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Topic:Exercise Test
Exercise tests are assessments used to evaluate the cardiovascular and respiratory function of horses during physical activity. These tests help in determining the fitness level, performance capacity, and potential health issues in equine athletes. Parameters such as heart rate, respiratory rate, blood lactate levels, and oxygen consumption are typically measured during these tests. Variations in these parameters can indicate the horse's adaptation to training or uncover underlying medical conditions. This page compiles peer-reviewed research studies and scholarly articles that explore the methodologies, applications, and implications of exercise tests in equine sports medicine and veterinary practice.
Muscle histopathology and plasma aspartate aminotransferase, creatine kinase and myoglobin changes with exercise in horses with recurrent exertional rhabdomyolysis. Six horses with a history of recurrent exertional rhabdomyolysis (RER) (Horses A-F) and 7 control horses performed a submaximal and later a near-maximal treadmill exercise test. Blood samples were obtained before, during and after exercise and muscle biopsies were taken before and after exercise. At rest, plasma aspartate aminotransferase (AST) activities in horses with RER were above 95% confidence intervals for control horses. During submaximal exercise, 3 horses with RER (A, B and C) had much greater increases in plasma AST, creatine kinase (CK) and myoglobin concentrations than did Horses ...
Blood chemistry and skeletal muscle metabolic responses to exercise in horses with recurrent exertional rhabdomyolysis. Six horses with a history of recurrent exertional rhabdomyolysis (RER) and 7 control horses performed both a 55-min submaximal and later a 10-min near-maximal exercise test on a treadmill. Blood samples were obtained during exercise and gluteus medius muscle biopsies were obtained before and immediately after each exercise test and at 24 h after completion of the submaximal test. Rhabdomyolysis was developed by 3 of 6 RER horses during submaximal exercise and in 1 of the RER horses during near-maximal exercise. Concentrations of potassium, glucose, free fatty acids, ammonia, lactate, cortisol,...
Respiratory mechanics of horses during stepwise treadmill exercise tests, and the effect of clenbuterol pretreatment on them. Normal Standardbred horses were given an incremental exercise test on a horizontal treadmill to evaluate the influence of exercise on gas exchange, resistance, dynamic compliance and inertance of the respiratory system. The exercise test consisted of 2 min exercise steps at each of the following speeds: 2.4 m/sec (walk), 4.5 m/sec (slow trot), 7.0 m/sec (fast trot) and 10 m/sec (gallop). At rest and after 1 min of exercise at each step, airflow, tidal volume, respiratory frequency, pharyngeal, mid-oesophageal and transdiaphragmatic pressures and arterial blood gas tensions were measured. The s...
[Blood lactate in the steeplechase horse: triangular and rectangular series of steps during short duration races]. Five steeplechase race horses were observed during incremental and constant-load exercises with the aim of separating effects of work rate and time on blood lactate. Each independent exercise (an incremental and three constant load tests) was a sequence of three two-minute runs, separated by two one-minute rest intervals for jugular blood sampling. The following observations were made: 1. During constant load exercises, in the five horses, blood lactate stabilized below 4 mmol.l-1: lactatemia critical velocity (LVC) = 3.33 +/- 0.16 mmol.l-1. Nevertheless, VCL, critical lactate velocity inducin...
Measurement of serum myoglobin concentrations in horses by immunodiffusion. Quantitative immunodiffusion in one dimension was performed in 6-mm Duran tubes containing a 1% Nobel agar solution and various dilutions of antisera. A series of dilutions of pure myoglobin in equine sera as well as plasma from horses with rhabdomyolysis were tested. Standard curves were prepared of the migration distance of the formed precipitate from the meniscus of the gel after 3, 6, 12, and 24 hours. The clearest line of precipitate was formed with a 1:20 dilution of antisera in agar. Standard curves were nonlinear and plasma myoglobin could be detected at 2 micrograms of myoglobin/ml or...
Cardiorespiratory parameters in draught horses before and after short term draught work pulling loads. In order to establish the relationship between draught force and cardiorespiratory responses to exercise heart rate (HR), respiratory rate (RR), arterial and venous blood gases, pH, hemoglobin concentration and temperature were measured in five draught horses during rest, immediately after exercise and 30 min post-exercise under field conditions. A wagon equipped with an odometer and a hydraulic dynamometer was used for measuring distance and draught force. The wagon was loaded with 946 kg for the low load, 1,979 kg for the medium load and 2,994 kg for the high load, and drawn for a distance o...
Exercise-induced phospholipid degradation in the equine skeletal muscle and erythrocytes. To understand the pathogenesis of equine exercise-induced myopathies and hemolysis, changes of phospholipid peroxidation products in the equine middle gluteal muscle and erythrocytes following the high-speed treadmill exercise were studied. In the skeletal muscle, the peroxidized phosphatidylethanolamine (PE) were increased at 24 hours after the exercise. The malondialdehydes (MDAs) were also increased as the protein-bound MDAs following exercise. In the erythrocytes, the peroxidized PE were significantly decreased at 24 hours after the exercise. The protein-bound MDAs were significantly incre...
