Iván Darío Martinez

Exercise physiology in Colombian Creole Horses remains poorly characterized despite the breed’s extensive use in athletic activities. The objective of this study was to evaluate exercise-induced changes in blood biochemical and gas parameters and to determine whether these responses differed according to sex, geographic origin, or gait modality. An analytical observational study with repeated measures was conducted in 76 athletic CCHs. Blood samples were obtained from the jugular vein at rest and immediately after exercise to measure acid–base indicators (pH, carbon dioxide pressure, bicarbonate), electrolytes (sodium, potassium, calcium, chloride), and metabolic variables (glucose, lactate, creatinine). Within-subject comparisons were performed to quantify exercise-induced changes, and subgroup analyses were conducted by sex, geographic region, and gait modality. Exercise resulted in physiologically consistent responses, including a mild reduction in pH (−0.01), decreases in carbon dioxide pressure (−2.39 mmHg) and bicarbonate (−1.7 mmol/L), and a moderate increase in lactate (+2.96 mmol/L), indicating exercise-associated metabolic acidosis and anaerobic metabolism. Glucose and creatinine also increased modestly, while electrolyte concentrations remained relatively stable. No meaningful differences were detected between sexes or geographic regions. As expected, gait modality significantly influenced acid–base responses, with horses performing trocha exhibiting greater reductions in carbon dioxide pressure and bicarbonate. These findings indicate that gait type modulates the magnitude of exercise-induced acid–base responses in Colombian Creole Horses.

Maximal lactate steady state (MLSS) and its predictive thresholds, including the lactate threshold (LT), are widely used to estimate endurance capacity, prescribe training, and assess the effects of training. The human literature identified approximately twenty‐five methods to predict the MLSS. This communication compares the concordance between the two D _MAX methods and the MLSS. Under laboratory conditions, ten teaching horses underwent a submaximal graded exercise test (GXT) on a treadmill to obtain their lactate‐velocity curves (LVC). They performed three to five 30‐min continuous running sessions to determine the MLSS. The traditional D _MAX method was determined using the maximal distance from LVC to the line formed by its endpoints. A new calculated D _MAX method (D _MAXC ) involved mathematically determining the point that results in the maximum distance from a curve connecting the start to the endpoint of the LVC. The agreement among the velocities corresponding to the D _MAX (V _MAX ), D _MAXC (V _MAXC ), and the MLSS (V _MLSS ) was established using a Bland‐Altman plot and ordinary least products (OLP) analysis. The average lactatemia at V _MLSS , V _MAX , and V _MAXC was 1.50 ± 0.36 mM, 2.02 ± 0.66 mM, and 1.92 ± 0.65 mM, with respective speeds of 5.42 ± 0.57 m/s, 6.42 ± 0.71 m/s, and 6.35 ± 0.66 m/s. The mean difference between V _MAX ‐V _MLSS and V _MAXC ‐V _MLSS was ‐1.01 ± 0.61 and ‐0.93 ± 0.67 m/s, respectively. V _MAX and V _MAXC did not show constant and proportional biases compared to V _MLSS . In the GXT protocol used in this current study, D _MAX approaches appear to be accurate and reliable methods for lactate threshold determination and estimating MLSS in teaching horses.

Colombian Paso horses (CPs) excel in gait competitions due to their endurance, speed, and precision, which demand a high level of cardiorespiratory fitness. However, their training regimes often lack scientific support, and few studies have linked physiological parameters to optimal training zones. This study aimed to estimate the aerobic lactate threshold (LTaer) using mathematical methods and to correlate it with heart rate (HR) zones and blood lactate. Eighteen CPs were evaluated and classified into trained (GT) and untrained (GD) groups. All animals underwent a field-based incremental exercise test (IET) with continuous HR monitoring and serial blood sampling for lactate, creatinine, BUN, AST, and CK analysis. LTaer was estimated using three methods: visual inspection, and fixed thresholds at 2 mmol/L (ZL2), and 4 mmol/L (ZL4). HR zones corresponding to each threshold were then calculated based on a maximum estimated HR of 220 bpm. The visual method placed LTaer in zone 2 for both groups. ZL2 located the threshold in zone 2 for GT and in zone 3 for GD, whereas ZL4 placed the threshold in zone 4 for both groups. Although no intergroup differences in lactate or HR were observed, intragroup differences emerged above 75% of HRmax, indicating exponential lactate accumulation. Biochemical parameters revealed significant pre- to post-exercise changes, but no differences between groups, suggesting a standardized workload. This is the first study to propose field-based prediction of LTaer in CPs using HR derived from wearable technologies, based on blood lactate and a standardized exercise test’s results. Correlating HR zones with lactate thresholds facilitates workload analysis in the field. Future studies should investigate the maximal lactate steady state (MLSS) in this breed.

Colombian Paso Horses (CPH) excel in gait competitions due to their endurance, speed, and precision, which demand a high level of cardiorespiratory fitness. However, their training often lacks scientific support, and few studies have linked physiological pa-rameters to optimal training zones. This study aimed to estimate the aerobic lactate threshold (LTaer) using non-invasive methods and to correlate it with heart rate (HR) zones. Eighteen CPH were evaluated and classified into trained (GT) and untrained (GD) groups. All animals underwent a field-based incremental exercise test (IET) with con-tinuous HR monitoring and serial blood sampling for lactate, creatinine, urea, AST, and CK analysis. LTaer was estimated using three methods: visual inspection, fixed thresholds at 2 mmol/L (ZL2), and 4 mmol/L (ZL4). HR zones corresponding to each threshold were then calculated based on a maximum estimated HR of 220 bpm. The visual method placed LTaer in zone 2 for both groups. ZL2 located the threshold in zone 2 for GT and in zone 3 for GD, whereas ZL4 placed the threshold in zone 4 for both groups. Although no intergroup differences in lactate or HR were observed, intragroup differences emerged above 75% of HRmax, indicating exponential lactate accumulation. Biomarker analysis revealed significant pre- to post-exercise changes, but no differences between groups, suggesting a standardized workload. This is the first study to propose field-based pre-diction of LTaer in CPH using HR derived from wearable technologies and a standardized exercise test. Correlating HR zones with lactate thresholds facilitates workload analysis in the field when blood biomarkers are not available. Future studies should investigate the maximal lactate steady state (MLSS) in this breed.

RESUMO O objetivo deste trabalho foi mensurar as dimensões da patela de cadáveres caninos e avaliar sua relação com a massa corporal. Para a realização das medidas patelares, foram utilizados 70 cadáveres de cães adultos, com massa corpórea de 1 a 50kg, sem evidência clínica de afecção na articulação femorotibiopatelar. Com auxílio de um paquímetro, foram mensurados os comprimentos externo e interno, a largura externa no terço médio, a largura e a espessura internas nos terços proximal, médio e distal das patelas. Também foram mensuradas a largura nos terços proximal, médio e distal, a profundidade nos terços proximal, médio e distal do sulco troclear; essas medidas foram exclusivamente internas. Observou-se, de forma geral, forte correlação entre as medidas patelares e a massa corporal de cadáveres de cães. Nas condições deste estudo, pode-se concluir que o tamanho da patela varia segundo a massa corporal do cão e que essas medidas devem ser consideradas ao se planejar uma substituição protética.