Show jumping is a century-old Olympic sport performed worldwide. However, despite the prominence of this sport, there is currently no satisfactory evaluation of the physical fitness of its horses. Our study compared two standardised exercise tests (specific and nonspecific for show jumpers) to determine the importance of a show jumping specific evaluation test. Sixteen horses were divided into two performance groups (high and low performance), and all horses performed standardised exercise tests without jumps (SET1) and with jumps (SET2). Heart rate, blood lactate, glucose, blood gas, haematological parameters, and plasma ions were measured before and after the tests, and performance indices were calculated. Both exercise tests (SET1 and SET2) resulted in changes in nearly all measured variables that were expected, based on other studies, for the duration and nature of the exercise performed. Differences between the two performance groups were observed for lactate and glucose, as well as some blood gas variables and performance indicators. These differences might have been the result of better cardiovascular and metabolic adaptation of the high performance group to the show jumping exercises. For the SET1, differences between groups were mainly noted for variables related to aerobic capacity, which suggests that this measurement is important for the evaluation of equine performance in show jumping. The SET2 was capable of detecting different horse performance levels that could not be detected by the SET1, which indicates that a specific test for show jumping (that includes jumping movements) could provide important information for the evaluation of show jumpers. Based on our findings, we recommend that the SET2 be included in future protocols for evaluating jumping horses.

The objective was to evaluate serum activity of the enzymes creatine kinase (CK) and aspartate aminotransferase (AST), which are leakage enzymes responsive to muscle injury, of athletic horses that underwent muscle biopsy and incremental jump test (IJT) involving incremental jumps. The animals were grouped as follows: the first group, horses with history of superior performance (SP); the second, with a history of inferior performance (IP); and lastly, a control group (CG). All groups underwent biopsy of the gluteus medius muscle, while groups SP and IP were also submitted to the incremental jump test (IJT) 24 hours after biopsy. The IJT consisted of three stages with 40 jumps each, where jump height increased progressively, from 40 to 60 and last, 80cm. Blood samples were drawn before biopsy, and 6 and 24 hours after the exercise as well. The levels of CK serum activity increased 6 hours after exercise and decreased 24 hours later in all groups, including CG. AST activity did not increase after biopsy and exercise. There was no increase of both enzyme activities that could be attributed to the exercise, possibly due to exercise short duration and/or low intensity. We conclude that the muscle biopsy was able to show that there was enough stimulus to cause CK enzyme leakage into the plasma, and consequent detection of increased serum activity, while the incremental jump test did not.

We compare the expression levels of the lactate transporter complex consisting of the lactate transporter, monocarboxylate transporter 1 (MCT1), and its ancillary protein, cluster of differentiation 147 (CD147), in the membranes of red blood cells (RBCs) from two breeds of jumping horses and associate the expression levels of these proteins with their jumping ability. The expression levels of MCT1 and CD147 proteins on the membranes of RBCs collected from 30 show jumping horses of two different breeds were quantified: the Brazilian Sport Horses (n ¼ 17) and the European Warmbloods (n ¼ 13). The levels of MCT1 and CD147 in the RBC membranes were measured by western blot using horse-specific antibodies. Statistical analyses included unpaired Student t test and chi-squared test. According to the expression levels of MCT1 and CD147 proteins, 88% of the Brazilian Sport Horses were categorized as high lactate transporters (HTs) and the remaining 12% as low lactate transporters (LTs). The opposite was found for the European Warmbloods, where most animals (77%) were classified as LTs and the remaining animals (23%) were classified as HTs. Brazilian Sport Horses express statistically significantly higher levels of CD147 and MCT1 than European Warmbloods. The classification of horses considering the expression of proteins involved in the ability to transport lactate through the complex MCT1-CD147 seems to be breed dependent, with horses that are able to jump higher obstacles showing lower expression of the MCT1-CD147 complex in their RBCs.

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