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

Abstract

Metabolic responses to exercise differ between Andalusian horses and other breeds, although changes in plasma muscle enzymes have not been reported and most useful information is obtained from animals subjected to different training programmes. The objectives of this study were to 1) describe the changes in plasma enzymes during exercise in different horse breeds in relation to other biochemical parameters (Experiment A) and 2) assess the effect of training duration on these measures (Experiment B). Twenty stallions, 9 Andalusian (AN), 7 Arabian (A) and 4 Anglo-Arabian (AA), age 5-10 years, were studied. They performed 3 exercise tests (ET), consisting of a warm-up of 800 m at 0.7 km/h and 4 workloads at 15, 20, 25 and 30 km/h, at respective distances of 1250, 1670, 2080 and 2500 m, with 5 min active recovery between each workload (Experiment A). Three ETs were performed at the beginning and after 2 and 6 months of training (Experiment B). Venous blood samples were collected during the ETs and plasma glucose (GLU), free fatty acids (FFA), lactate (LA), creatine kinase (CK), lactate dehydrogenase (LDH), alpha-hydroxybutyrate dehydrogenase (HBHD), aspartate aminotransferase (AST), Na+, K+ and Cl- were measured. AN horses responded to exercise with greater increases in GLU, HBHD, LDH, CK and AST compared to the other breeds. An unexpected result in Experiment A was the lack of interbreed differences in plasma peak LA concentrations, since it is commonly accepted that AA and A horses have greater athletic potential. Although the glycolytic response to exercise was reduced after 2 months of training in the AA and A horses, and after 6 months of training in the AN horses, at the end of Experiment B, AN horses produced more lactate than the other 2 breeds. Most of the adaptations linked to training were found in the AN breed. The more striking changes in plasma enzyme activities corresponded to CK in AN horses after 2 months of training. The attenuation of CK response to exercise was related to lower extrafibrilar GLU utilisation with LA formation and greater fat metabolism. The results show that plasma muscle enzyme concentrations for the diagnosis of equine myopathies must be interpreted in relation to breed and training.

Effect of exercise on physiological, blood and endocrine parameters in search and rescue-trained dogs

“…Exertional rhabdomyolysis is a well recognized clinical entity in dogs and it has been described after short races in Greyhounds (Wodecki and Heinrich, 1993), and after prolonged exercise in sled dogs (Hinchcliff et al, 2004). However, it should be taken into account that plasma muscle enzyme activities change with exercise, probably as a consequence of increased muscle metabolism and transient changes in muscle permeability, without significant fibrillar disruption (Munoz et al, 2002). In the research reported here, plasma CK and LDH activities rose at E, although in both cases resting values were reached at 30REC, indicating that persistent muscle damage did not developed in the dogs.…”

“…A negative significant correlation was found between circulating GLU and INS concentrations in this research (r 2 = -0.740). Previous studies have reported an enhanced lipid metabolism in exercising horses (Munoz et al, 2002) and dogs (Rovira et al, 2007b), as indicated by the increased circulating free fatty acid and TAG concentrations. This fact appears to be more marked after prolonged submaximal exercises, because muscle metabolism is mainly maintained by aerobic pathways.…”

“…LA is a metabolite derived from the anaerobic pathways, and its accumulation in blood/plasma is an indicator of fitness and training level and oxidative capacity (Munoz et al, 2002;Rovira et al, 2007b). LA concentration that exceeds the concentration of clinically normal dogs performing exercise of the same duration and intensity may be an evidence of reduced performance, lack of fitness or underlying disorder of metabolism (Matwichuk et al, 1999;Rovira et al, 2007b).…”

Alterations in muscular enzymes of horses competing long-distance endurance rides under tropical climate

“…Given that strenuous exercise can result in increased CK, AST, and LDH plasma activities without any sign of muscle damage or stiffness, it is rather difficult to differentiate between borderline functional or physiological and pathological changes (Muñoz et al, 2002).…”

The effect of training on plasma L-carnitine metabolism in purebred Arabian horses

“…A similar effect was described in a previous study of purebred Arabian horses (K^dzierski and Podolak, 2002). In the experiment described by Munoz et al (2002) even a two-month training period for Arabian horses had a significant effect on the regulation of energy metabolism in these animals. These observations can be explained by the progressive development of the mechanism for controlling lipid metabolism with training.…”