Trunk deformation in the trotting horse

Reasons for performing study: Estimates of the position of the centres of mass (CM) of body segments are usually extrapolated relative to bony landmarks as determined in cadaver studies. This extrapolation assumes that segments are rigid bodies. Since the trunk represents a large percentage of the total body mass in horses, violation of the rigid body assumption by the trunk segment has important consequences for studying the biomechanics of equine locomotion. Objectives: To assess the magnitude of error in CM position due to deformability of the trunk segment and the timing of these errors during the trotting stride. The hypothesis was that shape changes during a stride are repeatable and predictable. Methods: Forty skin markers were attached in a grid pattern on the trunks of 6 adult horses, with an additional marker attached to each hoof. The markers were tracked using an 8 camera motion analysis system. Each horse was tested at 10 different velocities during trotting. The CM of the trunk was calculated under the assumption of a rigid body, based on 5 spine markers and from the volume encompassed by the 40 markers. The difference between the 2 calculation methods quantifies the effect of trunk deformation on the position of the CM. Results: The trunk changed shape during locomotion in a repeatable manner resulting in cyclic changes in CM position. Amplitudes of the CM displacement due to trunk deformation were equal in magnitude in the transverse and longitudinal directions. In the vertical direction, the CM moved only at half the amplitude. Magnitudes were strongly horse‐dependent. Conclusions and potential relevance: Shape changes in the equine trunk segment in the horizontal plane should be taken into account when modelling locomotion of horses. Amplitudes are horse dependent, complicating the development of correction routines.     

Maximum permissible load for Kiso horses trotting over a short,straight course

This study aimed to determine the load‐bearing capacity of trotting Kiso horses using gait analysis. Ten Kiso horses with a height at withers of 128 cm were included. Their riders were fitted with a marker (70 mm in diameter placed on their chest) recorded by two digital DVD cameras while trotting along a short, straight course. In total, eight tests were performed for each horse: the first with a 70 kg load; six with randomly loaded weights ranging 80–130 kg; and then a final test again with a 70 kg load. Three‐dimensional movement of the marker was analyzed using a motion capture system. The time series of vertical displacement of the marker underwent spectrum analysis by the maximum entropy method, and the autocorrelation coefficient was calculated. The first two peaks of the autocorrelation were defined as symmetry and regularity, and their sum was defined as stability. Regularity in the 120 kg test (0.54) was lower than that in the first 70 kg test (0.61), and stability in the 120 kg test (1.31) was lower than that in the first 70 kg test (1.42). We concluded that the maximum permissible load for a trotting Kiso horse is < 120 kg, which represents 31% of its bodyweight.     

Kinematic Characterization of the Menorca Horse at the Walk and the Trot: Influence of Hind Limb Pastern Angle

This paper describes the handled walking and trotting kinematics (linear, temporal, and angular traits) of 35 Menorca Purebred (MEN) stallions, and the relationships among these variables is presented for the first time, along with a discussion of the influence of the hind limb pastern angle on kinematic variables at both gaits. For data collection, all animals, aged between 3 and 10 years old and belonging to 28 different studs, were recorded under the same experimental and environmental conditions, using a three-dimensional (3D) semiautomatic movement analysis system. A total of 24 kinematic variables (temporal, linear, and angular) at the walk and the trot and a morphometric variable measured at the mid stance position of walking (hind pastern angle) were included in this analysis. Angle-time diagrams of the hind pastern angle while walking and trotting normalized to stride duration were also obtained. Generally the MEN stallions' forelimb movements closely resembled the movement characteristics of other European dressage performance breeds, while the hind limb locomotion showed a greater likeness to Iberian dressage Purebreds. Despite this, their ability in collection and propulsion at the walk and the trot was relatively low. The hind limb pastern conformation was partially connected to the hind limb movements for both gaits, with an apparently negative effect of excessively upright pasterns on the amplitude at the trot, which indirectly reduced collection ability.     

