Amino acid concentrations in blood serum of horses performing long lasting low-intensity exercise.
Authors: Bergero D, Assenza A, Schiavone A, Piccione G, Perona G, Caola G
Journal: Journal of animal physiology and animal nutrition
Summary
# Editorial Summary Endurance exercise places substantial metabolic demands on horses, yet the specific aminoacidaemia profile during prolonged low-intensity work remained poorly characterised at the time of this investigation. Bergero and colleagues sampled 14 free amino acids via high-performance liquid chromatography from horses competing in both a 32-km and 72-km endurance ride, collecting blood at strategic points including the start, mid-ride (at an 819-metre elevation gain), and completion. The shorter 32-km ride produced net increases in serum amino acid concentrations, reflecting mobilisation from muscle stores to meet energy demands, whilst the 72-km ride demonstrated significant decreases in most amino acids measured—particularly notable reductions in alanine, arginine, phenylalanine and tyrosine—indicating substantial amino acid catabolism for gluconeogenesis as glycogen depletion progressed. This work demonstrates that exercise duration fundamentally alters amino acid dynamics: intense metabolic demands in extreme endurance events drive amino acid oxidation rather than simple mobilisation, suggesting that nutritional support strategies must account for the duration and intensity profile of the work intended, with particular attention to branched-chain amino acid availability during extended competition to mitigate performance-limiting protein catabolism.
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Practical Takeaways
- •Endurance ride distance fundamentally changes amino acid metabolism in horses; longer rides deplete circulating amino acids suggesting increased protein catabolism and potential recovery supplementation needs
- •Horses performing 72-km rides should receive pre- and post-exercise nutrition strategies that support amino acid availability, as extended exercise depletes rather than mobilizes reserves
- •Monitor training intensity and duration relative to individual horse metabolic response; shorter rides mobilize amino acids while longer ones consume them for energy
Key Findings
- •Amino acid concentrations differ significantly between pre-ride baselines in 32-km versus 72-km endurance races
- •Short-distance endurance (32 km) shows increased blood serum amino acids from start to finish, indicating mobilization without catabolism
- •Long-distance endurance (72 km) shows decreased blood serum amino acids, reflecting amino acid catabolism for energy production
- •Alanine, arginine, asparagine, phenylalanine and lysine increase significantly at the steep slope midpoint in shorter rides