Search Results (9)

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

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

Background/Objectives: Standardbreds, a breed of horses used in harness racing at either the trot or the pace, established a closed studbook in 1973. Concerns about genetic diversity within the breed led the United States Trotting Association (USTA) to establish a limit of mares bred per stallion (i.e., a studbook cap) in 2009. Here, we aimed to evaluate the impact of the breeding restrictions on genetic diversity between and among subpopulations. Methods: Sixteen short tandem repeats (STRs) were analyzed across a dataset of 176,424 Standardbreds foaled in the United States between 1998 and 2021. We examined allelic richness (Na), number of effective alleles (Ne), expected heterozygosity (H_E), observed heterozygosity (H_O), inbreeding coefficient (F_IS), and fixation index (F_ST) across 24 years, differentiating by gate type, and comparing pre-(1998–2009) and post-(2010–2021) studbook cap periods using regression analysis. Results: Our results support decreased genetic diversity for both trotters and pacers over time. However, pacing Standardbreds exhibited significantly slower rates of decrease in genetic diversity after the 2009 studbook cap, as evidenced by Ne, H_E, and F_IS (P_Bonferroni < 0.01). Additionally, moderate levels of genetic differentiation were found between trotters and pacers (0.05 < F_ST < 0.09), which increased over time. Conclusions: Given that the rate of loss of diversity does not appear to differ pre and post studbook cap in trotters and that there is an increase in genetic differentiation between the groups over time, developing additional breeding tools and strategies is necessary to help the subpopulation mitigate further decline. Full article

Subtle locomotor asymmetries are common in horses and may go unnoticed during routine pre-race clinical inspections, particularly when based solely on subjective evaluation. This study aimed to describe vertical head and pelvic movement asymmetries in racehorses that passed official pre-race inspections at a traditional racing event. Twenty-four horses were analysed using a markerless AI-based gait analysis system while trotting in-hand and during lungeing in both directions. Asymmetry parameters (HDmin, HDmax, PDmin, and PDmax) were extracted from video recordings, with values ≥0.5 considered clinically relevant. Vertical asymmetries were detected in 71% of horses during straight-line evaluation and in 79% during at least one lungeing direction. Some horses showed relevant asymmetries only under specific movement conditions, underscoring the complementary role of straight-line and lungeing assessments in comprehensive gait evaluation. These results suggest that objective gait analysis could enhance pre-race veterinary assessments, especially in traditional racing, where horses are subjected to significant biomechanical stress, including variable surface properties and repetitive directional loading. In such complex and dynamic environments, relying solely on visual assessment may result in the underdiagnosis of subtle locomotor alterations. The AI-based tools offer potential to improve the detection of subtle irregularities and support evidence-based decisions in performance horse management. Further investigations are warranted to validate the clinical relevance of currently adopted asymmetry thresholds, refine their diagnostic value, and support their integration into standardized pre-race evaluation protocols. Full article

Objectives: Training is essential for enhancing equine athletic performance, but the genetic mechanisms that regulate athletic performance are unknown. Therefore, this paper aims to identify candidate genes and metabolic pathways for the effects of training on equine athletic performance through multi-omics analyses. Methods: The experiment selected 12 untrained trot-type Yili horses, which underwent a 12-week professional training program. Blood samples were collected at rest before training (BT) and after training (AT). Based on their race performance, whole blood and serum samples from 4 horses were chosen for transcriptomic and metabolomic analyses. Results: The race performance of the horses is dramatically improved in the AT period compared to the BT (p < 0.01) period. The transcriptome analysis identified a total of 57 differentially expressed genes, which were significantly enriched in pathways related to circadian entrainment, steroid hormone biosynthesis, chemokine signaling, and cholinergic synapses (p < 0.05). Additionally, metabolomic analysis revealed 121 differentially identified metabolites, primarily enriched in metabolic pathways such as histidine metabolism, purine metabolism, and the PI3K-Akt signaling pathway. The integration of transcriptomic and metabolomic analyses uncovered five shared pathways, and further combined pathway analyses identified eight differentially expressed genes that correlate with 19 differentially identified metabolites. Conclusions: The current findings will contribute to establishing a theoretical framework for investigating the molecular mechanisms of genes associated with the impact of training on equine athletic performance. Additionally, these results will serve as a foundation for enhancing the athletic capabilities of trot-type Yili horses. Full article

Background: Racehorses commonly train and race in one direction, which may result in gait asymmetries. This study quantified gait symmetry in two cohorts of Thoroughbreds differing in their predominant exercising direction; we hypothesized that there would be significant differences in the direction of asymmetry between cohorts. Methods: 307 Thoroughbreds (156 from Singapore Turf Club (STC)—anticlockwise; 151 from Hong Kong Jockey Club (HKJC)—clockwise) were assessed during a straight-line, in-hand trot on firm ground with inertial sensors on their head and pelvis quantifying differences between the minima, maxima, upward movement amplitudes (MinDiff, MaxDiff, UpDiff), and hip hike (HHD). The presence of asymmetry (≥5 mm) was assessed for each variable. Chi-Squared tests identified differences in the number of horses with left/right-sided movement asymmetry between cohorts and mixed model analyses evaluated differences in the movement symmetry values. Results: HKJC had significantly more left forelimb asymmetrical horses (Head: MinDiff p < 0.0001, MaxDiff p < 0.03, UpDiff p < 0.01) than STC. Pelvis MinDiff (p = 0.010) and UpDiff (p = 0.021), and head MinDiff (p = 0.006) and UpDiff (p = 0.017) values were significantly different between cohorts; HKJC mean values indicated left fore- and hindlimb asymmetry, and STC mean values indicated right fore- and hindlimb asymmetry. Conclusion: the asymmetry differences between cohorts suggest that horses may adapt their gait to their racing direction, with kinematics reflecting reduced ‘outside’ fore- and hindlimb loading. Full article