Vertical head and trunk movement adaptations of sound horses trotting in a circle on a hard surface

Trotting a horse in circles is a standard and important part of the subjective equine lameness examination, yet objective data on this form of locomotion are sparse. The aim of this study was to investigate the effect of trotting in a circle on head and trunk movement symmetry. Vertical movements of the head, withers, os sacrum and left and right tuber coxae were measured using inertial sensors as 12 sound horses were trotted on a hard surface in a straight line and in a circle on both reins. Seven asymmetry measures and hip hike were calculated for each horse for at least nine strides of comparable stride duration across the three conditions (deviation on horse level ≤3.7% stride duration). Trotting in a circle introduced systematic changes to the movement pattern of all five body landmarks, affecting most asymmetry measures. On average the asymmetry magnitude was comparable for midline locations between reins and for the tuber coxae on opposite reins with few exceptions, although individual horses showed unsystematic differences between the two reins. The results from this study showed that the thresholds for objective discrimination between lame and non-lame horses will need adjustment on the circle due to the observed asymmetry bias.     

Objective determination of pelvic movement during hind limb lameness by use of a signal decomposition method and pelvic height differences

OBJECTIVE: To evaluate pelvic movement over a large number of strides in sound horses and in horses with induced hind limb lameness by applying methods to the pelvis that have been described for evaluating vertical head movement in horses with induced forelimb lameness. ANIMALS: 17 adult horses. PROCEDURE: Horses were filmed while trotting on a treadmill before and after induction of transient mild and moderate hind limb lamenesses. Vertical pelvic movement was measured by a signal decomposition method. The vertical pelvic signal was decomposed into a periodic component (A1) that occurred at half the stride frequency (representing vertical pelvic movement caused by lameness) and another periodic component (A2) that occurred at stride frequency (representing normal vertical pelvic movement of a trotting horse). Vertical pelvic and foot positions were correlated for each stride to compare the difference between the minimum and maximum heights of the pelvis during and after stance of the right hind limb to the minimum and maximum heights of the pelvis during and after stance of the left hind limb. RESULTS: Maximum pelvic height difference and lameness amplitude (A1) differed significantly between sound and mild or moderate hind limb lameness conditions. Mean A1 value for vertical pelvic movement in sound horses was less than that previously reported for vertical head movement. CONCLUSION AND CLINICAL RELEVANCE: Pelvic height differences and signal decomposition of pelvic movement can be used to objectively evaluate hind limb lameness in horses over a large number of strides in clinical and research settings.     

Individual speed dependency of forelimb lameness in trotting horses

Using a system for motion analysis, linear correlation of speed and forelimb lameness was measured in 16 horses trotting on a treadmill at a minimum of three different trotting speeds. Forelimb lameness was determined as asymmetry of vertical head motion during left and right forelimb stance.In seven horses with a moderate forelimb lameness (head motion asymmetry >40%), lameness increased significantly with trotting speed. In a further seven horses with mild or subclinical forelimb lameness (head motion asymmetry <40%) and in two horses with a moderate forelimb lameness, no significant correlation between speed and motion asymmetry was found.The results indicate that moderate forelimb lameness measured as head motion asymmetry depends on the speed at which the measurements are taken. If head motion asymmetry is measured at two trotting speeds, it can be standardized to any speed within the trotting speed range.     

Effect of laryngeal hemiplegia and laryngoplasty on airway flow mechanics in exercising horses

