Search Results (139)

This paper studies a MuJoCo-based locomotion framework that couples an adaptive-frequency central pattern generator (AFCO-CPG) with single rigid-body dynamics model predictive control (MPC) for the RENS Q1 quadruped with elastic parallel knee joints. AFCO-CPG combines multi-scale phase coordination, saturated phase correction, and load-gated feedback, while MPC supplies feasible ground-reaction forces and returns load cues to the timing layer. In MuJoCo, the controller achieves stable diagonal-trot speed tracking from 0.4 to 1.2 m/s and recovers from short external pushes. A matched elastic-versus-rigid timing sweep shows a favorable flat-ground parameter band around $\omega =1.8$ Hz, with a best-case cost-of-transport reduction of 12.83% for the elastic model under identical controller gains. A flat-to-slope ascent case further verifies that AFCO timing is modulated when load conditions change. Ablation across nine controller variants shows that multi-scale coordination is the dominant component, causing a 135% increase in phase error and a 536% increase in recovery time when removed. A reduced-order early/late-contact benchmark further confirms faster re-locking than diagonal-only and minimal variants. The results support the value of combining neural timing, predictive force optimization, and compliant-leg feedback in high-fidelity simulation, while hardware validation remains future work. Full article

Background/objectives: Knowledge of the genetic background of evaluated traits has been the basis for genetic progress in every horse-breeding population and is essential for precise breeding and up-to-date decision-making. The study aimed to estimate the heritability coefficients for field performance traits in mares. Methods: The research was based on 1408 evaluations of mares conducted during the years 2002–2021 in 51 training centers in Poland. The preliminary analyses of the effects, significant for the investigated traits, were obtained using analysis of variance, and these additional data are also presented (SAS program, GLM and Mixed procedures). The final statistical model for the AI-REML procedure of the DMU program included a fixed effect of the training center-season-year of evaluation, a random effect of the animal, and a regression on age in years. Results: The heritability coefficients of the performance traits were moderate to high (0.32–0.60) with the SE within the range of 0.06–0.08. The highest heritability was estimated for the free jumping, trot, and overall results. The lowest heritability was achieved for the rideability. Conclusions: The level of heritability estimations allowed for the population progress in the evaluated traits. Full article

Physiotherapeutic interventions in dogs frequently incorporate compliant surfaces to improve postural stability (PS), proprioception, and limb coordination; however, objective assessment of surface-related locomotor adaptations remains limited. This study investigated the effects of walking on surfaces with increasing compliance on PS in healthy adult dogs using paw center of pressure (pCOP) analysis. Fourteen orthopedically and neurologically sound dogs were assessed at walk and trot on a pressure-sensitive walkway under four surface conditions: a standard rubber mat (0.1 cm) and three yoga mats of increasing thickness (0.5 cm, 0.8 cm, and 1.0 cm). Vertical ground reaction force (vGRF) and pCOP parameters were recorded and analyzed for each limb. vGRF parameters were largely unaffected by surface conditions. In contrast, several pCOP metrics, including pCOP radius, craniocaudal displacement, and mediolateral displacement, showed a significant decrease with increasing surface compliance. These effects were more consistent and widespread during trot, whereas during walk changes were primarily observed in the forelimbs. The findings indicate that dogs adapt to increased surface compliance by reducing pCOP displacement, likely reflecting active postural stabilization strategies. While vGRF parameters appeared insensitive to these adaptations, pCOP measures proved more sensitive in detecting subtle neuromuscular adjustments. These results highlight the potential value of pCOP analysis for evaluating functional adaptations during physiotherapeutic interventions in canine rehabilitation. Full article

We propose a general methodology for constructing dynamic performance indicators (or strength metrics) in any sport that relies on comparative outcomes among competitors, using chronological positional data. Specifically, we develop a family of strength indicators for harness trotting races based on time-weighted, head-to-head results. Using the official Balearic trotting records (1990–2023), we construct win, draw, and confrontation matrices up to each event and apply a triweight kernel to reduce the influence of older results. From these matrices, we derive a family of five bounded, interpretable indicators on the interval $[0,1]$: an overall average win rate, a category-adjusted version, and three distance-specific versions (short, medium, and long). Indicator validation is performed via predictive validation, employing regularized logistic regression models (Elastic Net) based on indicator differences between horse pairs. Standard metrics (accuracy, calibration, discrimination, and Brier score) are used for the validation analysis. The results confirm that the indicators are coherent, stable, and interpretable, demonstrating that the generic construction procedure yields robust outcomes. We conclude that these indicators establish a solid and easily updatable foundation for developing dynamic ranking systems and practical selection/handicap procedures in trotting. Full article

