H. Chateau

Ground reaction force and kinematic analysis of limb loading on two different beach sand tracks in harness trotters.

REASONS FOR PERFORMING STUDYnAlthough beach training is commonly used in horses, limb loading on beach sand has never been investigated. A dynamometric horseshoe (DHS) is well adapted for this purpose.nnnOBJECTIVESnTo compare ground reaction force (GRF) and fetlock kinematics measured in harness trotters on 2 tracks of beach sand with different water content.nnnMETHODSnTwo linear sand tracks were compared: firm wet sand (FWS, 19% moisture) vs. deep wet sand (DWS, 13.5% moisture). Four French trotters (550 ± 22 kg) were used. Their right forelimb was equipped with a DHS and skin markers. Each track was tested 3 times at 7 m/s. Each trial was filmed by a high-speed camera (600 Hz); DHS and speed data acquisition was performed at 10 kHz on 10 consecutive strides. All recordings were synchronised. The components Fx (parallel to the hoof solar surface) and Fz (perpendicular) of the GRF were considered. For 3 horses the fetlock angle and forelimb axis-track angle at landing were measured. Statistical differences were tested using the GLM procedure (SAS; P < 0.05).nnnRESULTSnStance duration was increased on DWS compared to FWS. Fzmax and Fxmax (oriented, respectively, downwards and forwards relatively to the solar surface) and the corresponding loading rates, were decreased on DWS and these force peaks occurred later. Fxmin (backwards) was not significantly different between both surfaces; the propulsive phase (Fx negative) was longer and the corresponding impulse higher, on DWS compared to FWS. The forelimb was more oblique to the track at landing and maximal fetlock extension was less and delayed on DWS.nnnCONCLUSIONSnThis study confirms that trotting on deep sand overall reduces maximal GRF and induces a more progressive limb loading. However, it increases the propulsive effort and likely superficial digital flexor tendon tension at the end of stance, which should be taken into account in beach training.

Effect of the rider position during rising trot on the horse׳s biomechanics (back and trunk kinematics and pressure under the saddle)

Knowledge about the horse-saddle-rider interaction remains limited. The aim of this study was to compare the effect of the rider׳s position at rising trot on the pressure distribution, spine movements, stirrups forces and locomotion of the horse. The horse׳s back movements were measured using IMUs fixed at the levels of thoracic (T6, T12, T16) and lumbar (L2, L5) vertebrae, the pressure distribution using a pressure mat and stirrups forces using force sensors. The horse׳s and rider׳s approximated centres of mass (COM) were calculated using 2D reflective markers. To compare both trot phases (rider seated/rider standing), three horses were trotted at the rising trot by the same rider. Means±SD of each parameter for sitting and standing were compared using a Student׳s t test (p=0.05). Stirrups forces showed two peaks of equal magnitude in every stride cycle for left and right stirrups but increased during the standing phase. Simultaneously, the pressure for the whole mat significantly increased by +3.1kPa during the sitting phase with respect to standing phase. The T12-T16 and T16-L2 angular ranges of motion (ROM) were significantly reduced (-3.2° -1.2°) and the T6-T12 and L2-L5 ROM were significantly increased (+1.7° +0.7°) during sitting phase compared to standing phase. During rising trot, the sitting phase does not only increase the pressure on the horse׳s back but also reduces the back motion under the saddle compared to the standing phase. These results give new insights into the understanding of horse-rider interactions and equine back pain management.

Discrimination of two equine racing surfaces based on forelimb dynamic and hoof kinematic variables at the canter

The type and condition of sport surfaces affect performance and can also be a risk factor for injury. Combining the use a 3-dimensional dynamometric horseshoe (DHS), an accelerometer and high-speed cameras, variables reflecting hoof-ground interaction and maximal limb loading can be measured. The aim of the present study was to compare the effects of two racing surfaces, turf and all-weather waxed (AWW), on the forelimbs of five horses at the canter. Vertical hoof velocity before impact was higher on AWW. Maximal deceleration at impact (vertical impact shock) was not significantly different between the two surfaces, whereas the corresponding vertical force peak at impact measured by the DHS was higher on turf. Low frequency (0-200 Hz) vibration energy was also higher on turf; however high frequency (>400 Hz) vibration energy tended to be higher on AWW. The maximal longitudinal force during braking and the maximal vertical force at mid-stance were lower on AWW and their times of occurrence were delayed. AWW was also characterised by larger slip distances and sink distances, both during braking and at maximal sink. On a given surface, no systematic association was found between maximal vertical force at mid-stance and either sink distance or vertical impact shock. This study confirms the damping properties of AWW, which appear to be more efficient for low frequency events. Given the biomechanical changes induced by equestrian surfaces, combining dynamic and kinematic approaches is strongly recommended for a reliable assessment of hoof-ground interaction and maximal limb loading.

