Influence of seating styles on head and pelvic vertical movement symmetry in horses ridden at trot

Effect of circle, surface type and stride duration on vertical head and pelvis movement in riding horses with pre-existing movement asymmetries in trot

Head and pelvis vertical movement asymmetries in horses are often evaluated under different conditions yet better understanding is required of how these asymmetries are altered by factors such as surface type or circle size. This study investigated how stride duration, surface and lungeing in circles of different sizes influenced objectively measured head and pelvis movement asymmetries in riding horses in full training. Movement asymmetries were recorded with body mounted accelerometers and were based on the differences between the two vertical displacement minima or maxima of head (HDmin, HDmax) and pelvis (PDmin, PDmax) within a stride cycle. Each horse was evaluated during straight-line trot and during lungeing (d = 10m/15m) on hard and soft surfaces at slow and fast speed (determined by stride duration). All horses (N = 76) had at least one movement asymmetry parameter above a predefined thresholds (|HDmin| or |HDmax| >6mm, |PDmin| or |PDmax| >3mm) during a straight line trot on hard surface (baseline). The horses were assigned to a 'predominant asymmetry' group (HDmin, HDmax, PDmin, PDmax) based on which movement asymmetry parameter was the greatest during the baseline condition; the head movement asymmetry values were divided by two to account for the difference in magnitude of the thresholds. Analysis was carried out for each predominant asymmetry group separately using linear mixed models-outcome variable: predominant asymmetry parameter; random factor: horse; fixed factors: surface, direction with stride duration as covariate (P<0.05, Bonferroni post-hoc correction). The 'direction' conditions were either a straight-line locomotion ('straight') or lungeing with lungeing conditions further classified by circle diameter and by whether the limb which the predominant asymmetry was assigned to ('assigned limb') was on the inside or outside of the circle ('inside10', 'inside15', 'outside10', 'outside15'). Only parameters related to asymmetrical weight-bearing between contralateral limbs (HDmin, PDmin) were affected by changes in stride duration-the most common pattern was an increase in asymmetries as stride duration decreased. Only pelvic movement asymmetries were affected by lungeing. When the assigned hindlimb was on the inside of the circle, the PDmin asymmetries increased and PDmax asymmetries decreased compared to the straight-line condition. With the assigned hindlimb on the outside, PDmin asymmetries decreased but PDmax asymmetries did not change. Trotting on 10 m circle compared to 15 m circle did not increase movement asymmetries. In conclusion, circular motion and changes in stride duration altered movement asymmetries identified in horses in full ridden work but no changes were seen between the soft and hard surfaces. These patterns should be further investigated in clinically lame horses.

Adaptation strategies of the Icelandic horse with induced forelimb lameness at walk, trot and tölt

BACKGROUND AND OBJECTIVE

Lameness assessment in the gaited Icelandic horse is complex. We aimed to describe their kinematic and temporal adaptation strategies in response to forelimb lameness at walk, trot and tölt.

STUDY DESIGN

In vivo experiment.

METHODS

Ten clinically non-lame Icelandic horses were measured before and after reversible forelimb lameness induction. Upper body and limb kinematics were measured using 11 inertial measurement units mounted on the poll, withers, pelvis (tubera sacrale) and all four limbs and hoofs (Equimoves®, 500 Hz). Horses were measured on a straight line at walk and trot in-hand and at walk, trot and tölt while ridden. Linear mixed models were used to compare baseline and lame conditions (random factor = 'horse'), and results are presented as the difference in estimated marginal means or percentage of change.

RESULTS

Lameness induction significantly (p < 0.05) increased head vertical movement asymmetry at walk (HDmin/HDmaxHAND: 18.8/5.7 mm, HDmin/HDmaxRIDDEN: 9.8/0.3 mm) and trot (HDmin/HDmaxHAND: 18.1/7.8 mm, HDmin/HDmaxRIDDEN: 24.0/9.3 mm). At the tölt, however, HDmin did not change significantly (1.1 mm), but HDmax increased by 11.2 mm (p < 0.05). Furthermore, pelvis vertical movement asymmetry (PDmax) increased by 4.9 mm, sound side dissociation decreased (-8.3%), and sound diagonal dissociation increased (6.5%). Other temporal stride variables were also affected, such as increased stance duration of both forelimbs at walk, tölt and in-hand trot.

