Blood-Based Markers for Skeletal and Cardiac Muscle Function in Eventing Horses before and after Cross-Country Rides and How They Are Influenced by Plasma Volume Shift.
Authors: Giers Johanna, Bartel Alexander, Kirsch Katharina, Müller Simon Franz, Horstmann Stephanie, Gehlen Heidrun
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary Elite eventing horses competing at two- to four-star level experience profound physiological stress during cross-country phases, yet interpreting blood biomarkers requires careful consideration of plasma volume shifts that can artificially inflate or depress measured concentrations. Giers and colleagues examined 20 elite event horses before, immediately after, and 24 hours following cross-country competition, measuring muscle enzymes (creatine kinase and lactate dehydrogenase), metabolites, and cardiac-specific markers whilst mathematically accounting for haemoconcentration effects. Most exercise-induced changes resolved within 24 hours; however, CK remained elevated by 26% and LDH by 15% the morning after exercise, suggesting genuine muscle damage rather than simple concentration artefacts. Most striking was the finding that cardiac troponin I (cTnI)—a marker of myocardial injury—exceeded reference ranges in 73% of individual rides and in 18 of 20 horses by the following morning, despite horses completing competition. These findings highlight that cross-country exertion triggers measurable skeletal and cardiac muscle perturbation in elite performers, prompting practitioners to interpret elevated biomarkers in context of exertional demands rather than automatically assuming pathology, whilst warranting further investigation into whether repeated elevated cTnI predicts long-term cardiac dysfunction or represents benign physiological stress.
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Practical Takeaways
- •Elevated cardiac troponin after cross-country competition is common (73% of rides) and does not necessarily indicate pathology; establish individual baseline values and post-exercise protocols for your horses
- •CK and LDH remain elevated the morning after competition; use these as markers of muscular exertion intensity, but interpret within context of clinical signs and recovery
- •Blood sampling timing matters: 30 minutes post-exercise captures peak changes; next-morning samples show sustained muscle enzyme elevation that indicates degree of muscular stress
Key Findings
- •Cardiac troponin I (cTnI) elevated above reference range in 73% of rides and 90% of horses the morning after cross-country exercise
- •Creatine kinase showed sustained 26% increase and lactate dehydrogenase showed sustained 15% increase the morning after exercise despite initial recovery
- •Most blood-based markers of muscle and cardiac function changed significantly 30 minutes post-exercise but recovered by the next morning, except CK and LDH
- •Plasma volume shift methodology successfully eliminated concentration artifacts, allowing accurate assessment of true marker changes independent of hemoconcentration