Exercise physiology in horses involves the study of the physiological responses and adaptations of horses to physical activity. This field examines how exercise impacts various systems in the equine body, including the cardiovascular, respiratory, muscular, and metabolic systems. Researchers focus on understanding how these systems interact during different types and intensities of exercise, and how they contribute to performance and recovery. Key areas of interest include the assessment of aerobic and anaerobic capacity, muscle fiber composition, energy metabolism, and thermoregulation. This page compiles peer-reviewed research studies and scholarly articles that explore the mechanisms of exercise physiology in horses, with an emphasis on performance optimization, training regimens, and the prevention of exercise-related disorders.
Freeman DW, Potter GD, Schelling GT, Kreider JL.Nitrogen metabolism was measured in five mature geldings performing varying levels of work that simulated race training. Following an initial maintenance period without forced exercise, workload was increased in succeeding 18-d periods by doubling the distance the horses were galloped in each period from period 2 through 4. A 4-d N balance experiment was conducted at the end of each 18-d period. The maximum distance galloped daily, which was in period 4, was repeated in period 5. Then, workloads were decreased through period 7. Nitrogen balance was determined in two additional periods, 8 and 9...
Rose RJ, Hodgson DR, Kelso TB, McCutcheon LJ, Reid TA, Bayly WM, Gollnick PD.This study determined maximal O2 uptake (VO2max), maximal O2 deficit, and O2 debt in the Thoroughbred racehorse exercising on an inclined treadmill. In eight horses the O2 uptake (VO2) vs. speed relationship was linear until 10 m/s and VO2max values ranged from 131 to 153 ml.kg-1.min-1. Six of these horses then exercised at 120% of their VO2max until exhaustion. VO2, CO2 production (VCO2), and plasma lactate (La) were measured before and during exercise and through 60 min of recovery. Muscle biopsies were collected before and at 0.25, 0.5, 1, 1.5, 2, 5, 10, 15, 20, 40, and 60 min after exercis...
Evans DL, Rose RJ.Six Standardbred horses were used to evaluate the time course of pulmonary gas exchange, ventilation, heart rate (HR) and acid base balance during different intensities of constant-load treadmill exercise. Horses were exercised at approximately 50%, 75% and 100% maximum oxygen uptake (VO2 max) for 5 min and measurements taken every 30 s throughout exercise. At all work rates, the minute ventilation, respiratory frequency and tidal volume reached steady state values by 60 s of exercise. At 100% VO2 max, the oxygen consumption (VO2) increased to mean values of approximately 130 ml/kg.min, which ...
Landgren GL, Gillespie JR, Fedde MR, Jones BW, Pieschl RL, Wagner PD.We studied mechanisms of O2 transport in 6 adult (2-5 year old) horses at rest and during steady-state exercise on a treadmill (0% slope) at 12 m/s (a submaximal gallop). Oxygen consumption was measured using an open-flow system. Arterial and mixed venous blood samples were simultaneously obtained for measurement of O2 content and hemoglobin concentration. VO2 increased from 1.5 +/- 0.2 L/min at rest to 46.2 +/- 4.8 L/min during exercise. HR increased from a resting value of 36.9 +/- 2.5 bpm to 196.5 +/- 10.9 bpm and the arterio-venous O2 content difference (a-v O2) increased from 4.2 +/- 0.8 ...
Art T, Lekeux P.Exercise-induced variations in their ventilatory mechanics were studied in 8 healthy ponies 4.2 +/- 1.4 years old and weighing 282 +/- 11 kg. Airflow (V), tidal volume (VT), esophageal pressure, mask pressure and electrocardiogram were simultaneously recorded before, during and after a treadmill (incline 8.3 degrees) exercise which consisted of 2 min walking (1.5 m.sec-1), 3 min slow trotting (3.0 m.sec-1) and 3 min fast trotting (3.5 m.sec-1). The results of three consecutive daily measurements were averaged for each pony. Heart rate, minute volume (Ve), respiratory frequency (f) and peak ins...
Martínez R, Godoy A, Naretto E, White A.1. Packed cell volume (PCV) and plasma catecholamines, cortisol and glucose were determined in blood samples obtained from race horses, after competition. 2. All these parameters were higher than basals but catecholamines increased 6-7 times while cortisol was enhanced only by 25%. 3. The increase of glucose and PCV was related to the rise of catecholamines. 4. In samples withdrawn after overnight stress caused by change of horseshoes, it was not possible to find values from basal values significantly different. 5. Influence of nervous temperament was observed only in the higher hematocrit fou...