The effect of left laryngeal hemiplegia on airway flow mechanics in 5 exercising horses was examined, and the efficacy of surgical repair by prosthetic laryngoplasty was evaluated. Measurements of the upper airway flow mechanics were made with horses on a treadmill (incline 6.38 degrees) while standing (period A); walking at 1.3 m/s (period B); trotting at 2.6 m/s (period C); trotting at 4.3 m/s (period D); and standing after exercise (period E). Experiments were done on healthy horses before any surgical manipulation (control), at 10 days after left recurrent laryngeal neurectomy, and at least 14 days after prosthetic larynogoplasty. Increasing treadmill speed from period A to period D progressively increased heart rate, respiratory frequency, peak inspiratory flow, and peak expiratory flow, but inspiratory resistance and expiratory resistance remained unchanged. Neither left recurrent laryngeal neutrectomy nor prosthetic laryngoplasty affected heart rate, respiratory frequency, peak expiratory flow, or expiratory resistance when compared with those values at the control measurement periods. Left recurrent laryngeal neurectomy resulted in inspiratory flow limitation at peak inspiratory flow of approximately 25 L/s, and increased inspiratory resistance at periods D and E. Subsequent prosthetic laryngoplasty alleviated the flow limitation and reduced inspiratory resistance at measurement periods D and E.     

Detection of spinal ataxia in horses using fuzzy clustering of body position uncertainty

REASONS FOR PERFORMING STUDY: Subjective neurological evaluation in horses is prone to bias. An objective method of spinal ataxia detection is not subject to these limitations and could be of use in equine practice and research. HYPOTHESIS: Kinematic data in the walking horse can differentiate normal and spinal ataxic horses. METHODS: Twelve normal and 12 spinal ataxic horses were evaluated by kinematic analysis walking on a treadmill. Each body position signal was reduced to a scalar measure of uncertainty then fuzzy clustered into normal or ataxic groups. Correct classification percentage (CCP) was then calculated using membership values of each horse in the 2 groups. Subsequently, a guided search for measure combinations with high CCP was performed. RESULTS: Eight measures of body position resulted in CCP > or = 70%. Several combinations of 4-5 measures resulted in 100% CCP. All combinations with 100% CCP could be obtained with one body marker on the back measuring vertical and horizontal movement and one body marker each on the right fore- and hindlimb measuring vertical movement. CONCLUSIONS AND POTENTIAL RELEVANCE: Kinematic gait analysis using simple body marker combinations can be used objectively to detect spinal ataxia in horses.     

The effect of rising and sitting trot on back movements and head‐neck position of the horse

Reason for performing study: During trot, the rider can either rise from the saddle during every stride or remain seated. Rising trot is used frequently because it is widely assumed that it decreases the loading of the equine back. This has, however, not been demonstrated in an objective study. Objective: To determine the effects of rising and sitting trot on the movements of the horse. Hypothesis: Sitting trot has more extending effect on the horse's back than rising trot and also results in a higher head and neck position. Methods: Twelve horses and one rider were used. Kinematic data were captured at trot during over ground locomotion under 3 conditions: unloaded, rising trot and sitting trot. Back movements were calculated using a previously described method with a correction for trunk position. Head‐neck position was expressed as extension and flexion of C1, C3 and C6, and vertical displacement of C1 and the bit. Results: Sitting trot had an overall extending effect on the back of horses when compared to the unloaded situation. In rising trot: the maximal flexion of the back was similar to the unloaded situation, while the maximal extension was similar to sitting trot; lateral bending of the back was larger than during the unloaded situation and sitting trot; and the horses held their heads lower than in the other conditions. The angle of C6 was more flexed in rising than in sitting trot. Conclusions and clinical relevance: The back movement during rising trot showed characteristics of both sitting trot and the unloaded condition. As the same maximal extension of the back is reached during rising and sitting trot, there is no reason to believe that rising trot was less challenging for the back.     