Plasma beta-endorphin and adrenocorticotrophin in young horses in training. A controlled period of submaximal exercise on a treadmill was used as a standardised stress test in 6 young horses to monitor the effects of training. Circulating plasma concentrations of immunoreactive beta-endorphin (IR beta-EP) were measured before, during and after the exercise period. The stress test was conducted on 3 occasions during an intensive training program lasting 14 weeks. In week 3 a marked increase in plasma IR beta-EP (P = 0.003) was demonstrated as a result of training, but by the last exercise test performed in week 9 no significant increase in plasma IR beta-EP concentrati...
Clenbuterol plasma concentrations after repeated oral administration and its effects on cardio-respiratory and blood lactate responses to exercise in healthy Standardbred horses. To evaluate the effects of clenbuterol on cardio-respiratory parameters and blood lactate relation to exercise tolerance, experimental horses performed standardized exercise tests on a high-speed treadmill before and after administration of the drug. Clenbuterol was administered in feed to six healthy Standardbreds at a dose rate of 0.8 micrograms/kg b.wt twice daily for 5.5 days. Each horse was tested twice, without and with a respiratory mask, during two consecutive days. One week elapsed between the baseline tests without drug and the tests with clenbuterol treatment (each horse served as i...
Dietary protein level and energy metabolism during treadmill exercise in horses. Six conditioned Quarter Horse mares were used in a crossover design to assess the effect of the dietary protein level on intramuscular and hepatic glycogen and lactate, oxygen uptake and blood lactate, pyruvate and free fatty acids. After a 2-wk adaptation period to either a 9.0% (control) or an 18.5% crude protein diet, each horse performed an exercise test. The horses were exercised for 15 min on an 11% grade treadmill at 4.5 m/sec. The exercise test was performed 3-4 h after a meal. Venous, arterial and mixed-venous blood samples were taken simultaneously at rest and during exercise. Muscle...
Treadmill exercise testing. Treadmill installation and training protocols used for clinical evaluations of equine athletes. 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...
Application of clinical exercise testing for identification of respiratory fitness and disease in the equine athlete. Maximal exercise testing is a valuable diagnostic tool for the evaluation of exercise intolerance and level of fitness in the equine athlete. A description of the standardized incremental exercise testing protocol and interpretation of the results of the test is followed by a discussion of more specific diagnostic techniques aimed at identifying pulmonary dysfunction as a cause of suboptimal performance.
Comparison of yearling, two-year-old and adult Thoroughbreds using a standardised exercise test. The purpose of this study was to compare exercise measurements in yearling, two-year-old and adult Thoroughbreds using a standardised treadmill incremental exercise test. Peak oxygen consumption (VO2 peak: 128.0 +/- 2.1, 140.0 +/- 2.1, 163.7 +/- 3.4; ml/kg/min +/- se, P less than 0.05), peak packed cell volume (PCV peak: 0.50 +/- 0.01, 0.58 +/- 0.01, 0.64 +/- 0.01 litres/litre +/- se, P less than 0.05) and the maximum number of steps completed in the exercise test (STEPmax: 7.7 +/- 0.1, 8.1 +/- 0.1, 8.6 +/- 0.1; steps +/- se, P less than 0.05) increased with age and degree of physical activity...
Clinical evaluation of poor performance in the racehorse: the results of 275 evaluations. A clinical sports medicine evaluation was applied to 275 racehorses with a history of poor racing performance. The poor performance evaluation included a) general physical examination and basic laboratory screening; b) respiratory examination including auscultation, thoracic radiographs, ventilation-perfusion lung scintigraphy and upper airway endoscopy at rest and during maximal treadmill exercise c) examination of the musculoskeletal system including lameness examination, video gait analysis at high speed, post exercise serum chemistry to identify obvious as well as sub-clinical myopathies, ...
The influence of metabolic alkalosis upon exercise metabolism in the thoroughbred horse. Six thoroughbred horses exercised on a motorised treadmill on two separate occasions at a speed of 11 or 12 m.s-1 for up to 2 min. 4 h prior to exercise each horse was given a 21 test solution of sodium bicarbonate (NaHCO3; 0.6 g.kg-1 body mass) or a control solution of water by nasogastric intubation, the order of administration of the two solutions was randomised. Blood samples (n = 15) were obtained before and during the 4 h after intubation, during exercise and for 30 min after exercise. NaHCO3 ingestion resulted in changes in pre-exercise acid-base status. The changes in blood lactate and...
