Changes in intramuscular amino acid levels in submaximally exercised horses - a pilot study.
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: Intramuscular Amino Acid Dynamics and Post-Exercise Supplementation in Horses Understanding how muscle amino acid pools respond to exercise and nutritional intervention remains crucial for optimising recovery protocols in equine athletes. Van den Hoven and colleagues examined nine horses across four standardised exercise tests, measuring intramuscular free amino acid concentrations before, immediately after, and at 4 and 18 hours post-exercise, with half the tests followed by oral protein/amino acid supplementation within one hour of finishing. Submaximal exercise triggered significant time-dependent changes in 14 amino acids—including branched-chain amino acids (leucine, isoleucine, valine) and glutamine—with notably different profiles between the immediate post-exercise period and 4-hour recovery window. Post-exercise supplementation proved particularly effective at the 4-hour mark, significantly elevating intramuscular alanine, isoleucine, methionine and tyrosine; by 18 hours, alanine, asparagine, histidine, methionine and valine remained elevated, suggesting sustained replenishment of the intramuscular free amino acid pool. For practitioners designing recovery feeding strategies, these findings indicate that timely oral amino acid supplementation within the first hour after work measurably enhances muscle amino acid availability during the critical 4–18 hour window when tissue remodelling and adaptation occur, though the pilot nature of this work warrants confirmation in larger studies before firm recommendations can be established.
Read the full abstract on PubMed
Practical Takeaways
- •Post-exercise amino acid supplementation within 1 hour may enhance muscular recovery by elevating intramuscular amino acid pools, potentially supporting muscle repair and adaptation
- •Individual amino acids respond differently to exercise and supplementation; timing of supplementation (within 1 hour post-exercise) appears important for optimizing intramuscular amino acid availability
- •Extended recovery periods show sustained elevation of amino acids with supplementation, suggesting benefits beyond the immediate 4-hour window
Key Findings
- •Intramuscular free amino acid concentrations showed significant time-dependent changes in 14 amino acids (alanine, asparagine, aspartate, citrulline, glutamine, glycine, isoleucine, leucine, methionine, serine, taurine, threonine, tyrosine, valine) following standardized exercise
- •Oral protein/amino acid supplementation given within 1 hour post-exercise significantly increased intramuscular concentrations of alanine, isoleucine, methionine and tyrosine at 4 hours post-exercise
- •At 18 hours post-exercise, supplemented horses maintained elevated intramuscular amino acid levels including asparagine, histidine and valine compared to non-supplemented controls
- •Plasma amino acid changes were time-dependent and associated with feeding supplementation, consistent with previous studies