MAIN LIMITATIONS

Only one degree of lameness (mild) was induced with an acute lameness model.

CONCLUSIONS

Classical forelimb lameness metrics, such as vertical head and withers movement asymmetry, were less valuable at tölt compared to walk and trot, except for HDmax. Therefore, it is advised to primarily use the walk and trot to detect and quantify forelimb lameness in the Icelandic horse.

Riders' Effects on Horses-Biomechanical Principles with Examples from the Literature

Movements of the horse and rider in equestrian sports are governed by the laws of physics. An understanding of these physical principles is a prerequisite to designing and interpreting biomechanical studies of equestrian sports. This article explains and explores the biomechanical effects between riders and horses, including gravitational and inertial forces, turning effects, and characteristics of rider technique that foster synchronous movement with the horse. Rider symmetry, posture, and balance are discussed in the context of their relationship to rider skill level and their effects on the horse. Evidence is presented to support the feasibility of improving equestrian performance by off-horse testing followed by unmounted therapy and exercises to target the identified deficiencies. The elusive quality of harmony, which is key to a true partnership between riders and horses, is explored and described in biomechanical terms.

Saddle Thigh Block Design Can Influence Rider and Horse Biomechanics

The association between rider-saddle interaction and horse kinematics has been little studied. It was hypothesized that differences in a thigh block design would influence (a) rider-saddle interface pressures, (b) rider kinematics, and (c) equine limb/spinal kinematics. Eighteen elite sport horses/riders were trotted using correctly fitted dressage saddles with thigh blocks S (vertical face) and F (deformable face). Contact area, mean, and peak pressure between rider and saddle were determined using an on-saddle pressure mat. Spherical markers allowed for the measurement of horse/rider kinematics using two-dimensional video analysis. The kinematics of the equine thoracolumbosacral spine were obtained using skin-mounted inertial measuring units. Results were compared between thigh blocks (paired t-test p ≤ 0.05). With F, the contact area, mean, and peak pressure between rider and saddle were significantly higher (p = 0.0001), and the rider trunk anterior tilt was reduced, indicating altered rider-saddle interaction. The horse thoracic axial rotation and flexion/extension were reduced (p = 0.01-0.03), caudal thoracic and lumbar lateral bend was increased (p = 0.02-0.04), and carpal flexion increased (p = 0.01-0.05) with F compared to S. During straight-line locomotion when in sitting trot, thigh block F was associated with altered rider-saddle interaction and rider and equine kinematics, leading to a more consistent rider-saddle interface, a more upright rider trunk during stance, an increased horse thoracic stability and lumbar lateral bend, and forelimb flexion, supporting the importance of optimising rider-saddle-horse interaction.

Efficient Development of Gait Classification Models for Five-Gaited Horses Based on Mobile Phone Sensors

Automated gait classification has traditionally been studied using horse-mounted sensors. However, smartphone-based sensors are more accessible, but the performance of gait classification models using data from such sensors has not been widely known or accessible. In this study, we performed horse gait classification using deep learning models and data from mobile phone sensors located in the rider's pocket. We gathered data from 17 horses and 14 riders. The data were gathered simultaneously from movement sensors in a mobile phone located in the rider's pocket and a gait classification system based on four wearable sensors attached to the horse's limbs. With this efficient approach to acquire labelled data, we trained a Bi-LSTM model for gait classification. The only input to the model was a 50 Hz signal from the phone's accelerometer and gyroscope that was rotated to the horse's frame of reference. We demonstrate that sensor data from mobile phones can be used to classify the five gaits of the Icelandic horse with up to 94.4% accuracy. The result suggests that horse riding activities can be studied at a large scale using mobile phones to gather data on gaits. While our study showed that mobile phone sensors could be effective for gait classification, there are still some limitations that need to be addressed in future research. For example, further studies could explore the effects of different riding styles or equipment on gait classification accuracy or investigate ways to minimize the influence of factors such as phone placement. By addressing these questions, we can continue to improve our understanding of horse gait and its role in horse riding activities.

