Heart rates of horses during competitive dressage

Use of Infrared Thermography to Assess Body Temperature as a Physiological Stress Indicator in Horses during Ridden and Lunging Sessions

Equitation is a cause of physiological stress in the equine athlete, and personality is a factor generally associated with the different responses of equines to stressors. This study explored ocular temperature, measured via infrared thermography, associated with personality and stress in horses submitted to dressage exercising in riding lessons, ridden training and lunging. Infrared thermograms of 16 horses were taken before and after sessions using an FLIR F4 camera (FLIR Systems AB, Sweden) to determine maximum eye surface IRT temperature (IRTmax), and total training time was registered (T). A novel-stimulus test was conducted for personality assessment, and the ridden behavior was scored (mRBS). The results showed that T was statistically different (p ˂ 0.001) between modalities, but no differences were found in any IRTmax tests. Statistical correlations were found between mRBS and personality groups, sex and age (all p < 0.001). Additionally—and with caution, given the sample—no association was found between mRBS and post-workout IRT readings and modality, or between pre-workout IRT readings and personality groups. We conclude that trained horses show little stress when working in a familiar environment and when the workout plan is submaximal. The personality test was adequate and positively correlated with ridden behavior.

Skeletal Muscle Fiber Type Composition and Citrate Synthase Activity in Fit and Unfit Warmbloods and Quarter Horses

Selective breeding and discipline specific training has led to equine breeds adept at various athletic disciplines. Breed-specific skeletal muscle adaptations have been studied in many breeds but not Warmbloods (WB). We evaluated gluteal muscle contractile muscle fiber types and citrate synthase activity (CS), a marker for mitochondrial volume density, in WB trained for dressage (second level-Grand Prix) contrasted with Quarter Horses (QH). Gluteus medius muscle biopsies from 14 unfit/18 fit dressage-trained WB and 20 unfit/16 fit reining/working cow QH were analyzed fluorometrically and fiber types determined by ATPase activity. Comparisons were made by one-way ANOVA. Unfit and fit WB had significantly higher % type 1 and lower % type 2X fibers than QH. Unfit WB had significantly higher CS than unfit QH but CS did not differ between fit WB and fit QH. CS was only significantly higher in fit versus unfit QH, not fit versus unfit WB. In conclusion, WB gluteal muscle has an inherently high % type 1/low % type 2X fibers and high mitochondrial content whether unfit or trained for dressage, contrasting QH with an inherently low % type 1/high % type 2X and low mitochondrial content, that was enhanced in fit QH. Similar CS activity in fit WB versus QH despite a two-fold difference in % type 2X fibers indicates that mitochondrial volume density cannot accurately be predicted from contractile fiber type composition.

Peripheral Modulators of the Central Fatigue Development and Their Relationship with Athletic Performance in Jumper Horses

The current study aimed to investigate whether peripheral modulators of serotoninergic function and neurohumoral factors' changes in athletic horses during an official jumping competition, and to evaluate their relationship with the physical performance of competing horses. From 7 Italian Saddle mares (6-9 years; mean body weight 440 ± 15 kg), performing the same standardized warm-up and jumping course during an official class, heart rate (HR) was monitored throughout the competition. Rectal temperature (RT) measurement, blood lactate and glucose concentration, serum tryptophan, leucine, valine, the tryptophan/branched-chain amino-acids ratio (Try/BCAAs), dopamine, prolactin, and non-esterified fatty acids (NEFAs) were assessed before the exercise event (T0), at the end of the competition stage (5 min ± 10 s following the cessation of the exercise, TPOST5), and 30 min after the end of competition (TPOST30). Highest HR values were recorded during the course and at the outbound (p < 0.0001); blood lactate concentration and RT increased after exercise with respect to the rest condition (p < 0.0001). Lower leucine and valine levels (p < 0.01), and higher tryptophan, Try/BCAAs ratio, and NEFAs values were found at TPOST5 and TPOST30 with respect to T0 (p < 0.0001). A higher prolactin concentration was found at TPOST5 and TPOST30 compared to T0 (p < 0.0001), whereas dopamine showed decreased values after exercise compared to rest (p < 0.0001). Statistically significant correlations among the peripheral indices of serotoninergic function, neurohumoral factors, and athletic performance parameters were found throughout the monitoring period. The findings provide indirect evidence that the serotoninergic system may be involved in fatigue during jumper exercise under a stressful situation, such as competition, in which, in addition to physical effort, athletic horses exhibit more passive behavior.

