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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 measures that contribute to the general impression score in a group of 20 horse-rider combinations. Horses and riders were equipped with inertial measurement units (200 Hz) to represent angular motion of the horse’s back, and the motion of the rider’s pelvis and trunk. Each combination performed a standard dressage test that was recorded to video. Sections of the video were identified for straight line movements. The videos were analyzed by two or three judges. Four components were scored separately: gaits of the horse, rider posture, effectiveness of the aids, and harmony with the horse. The main contributor to the score for gaits was stride frequency (R=-0.252, p=0.015) with a slower frequency being preferred. Gait scores and all three rider scores were associated with dynamic symmetry of the trunk indicating that this measure was the most useful predictor of rider performance.

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 reliability of normalised sEMG activity profiles, from triceps brachii (triceps), latissimus dorsi (latissimus), longissimus dorsi (longissimus), biceps femoris (biceps), superficial gluteal (gluteal) and semitendinosus muscles in n = 8 clinically non-lame horses during in-hand trot. sEMG sensors were bilaterally located on muscles to collect data during two test sessions (session 1 and 2) with a minimum 24-hour interval. Raw sEMG signals from ten trot strides per horse and session were DC-offset removed, high-pass filtered (40 Hz), full-wave rectified, and low-pass filtered (25 Hz). Signals were normalised to peak amplitude and percent stride before calculating intra- and inter-subject ensemble average sEMG profiles across strides for each muscle and session. sEMG profiles were assessed using waveform similarity statistics: the coefficient of variation (CV) to assess intra- and inter-subject reliability and the adjusted coefficient of multiple correlation (CMC) to evaluate between-session reliability. Across muscles, CV data revealed that intra-horse sEMG profiles within- and between-sessions were comparatively more reliable than inter-horse profiles. Bilateral gluteal, semitendinosus, triceps and longissimus (at T14 and L1) and right biceps showed excellent between-session reliability with group-averaged CMCs > 0.90 (range 0.90–0.97). Bilateral latissimus and left biceps showed good between-session reliability with group-averaged CMCs > 0.75 (range 0.78–0.88). sEMG profiles can reliably describe fundamental muscle activity patterns for selected equine muscles within a test session for individual horses (intra-subject). Howeve

During turning, horses lean inwards to generate a centripetal force, but sport horses are trained to turn with a more vertical posture. The objective was to compare trunk roll angles in dressage horses performing true canter (TC) and counter canter (CC). Sixteen high-level dressage horses were ridden by their trainers in a 20×60 m arena with sand-fibre footing. Trunk roll angle was measured using an inertial measurement unit attached to mid-ventral girth. Data were analysed for 10 strides/horse on 20 and 10 m circles in TC and CC in each direction. Positive roll values indicated the trunk rolled down on the inside of the circle. Descriptive statistics were calculated and compared using a GLM and post hoc tests (P

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 profiles, from triceps brachii (triceps), latissimus dorsi (latissimus), longissimus dorsi (longissimus), biceps femoris (biceps), superficial gluteal (gluteal) and semitendinosus in n=8 clinically non-lame horses. sEMG sensors (Trigno, Delsys Inc.) were bilaterally located on muscles to collect data during in-hand trot on two occasions (day 1: 3.11±0.23 m/s, day 2: 3.07±0.35 m/s) with a minimum 24-hour interval. Raw sEMG signals from ten trot strides per horse and day were DC-offset removed, high-pass filtered (40 Hz), full-wave rectified, low-pass filtered (25 Hz), and normalised with respect to peak amplitude and percent stride. Within-subject, ensemble average sEMG profiles across strides from each muscle and day were calculated. The adjusted coefficient of multiple correlation (CMC) was used to evaluate the between-day repeatability of ensemble average sEMG profiles and tends to 1 when waveforms are similar. Bilateral gluteal, semitendinosus, triceps and longissimus (at T14 and L1) and left biceps showed excellent between-day repeatability with group-averaged CMCs>0.90 (range 0.90- 0.97). Bilateral latissimus and right biceps showed good reliability with group-averaged CMCs>0.75 (range 0.78-0.88). The sEMG profiles studied here are consistent across days, suggesting that it is reasonable to use sEMG to objectively monitor the activity of these muscles across multiple gait evaluation sessions at trot.