Evaluation of feedback methods for improved detection of hindlimb lameness in horses among riding instructors and trainers

Lameness, a wellknown issue in sport horses, impedes performance and impairs welfare. Early detection of lameness is essential for horses to receive needed treatment, but detection of hindlimb lameness is challenging. Riding instructors and trainers observe horses in motion in their daily work and could contribute to more efficient lameness detection. In this cross-sectional and prospective study, we evaluated the ability of riding instructors and trainers to assess hindlimb lameness. We also evaluated different feedback methods for improved lameness detection. For the cross-sectional part, n = 64 riding instructors and trainers of varying level and n = 23 high-level trainers were shown 13 videos of trotting horses, lameness degree: 0–3.5 (test 1) and tasked with classifying the horses as sound, left hindlimb lame, or right hindlimb lame. For the prospective part, the riding instructors and trainers of varying levels were randomly allocated to three different groups (a, b, c) and given 14 days of feedback-based, computer-aided training in identifying hindlimb lameness, where they assessed 13 videos (of which three were repeated from test 1) of horses trotting in a straight line. Participants in groups a-c received different feedback after each video (group a: correct answer and re-viewing of video at full and 65% speed; group b: correct answer, re-viewing of video at full and 65% speed, narrator providing explanations; group c: correct answer and re-viewing of video at full speed). After computer-aided training, the participants were again subjected to the video test (test 2). Participants also provided background information regarding level of training etcetera. Effects of participants' background on results were analyzed using analysis of variance, and effects of the different feedback methods were analyzed using generalized estimation equations. On test 1, 44% (group a), 48% (b), 46% (c), and 47% (high-level trainers) of horses were correctly classified. Group a participants significantly improved their test score, both with (p < 0.0001) and without (p = 0.0086) inclusion of repeated videos. For group c, significant improvement was only seen with inclusion of repeated videos (p = 0.041). For group b, no significant improvement was seen (p = 0.51). Although test 2 scores were low, computer-aided training may be useful for improving hindlimb lameness detection.

Upper Body Movement Symmetry in Reining Quarter Horses during Trot In-Hand, on the Lunge and during Ridden Exercise

Veterinary lameness examinations often comprise assessing ridden horses. Quantitative movement symmetry measurements can aid evidence-based decision making. While these are available for ‘English’ style riding, they are not for ‘Western’ style riding. This quantitative observational study quantified movement symmetry in reining Quarter Horses (QHs). Movement symmetry of the head, withers and sacrum (differences between minima, maxima and upward amplitudes) were quantified with inertial sensors in N = 30 medium/high level reining QHs during trot in-hand, on the lunge and ridden by one experienced rider (straight-line/circles) on reining-purpose riding surfaces. Mixed linear models for movement symmetry assessed the effects of ridden exercise and movement direction (fixed factors), stride time (covariate) and horse (random factor): single factors and two-way interactions with Bonferroni correction at p < 0.05. Three withers and pelvic parameters showed marginally more symmetrical movement when ridden (p ≤ 0.044; 1−5 mm differences). Three withers, three sacrum and one head parameter were significantly affected by movement direction (all p ≤ 0.026), five showed increased asymmetry on the inside rein, and two, quantifying vertical displacement maximum difference, showed the opposite. Riding QHs in ‘Western’ style showed small movement symmetry differences. Circular exercise confirmed increases in weight bearing asymmetry on the inside rein and in pushoff asymmetry on the outside rein. This should be further investigated for differentiating between different causes of lameness.