Electromyographic activity of cubital joint muscles in horses during locomotion

Electromyographic (EMG) activity of 4 muscles of the cubital joint and the strain of forelimb hooves were recorded telemetrically in 4 Thoroughbreds (with and without a rider) standing, walking, trotting, and cantering. Bipolar fine wire electrodes were inserted into the muscles, and strain gauges were attached to the hoof wall. Motion pictures (16 mm), synchronized with EMG tracings, were taken to obtain kinematic data. When horses were standing, the biceps brachii had tonic activity, but the brachialis and the caput longum and the caput laterale of the triceps brachii had no EMG activity. The biceps brachii had EMG activity during the stance phase. The brachialis had EMG activity from the end of the stance phase to the middle of the swing phase. Unlike the biceps brachii, the brachialis acted as a flexor muscle of the cubital joint during locomotion. The EMG activity of the caput longum of the triceps brachii was detected from midswing phase to early stance phase. The EMG activity of the caput laterale of the triceps brachii began in midswing or late-swing phase and ceased in early stance or midstance phase. During locomotion, caput longum EMG activity always preceded caput laterale activity. When horses were cantering, the brachialis and the caput longum (acting mainly in the swing phase) had an EMG activity phase different from those in leading and trailing forelimbs. These 4 muscles had similar EMG activity patterns during locomotion in horses with and without a rider.     

Validation of an equine inertial measurement unit system in clinically normal horses during walking and trotting

Objective-To validate an equine inertial measurement unit (IMU) system rigidly attached to a hoof against a 3-D optical kinematics system in horses during walking and trotting. Animals-5 clinically normal horses. Procedures-5 swing phases of the hooves of the right forelimb and hind limb were collected via both 3-D optical and IMU systems from 5 horses during walking and trotting. Linear and angular positions, velocities, and accelerations were compared between the 2 systems. Results-Of the 55 variables compared between the 2 systems, 25 had high correlations (r > 0.8) and 18 had moderate correlations (r > 0.5). Root mean squared errors were lowest in the sagittal plane and orientation (1.1 to 4.4 cm over a range of 1.5 to 1.9 m in the cranial-caudal direction and 2.5° to 3.5° over a range of 88° to 110° rotating around the medial-lateral axis). There were more differences between the 2 systems during small changes in motion, such as in the medial-lateral and proximal-distal directions and in the angular measures around the cranial-caudal and proximal-distal axes. Conclusions and Clinical Relevance-The equine IMU system may be appropriate for rigid attachment to a hoof of a horse and use in examination of linear and angular motion in the sagittal plane of the hoof during the swing phase while walking and trotting. Although promising in many respects, the IMU system cannot currently be considered clinically useful for lameness evaluation because of limitations in accuracy, attachment method, and lack of stance phase evaluation.     

Effects of vertebral mobilization and manipulation on kinematics of the thoracolumbar region

OBJECTIVE: To measure passive spinal movements induced during dorsoventral mobilization and evaluate effects of induced pain and spinal manipulative therapy (SMT) on passive vertebral mobility in standing horses. ANIMALS: 10 healthy adult horses. PROCEDURES: Baseline vertical displacements, applied force, stiffness, and frequency of the oscillations were measured during dorsoventral spinal mobilization at 5 thoracolumbar intervertebral sites. As a model for back pain, fixation pins were temporarily implanted into the dorsal spinous processes of adjacent vertebrae at 2 of the intervertebral sites. Vertebral variables were recorded again after pin placement and treadmill locomotion. In a randomized crossover study, horses were allocated to control and treatment interventions, separated by a 7-day washout period.The SMT consisted of high-velocity, low-amplitude thrusts applied to the 3 non-pin-placement sites. Control horses received no treatment. RESULTS: The amplitudes of vertical displacement increased from cranial to caudal in the thoracolumbar portion of the vertebral column. Pin implantation caused no immediate changes at adjacent intervertebral sites, but treadmill exercise caused reductions in most variables. The SMT induced a 15% increase in displacement and a 20% increase in applied force, compared with control measurements. CONCLUSIONS AND CLINICAL RELEVANCE: The passive vertical mobility of the trunk varied from cranial to caudal. At most sites, SMT increased the amplitudes of dorsoventral displacement and applied force, indicative of increased vertebral flexibility and increased tolerance to pressure in the thoracolumbar portion of the vertebral column.     