Clinical exercise testing in the normal thoroughbred racehorse. To evaluate normal cardiorespiratory and metabolic responses of Thoroughbred horses to a standardised treadmill exercise test, we examined 28 horses ranging in age from 1 to 4 years. The group consisted of eight yearlings, eight 2-year-olds and twelve 3 and 4-year-olds. All horses except the yearlings were in training, and either racing or ready to race, at the time of examination. None of the horses had histories of performance problems. On the first day the horses received a full physical examination, resting electrocardiogram, upper respiratory tract endoscopy and either one or two acclimat...
Application of a standardised treadmill exercise test for clinical evaluation of fitness in 10 thoroughbred racehorses. Clinical exercise stress testing is an important diagnostic tool for evaluating exercise intolerance and degree of fitness in human athletes. The purpose of this paper was to describe the methodology necessary to perform a clinical exercise test and report the results of performance evaluations on 10 Thoroughbred racehorses using this test. The test utilised an open flow gas analysis system for ease of use with untrained horses and a fast time response lactate analyser for rapid data analysis. Exercise test measurements used to evaluate fitness included peak oxygen consumption (mean VO2peak = ...
Kinetics of VO2 and VCO2 in the horse and comparison of five methods for determination of maximum oxygen uptake. To determine whether maximum oxygen uptake (VO2max) in the horse in influenced by type of exercise test, five different protocols were evaluated in eight untrained Thoroughbreds exercised on a treadmill. With all protocols, horses were given a 5 min warm-up on a 10 per cent treadmill slope. Three protocols were at a 10 per cent slope and included: 1) increasing the running speed by 1 to 2 m/sec every 60 secs from 4 m/sec to a maximum of 12 m/sec; 2) running at 12 m/sec until fatigue; and 3) running for 3 to 4 mins at speeds ranging from 6 to 12 m/sec with rest pauses between exercise bouts. Th...
Diaphragmatic perfusion heterogeneity during exercise with inspiratory resistive breathing. Regional distribution of diaphragmatic blood flow (Q; 15-microns-diam radionuclide-labeled microspheres) was studied in normal (n = 7) and laryngeal hemiplegic (LH; n = 7) ponies to determine whether the added stress of inspiratory resistive breathing during maximal exercise may cause 1) redistribution of diaphragmatic Q and 2) crural diaphragmatic Q to exceed that in maximally exercising normal ponies. LH-induced augmentation of already high exertional work of breathing resulted in diminished locomotor exercise capacity so that maximal exercise in LH ponies occurred at 25 km/h compared with 3...
Exercise-induced hypercapnia in the horse. The effects of exercise intensity and duration on blood gases in thoroughbred horses were studied to characterize the apparent exercise-induced failure in pulmonary gas exchange that occurs in these animals. In response to 2 min of exercise, arterial CO2 tension (PaCO2) decreased in mild and moderate exercise, returned to normocapnic levels in moderate to heavy exercise, and rose 5-10 Torr above resting values during very heavy exercise when CO2 production (VCO2) exceeded 20 times the resting value, and mixed venous CO2 tension approximated 140 Torr. Exercise-induced hypoxemia occurred at the ...
Dynamics of cardiorespiratory function in Standardbred horses during different intensities of constant-load exercise. 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 ...
Cardiac output and oxygen consumption in exercising Thoroughbred horses. 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 (...
An apparatus for collecting blood samples by radiotelemetry from horses during exercise. An apparatus was designed to collect four consecutive blood samples from exercising horses. The collection of each sample was controlled by valves activated by radiotelemetry signals transmitted by an observer. Using the device, venous blood samples were collected from ten thoroughbred racehorses before, during and after a 400 m training gallop. Blood glucose increased markedly post-exercise. Both phosphorus and potassium concentrations increased during exercise, decreased post-exercise and recovered to pre-exercise levels within 120 minutes. The system was modified to collect anaerobic sample...
Exercise testing. In the athletic horse, an exercise test may be required to measure the adaptation of the animal to a specific training program; to modify the training program in response to the progress achieved; to investigate the reasons for failure to perform at the expected level; and to form part of an overall clinical examination of a horse with a specific disability. This article includes information on the scope and form of an exercise test, the parameters measured during the test and their interpretation, treadmill and track tests, and the clinical applications of exercise tests.
Regional blood flow changes in response to near maximal exercise in ponies: a review. In recent years, increasing attention has been focused on the physiological responses of the horse to maximal exercise. Cardiovascular response in near maximally exercised galloping ponies (heart rate 225 +/- 7 beats/min; whole body oxygen consumption 122 +/- 12 ml/min/kg) comprised a marked increase in blood flow to the cerebellum, myocardium, diaphragm and the working muscles, while renal blood flow decreased precipitously. Cerebral and brainstem perfusion did not vary from resting values. Transmural homogeneity of myocardial blood flow persisted during near maximal exercise. It was reported...
