Effect of Regular Training on Platelet Function in Untrained Thoroughbreds.
Authors: Miglio Arianna, Falcinelli Emanuela, Cappelli Katia, Mecocci Samanta, Mezzasoma Anna Maria, Antognoni Maria Teresa, Gresele Paolo
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary Young, untrained Thoroughbreds undergo significant haemostatic changes during the early months of sprint training, with platelet function shifting markedly within the first 30 days of a structured 4-month programme. Researchers monitored 29 clinically healthy 2-year-old horses monthly across five timepoints, measuring platelet aggregation responses to multiple agonists (ADP, collagen, and calcium ionophore) alongside functional assessments using PFA-100® analysis and molecular markers of platelet activation including endothelial nitric oxide synthase and prostaglandin I₂ synthase expression. Training induced substantial platelet hyperactivity by day 30—aggregation responses increased by approximately 11–51% across different agonists—though closure times shortened significantly (75.6 versus 87.7 seconds on collagen/ADP cartridges), and importantly, these parameters trended towards baseline values by day 90, whilst plasma nitric oxide bioavailability rose concurrently. The findings suggest that conditioning horses gradually adapts their coagulation physiology to training demands, with initial hyperplatelet activity representing an acute haemostatic adjustment that normalises with ongoing exercise exposure, potentially conferring protective effects against thrombotic complications during intense athletic effort. For practitioners managing young racehorses, this indicates that platelet hyperactivity during early training phases is physiologically expected and reversible, supporting the rationale for progressive conditioning programmes rather than immediate high-intensity work.
Read the full abstract on PubMed
Practical Takeaways
- •Young Thoroughbreds show increased platelet activation in the first month of sprint training, which normalizes with continued conditioning—monitor for thrombotic risk early in training programs
- •Regular physical training appears to reduce negative hemostatic effects of acute exercise efforts, supporting the safety of progressive conditioning protocols
- •Incremental training programs allow physiological adaptation of blood coagulation systems; rapid training escalation may carry higher hemostatic risks
Key Findings
- •Platelet aggregation increased significantly at T30 compared to baseline (collagen: 32.6% vs 21.6%, ADP: 35.5% vs 24.5%, A23187: 30% vs 23.8%)
- •Closure time on C-ADP cartridges shortened from 87.7s to 75.6s at T30, indicating increased platelet activity
- •Plasma NOx concentrations significantly increased after 30 days of training, suggesting improved nitric oxide bioavailability
- •Platelet hyperactivity observed after 30 days of training tended to return toward baseline by T90 (T90), indicating adaptation to regular exercise