The effect of horseshoes and surfaces on horse and jockey centre of mass displacements at gallop

Horseshoes influence how horses' hooves interact with different ground surfaces, during the impact, loading and push-off phases of a stride cycle. Consequently, they impact on the biomechanics of horses' proximal limb segments and upper body. By implication, different shoe and surface combinations could drive changes in the magnitude and stability of movement patterns in horse-jockey dyads. This study aimed to quantify centre of mass (COM) displacements in horse-jockey dyads galloping on turf and artificial tracks in four shoeing conditions: 1) aluminium; 2) barefoot; 3) GluShu; and 4) steel. Thirteen retired racehorses and two jockeys at the British Racing School were recruited for this intervention study. Tri-axial acceleration data were collected close to the COM for the horse (girth) and jockey (kidney-belt), using iPhones (Apple Inc.) equipped with an iOS app (SensorLog, sample rate = 50 Hz). Shoe-surface combinations were tested in a randomized order and horse-jockey pairings remained constant. Tri-axial acceleration data from gallop runs were filtered using bandpass Butterworth filters with cut-off frequencies of 15 Hz and 1 Hz, then integrated for displacement using Matlab. Peak displacement was assessed in both directions (positive 'maxima', negative 'minima') along the cranio-caudal (CC, positive = forwards), medio-lateral (ML, positive = right) and dorso-ventral (DV, positive = up) axes for all strides with frequency ≥2 Hz (mean = 2.06 Hz). Linear mixed-models determined whether surfaces, shoes or shoe-surface interactions (fixed factors) significantly affected the displacement patterns observed, with day, run and horse-jockey pairs included as random factors; significance was set at p<0.05. Data indicated that surface-type significantly affected peak COM displacements in all directions for the horse (p<0.0005) and for all directions (p≤0.008) but forwards in the jockey. The largest differences were observed in the DV-axis, with an additional 5.7 mm and 2.5 mm of downwards displacement for the horse and jockey, respectively, on the artificial surface. Shoeing condition significantly affected all displacement parameters except ML-axis minima for the horse (p≤0.007), and all displacement parameters for the jockey (p<0.0005). Absolute differences were again largest vertically, with notable similarities amongst displacements from barefoot and aluminium trials compared to GluShu and steel. Shoe-surface interactions affected all but CC-axis minima for the jockey (p≤0.002), but only the ML-axis minima and maxima and DV-axis maxima for the horse (p≤0.008). The results support the idea that hoof-surface interface interventions can significantly affect horse and jockey upper-body displacements. Greater sink of hooves on impact, combined with increased push-off during the propulsive phase, could explain the higher vertical displacements on the artificial track. Variations in distal limb mass associated with shoe-type may drive compensatory COM displacements to minimize the energetic cost of movement. The artificial surface and steel shoes provoked the least CC-axis movement of the jockey, so may promote greatest stability. However, differences between horse and jockey mean displacements indicated DV-axis and CC-axis offsets with compensatory increases and decreases, suggesting the dyad might operate within displacement limits to maintain stability. Further work is needed to relate COM displacements to hoof kinematics and to determine whether there is an optimum configuration of COM displacement to optimise performance and minimise injury.

Differences in equine spinal kinematics between straight line and circle in trot

Work on curved tracks, e.g. on circles, is commonplace within all forms of horse training. Horse movements in circles are naturally asymmetric, including the load distribution between inner and outer limbs. Within equestrian dressage the horse is expected to bend the back laterally to follow the circle, but this has never been studied scientifically. In the current study 12 horses were measured (optical motion capture, 100 Hz) trotting on left and right circles and on the straight without rider (soft surface). Data from markers placed along the spine indicated increased lateral bending to the inside (e.g. left bending on the left circle) of the thoracolumbar back (difference left circle vs. straight − 3.75°; right circle + 3.61°) and the neck (left − 5.23°; right + 4.80° vs. straight). Lateral bending ROM increased on the circle (+ 0.87° and + 0.62°). Individual variation in straight-circle differences was evident, but each horse was generally consistent over multiple trials. Differences in back movements between circle and straight were generally small and may or may not be visible, but accompanying changes in muscle activity and limb movements may add to the visual impression.