What’s in a warm-up? A preliminary investigation of how European dressage riders and show jumpers warm-up their horses for training and at competition

Equestrian sports such as dressage and show jumping cause physical and physiological stress on the horses’ musculoskeletal structures, which can lead to decreased performance and injury. Warming-up prior to intense exercise can increase utilisation of the aerobic pathway, increase performance and decrease injury risk. Whilst duration of equestrian warm-up regimes has been reported, details of which gaits and skills related tasks, such as jumping and lateral movements, riders elect to use have not been evaluated to date. The purpose of this study was to understand dressage and show jumping riders’ decision-making when warming up at home and prior to a competition. Surveys (dressage: 39 questions; show jumping: 41 questions) were distributed online via social media. Mann Whitney U tests identified significant differences in warming up practice between dressage and show jumping riders. Most riders reported that a warm-up was beneficial for getting the horse ready for work, increasing responsiveness to aids, enhancing suppleness and relaxation, and decreasing injury risk. Both dressage and show jumping riders typically warm-up between 10-20 min. While dressage riders use the walk as their main warm-up gait, show jumpers preferred the trot. Both dressage riders and show jumpers incorporate technical skills in their warm-up such as lateral work, and quick transitions (when riders change gait for only few strides before changing again). Show jumpers include 4-10 jumping efforts, using different fence types. During a competition most dressage and show jumping riders agreed that factors such as perceived stress level of both the horse and rider, crowdedness of the arena, arena footing and size, as well as time allocated by the venue, were important factors that could impact the duration and content of their warm-up routines. Both groups of riders considered horses were sufficiently ‘warmed up’ when they were responsive to the aids and felt supple and relaxed.

Cardiovascular Response to Exercise and Training, Exercise Testing in Horses

The physiology of exercise and training is fascinating, and hundreds of interesting studies have given insight into its mechanisms. Exercise testing is a useful clinical tool that can help veterinarians assess poor performance, fitness, and performance potential and prevent injuries. The clinically applicable aspects of cardiovascular adaptions to training and exercise testing are highlighted in this review. Different exercise tests should be used to evaluate horses performing in different disciplines and levels. Exercise tests that simultaneously assess several body systems can be beneficial when assessing poor performance, because this is often a multifactorial problem with signs not detectable at rest.

The effect of repeated barrel racing on blood biomarkers and physiological parameters in Quarter Horses

The objective of this study was to evaluate barrel horses undergoing a field test with one repetition. Quarter-Horses were used (14 males and females; average age: 6.5 years old), and they ran two times for 5 min in the same field. Six different periods were evaluated: rest (T-0), immediately after the first (T-1) and second races (T-2), and after 15 (T-15), 30 (T-30) and 240 min (T-240) of recovery. Heart rate (HR), speed, distance and duration were measured using a HR monitor with GPS during the races. Blood was collected to determinate glucose, lactate, total proteins (TP), albumin, globulin, urea, creatinine, uric acid (UA), triglycerides, cholesterol, non-esterified fatty acids (NEFA), gammaglutamyltransferase (GGT), creatine kinase (CK), and cortisol concentrations, as well as to perform a haemogram. The results were analysed using ANOVA and Tukey’s tests using a P-value of 5%, and they showed a maximum HR>200 bpm after both races. The largest %HR>>170 bpm occurred in the second race (P<0.05). Glucose and lactate concentrations were elevated at T-2 (P<0.05). TP, creatinine, UA and triglycerides concentrations remained elevated at T-1, T-2 and T-30 (P<0.05). TP and creatinine concentrations returned to basal concentrations at T-30 (P>0.05), and UA and triglycerides returned to base concentrations at T-240 (P>0.05). NEFA, cholesterol, GGT and CK concentrations did not change (P>0.05). Cortisol concentrations were higher at T-2 (P<0.05) but at T-240 were similar to T-0 (P>0.05). Red blood cell concentrations and haematocrits had higher values after the second race (P<0.05). These results showed that barrel horses had intense exercise and that two races with a short rest interval between them produced similar metabolic and physiologic adaptations between races, showing that the proposed protocol may be a useful tool for field characterisation of horses’ training and may contribute to the implementation of adequate training and nutritional programs.

Differences in the electrocardiographic QT interval of various breeds of athletic horses during rest and exercise

OBJECTIVES

Quantitative measurements of cardiac repolarization, defined as the electrocardiographic QT interval, have important diagnostic implications in humans, as irregularities can trigger potentially fatal ventricular tachyarrhythmia. In both humans and horses, cardiac repolarization is influenced to some extent by heart rate, age, body weight (BW), sex, autonomic tone, and environment. In horses, there is substantial inter-breed variation in size and training, and the aims of this study were therefore to determine the best model describing the QT to RR relationship in breeds of various athletic horses and to test for differences in the QT interval.

ANIMALS

Ten Icelandic horses, 10 Arabian horses, 10 Thoroughbreds, 10 Standardbreds, six Coldblood trotters, 10 Warmbloods (dressage) and 10 Warmbloods (show jumping). All horses were geldings.

METHODS

QT intervals were measured from resting to peak exercise level and plotted against RR intervals. Data points were fitted with relevant regression models, and the effect of breed, BW, and estimated exercise intensity was examined.

RESULTS

For all breeds in this study, the QT interval was best described as a function of RR by the piecewise linear regression model. The breed of horse had a significant effect on the model. There was no systematic effect of BW or estimated exercise intensity, but a high inter-horse variability was observed.