Locomotor disorders involving the spine are a major cause of impaired performance and early retirement in sport horses. Swimming is increasingly incorporated into rehabilitation protocols, but its effects on spinal biomechanics remain poorly understood. This prospective study evaluated changes in thoracolumbar mobility in sixteen sport horses diagnosed with cervical or thoracolumbar axial musculoskeletal lesions over a 12-week rehabilitation program comprising 4 weeks of land-based training followed by 8 weeks during which swimming sessions were incorporated three times per week. Weekly measurements of thoracolumbar flexion–extension range of motion (ROM) were performed during straight-line trot on a hard surface using inertial measurement units attached to the withers, T18, and tubera sacrale. Group-level analyses revealed minimal changes across training phases: in horses with thoracolumbar lesions, mean ROM decreased slightly during the second month of aquatic training (−0.1° [95% CI −0.1; 0], Cohen’s d = 0.2), whereas no significant variation was detected in horses with cervical lesions. As the study did not include a control group, these temporal changes cannot be specifically attributed to swimming and should be interpreted as descriptive rather than causal. Individual trajectories showed heterogeneous patterns, but these were not consistent enough to alter the group-level interpretation. Overall, the findings suggest that thoracolumbar mobility remains relatively stable throughout this type of rehabilitation program, highlighting the importance of individualized monitoring rather than the expectation of a uniform biomechanical response. Full article

Equine Gastric Ulcer Syndrome (EGUS) is a worldwide disease described in different categories of animals. A causal relationship between exercise and EGUS has been suggested, attributed to stress as well as physiological changes in the position of abdominal organs, especially during trot and gallop. EGUS can influence athletic fitness, as has been described in various papers on racehorses. The aim of this work was to determine if gastric ulcer healing is associated with changes in selected fitness parameters (i.e., speed, heart rate during exercise and recovery, stride length and frequency) in 21 trained showjumping horses affected by gastric ulcers. Four animals were excluded for incomplete healing or loss to follow-up. In the remaining seventeen subjects, all healed completely, and fitness parameters were evaluated before and after healing of EGUS during a ridden exercise. The animals were equipped with a fitness tracker validated for use in horses while they performed both flat work and a small obstacle course. Results show that speed and stride length increased after healing, with no concurrent modification in maximal heart rate recorded during exercise and the heart rate recorded during recovery. The increase in speed and stride length is probably related to the disappearance of abdominal discomfort, already described in racehorses after healing of gastric ulcers. Full article

This study investigates the ozone generation characteristics of a nanosecond bipolar pulse-excited single-water electrode (dielectric barrier discharge) DBD reactor, with a particular focus on the effects of pulse width (T_p) on discharge behavior, plasma parameters, and ozone generation efficiency. The results indicate that the bipolar pulse voltage displays a symmetric alternating waveform, and the reactor demonstrates excellent thermal stability. Rotation temperature (T_rot) remains stable between 307 and 310 K (close to room temperature, which effectively suppresses O₃ thermal decomposition), while vibrational temperature (T_vib) stabilizes at 3120 ± 50 K (sufficient to ensure the electron energy required for O₂ dissociation). Electron excitation temperature (T_exc) increases with both the specific input energy (SIE) and T_p. At SIE = 200 J/L, extending T_p from 200 ns to 1000 ns results in an increase in T_exc from 2633 K to 2724 K. The ozone generation efficiency exhibits a “rise-then-decline” trend with increasing T_p. The optimal T_p is 500–600 ns, at which the maximum efficiency reaches 102 g/kWh (corresponding to SIE = 35.95 J/L), which is slightly higher than the peak efficiency of the unipolar pulse-driven water electrode reactor (99.64 ± 0.87 g/kWh, corresponding to SIE = 33.60 ± 1.53 J/L). This work innovatively applies nanosecond bipolar pulse excitation to a single-water electrode DBD reactor for ozone generation, an understudied configuration that integrates the discharge stability advantage of bipolar pulses and the superior cooling advantages of water electrodes. This study offers significant insights into the pulse power excitation of ozone generation. Full article

In this paper, a hybrid locomotion approach is proposed and experimentally validated for a quadrupedal robot to enhance energy efficiency on mixed terrains. A mechanical solution was implemented by adding passive wheels on the robot’s abdomen, to allow for gliding on flat portions of the faced terrains. This strategy aims to reduce the use of the legs, decreasing the overall energy consumption. To allow an efficient use of simulations, a data-driven approach was developed to estimate motor power consumption from joint dynamics on the real robot and subsequently applied within the simulation environment. The neural network achieved a coefficient of determination of R² = 0.97, ensuring accurate estimation of energy consumption under both simulated and real conditions. Experimental and simulated results show that the proposed sliding gait reduces the average Cost of Transport from approximately 4.5–6.0 during trotting to 0.8–1.1 during sliding, corresponding to a four–five-fold improvement in energy efficiency. Overall, the results demonstrate that a simple mechanical upgrade of the robot’s body structure can significantly enhance locomotion efficiency and versatility on flat or slightly descending terrains. Full article