Differential rotational movement and symmetry values of the thoracolumbosacral region in high-level dressage horses when trotting

High-level dressage horses regularly perform advanced movements, requiring coordination and force transmission between front and hind limbs across the thoracolumbosacral region. This study aimed at quantifying kinematic differences in dressage horses when ridden in sitting trot-i.e. with additional load applied in the thoracolumbar region-compared with trotting in-hand. Inertial sensors were glued on to the midline of the thoracic (T) and lumbar (L) spine at T5, T13, T18, L3 and middle of the left and right tubera sacrale of ten elite dressage horses (Mean±SD), age 11±1 years, height 1.70±0.10m and body mass 600±24kg; first trotted in-hand, then ridden in sitting trot on an arena surface by four Grand Prix dressage riders. Straight-line motion cycles were analysed using a general linear model (random factor: horse; fixed factor: exercise condition; covariate: stride time, Bonferroni post hoc correction: P<0.05). Differential roll, pitch and yaw angles between adjacent sensors were calculated. In sitting trot, compared to trotting in-hand, there was increased pitch (mean±S.D), (in-hand, 3.9 (0.5°, sitting trot 6.3 (0.3°, P = <0.0001), roll (in-hand, 7.7 (1.1°, sitting trot 11.6 (0.9°, P = 0.003) and heading values (in-hand, 4.2 (0.8), sitting trot 9.5 (0.6°, P = <0.0001) in the caudal thoracic and lumbar region (T18-L3) and a decrease in heading values (in-hand, 7.1 (0.5°, sitting trot 5.2 (0.3°, P = 0.01) in the cranial thoracic region (T5-T13). Kinematics of the caudal thoracic and lumbar spine are influenced by the rider when in sitting trot, whilst lateral bending is reduced in the cranial thoracic region. This biomechanical difference with the addition of a rider, emphasises the importance of observing horses during ridden exercise, when assessing them as part of a loss of performance assessment.

Differential Rotational Movement of the Thoracolumbosacral Spine in High-Level Dressage Horses Ridden in a Straight Line, in Sitting Trot and Seated Canter Compared to In-Hand Trot

Assessing back dysfunction is a key part of the investigative process of "loss of athletic performance" in the horse and quantitative data may help veterinary decision making. Ranges of motion of differential translational and rotational movement between adjacent inertial measurement units attached to the skin over thoracic vertebrae 5, 13 and 18 (T5, T13, T18) lumbar vertebra 3 (L3) and tuber sacrale (TS) were measured in 10 dressage horses during trot in-hand and ridden in sitting trot/canter. Straight-line motion cycles were analysed using a general linear model (random factor: horse; fixed factor: exercise condition; Bonferroni post hoc correction: p < 0.05). At T5-T13 the differential heading was smaller in sitting trot (p ≤ 0.0001, 5.1° (0.2)) and canter (p ≤ 0.0001, 3.2° (0.2)) compared to trotting in-hand (7.4° (0.4)). Compared to trotting in-hand (3.4° (0.4)) at T18-L3 differential pitch was higher in sitting trot (p ≤ 0.0001, 7.5° (0.3)) and canter (p ≤ 0.0001, 6.3° (0.3)). At L3-TS, differential pitch was increased in canter (6.5° (0.5)) compared to trotting in-hand (p = 0.006, 4.9° (0.6)) and differential heading was higher in sitting trot (4° (0.2)) compared to canter (p = 0.02, 2.9° (0.3)). Compared to in-hand, reduced heading was measured in the cranial-thoracic area and increased in the caudal-thoracic and lumbar area. Pitch increased with ridden exercise from the caudal-thoracic to the sacral area.