Many factors influence the overall score for a dressage test, which makes it challenging and complex to establish key performance determinants. The aim was to identify an objective locomotory measure to quantify overall rider performance in dressage. The chosen variable should be both easy to collect and useful in a practical context. Twenty dressage horse/ rider combinations (Int1-GP) were equipped with inertial measurement units (IMU’s, 200 Hz) attached to the rider’s sacrum and thorax. Transverse dynamic trunk symmetry and pelvis symmetry (symmetry measures) and trunk-to-pelvis 3-dimensional coordination variability (within rider coordination measure) were collected from the IMU’s during straight line walk, trot and canter on left and right reins with ≥9 strides/condition. Sixteen United States Dressage Federation senior judges evaluated the movements of interest from video footage with 2-3 judges scoring each rider’s performance in the movements of interest and awarding collective scores to represent the overall impression of each rider’s performance. Stepwise linear regression was used to seek associations between objective measurements from the IMUs and subjective scores awarded by the judges. The variable dynamic trunk symmetry was the strongest predictor of collective scores, specifically the score for rider position (R=0.357, P=0.001). The rider’s dynamic pelvic symmetry was a strong predictor of the judged score for the walk (R=0.607, P=0.010), but no relationships were found between objective and judged scores for trot or canter. The overall impression of trunk posture may be influential in judges’ collective scores. Symmetrical pelvic motion appears to be a key factor in producing a high-quality walk.

This study aims to determine the most effective surface electromyography (sEMG) measure, from individual muscles, for distinguishing between non-lame and induced fore- (iFL) and hindlimb (iHL) lameness conditions. We compared bilateral sEMG absolute value and asymmetry measures from triceps brachii (triceps), latissimus dorsi, longissimus dorsi (longissimus), biceps femoris (biceps), superficial gluteal (gluteal) and semitendinosus. sEMG and 3D-kinematic data were collected from n=8 clinically non-lame horses during in-hand trot. iFL and iHL were induced on separate days using a modified horseshoe, with baseline data initially collected each day. MinDiff was calculated from poll (HDMin) and pelvis (PDMin) vertical displacement. sEMG signals were DC-offset removed, high-pass filtered (40 Hz), and full-wave rectified. Average rectified value (ARV) was calculated per stride and normalised to the maximum observed value of individual muscles at baseline (sEMGabs). The difference between right and left normalised ARV were calculated per muscle and stride (sEMGasym). Receiver operating characteristic analysis was conducted, using area under the curve (AUC) as an overall measure of discrimination between baseline and iFL/iHL. MinDiff showed excellent discrimination for iFL (HDMin AUC=0.98) and iHL (PDMin AUC=0.96). Triceps sEMGasym was best (AUC=0.84) for differentiating iFL, with other measures showing fair to chance discrimination (AUC range=0.49-0.76). Lame-side gluteal, semitendinosus and longissimus sEMGabs (AUC range=0.90-0.91) showed excellent discrimination for iHL, followed by biceps sEMGasym (AUC=0.83). Evidently, the choice of sEMG variable is muscle/condition dependent: sEMGabs performed acceptably across muscles/conditions, but triceps and biceps sEMGasym, respectively, appear superior for discriminating iFL and iHL.

s of the 10th International Conference on Equine Exercise Physiology. Lorne, Australia, 12 - 16 November 2018.

