Changes in heart rate, arrhythmia frequency, and cardiac biomarker values in horses during recovery after a long-distance endurance ride.

The study explores the changes in heart rate, arrhythmia frequency, and cardiac biomarker values in horses following a long-distance endurance ride. The observations could suggest that extensive exercise like endurance riding might affect the cardiovascular system of the horses.

Study Design and Methods

• The study used a cross-sectional design, focusing on 28 Arabian horses that participated in a 120km or 160km endurance ride.
• ECG recordings were taken before and after each horse participated in the endurance ride. The goal was to assess alterations in heart rate and the standard deviation of normal R-R intervals (SDNN) in the first 12 hours of recovery. This also allowed for the evaluation of the occurrence of supraventricular and ventricular premature complexes (types of heart arrhythmia).
• Blood samples were collected before the ride and twice during the recovery process. These samples were subjected to hematologic analyses to measure the concentration of serum cardiac troponin I and the activity level of creatine kinase isoenzyme MB (both being cardiac biomarkers).

Results

• The analyses demonstrated a significant escalation in heart rate and a decline in SDNN throughout the recovery period compared to before the ride.
• The frequency of ventricular premature complexes showed an increase during recovery, although not significantly, while the frequency of supraventricular premature complexes did not reveal a significant difference between pre-ride and recovery periods.
• Both the concentration of serum cardiac troponin I and the creatine kinase isoenzyme MB activity demonstrated a significant increase during the recovery period compared to pre-ride.
• No correlation was found between cardiac biomarkers and the speed, distance, or average heart rate of the endurance ride.

Conclusions and Relevance

• The study conclusions indicate that endurance rides cause a rise in heart rate and a decrease in SDNN in horses.
• The observed cardiac variations suggest potential cardiovascular impacts in horses due to prolonged exercise, such as endurance riding. However, more research needs to be conducted to confirm the clinical relevance of these findings.