The influence of lameness on equine stride length consistency

The aim of this study was to assess the influence of orthopaedic pain on the variation of stride length as a kinematic system-parameter in 21 horses with forelimb lameness. Data were collected while the horses were trotting on a treadmill during a minimum of 12 motion cycles, both before and after intra-articular or perineural anaesthesia. Stride length was assessed for each motion cycle, and the mean and standard deviation were calculated for each condition. Forelimb lameness was documented as percentage of asymmetry of vertical head movement. With significant decrease of forelimb lameness after regional anaesthesia, the SD of stride length increased significantly (+0.35%, P< 0.05). Our results show that in the presence of orthopaedic pain horses keep stride variability low, possibly because the lame horse employs an optimum compensatory mechanism to reduce the pain in the affected limb, and every deviation from this pattern increases pain.     

Kinetic gait and subjective analysis of the effects of a tachykinin receptor antagonist in dogs with sodium urate-induced synovitis

OBJECTIVE: To examine the ability of preemptive administration of a proprietary neurokinin-1 (NK(1)) receptor antagonist to attenuate limb dysfunction associated with monosodium urate-induced synovitis in the stifle joints of dogs. ANIMALS: 16 clinically normal adult mixed-breed dogs (8 males and 8 females). PROCEDURES: A crossover study was conducted in 2 phases. Dogs were assigned to 2 groups (8 dogs/group) and orally administered an NK(1) receptor antagonist (3 mg/kg) or a control substance once daily for 4 days. Synovitis was then induced in the left stifle joint by intra-articular injection of monosodium urate. Investigators were not aware of treatment group assignments. Dogs were evaluated by use of subjective lameness scores during standing, walking, and trotting and by use of ground reaction force data 3, 6, 9, 12, and 24 hours after urate injection. After a 21-day washout period, the experiment was repeated with each dog administered the other treatment and injected with monosodium urate in the contralateral stifle joint. RESULTS: No significant differences were detected between the NK(1) receptor antagonist and control treatments with regard to peak vertical force, vertical impulse area, or subjective evaluations of lameness during standing, walking, or trotting, except during walking 24 hours after monosodium urate injection. CONCLUSIONS AND CLINICAL RELEVANCE: Preemptive administration of an NK(1) receptor antagonist failed to significantly improve subjective or objective outcome measures in dogs with monosodium urate-induced synovitis.     

Effects of exercise on gastric volume and pH in the proximal portion of the stomach of horses

OBJECTIVE: To assess effects of exercise on a treadmill with changes in gastric volume and pH in the proximal portion of the stomach of horses. ANIMALS: 3 healthy adult horses. PROCEDURE: A polyester bag of approximately 1,600 mL was placed into the proximal portion of the stomach of each horse via a nasogastric tube. Changes in bag volume, determined by an electronic barostat, were recorded before, during, and after a training session on a treadmill with and without prior withholding of food. In separate experiments, pH in the proximal portion of the stomach was continuously recorded during exercise for fed and food-withheld conditions. Finally, changes in intra-abdominal and intragastric pressure were simultaneously recorded during a training session. RESULTS: Bag volume rapidly decreased to nearly zero during trotting and galloping. Conversely, a return to walking resulted in a sharp increase in volume and a return to pre-exercise values. Intragastric and intra-abdominal pressures increased almost in parallel with walking, trotting, galloping, and galloping on a slope. Gastric pH decreased rapidly to < 4 at the beginning of walking, continued to decrease during trotting and galloping, and remained low until a return to walking. CONCLUSIONS AND CLINICAL RELEVANCE: Increased intra-abdominal pressure during intense exercise in horses causes gastric compression, pushing acidic contents into the proximal, squamous-lined region of the stomach. Increased duration of acid exposure directly related to daily duration of exercise may be the reason that squamous lesions tend to develop or worsen when horses are in intensive training programs.     

