Concentrations of Circulating Irisin and Myostatin in Race and Endurace Purebred Arabian Horses-Preliminary Study.

Summary

# Editorial Summary: Myokine Responses to Exercise in Arabian Horses Skeletal muscle functions as an endocrine organ, producing myokines—signalling molecules that regulate energy metabolism and adapt to training demands. Kowalik and colleagues measured circulating myostatin and irisin in 10 three-year-old racehorses and 10 endurance horses (mean age 7.4 years) at rest and 30 minutes post-exercise during a competitive season, examining how different training types influenced these biomarkers. A single exercise bout elevated myostatin concentrations in both groups but failed to trigger irisin release; notably, racehorses showed declining irisin levels across the training season whilst endurance horses maintained higher baseline myostatin than younger racehorses. These findings suggest myostatin may exert negative feedback on irisin production during exercise adaptation, implying that chronic training in endurance disciplines promotes sustained myostatin signalling—potentially underpinning the metabolic and muscular phenotype differences between sprint and distance athletes. For practitioners, this preliminary work hints that myokine profiling could eventually help characterise training adaptations and inform conditioning strategies, though larger studies are needed before applying myostatin and irisin measurements to individual horse management.

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Key Findings

• •Single acute exercise bout did not influence plasma irisin concentration but increased plasma myostatin concentration in both groups
• •Plasma irisin concentration decreased with length of training season in racehorses
• •Endurance horses had significantly higher plasma myostatin than three-year-old racehorses
• •Myostatin may provide negative feedback inhibition of irisin release in response to exercise

Conditions Studied

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