Long term intensive exercise training leads to a higher plasma malate/lactate dehydrogenase (M/L) ratio and increased level of lipid mobilization in horses
- 2 February 2012
- journal article
- research article
- Published by Springer Science and Business Media LLC in Veterinary Research Communications
- Vol. 36 (2), 149-155
- https://doi.org/10.1007/s11259-012-9515-0
Abstract
Continuous high intensity training may induce alterations to enzyme activities related to glucose and lipid metabolism in horses. In our study, five Thoroughbred race horses (3 male and 2 female, avg age = 5 yrs old) were compared against five riding horses (1 male, 1 female, 3 gelding, avg age = 13 yrs old) in terms of energy metabolism, by examining plasma malate (MDH) and lactate (LDH) dehydrogenase activities and M/L ratio. MDH is involved in NADH and ATP generation, whereas LDH can convert NADH back into NAD+ for ATP generation. An increase in plasma M/L ratio can reflect heightened energy metabolism in the liver and skeletal muscle of horses adapted to continuous intensive exercise. Moreover, plasma lipid metabolism analytes (adiponectin, NEFA, total cholesterol (T-Cho), and triglycerides (TG)) can reflect changes to lipolysis rate, which can also indicate a change in energy metabolism. Overall, race horses demonstrated increased MDH and LDH activity in plasma (4x and 2x greater, respectively), in addition to a plasma M/L ratio twice as high as that of riding horses (2.0 vs 1.0). In addition, race horses also demonstrated significantly higher levels of plasma NEFA (50% greater), TG (2x greater), and T-Cho (20% greater) as compared to riding horses. Therefore, race horse muscles may have adapted to prolonged high intensity endurance exercise by gaining a higher oxidative capacity and an increased capacity for fat utilization as an energy source, resulting in heightened energy metabolism and increased rate of lipid mobilization.Keywords
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