Relationships between the Rider's Pelvic Mobility and Balance on a Gymnastic Ball with Equestrian Skills and Effects on Horse Welfare

Riders need core stability to follow and guide the horse's movements and avoid giving unintended or conflicting signals. This study evaluated the rider's performance of exercises on a gymnastic ball with on-horse performance and indicators of stress in the horse. Twenty experienced riders were scored performing three exercises on a gymnastic ball and for quality and harmony when riding based on evaluation of video recordings in which conflict behaviours were evident. The horse's heart rate and number of conflict behaviors during the riding test and cortisol levels after completion of the test were measured. The rider's ability to roll the pelvis from side-to-side on a gymnastic ball was highly correlated with ability to circle the pelvis on the ball and with quality and harmony during riding. However, pelvic roll and riding quality and harmony showed a trend toward a negative correlation with balancing skills on the ball. It appears that the ability to actively move the pelvis is more relevant to equestrian performance than static balancing skill. Horses ridden by riders with better pelvic mobility and control showed significantly fewer conflict behaviors. On the contrary, high scores for balancing on the gymnastic ball were negatively correlated with the horses' working heart rates, suggesting a less energetic performance. Pelvic control and mobility may be predictive for equestrian skills and riding harmony.

Application of a Ridden Horse Pain Ethogram and Its Relationship with Gait in a Convenience Sample of 60 Riding Horses

A Ridden Horse Pain Ethogram (RHpE) comprising 24 behaviours has been developed to facilitate the identification of musculoskeletal pain. The aim was to further test the RHpE by its application to a convenience sample (n = 60) of sports horses and riding school horses in regular work and assumed by their owners to be working comfortably. All horses performed a purpose-designed dressage-type test of 8.5 min duration in walk, trot and canter, with their normal rider. The RHpE was applied retrospectively to video recordings acquired in a standardised fashion. Seventy-three percent of horses were lame (≤ grade 2/8) on one or more limbs; 47% had gait abnormalities in canter. Ridden Horse Pain Ethogram scores ranged from 3 to 16/24 (median 9); rider skill score ranged from 2.5 to 8/10 (median 4.75). The effect of horse age, breed, sex, work-discipline, epaxial muscle hypertonicity or pain, an ill-fitting saddle, rider skill score, the presence of lameness or gait abnormalities in canter on the RHpE score was assessed using Poisson regression. Two variables were retained in the final multivariable analysis, rider skill score as a continuous variable (p < 0.001), and lameness (p = 0.008). A RHpE score ≥8 was a good indicator of the presence of musculoskeletal pain.

The Effect of Tungsten Road Nails on Upper Body Movement Asymmetry in Horses Trotting on Tarmac

Tungsten road nails are commonly used by farriers to increase grip between the hoof and the ground surface. There is limited evidence relating the use of road nails to the fundamental mechanics of movement. Grip is important for efficient deceleration on landing and subsequent propulsion, but this must be balanced against an amount of slip to divide the landing force into horizontal as well as vertical subcomponents. Here, we conducted an intervention study to quantify the effect of lateral heel road nail placement on weight bearing and propulsion in 10 horses trotting on tarmac. Wireless inertial measurement units measured vertical movement asymmetry. Differences in head and pelvic movement asymmetry before/after subsequent application of laterally placed road nails to forelimb and hindlimb hooves in a randomized order were compared to zero value (no change) with a one-sample t-test, P < .05. Left-to-right tuber coxae movement amplitude difference was significantly more negative (-3.25 mm, P = .03), suggesting more right than left tuber coxae movement amplitude, after application of a road nail to the left hindlimb. No movement asymmetries at the poll, withers, or sacrum were detected after nail placement (all P > .055). Pelvic movement indicates a very small increase in weight bearing and propulsion provided by the hindlimb with a laterally placed road nail compared to the contralateral hindlimb. Further work is needed to investigate slip- and grip-related parameters at the level of the hoof and to investigate the long-term consequences of very small changes in movement asymmetry.

