Topic:Athletic Horses
The topic of athletic horses encompasses the study and analysis of horses that are trained and conditioned for performance in various disciplines such as racing, show jumping, dressage, and eventing. These horses are subject to specialized training regimens and nutritional plans to optimize their physical capabilities and performance outcomes. Research in this area often focuses on aspects such as biomechanics, cardiovascular fitness, muscle physiology, and injury prevention. This topic includes a collection of peer-reviewed research studies and scholarly articles that explore the physiological adaptations, training methodologies, and health management practices associated with maintaining and enhancing the performance of athletic horses.
Heat acclimation improves regulation of plasma volume and plasma Na(+) content during exercise in horses. This study determined the plasma volume (PV) and ion responses to heat acclimation and exercise in six trained Thoroughbred horses during 21 days of exposure to heat and humidity (33 degrees C, 83% relative humidity) for 4 h/day. During the 2nd h on days 0, 3, 7, 14, and 21, horses performed a standardized treadmill test, running at 50% of peak O(2) uptake until pulmonary artery temperature reached 41.5 degrees C. Heat acclimation resulted in an increase in PV from 21.3 +/- 1.1 liters on day 0 to 24.3 +/- 1.0 liters on day 14, returning to 22.6 +/- 0.9 liters on day 21. The corresponding total...
Dynamic tracheal collapse as a cause of exercise intolerance in a thoroughbred. A 2-year-old Thoroughbred filly was admitted to the hospital for evaluation of exercise intolerance. Resting videoendoscopic evaluation (i.e., while the horse was standing) of the nasopharynx and trachea revealed right arytenoid paresis and a tracheal defect that was 100 cm distal to the external nares. Surgery, consisting of a right prosthetic laryngoplasty, was performed. However, postoperative videoendoscopic evaluation revealed minimal abduction of the affected arytenoid cartilage. Dynamic videoendoscopic evaluation (i.e., while the horse was exercising) revealed the right arytenoid to be ...
The use of a polypropylene mesh for treatment of ruptured collateral ligaments of the equine metatarsophalangeal joint: a report of two cases. The prognosis of ruptured collateral ligaments of the metacarpophalangeal or metatarsophalangeal joint in horses is usually considered to be poor, especially for future athletic performance. The main problem is the development, due to joint instability, of osteoarthritis, which may result in persistent lameness. In this paper a surgical technique is described in which joint stabilisation is realised by using a polypropylene mesh as a substitute for the ruptured ligaments, with the subsequent application of a cast for 7 weeks. The technique was successfully performed in 2 horses with ruptured l...
Muscle adenine nucleotide degradation during submaximal treadmill exercise to fatigue. The aim was to investigate metabolic response in muscle during submaximal treadmill exercise to fatigue, with a special emphasis on adenine nucleotide degradation products such as inosine monophosphate (IMP) in muscle and hypoxanthine, xanthine and uric acid in plasma. Five Standardbred trotters performed treadmill exercise on 2 occasions, once at 7 m/s and once at 10 m/s. Venous blood samples were taken at rest, during exercise and at the end of exercise. Muscle biopsies were taken before and after exercise and muscle temperature was measured before and after exercise. Running time differed a...
Cardiac responses to training in 2-year-old thoroughbreds: an echocardiographic study. Guided M-mode echocardiography was performed in seven 2-year-old Thoroughbreds before commencement of commercial flat-race training, and 18 weeks later, when all horses were either racing regularly (5 horses), or at racing fitness (2 horses). M-mode echocardiography was performed using a 2.5 MHz annular phased array ultrasound transducer and a Vingmed 800 Supervision echocardiograph. Images were obtained from the right hemithorax; a short axis view of the left ventricle (LV) at the level of the chordae tendinae was used to position the M-mode cursor. The following variables were measured: left...
Contributions of equine exercise physiology research to the success of the 1996 Equestrian Olympic Games: a review. Following public concern about the weather conditions for the 1996 Olympic Games in Atlanta an international research programme was initiated. The primary objective of this effort was to identify strategies for ensuring welfare of horses competing in the heat. Field observations of horses during the endurance test of 3-day events in Europe, Canada, and the USA characterised the work effort of this form of competition; laboratory treadmill studies assessed limitations to performance of heat and humidity, explored the relationships of thermoregulatory demands to the phases of the competition and...