Poor performance in racehorses is commonly associated with subclinical diseases. This study aims to evaluate the associations between medical disorders and racing results in Standardbred trotters. The clinical records of 248 poorly performing Standardbreds were retrospectively reviewed, and their racing results were extracted from an online database, concerning the periods 3 months before and 6 months after hospitalization and the entire lifetime. Generalized linear models were used to evaluate the effects of different disorders on racing outcomes. Airway neutrophilia was associated with limiting lifetime starts and wins pre- and post-hospitalization, while mastocytosis was associated with less wins in the post-hospitalization period. Therefore, lower airway inflammation showed both short- and long-term impacts on racing performance. Severe upper airway obstructions and gastric ulcers showed associations with less placings in the post-discharge period but no long-term influence on performance. The significance of exertional rhabdomyolysis was indeterminable, yet interference with the number of starts in the post-discharge period was reported and associated with lower total career earnings. Exercise-induced pulmonary hemorrhage and cardiac arrhythmias were not associated with worse racing outcomes: therefore, their role in poor performance remains unclear. Full article

Injuries to racehorses and their jockeys are not limited to the racetrack and high-speed work. To optimise racehorse-jockey dyads’ health, well-being, and safety, it is important to understand their kinematics under the various exercise conditions they are exposed to. This includes trot work on roads, turf and artificial surfaces when accessing gallop tracks and warming up. This study quantified the forelimb hoof kinematics of racehorses trotting over tarmac, turf and artificial surfaces as their jockey adopted rising and two-point seat positions. A convenience sample of six horses was recruited from the British Racing School, Newmarket, and the horses were all ridden by the same jockey. Inertial measurement units (HoofBeat) were secured to the forelimb hooves of the horses and enabled landing, mid-stance, breakover, swing and stride durations, plus stride length, to be quantified via an in-built algorithm. Data were collected at a frequency of 1140 Hz. Linear Mixed Models were used to test for significant differences in the timing of these stride phases and stride length amongst the different surface and jockey positions. Speed was included as a covariate. Significance was set at p < 0.05. Hoof landing and mid-stance durations were negatively correlated, with approximately a 0.5 ms decrease in mid-stance duration for every 1 ms increase in landing duration (r² = 0.5, p < 0.001). Hoof landing duration was significantly affected by surface (p < 0.001) and an interaction between jockey position and surface (p = 0.035). Landing duration was approximately 4.4 times shorter on tarmac compared to grass and artificial surfaces. Mid-stance duration was significantly affected by jockey position (p < 0.001) and surface (p = 0.001), speed (p < 0.001) and jockey position*speed (p < 0.001). Mean values for mid-stance increased by 13 ms with the jockey in the two-point seat position, and mid-stance was 19 ms longer on the tarmac than on the artificial surface. There was no significant difference in the breakover duration amongst surfaces or jockey positions (p ≥ 0.076) for the ridden dataset. However, the mean breakover duration on tarmac in the presence of a rider decreased by 21 ms compared to the in-hand dataset. Swing was significantly affected by surface (p = 0.039) and speed (p = 0.001), with a mean swing phase 20 ms longer on turf than on the artificial surface. Total stride duration was affected by surface only (p = 0.011). Tarmac was associated with a mean stride time that was significantly reduced, by 49 ms, compared to the turf, and this effect may be related to the shorter landing times on turf. Mean stride length was 14 cm shorter on tarmac than on grass, and stride length showed a strong positive correlation with speed, with a 71 cm increase in stride length for every 1 m s⁻¹ increase in speed (r² = 0.8, p < 0.001). In summary, this study demonstrated that the durations of the different stride cycle phases and stride length can be sensitive to surface type and jockey riding position. Further work is required to establish links between altered stride time variables and the risk of musculoskeletal injury. Full article

Vaquejada is a high-intensity and short-duration exercise in which helper horses (HH) are responsible to keep a bull running in a line while pull horses (PH) work to put the bull down after 100 m of running. The purpose of this study was to quantify and compare energy expenditures (EE), transport costs (COT) and metabolic energy requirements (Pmet) of horses used in Vaquejada. Thus, eight Quarter Horses, in randomly formed pairs, performed a vaquejada simulation test (VST), which consisted of three races on a sand track (130–150 m), with a 5-min interval between them. All horses used an integrated heart rate (HR) and GPS monitoring system (V800, Polar Electro) and, from these data, EE, COT and Pmet were calculated using the formulas: EE (J/kg/min) = 0.0566 × HR^1.9955, COT = (HR-35)/kg/m × 10³ and Pmet = (HR-35)/min/kg. Blood samples were collected for lactate analysis at rest, immediately after the first, second and third race and after 30 min of recovery. Data obtained were submitted to one-way ANOVA and Tukey tests (p ≤ 0.05). In VST, HH had higher EE and higher HR at trot; while PH presented higher EE and HR at canter. Finally, considering total VST, PH had higher EE and COT, while HH had higher Pmet. Lactate was higher in PH. Despite practicing the same sport, PH and HH should be considered distinct athletes, and these must be considered to set up appropriate physical and nutritional programs, which will lead to better performance and guarantees of well-being. Full article