Littlejohn A, Snow DH.These studies investigated circulatory, respiratory and metabolic responses in four Thoroughbred geldings during the first 400 metres of galloping (mean speed 14.4 +/- 0.38 m.s-1), cantering (mean speed 10.0 +/- 0.61 m.s-1) and walking (mean speed 1.58 +/- 0.05 m.s-1) from a standing start. A radio-controlled device which collected blood samples anaerobically during each 100 m section of the exercise track allowed analyses of changes in and functional relationships of the variables measured. During the 400 m gallop, the mean heart rate (HR) increased from 125 to 201 beats.min-1 and the haemato...
Art T, Lekeux P.Pulmonary function measurements during exercise were tested for accuracy and reproducibility in 5 saddle ponies weighing 267 +/- 9 Kg. Airflow (V) and tidal volume (VT) were measured with a Fleisch pneumotachograph mounted on a face mask. The linearity of the response and the symmetry of this device were carefully checked. Pleural pressure changes were measured by pleural puncture (Ppl) and with an esophageal balloon catheter (Pes). The elastance of the esophageal wall and the effect of the position of the esophageal catheter tip on Pes were also investigated. Airflow, VT, Ppl, Pes, mask press...
Evans DL, Rose RJ.Six detrained Thoroughbred horses performed incremental treadmill tests. Maximal oxygen uptake (VO2max) was measured during exercise by analysis of expired gas. The relationships between oxygen consumption (VO2) and work rate, heart rate (HR), cardiac output (Q), stroke volume (SV) and arteriovenous oxygen content difference [C(a-v)O2] were examined during submaximal and maximal exercise. The relative contributions of blood flow and extraction of oxygen from muscle capillaries were assessed during exercise at VO2max. Mean VO2max was 129.7 +/- 2.9 (mean +/- S.E.M.) ml kg-1 min-1, which occurred...
Forster HV, Pan LG.In humans alveolar ventilation (VA) is adjusted almost perfectly to the metabolic demands of mild and moderate exercise. For example, in exercise transitions and in the steady state, PaCO2 rarely deviates by more than 1 to 3 mmHg from the value at rest. This near-homeostasis contrasts to most other mammalian species; equines for example, demonstrate a progressive hypocapnia and alkalosis as exercise intensity is increased to moderate levels. In equines, the control systems seem programmed for a specific hyperventilation that contributes to maintenance of PaO2 homeostasis. Generally, during hea...
Weber JM, Dobson GP, Parkhouse WS, Wheeldon D, Harman JC, Snow DH, Hochachka PW.This study characterizes the effects of exercise on the cardiac output (Q) and the metabolic rate (VO2) of trained Thoroughbred racehorses. Heart rate, Q, and arteriovenous (a-v)O2 difference were measured at rest and at three levels of submaximal treadmill exercise (1.6 m/s walk and 3-4 m/s trot at 6% incline, and 6.5 m/s horizontal canter). Heart rate and (a-v)O2 difference were also measured during maximal exercise (12.5 m/s gallop, 5% incline) to obtain an estimate of maximum O2 uptake (VO2max). The walk, trot, and canter represented 25, 45, and 55% VO2max. Mean heart rate went from 48.9 (...
Weber JM, Parkhouse WS, Dobson GP, Harman JC, Snow DH, Hochachka PW.Plasma lactate turnover rate of Thoroughbred racehorses was measured by bolus injection of [U-14C]lactate at rest and two levels of submaximal treadmill exercise (3-4 m/s trot, 6% incline, and 6.5 m/s horizontal canter). Our goals were 1) to determine the relative effects of changes in cardiac output and in plasma lactate concentration on turnover rate [using cardiac output data from Weber et al. (28)] and 2) to assess the importance of lactate as a metabolic fuel in a trained animal athlete. Lactate turnover rates were 9.3 mumol.min-1.kg-1 (rest), 75.9 mumol.min-1.kg-1 at the beginning of the...