An In Vitro Biomechanical Investigation of an Interlocking Nail for Fixation of Diaphyseal Tibial Fractures in Adult Horses

The compressive, bending and torsional mechanical properties of osteotomized adult equine tibiae stabilized with an interlocking intramedullary nail (nail-tibia composite) were compared with those of intact tibiae to determine the clinical applicability of the nail for repair of tibial fractures in adult horses. The mean yield load, failure load, and stiffness for the nail-tibia composites were significantly less ( P < .05) than those for the intact tibiae in all loading configurations. The mean compressive yield load for the nail-tibia composites was greater than the compressive load calculated from previously reported in vivo data for walking and trotting, and was equal to the load calculated for recovery from anesthesia. The mean yield bending moment for the nail-tibia composites was greater than the bending moment previously calculated for standing, walking, and recovery from anesthesia. The mean torsional yield load for the nail-tibia composites was less than the torsional load determined for the walk from another in vivo study. The design of the interlocking nail evaluated in the present study should be modified to increase torsional and compressive yield strengths and torsional stiffness before reasonable success could be expected for the treatment of adult equine tibial fractures.     

Effect of standing tarsal angle on joint kinematics and kinetics

REASONS FOR PERFORMING STUDY: The tarsal joint is a frequent site of lameness, but little objective information is available regarding the effects of tarsal conformation on joint movements or forces. OBJECTIVE: To compare tarsal kinematics and kinetics in horses with large, intermediate and small tarsal angles. METHODS: Sagittal plane standing angle of the right tarsal joint was measured in 16 horses as they stood squarely with the hind hooves vertically beneath the hip joint. Tarsal angles were classified as small (< 155.5 degrees), intermediate (155.5-165.5 degrees) or large (> 165.5 degrees). Reflective markers, attached over the centres of joint rotation, were tracked during stance as the horses trotted across a force plate at a standardised speed. Joint angles and ground reaction forces were combined with morphometric data to calculate net joint moments and net joint powers across the tarsus using inverse dynamics. RESULTS: In all horses, the tarsus flexed during the impact phase and extended in late stance. Tarsal angles were stratified according to standing tarsal angle throughout stance. Horses with large standing angles showed less flexion and less energy absorption at the tarsus during the impact phase than those with intermediate or small angles and generated less vertical impulse than horses with small standing angles. Net extensor moment at the tarsus during stance was lower for horses with large standing angles. CONCLUSIONS: In horses with large tarsal angles, less concussion was absorbed during the impact phase, which may be a factor in the development of degenerative joint disease; and the smaller vertical impulse and extensor moment later in stance may limit propulsive ability. However, the smaller net joint moment may reduce the risk of plantar ligament desmitis. CLINICAL SIGNIFICANCE: The effects of conformation on kinematics and kinetics of the tarsal joint may influence both performance and soundness.     

Changes in kinematic variables observed during pressure-induced forelimb lameness in adult horses trotting on a treadmill

OBJECTIVE: To determine whether kinematic changes induced by heel pressure in horses differ from those induced by toe pressure. ANIMALS: 10 adult Quarter Horses. PROCEDURE: A shoe that applied pressure on the cuneus ungulae (frog) or on the toe was used. Kinematic analyses were performed before and after 2 levels of frog pressure and after 1 level of toe pressure. Values for stride displacement and time and joint angles were determined from horses trotting on a treadmill. RESULTS: The first level of frog pressure caused decreases in metacarpophalangeal (fetlock) joint extension during stance and increases in head vertical movement and asymmetry. The second level of frog pressure caused these changes but also caused decreases in stride duration and carpal joint extension during stance as well as increases in relative stance duration. Toe pressure caused changes in these same variables but also caused maximum extension of the fetlock joint to occur before midstance, maximum hoof height to be closer to midswing, and forelimb protraction to increase. CONCLUSION AND CLINICAL RELEVANCE: Decreased fetlock joint extension during stance and increased head vertical movement and asymmetry are sensitive indicators of forelimb lameness. Decreased stride duration, increased relative stance duration, and decreased carpal joint extension during stance are general but insensitive indicators of forelimb lameness. Increased forelimb protraction, hoof flight pattern with maximum hoof height near midswing, and maximum fetlock joint extension in cranial stance may be specific indicators of lameness in the toe region. Observation of forelimb movement may enable clinicians to differentiate lameness of the heel from lameness of the toe.     

