Plasma Apelin Concentration in Exercised Horses: Preliminary Study.
Authors: Kędzierski Witold, Cywińska Anna, Wawak Tatiana, Janczarek Iwona, Wilk Izabela, Kowalik Sylwester
Journal: Journal of equine veterinary science
Summary
# Editorial Summary: Plasma Apelin Concentration in Exercised Horses Apelin, a recently identified cytokine produced by adipose and muscle tissue, regulates energy metabolism through its effects on fat mobilisation and adipogenesis—yet its behaviour during equine exercise remained unknown until this preliminary investigation. Kędzierski and colleagues examined 20 purebred Arabian horses split between racing (3-year-olds in short-duration training) and endurance (6–12-year-olds) populations, collecting blood samples at rest and post-exercise to measure apelin alongside traditional metabolic markers including lactate, cortisol, uric acid, triglycerides, total protein, and glucose. Racing exercise provoked a significant decrease in plasma apelin concentration (P < 0.05), whereas endurance work produced no comparable change; notably, in endurance horses, apelin responses correlated moderately with cortisol elevation (r = 0.55) and more strongly with uric acid increases (r = 0.67). Resting apelin levels were consistently lower in long-term trained endurance horses than in early-career individuals, suggesting physiological adaptation to chronic training stimulus. These findings indicate that apelin may serve as a discriminatory biomarker for exercise intensity and training chronicity, potentially offering farriers, veterinarians, and trainers additional insight into metabolic adaptation and stress responses—though larger, longitudinal studies are needed before integrating apelin measurement into routine fitness assessment protocols.
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Practical Takeaways
- •Plasma apelin may serve as a blood biomarker to differentiate training responses between race and endurance horses, potentially helping assess training adaptation
- •Lower resting apelin in well-trained endurance horses suggests this marker could indicate training chronicity and conditioning status
- •Consider apelin alongside cortisol and uric acid measurements when evaluating exercise-induced metabolic stress in performance horses
Key Findings
- •Race training induced significant decreases in plasma apelin concentrations (P < 0.05)
- •In endurance horses, significant correlations found between exercise-induced apelin changes and cortisol (r = 0.55) and uric acid (r = 0.67)
- •Resting plasma apelin concentration is lower in long-term regularly trained horses compared to horses at the beginning of training
- •Apelin response to exercise differs between short-duration high-intensity exercise and long-duration endurance exercise