Bertone JJ, Paull KS, Wingfield WE, Boon JA.M-mode echocardiographic structures, and cardiac function indices, PCV, and total plasma protein values were determined for 34 endurance equine athletes before (base line) and after (after race) a 161-km endurance competition and were compared. The PCV (base-line mean, 37%; after-race mean, 46%) and total plasma protein value (base-line mean, 6.9 g/dl; after-race mean, 7.5 g/dl) increased. Compared with base-line echocardiography, after-race echocardiography indicated an increase in heart rate, as determined from the simultaneous ECG recorded on the echocardiograph (base-line mean, 41 beats/mi...
Pösö AR, Soveri T, Alaviuhkola M, Lindqvist L, Alakuijala L, Mäenpää PH, Oksanen HE.Previous studies in humans have shown that alanine is released from the skeletal muscle in proportion to the work load. We have measured plasma alanine and urea concentrations in well-trained Standardbred and Finnish-bred (cold-blooded) trotters after a graded-intensity exercise and during recovery to study metabolic responses to exercise in this animal model. As controls we measured blood lactate, pyruvate, and glucose concentrations as well as hematocrit values. Metabolic responses to exercise were closely reflected in all these parameters. Plasma alanine increased relatively more than plasm...
Powers SK, Beadle RE, Lawler J, Thompson D.The O2 deficit-O2 debt relationship in ponies was examined at two levels of treadmill exercise. Five healthy ponies exercised for 8 min at two work rates (WR):(1) 50 m/min at 6% grade and (2) 70 m/min at 12% grade. The O2 deficit and O2 debt were calculated using open-circuit measurement of pulmonary gas exchange during the transition from rest to steady-state exercise and during recovery from exercise. The O2 deficit was significantly lower (P less than 0.05) than the O2 debt at each of the two work rates. The means (+/- SEM) for the deficit and the O2 debt, respectively, in liters were: (1) ...
Hodgson DR, Rose RJ.Muscle biopsy samples were collected from the middle gluteal muscle of seven horses undergoing a nine-month endurance training programme. Samples were collected before the programme began and again after three, six and nine months of training. A fifth sample was collected three months after training ceased. Serial muscle sections were reacted histochemically for myosin adenosine triphosphatase after either acid (pH 4.3 and 4.6) or alkaline (pH 10.3) pre-incubation, and muscle fibres identified as type I, IIA, IIB or IIC. The oxidative capacity of individual fibres was assessed, using the reduc...
Bayly WM, Schultz DA, Hodgson DR, Gollnick PD.Experiments were undertaken to determine whether respiratory masks worn by horses exercising strenuously on a treadmill may interfere with normal gas exchange. Four collection systems, two flow-through systems and two incorporating one-way valve systems with subject-generated airflow were studied. Six horses performed standard treadmill exercise tests consisting of a 2-min warm up followed by galloping 1 min each at 8,9, and 10 m/s. Each horse exercised six times while wearing each of the four respiratory masks. Each flow-through system was used twice with flow rates of 2,360 and 3,840 l/min f...
Harris RC, Marlin DJ, Snow DH.To define the metabolic response to maximal exercise in the thoroughbred horse under field conditions, muscle biopsies and venous blood samples were taken from five horses after a single 800-m gallop and from four horses after a single 2,000-m gallop. Muscle and blood samples were also collected during 60 min of recovery. After exercise muscle ATP contents were decreased by 30 +/- 7 (SD) and 47 +/- 3% after the 800- and 2,000-m gallops, respectively. As indicators of purine catabolism, ammonia and uric acid increased in plasma, the accumulation being greater after the 2,000-m gallop. Blood amm...
Manohar M.1. Transmural distribution of myocardial blood flow was studied using 15 micron diameter radionuclide-labelled microspheres in six normal ponies and nine splenectomized ponies at rest, and during maximal exercise performed without as well as with adenosine infusion (3 microM kg-1 min-1). The splenectomized ponies were also studied during submaximal exercise performed at 75% of the workload. 2. Maximal exertion in normal ponies increased heart rate (348%), mean arterial blood pressure (40.9%), rate-pressure product (563%), arterial O2 content (43.2%), and mean pulmonary artery pressure (247%). ...
