Hilary Clayton

Sport Horse Science, LC · Professor and Mary Anne McPhail Dressage Chair Emerita

This study follows a previously defined framework to investigate the impact of impairment on performance in Para dressage athletes. Twenty-one elite Para dressage athletes (grades I to V) and eleven non-disabled dressage athletes (competing at Prix St. Georges or Grand Prix) participated. Data were collected in two phases: performing a two minute c...

The repeatability of surface electromyography (sEMG) is an important consideration for its potential clinical application in equine gait analysis. We hypothesize that equine sEMG profiles are repeatable between measurement sessions, but this has not been demonstrated. Thus, we evaluated the between-day repeatability of normalised sEMG activity prof...

In the sport of dressage, one or more judges score the combined performance of a horse and rider with an emphasis on the technical correctness of the movements performed. At the end of the test, a single score is awarded for the ‘general impression’, which considers the overall performance of the horse and rider as a team. This study explored origi...

The reliability of surface electromyography (sEMG) has not been adequately demonstrated in the equine literature and is an essential consideration as a methodology for application in clinical gait analysis. This observational study investigated within-session, intra-subject (stride-to-stride) and inter-subject reliability, and between-session relia...

This study compared muscle activity and movement between the leading (Ld) and trailing (Tr) fore- (F) and hindlimbs (H) of horses cantering overground. Three-dimensional kinematic and surface electromyography (sEMG) data were collected from right triceps brachii, biceps femoris, middle gluteal, and splenius from 10 ridden horses during straight lef...

Body condition in horses is a growing concern that has different patterns of development in horses that are above and below the ideal range. This study used professional and para-professional evaluators (veterinarians, farriers, trainers, Danish Equestrian Federation (DEF) officials) who were trained and certified in the use of a modified Henneke s...

Background: The inter-relationship between equine thoracolumbar motion and muscle activation during normal locomotion and lameness is poorly understood. Objectives: To compare thoracolumbar and pelvic kinematics and longissimus dorsi (longissimus) activity of trotting horses between baseline and induced forelimb (iFL) and hindlimb (iHL) lameness...

Conformation of the hooves and distal limbs of foals and factors influencing their morphological development have not been reported in detail for the Thoroughbred breed. In this paper we explore morphogenesis of the equine distal limb in Thoroughbred foals with emphasis on adaptations in response to weight bearing early in life that prepare the foa...

The relationship between lameness-related adaptations in equine appendicular motion and muscle activation is poorly understood and has not been studied objectively. The aim of this study was to compare muscle activity of selected fore- and hindlimb muscles, and movement of the joints they act on, between baseline and induced forelimb (iFL) and hind...

Knowledge of vertical motion patterns of the axial body segments is a prerequisite for the development of algorithms used in automated detection of lameness. To date, the focus has been on the trot. This study investigates the temporal synchronization between vertical motion of the axial body segments with limb kinematic events in walk and trot acr...

Not too long ago, tack often fell into the "one size fits all" category but, fortunately, times have changed. In recent years, tack has become not only more functional but also a fashion statement. This article describes scientific concepts of the saddle, bridle, and bit with emphasis on clinical signs associated with ill-fit or incorrect use.

• Horses are exceptional athletes that compete in a wide range of sports each requiring a unique combination of speed, power, balance, and gymnasticism. • There are three Olympic equestrian sports each requiring distinct and different athletic attributes. • Together, horse and rider combinations competing in Olympic equestrian sports fulfill the Ol...

This study addresses the presence and location of natural pigmentation, potentially pathological changes in pigment, interruptions of the natural lining (scars), roughness, and erosions/contusion (bruising) in and around the corners of the lips of 206 horses presented to a veterinarian for routine preventative dental treatment. After sedation, phot...

This study addresses the presence and location of oral lesions in 342 dressage, show jumping, and eventing horses examined at an obligatory veterinary inspection before competing in the Danish National Championship in 2020. Ulcers in the lip commissures were photographed for subsequent pathological analysis. If a lesion was found at the lip commiss...

