Cardiovascular and metabolic adaptations in horses competing in cross-country events.

This research paper reports on a study that analyzed the cardiovascular and metabolic responses of eventing horses to cross-country competitions at preliminary and advanced levels. By analyzing heart rate and various hematological parameters in blood samples taken before, immediately after, and at intervals during recovery periods, the researchers concluded that the muscle energy synthesis during a cross-country event is supplied by both oxidative processes and glycolysis with lactic acid formation, and thus both stamina and power exercises are necessary for these horses.

Study Overview

• This study explored how eventing horses’ cardiovascular and metabolic systems respond to cross-country competitions. The researchers examined 8 male Anglo-Hunter and Anglo-Arabian horses, comparing their responses to a preliminary level and an advanced level event.

Methodology

• Various biological markers were explored during the study. Heart rates were recorded throughout the events, and blood samples were taken at different times – before warm up, immediately after the event, and at 5 and 10 minutes into the recovery period. These samples were tested for a suite of haematological parameters including red blood cells, packed cell volume, haemoglobin concentration, mean corpuscular volume, mean corpuscular haemoglobin, mean corpuscular haemoglobin concentration, white blood cells, and the number and percentages of lymphocytes and granulocytes and monocytes.

Findings

• The study found that these competitions induced significant increases in blood parameters including red blood cells, haemoglobin concentration, packed cell volume, mean corpuscular volume, and total plasma protein. The authors noted that plasma lactic acid response exceeded the anaerobic threshold, reaching a peak level signifying a high rate of glycolysis.
• During the events, the heart rate of the horses varied between 140 to 200 beats per minute, reaching a maximum of 230 beats per minute which indicated a limitation in oxygen supply to the working muscles.

Conclusion

• The findings led the investigators to conclude that both oxidative processes and glycolysis with lactic acid formation are needed to regenerate energy in muscles during cross-country horse events. This means that effective training for eventing horses must incorporate both stamina and power exercises.