Denny JE.Horses receiving a pelleted or cubed dietary supplementation with roughage, have serum inorganic phosphate (SIP) concentrations consistently below an accepted mean of 1,032 mmol l-1 or 3, 1 mg dl-1. Further, it has been reported that the best eight, two-year-old Irish Thoroughbred track performers of 51 horses tested over a 10 month period, had significantly lower SIP concentrations than the worst eight track performers. In an endeavour to assess any nutritive effect on SIP concentrations and also to assess any effect of SIP concentrations on track performance, metabolic blood profiles from 30...
Drevemo S, Fredricson I, Hjertén G, McMiken D.Ten trotting Standardbred colts were recorded by high-speed cinematography at the ages of eight, 12 and 18 months. The horses were trotting on a treadmill operating at 4.0 m/secs. Five horses were subjected to a programme of intensified training from eight months of age, whereas the others were not trained and acted as controls. The films were analysed on a semi-automatic film-reading equipment and a number of variables used to demonstrate the gait symmetry were calculated and scaled by computer. Certain differences between left and right diagonal and contralateral pair of limbs, respectively,...
Li WI, Chen CL.A specific RIA for beta-endorphin (B-END) was developed to measure horse plasma levels of B-END-like material (B-END-LI) during exercises and shipping. Three exercise speeds and durations were: trot at 260-300 m/min for 10 min; slow gallop at 390-420 m/min for 5 min and fast gallop at 700-800 m/min for 2 min. Blood samples were taken from 4 horses before, immediately after, 30 and 60 min after exercise. Trotting increased plasma B-END-LI from a basal level of 109 +/- 7 pg/ml to 172 +/- 22 at the end of exercise and returned to 127 +/- 17 and 107 +/- 10 pg/ml at 30 and 60 min after exercise. Si...
Manohar M.It has been reported in exercising ponies that O2 supply to all regions of the brain increased primarily due to a large increment in CaO2 and it was implied that this may reflect a generalized increase in brain metabolism during strenuous exercise. Splenectomy ameliorates the rise in CaO2 observed with exercise in ponies. Thus, the objective of the present study was to examine changes in regional brain blood flow and O2 supply of splenectomized ponies with sub-maximal and maximal exercise and to compare these data with previous observations in normal ponies. It was reasoned that in the absence...
Pan LG, Forster HV, Bisgard GE, Lowry TF, Murphy CL.Our purpose was to assess compensatory breathing responses to airway resistance unloading in ponies. We hypothesized that the carotid bodies and hilar nerve afferents, respectively, sense chemical and mechanical changes caused by unloading, hence carotid body-denervated (CBD) and hilar nerve-denervated ponies (HND) might demonstrate greater ventilatory responses when decreasing resistance. At rest and during treadmill exercise, resistance was transiently reduced approximately 40% in five normal, seven CBD, and five HND ponies by breathing gas of 79% He-21% O2 (He-O2). In all groups at rest, He...
McKeever KH, Schurg WA, Jarrett SH, Convertino VA.The purpose of this study was to determine if a chronic hypervolemia would accompany endurance exercise training in the horse. Six mature previously inactive horses were utilized for this study. During the 5-wk experiment, five of the horses were trained for 14 d on a treadmill ergometer at a constant treadmill speed of 5.6 km X hr-1 and a constant grade of 12.5% for graduated lengths of time. One horse was trained by lunging at a trotting pace in a round pen. Following training, plasma volume increased by 4.7 1 (29.1%, P less than 0.05). Although the rate of daily water intake did not change ...
Powers SK, Beadle RE, Thompson D, Lawler J.The purpose of these experiments was to examine the temporal pattern of arterial carbon dioxide tension (PaCO2) to assess the relationship between alveolar ventilation (VA) and CO2 return to the lung at the onset and offset of submaximal treadmill exercise. Five healthy ponies exercised for 8 min at two work rates: 50 m/min 6% grade and 70 m/min 12% grade. PaCO2 decreased (P less than 0.05) below resting values within 1 min after commencement of exercise at both work rates and reached a nadir at 90 s. PaCO2 decreased maximally by 2.5 and 3.5 Torr at the low and moderate rate, respectively. Aft...