As techniques for equine biomechanical research have become more accessible and affordable, the literature published in this area has exploded. Literature reviews have become more popular of late and, more specifically, several literature reviews in areas related to equine biomechanics have been published. A scoping review is a relatively new appro...

In equestrian sports the novice rider learns first to follow the movements of the horse's back and then how to influence the horse's performance. One of the rider's challenges is to overcome inherent horse/rider asymmetry patterns when riding in straight lines, mirroring the movements on the left and right sides when turning. This study compares th...

In dressage, horse-rider combinations must demonstrate harmony whilst performing a test of gaits and movements, scored by judge(s) using predetermined criteria. The para dressage governing body is working towards compliance with the International Paralympic Committee's mandate for evidence-based classification, which requires a comprehensive unders...

The popularity of equestrian sports provides an increasing market for horse gear or tack. While manufacturers have launched new designs to enhance the safety, comfort, effectiveness and aesthetics of their products, few items of tack have been evaluated quantitatively. Nosebands are not an essential component of a bridle, but are widely used across...

As a first step in achieving an evidence-based classification system for the sport of Para Dressage, there is a clear need to define elite dressage performance. Previous studies have attempted to quantify performance with able-bodied riders using scientific methods; however, definitive measures have yet to be established for the horse and/or the ri...

Show jumping horses must execute fences of varying height and width, but the effect of this on jumping kinematics during the airborne phase have not been described. The aim of this study was to describe differences within- and between-horses in CM trajectory, trunk orientation and average trunk angular velocity in a group of elite horses executing...

Injuries to the locomotor system are a common problem in athletic horses. Veterinarians address these injuries using appropriate medical, surgical, and pharmacological treatments. During or after recovery from the initial injury, horses may be treated for functional locomotor deficits using specific rehabilitation techniques aimed at restoring full...

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 a...

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 a...

Selection and training practices for jumping horses have not yet been validated using objective performance analyses. This study aimed to quantify the differences and relationships between movement and muscle activation strategies in horses with varying jump technique to identify objective jumping performance indicators. Surface electromyography (s...

This study described the 3D ground reaction forces in highly trained horses performing piaffe. It shows that the vertical force and impulse distribution is more similar in piaffe than in passage or trot. The longitudinal forces are small since there is no forward motion. The transverse forces are similar in magnitude to the longitudinal forces. A n...

North American Thoroughbred racing is conducted on three types of surfaces—dirt, turf, and synthetic. The tracks are oval, and races are run counterclockwise. The loading on right and left limbs is expected to differ as a function of turn radius, banking, surface, and gait asymmetry. Hind limbs and forelimbs also have different functions related to...

The objective was to evaluate the effects of gymnastic training on stride characteristics of walk and trot in therapy horses carrying riders of different weights. Eighteen horses used for therapeutic riding 5 days/ week were randomly divided into 2 groups. Nine horses performed gymnastic (GYM) exercises after therapeutic riding on 4 days/week for 3...

As a first step in achieving an evidence-based classification system for the sport of Para Dressage, there is a clear need to define elite dressage performance. Previous studies have attempted to quantify performance with able-bodied riders using scientific methods; however, definitive measures have yet to be established for the horse and/or the ri...

Background: Left-right movement symmetry is a highly desirable characteristic in sport horses. Objectives: This study compared movement symmetry in well-trained dressage horses unridden and unrestrained, and ridden in a dressage frame, and investigated possible associations between gaits. Study design: Experimental study. Methods: Seven soun...

It has been suggested that one of the underlying causes of asymmetrical performance and left/right bias in sound riding horses is laterality originating in the cerebral cortices described in many species. The aim of this paper is to review the published evidence for inherent biomechanical laterality in horses deemed to be clinically sound and relat...

Gaits are typically classified as walking or running based on kinematics, the shape of the vertical ground reaction force (GRF) curve, and the use of inverted pendulum or spring-mass mechanics during the stance phase. The objectives of this review were to describe the biomechanical characteristics that differentiate walking and running gaits, then...