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 variables and vertical ground reaction forces (vGRFs). Seven dressage horses, judged clinically as being sound, walked unridden and unrestrained on a treadmill with an integrated force measuring system (480 Hz), from which spatiotemporal and vGRF variables were extracted. Markers were tracked by 12 infrared cameras (240 Hz). The vertical position of the sixth thoracic vertebra (T6), limb protraction and retraction distances throughout stance, and global limb lengths were determined. Contralateral trial-mean differences were calculated, including difference in T6 minimum vertical position between contralateral steps (T6minDiff). Mixed models were used to study associations between symmetry parameters. Trial-mean T6minDiff ranged between 0.3-23 mm. Of the seven horses, five consistently dropped the withers more in early left forelimb stance, one was fairly symmetrical, and one dropped the withers more in early right forelimb stance. Comparisons between contralateral limbs showed the following associations. The forelimb that was retracted when T6min was lowest showed greater retraction at toe-off (1 mm increase predicted 0.17 mm T6minDiff increase) and shorter stance duration (1 ms decrease predicted 0.3 mm T6minDiff increase). The hind limb that was in midstance when T6min was lowest showed a greater range of motion during the stance phase (1 mm increase in protraction or retraction predicted 0.2 mm T6minDiff increase). The haunches were displaced away from the side of the forelimb that was protracted when T6min was lowest (1 mm lateral shift predicted 0.07 mm T6minDiff increase). Forelimb and hind limb vGRF parameters were non-s

Background. Although the trot is described as a diagonal gait, contacts of the diagonal pairs of hooves are not usually perfectly synchronized. Although subtle, the timing dissociation between contacts of each diagonal pair could have consequences on gait dynamics and provide insight into the functional strategies employed. This study explores the mechanical effects of different diagonal dissociation patterns when speed was matched between individuals and how these effects link to moderate, natural changes in trotting speed. We anticipate that hind-first diagonal dissociation at contact increases with speed, diagonal dissociation at contact can reduce collision-based energy losses and predominant dissociation patterns will be evident within individuals. Methods. The study was performed in two parts: in the first 17 horses performed speedmatched trotting trials and in the second, five horses each performed 10 trotting trials that represented a range of individually preferred speeds. Standard motion capture provided kinematic data that were synchronized with ground reaction force (GRF) data from a series of force plates. The data were analyzed further to determine temporal, speed, GRF, postural, mass distribution, moment, and collision dynamics parameters. Results. Fore-first, synchronous, and hind-first dissociations were found in horses trotting at (3.3 m/s � 10%). In these speed-matched trials, mean centre of pressure (COP) cranio-caudal location differed significantly between the three dissociation categories. The COP moved systematically and significantly (P D :001) from being more caudally located in hind-first dissociation (mean locationD0.41�0.04) through synchronous (0.36 � 0.02) to a more cranial location in fore-first dissociation (0.32 � 0.02). Dissociation patterns were found to influence function, posture, and balance parameters. Over a moderate speed range, peak vertical forelimb GRF had a strong relationship with dissociation time (RD:594; P <:01) and

The objectives were to compare sagittal plane posture of the pelvis, trunk and head of elite dressage riders when they ride actively to train the horse versus sitting passively and following the horses’ movements at trot, and to evaluate the effects of these changes in rider posture on load distribution on the horse’s back. Synchronised motion capture and saddle mat data of seven elite dressage riders were used to measure minimal and maximal angles and range of motion (ROM) for the pelvic, trunk and head segments, the angle between pelvis and trunk segments, phase-shift between pitching motions of pelvis and trunk, and pelvic translation relative to the saddle. Non-parametric statistical tests compared variables between the two rider postures. In the passive rider posture the pelvis, trunk and head showed two pitching cycles per stride. Maximal posterior and anterior pelvic rotation occurred, respectively, early and late in the horse’s diagonal stance phase. Compared with pelvic movements, trunk movements were slightly delayed and head movements were out-of-phase. In the active rider posture the pelvis and trunk pitched further posteriorly throughout the stride. Most of the riders showed similar sagittal plane movements of the axial body segments but with some notable individual variations.