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Biochemical changes in three-day-event horses at the beginning, middle and end of Phase C and after Phase D
L H Williamson1, F M Andrews, P L Maykuth
1Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens 30602-7385, USA.
Insights
This study tracked biochemical changes in horses during a 3-day event. Key parameters like packed cell volume and lactate levels shifted post-exercise, indicating physiological stress and recovery phases.
Area of Science:
- Equine Sports Medicine
- Exercise Physiology
- Veterinary Biochemistry
Background:
- The 3-day event (3DE) in equestrian sports involves strenuous activity, necessitating an understanding of equine physiological responses.
- Assessing biochemical markers during competition is crucial for monitoring horse welfare and performance.
Purpose of the Study:
- To investigate changes in various biochemical parameters in horses competing at CCI* and CCI** levels during a 3-day event.
- To evaluate the physiological impact of different phases of the 3DE on equine health and recovery.
Main Methods:
- Blood samples were collected from 36 horses at multiple time points before, during, and after a 3DE.
- Analyzed parameters included packed cell volume (PCV), electrolytes (sodium, potassium, chloride, calcium), acid-base balance (pH), lactate, total protein (TP), albumin, glucose, creatinine, and liver/muscle enzymes (AP, GGT, CK, AST).
Main Results:
- No significant biochemical differences were observed between CCI* and CCI** levels, despite variations in test demands.
- Significant changes in PCV, calcium, potassium, lactate, TP, and albumin occurred post-exercise (Phase B), with a trend towards pre-exercise levels during Phase C, supporting its recovery role.
- Chloride, creatinine, and CK increased from Phase B to Phase C, likely due to sweat loss, reduced renal blood flow, and muscle activity.
Conclusions:
- Phase C of the 3DE serves as a recovery period, allowing some biochemical parameters to return towards baseline.
- The extended distance within Phase C aids in further lactate dissipation, crucial for subsequent performance.
- Monitoring these biochemical markers provides insights into equine physiological stress and recovery during demanding equestrian events.
Abstract:
Blood samples were collected 12-16 h before the Speed and Endurance test, immediately after steeplechase, midway through Phase C (4 km marker), at the end of Phase C and immediately after cross-country from 36 horses that completed a 3-day-event at the CCI* (n = 19) or CCI** (n = 17) level. Packed cell volume (PCV), plasma concentrations of sodium, potassium, chloride, ionized calcium, pH and lactate; and serum concentrations of total protein (TP), albumin, total calcium, alkaline phosphatase (AP), gamma glutamyl transferase (GGT), creatine kinase (CK), aspartate aminotransferase (AST), glucose and creatinine were measured. No differences were noted in any biochemical measurements between the CCI* and CCI** horses at any sampling time, despite differences in speed and length of various phases of the Speed and Endurance test. For all horses (n = 36), biochemical parameters changed significantly over time (P < 0.01). The PCV, calcium, potassium, lactate, total protein and albumin concentrations were significantly increased over pre-exercise concentrations immediately after Phase B. During Phase C, these parameters decreased towards pre-exercise concentrations, thereby supporting the concept that Phase C is a recovery phase. In contrast, chloride concentration decreased, and the creatinine concentration and CK increased compared to pre-exercise concentrations from the end of Phase B to the end of Phase C. These changes probably resulted from fluid and electrolyte losses in sweat, reduced renal blood flow and continued muscular activity. Many parameters did not change significantly between the 4 km marker (midway point on Phase C) and the end of Phase C. However, there were a few notable exceptions: potassium, chloride, lactate and glucose concentrations decreased, whereas pH and creatinine concentrations increased significantly from the 4 km marker to the end of Phase C. The most significant benefit of the extra distance from the 4 km marker to the end of Phase C was that it facilitated further dissipation of lactate concentrations prior to the start of Phase D.