Kuwabara M, Inukai N, Inanami O, Miyake YI, Tsunoda N, Maki Y, Sato F.Hotbred (Thoroughbred) horses were grouped into three classes according to the levels of constant physical exercise (foals, 6 months old; racing horses, 5 years old; horses for breeding, 6-10 years old), and lipid peroxide levels in their sera were measured as thiobarbituric acid-reactive substances. No significant differences were observed among them. The superoxide-scavenging abilities of sera were measured next; to examine the antioxidative properties of hotbreds, and were found to be highest in the racing horses. The higher scavenging ability of the racing horses might contribute to keep t...
Manohar M, Goetz TE, Hassan AS.Work is required to establish the role of endogenous nitric oxide (NO) in metabolism of resting and exercising horses. Objective: To examine the effects of NO synthase inhibition on O2 extraction and anaerobic metabolism at rest, and during submaximal and maximal exertion. Methods: Placebo and NO synthase inhibition (with Nomega-nitro-L-arginine methyl ester [L-NAME] administered at 20 mg/kg bwt i.v.) studies were performed in random order, 7 days apart on 7 healthy, exercise-trained Thoroughbred horses at rest and during incremental exercise leading to 120 sec of maximal exertion at 14 m/sec ...
Busse NI, Gonzalez ML, Wagner AL, Johnson SE.Optimal athletic performance requires meeting the energetic demands of the muscle fibers, which are a function of myosin ATPase enzymatic activity. Skeletal muscle with a predominant oxidative metabolism underlies equine athletic success. Sodium butyrate, a short-chain fatty acid, can affect muscle fiber composition in pigs. To determine if a similar scenario exists in horses, 12 adult Thoroughbred geldings (7.4 ± 0.6 yr of age; mean ± SEM) were fed 16 g of calcium butyrate (CB) or an equivalent amount of carrier (CON) daily for 30 d in a crossover design. Middle gluteal muscle biopsies were...
Hallebeek JM, van Doorn DA, Beynen AC.In horses that exercise intensively (for example, event horses in training) the intake and energy requirements were compared on the basis of a diet record and estimates of energy required for exercise. Daily net energy intake over a 7 days period was on average 30% (n = 15) higher than the net energy requirement. Since the horses had a constant body weight, and thus were in energy balance, the energy intake was overestimated and/or the energy requirement was underestimated. The intake of digestible protein was 92% higher than the protein requirement. This study illustrates the problems concern...
Greene HM, Hurson MJ, Wickler SJ.Despite the common use of equids as visitors to high altitude mountainous environments, there are a paucity of carefully orchestrated scientific approaches. Further, again as a function of a common perceived advantage of mules over horses in these similar environments there are needs for controlled comparisons between these 2 equids. Objective: To measure haematological and respiratory function in horses and mules at low altitude (225 m), at rest and post exercise. In addition the rate and magnitude of these changes were followed over a 13 day period at high altitude (3800 m) to contrast accli...
Rolling is a natural behavior of equids that is beneficial to their well-being. However, more intensive domestic environments offer fewer opportunities for animals to roll, neglecting its importance. We believe that the inclusion of recreational areas for animals, containing substrates and conditions that encourage the occurrence of natural behaviors, is essential to promote their well-being. Therefore, we evaluated the preference of horses (; n = 8) and mules (E. asinus x E. caballus; n = 8) for different rolling substrates (sand, grass, manure), and the influence of this behavior on thermo...
de Graaf-Roelfsema E, Keizer HA, van Breda E, Wijnberg ID, van der Kolk JH.To determine the influence of intensified training and subsequent reduced training on glucose metabolism rate and peripheral insulin sensitivity in horses and identify potential markers indicative of early overtraining. Methods: 12 Standardbred geldings. Methods: Horses underwent 4 phases of treadmill-based training. In phase 1, horses were habituated to the treadmill. In phase 2, endurance training was alternated with high-intensity exercise training. In phase 3, horses were divided into control and intensified training groups. In the intensified training group, training intensity, duration, ...
Mitten LA, Hinchcliff KW, Pate JL.The effect of inhibition of cyclooxygenase activity on the hemodynamic response to exertion was examined in 6 horses. Rates of O2 consumption and CO2 production and carotid, pulmonary arterial, and right atrial pressures were measured while the horses performed a standardized exercise test on a treadmill after treatment with phenylbutazone or a placebo. Phenylbutazone (8.8 mg/kg p.o. for 2 days and 4.4 mg/kg i.v. 60 min before exertion) abolished the exertion-induced increases in plasma 6-ketoprostaglandin F1 alpha and thromboxane B2 concentrations, confirming inhibition of cyclooxygenase acti...