Sweat production and localisation of carbonic anhydrase in the equine sweat gland during exercise at two ambient temperatures. The aim of this investigation was to study sweat production during exercise at 2 ambient temperatures (20 degrees C and 35 degrees C) and the concurrent localisation of carbonic anhydrase (CA) in the sweat gland. Horses develop alkalosis during prolonged exercise and the sweat contains HCO3-. Carbonic anhydrase is therefore of interest since it catalyses the reaction CO2 + H2OHCO3- + H+. Four standardbred trotters performed an exercise test. Skin biopsies were taken from the neck, and sweat rate, blood and skin temperatures were measured. There was a close relationship between sweat rate, temp...
The effects of training on ventilation and blood gases in exercising thoroughbreds. The effects of training on ventilation and blood gases during exercise were investigated in 6 clinically normal, detrained Thoroughbred horses. They underwent a 16 week training programme similar to the type frequently used for Thoroughbred racehorses in Great Britain. Standardized treadmill exercise tests (2 min canter at 8 and 10 m/s C8 and C10[ and 2 min gallop at 12 m/s [G12], on a level surface) were performed prior to and after 16 weeks of training. Respiratory flow rates were measured using ultrasound flow transducers. Blood samples were drawn from a transverse facial artery and the rig...
Effects of frusemide on electrolyte and acid-base balance during exercise. This study was undertaken to evaluate the effects of frusemide on the concentration of plasma electrolytes and the relationship between changes in electrolyte concentration and the simultaneous changes in acid-base balance in arterial and venous blood during intense exercise. Five exercise-conditioned Thoroughbred horses were exercised on a high-speed treadmill at a slope of 10% at speeds known to exceed VO2max. Horses participated in 3 randomised exercise trials in which they received either placebo (control), low-dose frusemide (0.5 mg/kg bwt), or high-dose frusemide (1.0 mg/kg) 4 h prior to...
Blood gas changes during incremental and sprint exercise. We investigated and compared arterial blood gas and ventilatory changes during rapid acceleration sprint and during incremental treadmill exercise. Seven clinically normal racehorses completed standardised incremental exercise tests and rapid acceleration tests at speeds calculated to elicit 115% VO2max. Arterial oxygen tension decreased (P < 0.001) between 15 s (mean +/- s.d. 103.8 +/- 14.3 mmHg) and 30 s (85.0 +/- 7.7 mmHg) after the onset of rapid acceleration exercise, but did not change significantly during the remainder of the sprint. This was accompanied by an increase in PaCO2 of 5....
Biomechanical analysis of horse shoeing. Most of the principles of farriery have been derived from practical experience and traditional skills of individual farriers. To date, there has been little done in the way of good science and few publications have appeared to advance the discipline. Therefore, opinions or policies on horse shoeing vary greatly between farriers and members of the veterinary profession. The aim of this workshop was to present the latest information on biomechanical analysis of horse shoeing as it relates to modern day farriery and could have direct benefits for the future of shoeing in performance horses.
Muscular and metabolic responses to moderate-intensity short-term training. The objectives of this study were to determine the effects of 10 consecutive days of moderate-intensity training on 1) the muscular metabolic response to exercise at 100% of the pre-training maximum rate of oxygen consumption (VO2max); and 2) mitochondrial enzyme markers (citrate synthase, CS; succinate dehydrogenase, SDH; 3-hydroxy-acyl-CoA dehydrogenase, HAD) of oxidative capacity in middle gluteal muscle. Six mature, unfit Thoroughbred horses completed both incremental (for determination of VO2max) and high-intensity exercise protocols before (HI1) and after (HI2) training. Training consist...
Relationship between VO2max, heart score and echocardiographic measurements obtained at rest and immediately following maximal exercise in thoroughbred horses. We evaluated the relationships of heart score (HS) and echocardiographic measures to maximal oxygen consumption (VO2max), maximal cardiac output (Qmax), and maximal stroke volume (SVmax). Six fit, mature Thoroughbred horses weighing (mean +/- s.e.) 487 +/- 11 kg were run 4 times on an inclined (10%) treadmill. Each run consisted of a 3 min warm-up at 4 m/s followed by completion of an incremental exercise test in which each horse ran until VO2max was reached. Arterial and mixed venous blood was collected to determine arteriovenous oxygen content difference C(a-v)O2[ in the last 15 s of exercis...
Effects of conditioning horses with lactate-guided exercise on muscle glycogen content. The effects of 3 different conditioning programmes on muscle glycogen concentration in horses were examined. Speed of exercise was selected according to the blood lactate values for each horse derived from a standardised exercise test before beginning a conditioning programme. Six 2-year-old Haflinger stallions were assigned randomly to one of 3 conditioning programmes according to a 6 x 3 latin square design: 45 min at their individual v1.5 or v2.5 and 25 min at v4. Each conditioning programme lasted 6 weeks (21 exercise sessions), followed by 5 weeks without conditioning (resting period). Al...