The superimposed influences of different head and neck positions (HNPs) and rider effects on symmetry in sound horses have not been studied. Our aim was to investigate the effects of HNPs and rider on the symmetry in minimum height of the withers at the walk. Seven high-level dressage horses were studied with and without rider in six HNPs: HNP1, fr...

The objectives of this observational, cross-sectional study were to characterize and establish the prevalence of osseous proliferation of articular surfaces, joint margins and adjacent soft tissue attachments (i.e., joint capsule and deep spinal muscles) in a mixed population of horses of variable ages, sizes, and breeds to better capture the full...

One of the goals of the neuromotor control system is to minimize the cost of locomotion by reducing mechanical energy losses. Collisional mechanics, which studies the redirection of the downwards motion of the center of mass (COM) by ground reaction forces (GRF) generated by the limbs, represents an important source of energy loss. The primary obje...

The symmetry of the rider is highly relevant, and in the equestrian community it is generally thought that a symmetrical rider has a better possibility to influence the horse in an optimal way. The aim of the study was to analyse and compare frontal plane kinematics of the core body segments in ten riders while riding and while rocking a balance ch...

To reduce anatomically unrealistic limb postures in a virtual musculoskeletal model of a horse's forelimb, accurate knowledge on forelimb joint constraints is essential. The aim of this cadaver study is to report all orientation and position changes of the finite helical axes (FHA) as a function of joint angle for different equine forelimb joints....

Clayton HM, Hampson A, Fraser P, White A, Egenvall A. Rider stability improves when riding in a flapless saddle versus a conventional saddle. PlosOne 2018;13(6): e0196960. Performed with approval of the MSU animal care and use committee. No competing interests declared. ROM of the rider's COP in AP and ML directions will be smaller with the flaples...

Legged locomotion results from the feet pressing against the ground to generate ground reaction forces (GRFs) that are responsible for moving the body. By changing limb coordination patterns and muscle forces, the GRFs are adjusted to allow the horse to move in different gaits, speeds, and directions with appropriate balance and self-carriage. This...

The main functions of a saddle are to improve rider stability and comfort, with the stirrups providing support for the rider’s legs. The criteria upon which riders base their choice of stirrup length for different equestrian disciplines does not appear to have been reported. Therefore, this study was designed to investigate the factors that play a...

Although stirrups may be considered an essential part of equestrian equipment, there is little research describing their use and function. The aim of the present study was to compare stirrup lengths chosen for flatwork by novice and experienced riders, and to measure the associated leg position and knee angles. Ten novice and ten experienced riders...

For efficient rider-horse communication, the rider needs to maintain a balanced position on the horse, allowing independent and controlled movements of the rider’s body segments. The rider’s balance will most likely be negatively affected by postural asymmetries. The aims of this study were to evaluate inter-segmental symmetry of movements of the r...

General additive modelling (GAM-modelling) is an exploratory technique that can be used on longitudinal (time series) data, e.g. rein tension, over a period of time. The aim was to apply GAM-modelling to investigate changes in rein tension during a normal flatwork training session. Six riders each rode two or three of their horses (n=17 horses) dur...

The walk and trot are inherently symmetrical gaits, making them potentially suitable for the detection of left-right asymmetries. The aims of this study were to describe asymmetrical vertical excursions of the withers at walk in non-lame high-level dressage horses and to seek associations between these asymmetric movements and other kinematic varia...

The marker set up. The markers used in the current study were those on the sixth, tenth and thirteenth thoracic vertebrae (T6, T10, T13), third sacral vertebra (S3), spina scapula (3), elbow joint space (5) and lateral fore and hind hoof walls (not numbered). (TIF)

Raw data for vertical positions of T6, T10, T13 and means of the vertical positions of the tubera spina scapulae markers for the trials in median speed for each horse. The curves showing vertical positions are centered around zero. For the ground reaction forces, the upper tracks are for the forelimbs and the lower tracks are for the hind limbs; in...