Equine hoof slip distance during trot at training speed: Comparison between kinematic and accelerometric measurement techniques

Longitudinal sliding of horses hooves at the beginning of stance can affect both performance and orthopaedic health. The objective of this study was to compare two measurement methods for quantifying hoof slip distances at training trot. The right front hoof of four French Trotters was equipped with an accelerometer (10 kHz) and kinematic markers. A firm wet sand track was equipped with a 50 m calibration corridor. A high-frequency camera (600 Hz) was mounted in a vehicle following each horse trotting at about 7 m/s. One of the horses was also trotted on raw dirt and harrowed dirt tracks. Longitudinal slip distance was calculated both from kinematic data, applying 2D direct linear transformation (2D-DLT) to the markers image coordinates, and from the double integration of the accelerometer signal. For each stride, both values were compared. The angle of the hoof with respect to the track was also measured. There was middling/satisfactory agreement between accelerometric and 2D-DLT measurements for total slip and fairly good agreement for hoof-flat slip. The influence of hoof rotation on total slip distance represented <6% of accelerometric measures. The differences between accelerometric and kinematic measures (from -0.5 cm to 2.1cm for total slip and from -0.2 cm to 1.4 cm for hoof-flat slip) were independent of slip distance magnitude. The accelerometric method was a simple method to measure hoof slip distances at a moderate training speed trot which may be useful to compare slip distances on various track surfaces.

Comparison of superficial digital flexor tendon loading on asphalt and sand in horses at the walk and trot

The incidence of superficial digital flexor tendon (SDFT) injuries is one of the highest of all equine musculoskeletal conditions. Horses with SDFT injuries commonly show no improvement of lameness on soft ground, unlike those suffering from distal bone or joint lesions. The aim of this study was to compare the SDFT loading in five horses at the walk and trot on asphalt and sand using a non-invasive ultrasonic tendon force measurement device. Three horses were equipped with the ultrasonic device, whereas the other two horses were equipped with the ultrasonic device and a dynamometric horseshoe (DHS); the DHS was used to calibrate the measured values of tendon speed of sound (SOS) converted to tendon force, while a previously established ground reaction force pattern was used to calibrate SOS measurements for the other three horses. Although the horses tended to be slower on S, maximal tendon force was higher on sand than on asphalt at the trot (+6%); there was no significant difference between the two surfaces at the walk. The duration of tendon loading was longer on S (+5%) and the area under the tendon force-time curve was larger on S (+10%) at both walk and trot. SDFT loading is significantly affected by the ground surface and the observed increase in SDFT loading on sand compared with asphalt is consistent with clinical observations in horses with SDFT injuries.

Comparative kinematic analysis of the leading and trailing forelimbs of horses cantering on a turf and a synthetic surface