Is ventilation during maximal exercise limited by dynamic airway closure? A study was undertaken to find if the reason why horses hypoventilate when running is that they experience expiratory flow limitation due to dynamic airway closure. To test this hypothesis, we measured peak expiratory flows on a Thoroughbred galloping on a treadmill and hypoventilating and compared those flows with the peak dynamically-limited flow that the same horse could achieve during a forced expiratory flow-volume manoeuvre. At the approximate lung volumes at which the horse was ventilating while running, it did not appear to be mechanically limited and appeared to have reserve capacity ...
Skeletal myosin heavy chain composition and carriage training. Three different myosin heavy chain (MHC) isoforms have been identified in the equine gluteus medius muscle: the slow or MHC-I and the 2 fast MHC-IIA and MHC-IIX isoforms. They are distributed in 3 fibre types containing a single MHC (I, IIA, IIX) and 2 hybrid types co-expressing 2 isoforms (I + IIA, IIA + IIX). The aim of this study was to determine if heavy carriage training alters skeletal MHC composition in horses. Fourteen Andalusian mares age 42-46 months were used. Seven horses were used as controls to estimate the effects of growth on muscle. The remaining 7 horses underwent a training ...
Environmental stress and 3-day eventing: effects of altitude. Three-day event horses are subject to various external environmental stresses including changes in ambient temperature, humidity, altitude, and test severity. Considerable research on the adverse effects of increased heat and humidity preceded the 1996 Olympic Summer Games in Atlanta, Georgia USA, but no research has been done previously on the effects of altitude on 3-day eventing. Physical and venous blood gas data were collected on horses (n = 24) competing in the High Prairie Preliminary (CCN*) and Intermediate (CCN**) 3-day events and Preliminary Horse Trials in Parker, Colorado (1900 m a...
Frusemide and weight carriage alter the acid:base responses of horses to incremental and to brief intense exertion. We speculated that frusemide would attenuate the acidosis associated with intense exertion, and that weight carriage would mitigate this effect. Therefore, in each of 2 experiments we measured pulmonary artery and systemic arterial blood pH, PCO2, PO2 and pulmonary artery temperature in 9 horses during exertion on a treadmill after each of 3 treatments. The treatments were: 1) injection of saline solution (C), 2) injection of frusemide (1 mg/kg bwt, i.v. 4 h before running) (FU) and 3) injection of frusemide (F) as for FU and the horses carried weight equal to that lost in the 4 h after frusem...
Effect of exercise on bone density in distal regions of the equine third metacarpal bone in 2-year-old thoroughbreds. The present study addressed the question of whether training induces changes in bone density in the younger racehorse in regions relevant to the genesis of the common sagittal condylar fracture pattern and, if so, the nature of such alteration. Third metacarpal bones (McIII) were obtained from 12 experimental Thoroughbred, unbroken fillies, age 18.1-21.0 months at entry to the study. Six (Group E) undertook 19 weeks of progressive high intensity exercise on a high-speed treadmill at 3% incline. Six (Group C) walked 40 min each day. Clinical bone density was studied by Computed Tomography (CT) ...
Hyperbolic relationship between time-to-fatigue and workload. The power:time-to-fatigue relationship for high-intensity exercise in man is useful in determining anaerobic work capacity. The purpose of this study was to determine the nature of this relationship in horses. Eight Standardbred horses performed 5 or 6 run-to-fatigue trials on a treadmill. Exercise intensities were chosen to induce fatigue in 30 to 240 s. The order of trials was randomised for each horse, but balanced overall for the first 4 trials. The data for power (independent variable) and time-to-fatigue (dependent variable) were tested for goodness of fit to hyperbolic, linear and expon...
Pulmonary vascular resistance of horses decreases with moderate exercise and remains unchanged as workload is increased to maximal exercise. This study was carried out to examine changes in pulmonary vascular resistance (PVR) induced by moderate and strenuous exercise; the objective being to understand why pulmonary artery blood pressure of exercising horses increases progressively as work intensity increases. Pulmonary arterial and wedge pressures (referenced at the point of the left shoulder) were determined simultaneously with cardiac output in 2 groups of healthy, sound, exercise-trained horses. Horses in Group 1 (n = 8) were studied at rest and during exercise performed at 8 and 13 m/s; the latter workload eliciting maximal he...
