A preliminary study on the changes in some potential markers of muscle-cell degradation in sub-maximally exercised horses supplemented with a protein and amino acid mixture.
Authors: van den Hoven R, Bauer A, Hackl S, Zickl M, Spona J, Zentek J
Journal: Journal of animal physiology and animal nutrition
Summary
# Editorial Summary This preliminary investigation examined whether post-exercise protein and amino acid supplementation could modulate markers of muscle protein breakdown in nine horses subjected to repeated high-intensity standardised exercise tests. The researchers measured plasma and intramuscular concentrations of various metabolites (including tyrosine and 3-methylhistidine), enzyme activities (creatine kinase, aspartate aminotransferase, cathepsin B), and muscle gene expression (ubiquitin mRNA) before exercise and at 4 and 18 hours post-exertion, comparing exercise alone with exercise followed by supplementation within one hour. Most notably, the protein and amino acid mixture significantly suppressed ubiquitin mRNA expression at four hours post-exercise, suggesting reduced activation of the ubiquitin-proteasome proteolytic pathway—the major mechanism of exercise-induced muscle breakdown. Unexpectedly, creatine kinase activity did not show the anticipated post-exercise elevation after supplementation, and markers of lysosomal involvement were minimal. For practitioners, these findings suggest that timed protein-amino acid supplementation immediately after training may help attenuate protein catabolism in exercised horses, though the relatively small sample size and preliminary nature of the work warrants cautious interpretation until larger, mechanistically-detailed studies confirm these encouraging results.
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Practical Takeaways
- •Post-exercise protein and amino acid supplementation within 1 hour may reduce muscle protein breakdown in exercised horses, potentially supporting recovery and performance
- •Ubiquitin mRNA expression appears to be a sensitive molecular marker of exercise-induced proteolysis and may help evaluate the efficacy of nutritional interventions
- •Consider implementing protein/AA supplementation after intense training sessions, though further research is needed to determine optimal dosing and long-term performance benefits
Key Findings
- •Protein and amino acid supplementation significantly decreased ubiquitin mRNA expression at 4 hours post-exercise, indicating reduced muscle protein breakdown
- •Plasma and intramuscular tyrosine levels showed significant time-dependent changes in relation to exercise and were modified by protein/AA supplementation
- •CK activity showed normal post-exercise patterns but demonstrated a clear reduction following protein/AA supplementation, suggesting altered muscle damage response
- •Lysosomal involvement markers (cathepsin B, acid phosphatase) showed only borderline increases post-exercise regardless of supplementation