The Effect That Induced Rider Asymmetry Has on Equine Locomotion and the Range of Motion of the Thoracolumbar Spine When Ridden in Rising Trot

There is a paucity of evidence on the effect that rider asymmetry has on equine locomotion. The aim of this study was to evaluate the effect of rider asymmetry on equine locomotion by using a novel approach to induce rider asymmetry. Ten nonlame horses were recruited for this study. Joint center markers were used to capture 2D kinematics (Quintic Biomechanics) of the horse and rider and horses were equipped with seven inertial sensors positioned at the fifth (T5) and eighteenth (T18) thoracic vertebrae, third lumbar (L3) vertebra, tubera sacrale (TS), and left and right tubera coxae. Rider asymmetry was induced by shortening the ventral aspect of one stirrup by 5 cm. Kinematic data were compared between conditions using a mixed model with the horse defined as a random factor and stirrup condition (symmetrical stirrups and asymmetrical stirrups) and direction (inside and outside) defined as fixed factors. Data from riders where the right stirrup was shortened were mirrored to reflect a left stirrup being shortened. To determine differences between conditions, a significance of P ≤ .05 was set. On the rein with the shortened stirrup on the outside: an increase in lateral bending range of motion (ROM) at T5 (P = .003), L3 (P = .04), and TS (P = .02), an increase in mediolateral displacement at T5 (P = .04), T18 (P = .04), and L3 (0.03) were found. An increase in maximum fetlock extension was apparent for both the front (P = .01) and hind limb (P = .04) on the contralateral side to the shortened stirrup; for the asymmetrical stirrup condition on the rein with the shortened stirrup on the inside: an increase in flexion-extension ROM at T5 (P = .03) and L3 (P = .04), axial rotation at T5 (P = .05), and lateral bending of T5 (P = .03), L3 (P = .04), and TS (P = .02). Asymmetric rider position appears to have an effect on the kinematics of the thoracolumbar spine. These findings warrant further investigation to understand the long-term impact this may have on equine locomotor health.

Increased Rider Weight Did Not Induce Changes in Behavior and Physiological Parameters in Horses

Simple Summary

The influence of rider weight on horse welfare, health and performance is often debated. We measured the effects of increasing the weight of the regular rider by 15% and 25% on horse behavior, gait symmetry and physiological responses in a standard dressage test. Cortisol levels increased in response to exercise, but we found no effect of the weight treatment, i.e., cortisol levels did not increase when the rider became heavier. Behavior, heart rate and gait symmetry also did not differ between treatments. We conclude that increasing the weight of the regular rider by 15% and 25% did not result in significant short-term alterations in cortisol, heart rate, behavior and gait symmetry in horses during low-intensity exercise. Further studies are required to develop appropriate guidelines for rider weight.

Abstract

Recent studies have reported significant alterations in horse physiological and gait parameters when exposed to increased rider weight during moderate to high intensity exercise. This study aimed to evaluate the effect of increased rider weight (+15% and +25% of the regular rider’s bodyweight) on horse behavioral, physiological and gait symmetry parameters during a standard dressage test. Twenty rider-horse equipages performed the same test three times in a randomized, crossover design. Salivary cortisol (SC), heart rate (HR), heart rate variability (HRV), behavior and gait symmetry (GS) were measured. SC concentrations increased from baseline (p < 0.001), but there was no significant treatment effect (difference from baseline (ng/mL): Control: 0.21 ± 0.1; +15%: 0.37 ± 0.1; +25%: 0.45 ± 0.2, p = 0.52). Similarly, there were no overall treatment effects on HR or HRV variables (avg HR across treatments (bpm): 105.3 ± 1.3), nor on GS parameters. There was large individual variation in conflict behavior but no effect of weight treatment. We conclude that increasing the weight of the regular rider by 15% and 25% did not result in significant short-term alterations in the measured parameters. Maximum rider:horse weight ratios were 15–23% and the exercise intensity was relatively low; thus the results should not be extrapolated to other weight ratios and exercise intensities.

