Effect of training duration and exercise on blood-borne substrates, plasma lactate and enzyme concentrations in Andalusian, Anglo-Arabian and Arabian breeds.

This research investigates how exercise impacts metabolic responses in different horse breeds, primarily focusing on Andalusian, Arabian and Anglo-Arabian breeds. The study explores how these breeds react to varying exercise intensities and training durations.

Research Methodology

In this study, 20 stallions of three different breeds, namely Andalusian (AN), Arabian (A), and Anglo-Arabian (AA) between the ages of 5-10 years were observed. They underwent three exercise tests which involved a warm-up and 4 workloads at increasing speeds and distances, with active recovery periods between each workload.

• These tests were performed at the start, after 2, and after 6 months of training.
• Venous blood samples were collected during the exercise tests.
• Various parameters like glucose, free fatty acids, lactate, creatine kinase, lactate dehydrogenase, alpha-hydroxybutyrate dehydrogenase, aspartate aminotransferase, and electrolytes such as sodium, potassium, and chloride were measured in the plasma.

Key Research Findings

The Andalusian horses showed a greater increase in glucose, α-hydroxybutyrate dehydrogenase, lactate dehydrogenase, creatine kinase, and aspartate aminotransferase concentrations compared to the other breeds when subjected to exercise.

• Surprisingly, the researchers found no significant differences across breeds in peak lactate concentrations in plasma in the initial experiment (Experiment A), which was unexpected as Arabian and Anglo-Arabian horses are usually thought to have a higher athletic capacity.
• By 2 months into the training program, the glycolytic response to exercise (the breakdown of glucose for energy) was reduced in Arabian and Anglo-Arabian horses. This response was also observed in Andalusian horses, although it took 6 months of training for this response to manifest.
• By the end of the study (Experiment B), it was found that Andalusian horses produced more lactate than the other breeds, suggesting different metabolic responses based on breed.

Conclusions and Implications

The most notable changes in plasma enzyme activities were seen in Andalusian horses after 2 months of training. The reduction of creatine kinase response to exercise was related to lower utilisation of glucose outside the muscle fibers, coupled with an increased fat metabolism pathway. These findings indicate that different horse breeds can have varied metabolic responses to exercise, and that these responses can change over the course of a training period. The study concludes that when diagnosing equine myopathies (muscle diseases in horses), these breed and training effects should be taken into consideration. This research contributes to our understanding of equine physiology and highlights the importance of considering breed differences when designing training programmes for horses.