REASONS FOR PERFORMING STUDYnThe relationship between track surface properties and limb kinematics is poorly understood. Hoof orientation within the track surface has never been quantified under training conditions. Previously described kinematic and dynamic differences between leading and trailing forelimbs at the canter poorly correlate with epidemiological data regarding injuries.nnnOBJECTIVESnTo compare joint kinematics and hoof orientation in the leading and trailing forelimbs of horses cantering on turf and on a synthetic surface.nnnSTUDY DESIGNnNoninvasive experimental study.nnnMETHODSnThe right forelimb of 5 horses was equipped with markers facing the main joints while markers and a dynamometric horseshoe were placed on the hoof. The horses were filmed with 2 high-speed cameras (1000u2009Hz) while cantering (30u2009km/h). Recordings were repeated at each lead and alternated on turf and on a synthetic surface. Joint angles and angles of the hoof and limb to the track were measured from the 2-dimensional coordinates of the markers.nnnRESULTSnElbow, carpus and fetlock were more maximally flexed during swing and had a larger range of motion throughout the stride in the leading forelimb. Maximal carpal extension during stance was also larger on this limb, which had a more toe-up orientation. Comparing surfaces, the limb was more oblique at landing, the range of motion of the hoof into the surface was larger, most kinematic events were delayed and fetlock and carpus extension velocities were smaller on the synthetic surface.nnnCONCLUSIONSnThe differences between limbs were more prominent than those between surfaces and the more toe-up orientation on the hoof of the leading forelimb suggests a different loading of that limbs joints and tendons. Differences between limbs may be important in the interpretation of lead changes in lame horses. While the synthetic surface appears to be less strenuous for the joints in the forelimbs, it was associated with changes in timing of the kinematic events of the stride.

Effects of the rider on the kinematics of the equine spine under the saddle during the trot using inertial measurement units: Methodological study and preliminary results

Many factors associated with the saddle and the rider could produce pain in horses thus reducing performance. However, studies of horse-saddle-rider interactions are limited and determining their effects remains challenging. The aim of this study was to test a novel method for assessing equine thoracic and lumbar spinal movement under the saddle and collect data during trotting. Back movement was measured using inertial measurement units (nu2009=u20095) fixed at the levels of thoracic vertebrae T6, T12 and T16, and lumbar vertebrae L2 and L5. To compare unridden and ridden conditions, three horses were trotted in hand then at the rising trot (seated phase: left diagonal, rider seated; standing phase: right diagonal, rider standing). The protraction-retraction angles of the forelimbs and the hind limbs were also calculated in two dimensions (2D) using reflective markers. To compare conditions, linear mixed-effects regression models were used and estimated means (standard error) were calculated. The range of motion (ROM) of the caudal thoracic and thoracolumbar regions decreased respectively by -1.3 (0.4)° and -0.6 (0.2)° during the seated phase compared to the unridden condition. Concomitantly, the ROM of protraction and retraction angles increased in the ridden condition. This study demonstrated the ability of inertial measurement units to assess equine vertebral movements under the saddle. The rider, at the rising trot, affected the horses global locomotion with measurable changes in the vertebral kinematics under the saddle.

Effects of Large Saddle Panels on the Biomechanics of the Equine Back During Rising Trot: Preliminary Results

&NA; The saddle panels, directly in contact with the horses back, are likely an important element to optimize the fitting of the saddle, the comfort of the horse, and subsequently, the pain management in dorsalgic horses. The aim of this study was to better understand the effect of the saddle panels on the horses back, by evaluating a prototype saddle (comfort panels: CP) compared to a standard saddle (STD). The horses back movements were measured using inertial measurement units (IMUs) fixed at the levels of thoracic vertebrae T6, T12, T16 (under the saddle) and lumbar vertebrae L2 and L5. The centers of mass (COMs) of the horse and the rider and limbs protraction‐retraction angles, pressure between saddle and horses back, and force on the stirrups were measured using respectively 2D motion capture, pressure mat and force sensors in the stirrup leather. Three horses were trotted at the rising trot (sitting: left diagonal‐rider seated; standing: right diagonal‐rider standing) by the same rider. To compare saddles, linear mixed‐effects regression models were used. The estimated means (SE) were calculated. During sitting phase, pressure in the cranial and middle areas of the saddle significantly increased for CP compared to STD (+0.9 (0.2) kPa and +1.0 (0.1) kPa, respectively) whereas caudal pressure decreased (−1.8 (0.4) kPa). Concurrently, the range of motion of angles T12‐T16 and T16‐L2 under the saddle significantly increased (+1.8 (0.2)° and +2.3 (0.3)°, respectively). The results showed that modifications of the panels shape not only affect the pressure distribution but also the kinematics of the thoracic and lumbar regions of the equine back. HighlightsA new protocol developed to better understand the horse‐saddle‐rider interactionA homogeneous pressure distribution under the saddle improve the back movement (FE)Saddle panels shape influences the backs movement of the horse