Transendoscopic contact neodymium:yttrium aluminum garnet laser correction of epiglottic entrapment in standing horses

Fifty-seven Standardbred and 44 Thoroughbred racehorses and 1 Thoroughbred polo mare with primary clinical signs of exercise intolerance or respiratory tract noise or combined exercise intolerance and respiratory tract noise were referred for laser correction of epiglottic entrapment. Significantly (P less than 0.001) more Standardbred than Thoroughbred racehorses were affected, compared with the observed hospital population during the same period. At referral, 14 horses did not have evident epiglottic entrapment and were returned to exercise without development of entrapment after treatment, which consisted of 1 week of rest and administration of anti-inflammatory medication. In 88 standing horses under sedation and topical anesthesia, epiglottic entrapment was corrected transendoscopically by use of a contact neodymium:yttrium aluminum garnet laser. In these 88 horses, 98% of entrapments were persistent, 92% were thick, 97% were wide, and 45% were ulcerated. Thirty-one percent of the horses had endoscopic evidence of epiglottic hypoplasia, and 8% had deviated epiglottic axis. Complete correction was achieved in 97% of the horses, Persistent dorsal displacement of the soft palate in 1 horse and severe epiglottic hypoplasia with thick, chronic entrapping membranes in 2 horses precluded successful transendoscopic correction with the horses in standing position. Most horses were treated on an outpatient basis, and all were able to be returned to exercise after 7 to 14 days of rest and treatment with anti-inflammatory medication. Entrapment recurred in 4 horses (5%), 3 of which had hypoplastic epiglottis. Dorsal displacement of the soft palate developed after surgery in 9 horses (10%) and continued in 4 horses (5%) that had displaced soft palate before surgery. All these horses had epiglottic hypoplasia. Laser correction of epiglottic entrapment in standing horses was safe, well tolerated, and effective. Laser surgery was an alternative to conventional surgery, and eliminated the need for general anesthesia and laryngotomy. It also reduced convalescence and postoperative complications.     

Effects of Whole Body Vibration on the Horse: Actual Vibration,Muscle Activity,and Warm-up Effect

Whole body vibration (WBV) exercise has been introduced into human and recently also into equine training. Only a few studies about physical and physiological effects on horses are available. This study should clarify the actual physical vibration of a commercially available WBV plate itself and on the horse as well as the muscular activity in the limbs and back. Furthermore, the effects of WBV warm-up on clinical parameters and body surface temperatures were compared to standard warm-up exercises. Ten sound horses (vibration and muscle activity of six horses) were recorded while standing (control) and during 15 and 25 Hz (manufacturer information) vibration exercise. The vibration of plate, hoof, fetlock, withers, and sacrum was analyzed for frequency, peak-to-peak displacement, and peak acceleration. Activity of M. triceps, quadriceps, and longissimus dorsi was assessed using surface electromyography. Warm-up effects were compared between four different warm-up scenarios: standing (control), 10-minute vibration, 10-minute lunging (walk), and 12-minute lunging (walk and trot). Maximal body surface temperature of upper forelimb, thigh, and back was measured. Actual plate vibration frequency was 7 or 11 Hz with a maximum peak-to-peak displacement of 9 mm in longitudinal direction. WBV exercise induced no increase in electromyographic activity, clinical parameter, or body surface temperature. It was concluded that actual plate vibration was mainly longitudinal with a lower frequency than proposed and 10-minute exercise had no significant effect. Different vibration protocols and vibration acting in the vertical direction might enable more effective exercise in horses.