Should equine athletes commence training during skeletal development?: changes in tendon matrix associated with development, ageing, function and exercise. In human athletes, conditioning, training and competition are commenced before skeletal maturity. Yet in equine athletics, racing of young (age 2 years) horses remains contentious. Tendon injury persists as major causes of wastage in equine athletes. Minimising injury and associated welfare issues could involve a radical approach to the timing and implementation of conditioning and training. Tendons were examined from Thoroughbreds, Dutch Warmblood foals, working horses and also a group of wild horses to evaluate effects of age, function and exercise. Gross mechanical properties did not differ...
Comparison of exercise variables measured during intensity of simulated training to variables at maximal effort in standardbreds. 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...
Haematological and biochemical responses to training and overtraining. We sought a physiological marker of overtraining in horses, using commonly practised field and laboratory tests to allow early prediction and treatment of the syndrome. Thirteen Standardbred horses were trained as follows: phase 1 (endurance, 7 weeks), phase 2 (high intensity, 9 weeks) and phase 3 (overload, 18 weeks). In phase 3 the horses were divided into 2 groups: overload training (OLT) and control (C). The OLT group exercised at greater intensities, frequencies and durations than the C group. Overtraining occurred after 31 weeks and was defined as a significant decrease in treadmill run ...
Electrolyte and glycerol supplementation improve water intake by horses performing a simulated 60 km endurance ride. To replace electrolytes lost in sweat during endurance competitions, riders frequently supplement horses with hypertonic oral electrolyte pastes. To determine whether this practice and concurrent administration of the so-called hyperhydrating substance glycerol are of benefit, weight loss, voluntary water intake, plasma osmolality, and plasma protein and electrolyte concentrations were measured in 6 Arabian horses supplemented with a total of 2.4 ml/kg bwt of water (W); 0.2 g/kg bwt KCl and 0.4 g/kg bwt NaCl in 2.4 ml/kg bwt of water (E); or 0.2 g/kg bwt KCl and 0.4 g/kg bwt NaCl in 2.4 ml/kg ...
Influence of frusemide on dynamic cardiac variables during exercise. Exercising horses have extremely high right and left atrial pressures. Limitation in ventricular function (i.e. relaxation) may play a role in these high pressures. We studied relaxation characteristics of the right ventricular myocardium and the impact of frusemide (2.0 mg/kg bwt i.v.) on these characteristics in horses exercising at 8, 10, 12 and 14 m/s. Exercise tests were performed 4 h after administration of frusemide. Right ventricular (RV) pressure was analysed using Fast Fourier Transform techniques to remove non cardiac components of the pressure signal. Mean right atrial (RA) pressur...
Maximal exercise transiently disrupts hormonal secretory patterns in standardbred geldings. Basal concentrations of cortisol (CORT), beta-endorphin (beta EP), growth hormone (GH) and testosterone (T) and their disruption during 32 h of recovery after treadmill exercise were investigated in 4 geldings. Blood samples were collected from resting horses every 20 min between 0600-1000 and 1500-1900 h, and hourly between 1000-1500 h on 3 consecutive days. Treadmill exercise tests comprising 2 min intervals at 30, 50, and 70% VO2max then to fatigue at 100% VO2max were conducted between 1020-1130 h on Day 2. Blood was collected before, during and 15, 30, 60 and 90 min after exercise. Mean (C...
Effects of low- and moderate-intensity training on metabolic responses to exercise in thoroughbreds. This experiment was undertaken to determine whether there were differences in cardiorespiratory, haematological and muscular responses in horses trained at either low or moderate intensities. Ten Thoroughbred horses previously rested in paddocks for 4 months were trained 5 days/week for 9 weeks. Horses were allocated randomly into fast or slow groups and exercised the same distance each day. Training distances were 1600 m in Weeks 0 and 1 up to 4000 m in Week 9. The fast group were trained at an intensity inducing a post training blood lactate of 4-8 mmol/l. This intensity was determined for e...
Forelimb kinematics and net joint moments during the swing phase of the trot. The purpose of this study was to calculate net moments of force at the joints of the forelimb during the swing phase of the stride. An optoelectronic system was used to measure segmental kinematics for 3 strides in 5 sound, Warmblood horses trotting at a mean velocity +/- s.d. of 3.03 +/- 0.16 m/s. A link segment model was used to determine the net moments of force about the joints of the left forelimb. The model combined kinematic data with morphometric data describing the inertial parameters of the limb segments of warmblood horses, and incorporated correction factors for skin displacement. ...