CONCLUSIONS

The equine QT interval should preferably be corrected for heart rate according to breed. In addition, the results indicate that equine studies of the QT interval must be designed to eliminate the influence of a large inter-horse variation.

Exercise testing in Warmblood sport horses under field conditions

Regular exercise testing in Warmblood sport horses may, as in racing, potentially help to characterise fitness indices in different disciplines and at various competition levels and assist in understanding when a horse is 'fit to compete'. In this review an overview is given of the current state of the art of exercise testing in the Olympic disciplines of eventing, show jumping and dressage, and areas for further development are defined. In event horses, a simple four-step incremental exercise test measuring heart rate (HR), lactate concentration (LA) and velocity (V) is most often used. In dressage and riding horses, a wide variety of exercise tests have been developed, including incremental exercise tests, indoor riding tests and lunging tests. In show jumping, the use of a five-step incremental exercise test and exercise tests evaluating technical skills and fatigue of the horse has been reported. The velocity at a plasma LA of 4 mmol/L (VLA4) and HR recovery during submaximal exercise intensity have been shown to be the best parameters in event horses for predicting performance and impending injuries. In riding horses, the fitness level of horses is also an important determinant of injuries. Implementation of regular exercise testing and monitoring of training sessions may have important added value in the assessment of performance ability and potential future injuries in Warmblood sport horses. However, there is an urgent need to standardise methodologies and outcome parameters in order to make results comparable.

Estimation of the workload in horses during an eventing competition

The aim of this study was to evaluate workload using suitable parameters related to the physical effort exerted by horses involved in eventing competitions in order to describe the workload intensity and energy demands placed upon such horses. Heart rate (HR), running speed (S), distance covered (Dist), performance duration (D) and blood lactate (Lact) concentrations were measured in horses competing at either the intermediate level (IL) or advanced level (AL) in order to identify workload differences between experience classes. Ten warmblood horses were monitored during an official two-day eventing competition; mean HR (HRmean, bpm), maximum HR (HRmax, bpm), mean S (Smean, m/min), max S (Smax, m/min), D (min) and Dist (m) were assessed during the warm-up and competition phases of each eventing test (dressage, show jumping, cross country). To calculate heart rate recovery (HRR), HR data were collected within the first 3 minutes following the completion of each of the 3 competition phases. Energy expenditure (EE) was estimated using the HR/VO2 relationship. Differences between the groups (AL vs. IL) in HRmean, HRmax, %HRmean, %HRpeak (HR expressed as a percentage of the maximum HR peak obtained during a fast gallop training session), S, D, and Dist were assessed using one-tailed unpaired t-tests for both warmup and competition phases; also differences for EE were evaluated. The relationship between HR and S was also determined for warm-up and competition phases using one-tailed Person's correlations. The relationship between HR decrease during the first 3 min following competition phase completion and recovery time was investigated by multiple nonlinear curve estimation procedures. The results reveal the cross country test to be the most demanding of the eventing competition, requiring significantly greater levels of muscular and energetic effort, in terms of Lact production and EE, with higher values recorded in the AL horses compared to IL horses. The data also show that riders need to optimise warm-up duration and quality in accordance with their competition category. The calculation of HRR is also shown to be an appropriate approach for gauging workload after high-intensity exercise, but not after low-intensity exercise since HRR may be influenced by external factors, like how excited a horse is.

Heart rate responses of two breeds of four-gaited horses to a standardised field gaited test

In order to understand how gaited horses use their energy during exercise, a standardised field gaited test (SFGT) was developed to assess energy expenditure of four beat gaited horses independently of size, sex or breed. This work aimed at developing such an SFGT, using as main measurement parameter the heart rate (HR) of horses during the SFGT performance. Thirty-one four beat gaited horses were evaluated and divided into two groups: FIT (conditioned) and UNFIT (not conditioned). Horses were submitted to the SFGT and their heart rates were measured with a heart rate monitor as follows: right after being mounted, at the beginning of pre-test (HRSADDLE); at 5, 10, 15, 20, 25 and 30 minutes of four beat gait dislocation; and at 15 minutes after the recovery period (T+15). Maximum HR (HRMAX); HR percentage over 150 beats per minute (HR%≯150), HR percentage over 170 beats per minute (HR%≯170), and average HR during the four beat gait stage (HRM@M) of SFGT were calculated. Results were analysed by ANOVA for repeated measures. Where significant differences were observed, ‘T’ test was performed and significance was set at 5%. The FIT group presented HRMAX, HR+15, HRM@M, HR%≯150 and HR%≯170 rates lower (P<0.05) than the UNFIT group. It was noted that there was a negative correlation between fitness and HRMAX (R=−0.67; P<0.001) and a positive correlation between HRMAX and HR+15 (R=0.60; P<0.001) when comparing the FIT to the UNFIT horses. In conclusion, during the SFGT, the FIT group was more efficient in energy expenditure than the UNFIT group, based on the results observed for the significantly lower HRs during the SFGT. It is relevant to note that the SFGT developed and used in this research, which was easily reproduced and accurate, was able to detect and confirm important adaptations related to fitness in the athletic horse.