Dynamic mobilization exercises (DME) are an effective strategy to prevent musculoskeletal injuries and promote back health in sport horses. Previous studies focused mainly on multifidus muscle cross-sectional area, with limited data on locomotion and adaptation timing. This study evaluated locomotor changes using accelerometry, over 8 weeks of DME application in 14 sedentary horses: a DME group (n = 8) performing 10 different DME (3 neck flexions, 1 neck extension and 3 lateral bending exercises to each side), 5 repetitions of each DME per session, 3 sessions/week, and a control group (n = 6), that continued with their daily routine activities without any other training. During the study period, all horses were housed in medium-sized paddocks. Accelerometric measurements were performed at walk and trot before intervention, 2 h and 24 h after a DME session, and at 2, 4, 6, and 8 weeks. The DME group showed significant increases in dorsoventral displacement and dorsoventral and mediolateral activities from week 4, at both walk and trot, which then stabilized. Longitudinal activity increased from week 2 on trot and from week 4 at walk. Locomotor symmetry and stride length improved at week 6, while stride frequency decreased at week 8; velocity remained unchanged. These findings indicate that DME enhances dorsoventral, mediolateral and longitudinal activities, producing longer, more symmetrical strides. Overall, DME appears to promote more symmetrical movement patterns. Full article

The aim of this study was to investigate the effect of girth design and girth tension; six horses regularly ridden were used. Each horse underwent four experimental sessions in an unbalanced Latin-square design with two girth tensions (8 kg or 16 kg) and two girth designs (straight girth (S) or anatomical girth (A)). Pressure between the saddle and the horse was measured at 100 Hz with a pressure mat (0.5 sensels per cm²). Notably, 2D limb kinematics were determined from anatomical markers placed on the fore and hindlimbs. Video was collected at 240 fps. There was no significant effect of girth type, girth tension, or girth type*tension interaction for any of the measured variables, with the exception of carpal flexion, which was significantly greater for A8 (median: 103°, 25th–75th percentile: 100–112°) than S8 (101°, 96–106°; p = 0.043). There was no effect of girth type (A or S) on mean saddle pressure for either cranial or caudal regions (p > 0.05), but caudal average pressure was significantly lower than cranial average pressure both at 8 and 16 kg tensions (p < 0.05). For both mean and peak pressure, the ratio cranial: caudal was significantly higher with 16 kg tension (p < 0.05), indicating that as the girth tension increases, the pressures shift towards the cranial aspect. In conclusion, neither girth tension nor girth type significantly influenced 2D limb kinematics, but higher tension has shifted the load towards the cranial area significantly, which could contribute to cranial thoracic back pain or injuries. Full article

The aim of the study was to determine the fluctuations of selected physiological parameters in young Lipizzan stallions (n = 10) during the initial phase of their training as indicators of adaptation to a graded exercise load and stress exposure. For this purpose, four exercise tests (ExT) with lunging were carried out over a period of one year. Physiological parameters (gait speed, heart and respiratory rate (HR and RR), rectal and body surface temperature (RT and BST), and cortisol and lactate concentration (CORT and LAC)) were measured before and after training. In all ExT, gait speeds increased (p < 0.001) during the transitions from walk to trot and canter, followed by a significant (p < 0.001) increase in HR, RT, BST, and CORT, but not LAC values. However, the gate speed has no influence on the measured parameters. The highest BST values and corresponding warming were measured in the cranial region, followed by the caudal and distal body regions. The values of the measured variables remained within the ranges for warm-blooded horses, indicating adequate adaptation of the stallions to the applied stress level, but their variations could depend on air temperature or humidity. The results presented contribute to the knowledge of the complex physiological processes that occur in horses during exercise and point to the importance of environmental factors for adaptation to exercise. Full article