Stance minimum vertical positions of T6 plotted against stance minimum vertical positions of other midline and forelimb markers evacuated from the time point during early stance of the left forelimb (only values for left forelimb stance are plotted to avoid stride-level clustering within trial). Minimal vertical positions for markers on the tuber s...

The data used for the statistical analysis. (XLSX)

Distributions of trial-level models independent data tested in kinetic and kinematic models. All variables are expressed as differences between left and right. Data—see S1 Table. (PDF)

Video of horse 2. Original speed 1.58 m/s; shown at 50% of original speed. (MP4)

Asymmetry in forelimb dorsal hoof wall angles, termed unevenness, is associated with forelimb gait asymmetries, but compensatory mechanisms and out of plane ground reaction forces (GRFs) due to unevenness have yet to be documented. The aim of this study was therefore to investigate the effects of fore hoof unevenness on contralateral fore and hind...

Additional data exploring hoof shape, centre of pressure (COP) and vector variables. (XLSX)

This protocol describes a method of collecting, displaying and analysing ground reaction force (GRF) vector patterns in horses during locomotion. The method may be applied to other quadrupeds.

The purpose of a saddle is to improve the rider’s safety, security, and comfort, while distributing the forces exerted by the rider and saddle over a large area of the horse’s back without focal pressure points. This study investigates the effects on rider stability of an innovative saddle design that differs from a conventional saddle in having no...

Data describing segmental masses and moments of inertia (MOI) of limb segments are required for inverse dynamic calculations. In horses, these values are usually calculated using regression equations that have been developed from a limited number of horses representing a small number of breeds. The objective of the present study was to evaluate the...

Background: Information is needed to guide sport administrators in formulating rules for equipment use in competitions. Objectives: To seek associations between spurs, bits, nosebands and whips with injuries in horses during competitions in four equestrian sports. Study design: Cross sectional study. Methods: Post-competition evaluations wer...

Background Ground reaction forces (GRF) measured during equine gait analysis are typically evaluated by analyzing discrete values obtained from continuous force-time data for the vertical, longitudinal and transverse GRF components. This paper describes a simple, temporo-spatial method of displaying and analyzing sagittal plane GRF vectors. In addi...

Supplementary information investigating stance phase threshold

The effect of using a different threshold on ground reaction force traces normalized to 101 points (A) Mean vertical and (B) mean longitudinal ground reaction forces for horse 10 (N/kg). Black: 50 N threshold; blue: 100 N threshold; red: 150 N threshold.

Typical force variables and vector summary variables

Normalized stance phase data for SPM analysis

Example file of vector diagram construction with data included from Fig. 5

SPM Data sorted into high and low groups

This study reports tension in the left and right reins when riding a horse simulator that moved only in the sagittal plane. The objective was to determine whether asymmetries in rein tension of novice riders at the rising trot, canter, and halt were present, and if so, to investigate their relationship with the rider’s handedness. The experimental...

Background Locomotion results from the generation of ground reaction forces (GRF) that cause translations of the center of mass (COM) and generate moments that rotate the body around the COM. The trot is a diagonally-synchronized gait performed by horses at intermediate locomotor speeds. Passage is a variant of the trot performed by highly-trained...

Dataset used in the study Raw data and calculated variables.

Horse performing passage Animated stick figure of a horse from analysis of motion capture data.

Equestrian sports are unique in that they involve the participation of two athletes that differ greatly in morphology yet are able to move together harmoniously; experienced riders not only move in phase with the horse, they can even improve the consistency of the horse’s movements. The motion of the horse imposes perturbations on the rider that di...

In this study, sagittal plane ground reaction forces (GRFs) in ridden elite dressage horses performing ‘collected trot’ and in ‘passage’ over ground were determined. In-ground force plates captured GRF data from four Dutch Warmblood and four Lusitano horses ridden by their trainers. At least three stance phases were analysed for forelimbs and hind...

Background: Previous studies have validated methods for determining kinematic gait events using threshold-based techniques. However, a simple method that can be successfully applied to walk, trot and canter is yet to be identified. Objectives: To develop a simple kinematic method to identify the timing of hoof contact (hoof-on), peak vertical fo...