Manohar M, Duren SE, Sikkes B, Day J, Baker JP.Distribution of blood flow among various respiratory muscles was examined in 8 healthy ponies during submaximal exercise lasting 30 minutes, using radionuclide labeled 15-microns diameter microspheres injected into the left ventricle. From the resting values (40 +/- 2 beats/min; 37.3 +/- 0.2 C), heart rate and pulmonary arterial blood temperature increased significantly at 5 (152 +/- 8 beats/min; 38.6 +/- 0.2 C), 15 (169 +/- 6 beats/min; 39.8 +/- 0.2 C), and 26 (186 +/- 8 beats/min; 40.8 +/- 0.2 C) minutes of exertion, and the ponies sweated profusely. Mean aortic pressure also increased progr...
Kozlov SA.The results of applying N. N. Sirotinin's concept of the use of hypoxic adaptation to enhance working capacity are given. There is evidence for the efficiency of adaptation of trotters to two hypoxias: to hypoxic hypoxia (in the midmountains) and to exercise hypoxia (during interval training under the conditions of Moscow) for increasing their performance. These studies demonstrated that in the midmountains, the trotters had more infrequent respiration, increased respiratory and minute respiratory volumes which were more obvious by the end of a monthly mountain stay. The monthly training of tr...
Kovár J.The possibility of using the test for pulse-rate response to gradated load in the evaluation of the endurance component of horse performance (in other words, response to the degree of horse adaptation to load) is discussed in detail. A mathematic-statistical analysis of regression coefficients is performed in the equations of the dependence of pulse rate on speed obtained in 278 three years old horses in the period following the termination of the basic training (145 Bohemian Warm-Blooded horses, 115 Kladrub Black horses and 18 English Half-Breds). A ten-score scale is calculated on the basis ...
Pringle J, MacMillan K, Briand H, Stämpfli H.The heart rate changes during routine training in a group of 8 actively racing Standardbreds were used to simulate the training work on a treadmill (ST) and indices of exercise compared to maximal effort (MAX) on the treadmill. The following parameters were recorded during treadmill work: heart rate, velocity, O2 consumption, respiratory and stride frequency, and stride length. Blood lactate concentrations were measured before and after each work test. Heart rate during simulated training was mean +/- s.d. 87.8 +/- 5.5% heart rate in MAX, one of the 8 horses working 0.05), being higher during...
Larsdotter S, Holm L, Dahlborn K, Jansson A, Josefsson M, Ridderstråle Y.Sweat gland morphology and carbonic anhydrase (CA) distribution was studied after exercise in trained and untrained horses using a histochemical technique and light microscopic image analysis. Three trained and 3 untrained Standardbred trotters performed an exercise test (20 min trot at 6 m/s with 5 min walk at 1.8 m/s in the beginning and end) on a high-speed treadmill at 35 degrees C. Skin biopsies were taken before exercise and after trot. The fluid loss after exercise was 10, 12 and 12 g/kg bwt in the untrained horses and 4, 6 and 11 g/kg in the trained. Trained horses had a larger cell ar...
Muñoz A, Esgueva M, Gómez-Díez M, Serrano-Caballero JM, Castejón-Riber C, Serrano-Rodríguez JM.Changes in blood pressure (BP) during acute hypertension in response to angiotensin-converting enzyme inhibitors (ACEIs) have not been investigated in normotensive horses. In this study, six healthy horses were subjected to five trials, consisting in a treadmill exercise workload of 8 m/s for 1 min, 2 h after oral administration (PO) of placebo (0 mg/kg), enalapril (2.0 mg/kg), quinapril (1.0 mg/kg), ramipril (0.2 mg/kg) or benazepril (0.5 mg/kg). Serum angiotensin converting enzyme (ACE) activity was measured and systolic (SBP) and diastolic (DBP) blood pressures were recorded...
Bertuglia A, Pagliara E, Manca F, Pozzolo P, Mannelli A.The objective of this study was to report recovery time, retirement rate, racing performance, and presence of compensation pattern after musculoskeletal injuries (MSIs) in Standardbred racehorses (STBRs). This is a retrospective single open-cohort study, enrolling 356 STBRs in training in a single racetrack. Musculoskeletal injury was defined as any training-related injury after which the horse did not train for at least 15 days. The first and second MSIs encountered during the horse's racing career were considered. Medical records, training logbooks, and racing data were reviewed to determin...