Based on fundamental mechanics, movement and force associate head and pelvic movement asymmetry with asymmetry of force production. We investigate, how often racehorses undergoing strenuous training regimens show evidence of switching between “preferred” limbs, i.e. one limb producing increased force, when assessed at monthly intervals? We hypothesize that clinical asymmetry thresholds designed for “detecting lameness” are frequently exceeded and that when applying previously established Thoroughbred-specific repeatability values, horses rarely switch between showing left- and right-sided asymmetry. Monthly gait assessments (inertial sensors) were conducted in 256 Thoroughbred racehorses at least twice per horse (up to 16 times per horse). Descriptive statistics for absolute differences for head and pelvic movement were compared to published Thoroughbred-specific repeatability values. The percentage of left–right switches between repeat assessments was calculated in comparison to three different levels of pre-defined thresholds (perfect symmetry, clinical lameness thresholds, previously established Thoroughbred-specific repeatability values) and switch frequencies compared between the three thresholds. Ranges containing 95% of monthly differences were higher than published daily and weekly values except for pelvic vertical range of motion. Approximately 30% of monthly differences in individual symmetry parameters showed left–right switches around “perfect symmetry”. Utilizing clinical lameness thresholds for categorizing left–right switches, a significantly (p < 0.001) reduced percentage of 4–11% of measurements for head movement and 7–17% for pelvic movement showed switches. Using daily repeatability values for categorization, a further significantly (p < 0.001) reduced percentage of switches was observed: 0.3–3.6% for head movement and 0.6–7.0% for pelvic movement. While racehorses in training regularly switch between small left- or right-sided movement symmetries, they less frequently switch between more pronounced left- and right-sided movement symmetries defined based on daily variations. Further studies should investigate the reasons for these rare switches. Full article

Differences in horseshoe materials may have effects on gait that could change perceived esthetic qualities. Objective information regarding effects of shoeing on gait characteristics of horses is scant. The aim of this study was to determine differences in gait characteristics for horses under various experimental shoeing conditions (barefoot, aluminum shoes, steel shoes) on two surfaces (asphalt and soft footing) using body- and hoof-mounted sensors. We hypothesized that shoeing would affect hoof arc height during early (arc height a) and late (arc height b) swing phases but would not affect other gait variables. Twelve healthy, adult, client-owned horses were evaluated at a trot on asphalt and soft footing under the three experimental shoeing conditions. No significant (p < 0.05) effects of shoeing were detected for gait symmetry (Q score), mediolateral hoof deviation, stride length, or midstance, breakover, swing, and landing stride phase times. Hoof arc height a was significantly (p < 0.001) lower for aluminum versus steel shoes for right and left forelimbs on asphalt and soft footing. Hoof arc height b was significantly higher for aluminum versus steel shoes on soft footing for left (p < 0.001) and right (p = 0.02) forelimbs. Findings indicate that shoe weights affect early and late swing phase hoof heights differently. Further investigation is warranted to determine whether measured hoof arc height changes affect subjective esthetics of gait. Full article

This study examines the associations between linearly scored phenotypic traits and auction sales prices of young event horses in Ireland, aiming to identify key traits influencing market value. Data from 307 horses sold at public auctions (2022–2023) were analysed using regression analysis, binary optimisation, and Principal Component Analysis (PCA). Regression identified Head–neck Connection, Quality of Legs, Walk length of Stride, and Scope as highly significant predictors of sales price (p < 0.001), with Length of Croup, Trot Elasticity, Trot Balance, and Take-off Direction also significant (p < 0.05). Optimised regression reduced the number of relevant traits from 37 to 8, streamlining evaluation. PCA highlighted eight principal traits, including Scope, Elasticity, and Canter Impulsion, explaining 61.19% of variance in the first four components. These results demonstrate that specific conformation, movement, and athleticism traits significantly affect auction outcomes. The findings provide actionable insights for breeders and stakeholders, suggesting that targeted selection for high-impact traits could accelerate genetic progress and improve market returns. Furthermore, these traits could underpin the development of economic or buyer indices to enhance valuation accuracy and transparency, with potential application across equestrian disciplines to align breeding objectives with market demands. Full article

Orthotics are often used to support the metacarpophalangeal joint (MCPj) in horses recovering from soft tissue injury; however, their effect on the MCPj biomechanics remain largely underexplored. The MCPj moves primarily in the sagittal plane, flexing during the swing phase and extending during the stance phase. The suspensory ligament and flexor tendons act as biological springs resisting MCPj extension. Injuries to these structures are common and, although early mobilization promotes their healing, controlled loading may be beneficial during rehabilitation. This study aims to evaluate the efficacy of a semirigid orthotic in limiting the MCPj extension and the MCPj range of motion, and its influence on the MCPj kinematics. Twelve healthy horses were equipped with portable inertial sensors on the distal limb. The MCPj extension and the MCPj range of motion were assessed during walking and trotting without the orthotic (S0) and with the orthotic using two different support settings (S1 and S4). Data were evaluated for normality and homoscedasticity. A Student t-test was used to compare the MCPj angle pattern of the two forelimbs of each horse at the baseline. Data were analysed using one-way ANOVA to compare the mean values across conditions, followed by paired t-tests for post-hoc comparison (significance set at p < 0.05). The results showed significant reductions in both the MCPj extension and the MCPj range of motion, with the greatest restriction occurring at the highest support setting. These results suggest that the semirigid orthotic limits the MCPj movement in the sagittal plane and consequently the load on the suspensory ligament and flexor tendons. Therefore, this orthotic device is an effective tool during rehabilitation for forelimb tendon and ligament injuries. Full article