cl 16.5 mg/kg bwt/12 h). Renal K output was less influenced by the different treatments, A 43, B and C 61 mg/kg bwt/12 h. However, the renal Na and Cl excretion was lower in relation to intake when horses received the supplement. In these cases, losses of water, Na and Cl via sweat were compensated for at the end of exercise and a positive balance therefore maintained 12 h after feeding. The total plasma protein concentration increased during exercise, indicating a reduction in plasma volume. The Na and K concentrations in plasma during exercise showed minor changes whereas the Cl concentrations decreased significantly by 2.6 (A), 4.0 (B) and 1.4 (C) mmol/l. Changes in plasma Na and Cl in treatments B and C occurred at constant higher levels than in treatment A.The results suggest a positive impact of NaCl suplementation on water and electrolyte metabolism in exercised horses. The increased water intake indicates that supplementary salt intake is more effective about 4 h than 1 h before exercise.
Effects of oral fluid on cardiorespiratory and metabolic responses to prolonged exercise
Authors: LEÓN L. A. SOSA , DAVIE A. J. , HODGSON D. R. , EVANS D. L. , ROSE R. J. 
Published: June 2010

SummaryAdministration of oral fluids prior to exercise may provide a fluid ‘buffer’ supporting cardiorespiratory and thermoregulatory function during prolonged exercise. Six Standardbred horses, previously acclimatised to a treadmill and a respiratory gas collection mask, were used in a crossover study and were given ∼17.5 litres hypotonic commercial electrolyte mixture via a nasogastric tube, 90 min before exercise. Total fluid was equivalent to 4% bwt, administered in 3 equal doses, 20 min apart, the last 50 min before exercise resulting in a mean ± s.e. pre‐exercise plasma total protein (TPP) of 57.6 ± 0.6 g/l, compared with 63.5 ± 0.5 g/l (P < 0.01) when no fluid was given. One week later, each horse received the alternate treatment. The exercise test consisted of 90 min at 30% V̇O2max with measurements taken throughout exercise. Exercise increased temperature, haematocrit, TPP, [glucose], [lactate] and pH and decreased plasma [K] and [Cl], respiratory exchange ratio and PaCO2. There was no effect of exercise duration on heart rate, cardiac output, stroke volume, V̇O2 V̇CO2, [HCO3] or PaO2. Fluid administration resulted in lower TPP, plasma [Cl], [HCO3] and [Na] during exercise. Although fluid administration before exercise did not improve cardiorespiratory and thermoregulatory function, the fluid treated group had a higher plasma volume which may be advantageous to horses exercising in hot and humid environments.
Effects of terrain, speed, temperature and distance on water and ion losses
Authors: ECKER GAYLE L. , LINDINGER M. I. 
Published: June 2010

SummaryFactors contributing to water and ion losses due to sweating have not been well studied during prolonged exercise in horses. This study examined temperature (T; °C; range 6–32°C), distance (D; km; 48–161 km), speed (S; km/h; 8–19 km/h) and muddy terrain (M) as factors determining water and ion losses. Jugular venous blood samples (analysed for plasma ions and refractive index) and body mass (BM) were obtained from 176 endurance horses at 13 events at rest, mid‐ride and finish. Regression analysis determined correlations between losses of total body water (TBW) and extracellular (ECF) ions and the variables T, M, S and D. Losses of ECF ions and TBW were calculated assuming an ECF volume (ECFV) of 1 litre/5 kg BM. There were significant decreases in BM (range of means 2–7%) and ECFV (range of means 2–14%) at mid‐ride and finish; however, these were independent of the variables tested. Losses of Na+, K+, Cl−and Ca++were correlated with T, D, S and M. Inclusion of S in the model eliminated T and M as factors for Na+, Cl−and Ca++loss. Speed was not a predictor of K+loss. ECF ion losses at the mid‐ride were correlated to T, S, D and M. In conclusion, factors affecting ion losses at the finish, in descending order of importance, were speed (except for K+due to rapid intercompartmental shifts), muddy terrain, temperature, then distance (for Cl−). Using the data from the literature models were used to predict ECF ion losses in endurance events.
Plasma and erythrocyte ion concentrations during exercise in Arabian horses
Authors: FERRANTE PAMELA L. , TAYLOR LYNN E. , WILSON JUDY A. , KRONFELD D. S. 
Published: June 2010

SummarySix conditioned Arabian horses were subjected to an intermittent exercise test to examine alterations in plasma and erythrocyte ions during exercise. Haematocrit, erythrocyte haemoglobin concentration, plasma potassium [K+] and lactate [La−] concentrations increased and plasma sodium [Na+] and chloride [Cl−] concentrations decreased during exercise. Erythrocyte [K+] and [La−] increased and erythrocyte [Na+] decreased during exercise. When cell volume was held constant at resting values, potassium content of the cells was slightly greater than resting values; and sodium and chloride content decreased during exercise. Increased haematocrit in horses during exercise due to splenic contraction increases the erythrocyte membrane surface area and distribution space for blood ions. Movement of lactate into erythrocytes may modulate the increase in plasma [La−), maintaining the muscle to plasma gradient and facilitating the movement of lactate from muscle into plasma.