Stampfli HR, Misiaszek S, Lumsden JH, Carlson GP, Heigenhauser GJ.The plasma proteins are a significant contributor to the total weak acid concentration as a net anionic charge. Due to potential species difference, species-specific values must be confirmed for the weak acid anionic concentrations of proteins (Atot) and the effective dissociation constant for plasma weak acids (Ka). We studied the net anion load Atot of equine plasma protein in 10 clinically healthy mature Standardbred horses. A multi-step titration procedure, using a tonometer covering a titration range of PCO2 from 25 to 145 mmHg at 37 degrees C, was applied on the plasma of these 10 horses...
Clark L, Bradley EJ, Mackechnie-Guire R, Taylor A, Ling J.Asymmetry of horses and humans is widely acknowledged, but the influence of one upon the other during horse riding is poorly understood. Riding simulators are popular for education of beginners and analysis of rider biomechanics. This study compares trunk kinematics and saddle forces of 10 experienced riders (ER) and 10 novice riders (NR) performing rising trot on a simulator. Markers were placed on the 4th lumbar (L4) and 7th cervical (C7) spinous processes, and both acromion processes. Displacements in three axes of motion were tracked using 10 high-speed video cameras sampling at 240 Hz. Di...
Johnson SE, Barshick MR, Gonzalez ML, Riley JW, Pelletier ME, Castanho BC, Ealy EN.Strenuous exercise can cause tissue damage, leading to an extended recovery period. To counteract delayed post-exercise recovery, a commercial product containing L-carnitine (AID) was tested in adult horses performing consecutive exercise tests to exhaustion. Fit Thoroughbreds were administered an oral bolus of placebo (CON) or AID prior to performing an exercise test to exhaustion (D1). The heart rate (HR) and fetlock kinematics were captured throughout the exercise test. Blood was collected before, 10 min and 1, 4 and 6 h relative to exercise for the quantification of cytokine (1, 8, 10, ) g...
Lindner A.The mean maximal lactate concentration of horses after exercise (Lamax) amounted to 4.5 +/- 2.2 mmol/l for gallop workouts of less than 11 m/s and more than 180 s (n = 35; category A), at more than 11 m/s and less than 180 s duration (n = 17; category B) to 16.3 +/- 4.8 mmol/l and at less than 11 m/s and less than 180 s duration (n = 10; category C) to 4.6 +/- 1.6 mmol/l. Lamax was always measured immediately after exercise following exercise of categories A and C. But for exercise bouts of category B Lamax was measured between the first and the tenth minute after exercise. Following exercise ...
Soroko M, Górniak W, Godlewska M, Howell K.The aim of this study was to evaluate the influence of training on body surface temperature over the joints in racehorses, measured by infrared thermography. The study involved monitoring of 14 Thoroughbred racehorses in 6 imaging sessions over a period of 3 months. Temperature measurements of the forelimb and hindlimb joints were made before and just after training. Joint temperature of limbs increased significantly after training. Environmental temperature had a statistically significant influence on surface temperature over the joints. The lowest surface temperatures were recorded over the ...
Fortier J, Deley G, Julliand V.This study aimed at quantifying energy expenditure during 4 specific training exercises, that is, promenade, jogging, parcours, and interval exercises, using field measurements of oxygen consumption and heart rate in trotters. Six animals performed 2 preliminary tests to determine their individual maximum velocity and to establish their individual oxygen consumption/heart rate relationship from an incremental test. Then, they undertook each of the 4 specific exercises separated by 1 wk to avoid fatigue. The intensity of the 4 exercises was expressed in percent of individual maximum velocity as...
McKeever KH, Malinowski K, Christensen RA, Hafs HD.The purpose of this experiment was to test the hypothesis that chronic (89 days) administration of recombinant equine somatotropin (eST) would increase aerobic capacity and improve exercise performance in old mares. Fifteen, healthy, unfit, aged (20-26 year old) mares were randomly assigned to a treatment (eST, 12.5 mg day-1 in 3 ml glycine/manitol buffer, s.c., n = 7) or control (vehicle, 3 ml day-1, s.c., n = 8) group. Aerobic capacity and exercise performance were measured using a standardized exercise test (SET) performed on a high speed treadmill. Tests were conducted before (-21 days), d...
