Training-induced modifications of circadian rhythmicity of peroxidative parameters in horses.
Authors: Piccione G, Giannetto C, Marafioti S, Faggio C, Alberghina D, Fazio F
Journal: Journal of animal physiology and animal nutrition
Summary
# Editorial Summary: Training-induced modifications of circadian rhythmicity of peroxidative parameters in horses Oxidative stress during exercise is a well-established concern in equine performance, yet little is known about how training alters the body's daily antioxidant defence patterns. Piccione and colleagues conducted a 48-hour blood sampling protocol at 4-hourly intervals in both untrained and trained horses, measuring reactive oxygen metabolites (d-ROMs), total antioxidant barrier (Oxy-ads), thiol antioxidants (SHp), and lipid peroxidation (LPO) to track circadian variations in these parameters. Training significantly elevated both Oxy-ads and SHp concentrations across the monitoring period (p < 0.01), with all antioxidant parameters—excluding LPO—demonstrating pronounced daily rhythms; notably, the timing of peak antioxidant activity shifted from daytime in untrained horses to evening in trained animals. These findings suggest that systematic training enhances the horse's intrinsic antioxidant capacity and reshapes the circadian timing of these protective mechanisms, potentially optimising metabolic defences during typical evening/night recovery phases when tissue repair accelerates. For practitioners, this supports the rationale for conditioning programmes aimed at building oxidative resilience, whilst the shift in antioxidant rhythm patterns warrants consideration when timing intensive work or nutritional antioxidant supplementation protocols.
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Practical Takeaways
- •Regular training increases horses' natural antioxidant defences, improving their ability to manage oxidative stress from exercise
- •Timing of exercise may interact with circadian changes in antioxidant capacity, with trained horses showing evening peaks rather than daytime peaks—relevant for scheduling demanding work
- •Monitoring antioxidant status and understanding circadian variations could inform training intensity and recovery protocols to optimise adaptation
Key Findings
- •Training significantly increased antioxidant barrier (Oxy-ads) and thiol antioxidant barrier (SHp) values in horses compared to untrained animals (p < 0.01)
- •All peroxidative parameters except lipid peroxidation showed robust daily circadian rhythms with acrophases shifting from daytime in untrained horses to evening in trained horses
- •Two-way ANOVA demonstrated significant time-of-day effects on all parameters studied except lipid peroxidation
- •Training modifies the circadian rhythmicity of antioxidative parameters, suggesting adaptation to exercise-induced oxidative stress