The Effect of Tree Width on Thoracolumbar and Limb Kinematics, Saddle Pressure Distribution, and Thoracolumbar Dimensions in Sports Horses in Trot and Canter

Simple Summary

Determining the correct saddle fit is essential in order to optimise the interaction between the horse and rider dyad, and to reduce the risk of back-related problems or loss of performance as a result of incorrect saddle fit. Although there are industry guidelines (Society of Master Saddlers) on correct saddle fit, some saddle fitters (and others) choose to fit saddles that are wider than industry guidelines on the assumption that increased saddle width will enhance equine locomotion and allow the horses’ thoracolumbar spine to function unhindered. This study quantified the effect that a saddle that was one width fitting wider and narrower (based on the Society of Master Saddlers industry guidelines) had on the kinematics of the thoracolumbar spine, thoracolumbar epaxial musculature profiles, equine locomotion, and saddle pressure distribution. It was found that a saddle that was one width fitting wider and narrower affected the kinematics of the thoracolumbar spine, resulting in concavities in epaxial musculature at T13 when using the wide saddle and at T18 when using the narrow saddle. The wide saddle caused areas of high pressures in the cranial region of the saddle and the narrow saddle caused areas of high pressures in the caudal region of the saddle. It is essential that the correct saddle fit is achieved for each horse and rider combination in order to optimise the horse-rider system and reduce the risk of back-related problems or loss of performance that may occur as a result of incorrect saddle fit.

Abstract

This study evaluated the effect of saddle tree width on thoracolumbar and limb kinematics, saddle pressure distribution, and thoracolumbar epaxial musculature dimensions. Correctly fitted saddles were fitted by a Society of Master Saddler Qualified Saddle Fitter in fourteen sports horses (mean ± SD age 12 ± 8.77 years, height 1.65 ± 0.94 m), and were altered to one width fitting wider and narrower. Horses were equipped with skin markers, inertial measurement units, and a pressure mat beneath the saddle. Differences in saddle pressure distribution, as well as limb and thoracolumbosacral kinematics between saddle widths were investigated using a general linear model with Bonferroni adjusted alpha (p ≤ 0.05). Compared with the correct saddle width, in trot, in the wide saddle, an 8.5% increase in peak pressures was found in the cranial region of the saddle (p = 0.003), a 14% reduction in thoracolumbar dimensions at T13 (p = 0.02), and a 6% decrease in the T13 range of motion in the mediolateral direction (p = 0.02). In the narrow saddle, a 14% increase in peak pressures was found in the caudal region of the saddle (p = 0.01), an 8% decrease in the range of motion of T13 in the mediolateral direction (p = 0.004), and a 6% decrease in the vertical direction (p = 0.004) of T13. Compared with the correct saddle width, in canter, in the wide saddle, axial rotation decreased by 1% at T5 (p = 0.03) with an 5% increase at T13 (p = 0.04) and a 5% increase at L3 (p = 0.03). Peak pressures increased by 4% (p = 0.002) in the cranial region of the wide saddle. Altering the saddle fit had an effect on thoracolumbar kinematics and saddle pressure distribution; hence, correct saddle fit is essential to provide unhindered locomotion.

Sensor-based equine gait analysis: more than meets the eye?

Quantitative gait analysis in the lame horse has gained in popularity, likely related to the potential to remove bias from the clinical decision-making process. Its implementation into clinical practice is, however, not without challenges. This review visits some of the challenges related to the use of thresholds and guideline values in the context of clinical decision making, as well as when applied to scientific studies based on relevant published studies: issues such as ‘normal day-to-day variation’, conformational asymmetry and the often limited number of parameters that are being quantified. Emphasis is put on outlining the basic underlying principles relating to head nod and hip hike, which are explained in the context of Newtonian mechanics associating reduced vertical acceleration of the upper body to reduced force production with the limb that is in contact with the ground during that time period. Further to quantifying what can be seen ‘by eye’, the review also visits phenomena such as asymmetries in weight bearing or pushoff and compensatory mechanisms, with emphasis on measurement of withers movement and thoughts about multilimb lameness. The review concludes with thoughts about additional parameters such as limb movement and movement of the thoraco-lumbo-sacral area, which may provide additional insights into lameness and poor performance but are at current less frequently included into clinical gait analysis in the horse.