Ehrlich PJ, Seeherman HJ, Morris E, Kolias C, Cook WR.The effect of left recurrent laryngeal neuropathy (LRLN) on the metabolic cost of locomotion (MCL) and peak aerobic power (VO2peak) was evaluated in four trained Thoroughbred racehorses. Oxygen consumption (VO2), carbon dioxide production (VCO2), venous lactate concentrations (LAC), and heart rate (HR) were measured during a treadmill exercise test (TET). Each horse performed the exercise test four times, alternating between normal upper airway function and reversibly induced LRLN. Subcutaneous infusion of 2% mepivicaine, a local anesthetic, into the region were the left recurrent laryngeal ne...
Danek J, Flosadóttir S.The purpose of this work was to assess the impact of a specific equestrian training, conducted in winter weather conditions, on the thermovision temperature distribution of a rider's body surface. The study included a riding pair with 12 years of experience (female rider, aged 25, sports active and 16-year-old horse, Trakehner breed). Methods: The study included the temperature distribution of selected parts of the rider's body (the area of the right and left shoulder blade, chest and lumbar section, and the region of the left and right cross) was carried out before and after recreational, jum...
Kallings P, Persson SG, Essén-Gustavsson B.Since nonsteroidal anti-inflammatory drugs, such as flunixin, on account of their anti-inflammatory and analgesic properties, are used in both racing and equestrian sport horses, the question has been raised as to whether these drugs affect the physiological responses to exercise and thus performance potential. Objective: The aims of this investigation were to study the effects of flunixin on cardiorespiratory, metabolic and locomotor parameters in horses during intense treadmill exercise. Methods: Six Standardbred trotters underwent an incremental treadmill exercise test to fatigue, without d...
Guhl A, Lindner A, von Wittke P.To examine the reproducibility of blood lactate-running speed curve parameters derived by a curve-fit equation and by linear interpolation from the results of 4-speed tests of sport horses under field conditions. Methods: Thoroughbreds completed 10 test pairs with 3 to 11 days between tests and retest. Methods: 7 Thoroughbreds. Methods: The 4-speed test consisted of 4 runs over a distance of 2,110 m. Exercise intensity was increased by 1 m/s for each run. Blood lactate concentration measured after each run was plotted against running speed to determine the blood lactate-running speed relation....
Kritchevsky J, Olave C, Tinkler S, Tropf M, Ivester K, Forsythe L, Couetil L.The use of thyroid supplement is pervasive in athletic horses although its effects on measures of performance are not known. Objective: One purpose of this study was to determine whether supra-physiologic doses of levothyroxine affect the velocities at which blood lactate was greater than 4 mmol/L (VLa4 ) and heart rate was over 150 (V150 ) and 200 (V200 ) beats per minute respectively. Additionally, a survey of post-race blood samples was also conducted to determine whether high thyroxine concentrations were common in racehorses. Methods: A randomised, crossover, trial was performed in six h...
Seeherman HJ.The use of motorized treadmills has made it possible to evaluate equine poor performance with sophisticated diagnostic techniques during peak exercise. Treadmill exercise tests currently being used for clinical evaluations include treadmill gait analysis, dynamic hoof balancing, endoscopic evaluation of upper airway function, and exercise performance profiling. Large motorized treadmills (1 to 1.5 m in width and 4 to 5 m in length) are best suited for clinical evaluations. Ideally, the treadmill should be installed in-ground using a pit. This type of installation results in the tread surface b...
Cornelisse CJ, Holcombe SJ, Derksen FJ, Berney C, Jackson CA.To determine the effect of a tongue-tie on upper airway mechanics in exercising horses. Methods: 5 Standardbreds. Methods: Peak inspiratory and expiratory tracheal and pharyngeal pressures and airflow were measured while horses exercised on a treadmill with and without a tongue-tie. Respiratory rate was also measured. Horses ran at speeds that corresponded to 50 (HR50), 75, 90 (HR90), and 100% of maximal heart rate. The tongue-tie was applied by pulling the tongue forward out of the mouth as far as possible and tying it at the level of the base of the frenulum to the mandible with an elastic g...
