Effects of shortening the steeplechase phase (phase B) of a 3-day-event.

The study looks at how shortening the steeplechase phase of a 3-day endurance event for horses impacts various physiological parameters. The research found that even with this modification, horses still experienced significant fluid and electrolyte losses along with certain other physiological alterations.

Study Design & Participants

• 34 horses were involved in the study and divided into three groups. Group 1 entertained 15 horses competing in a 3.5-minute steeplechase phase, Group 2 consisted of 13 horses in a 3-minute steeplechase phase, and Group 3 comprised 6 horses in a 2.5-minute steeplechase phase.
• The shortening of the steeplechase phase (Phase B) was compensated by a lengthening of Phase C such that the total distance covered by all horses remained the same at 14,940 m.

Data Collection

• Bodyweight (BW) was measured and total body water (TBW) along with water loss was estimated before and after the endurance test.
• Blood samples were collected at different stages – before the test, end of Phase B, 4 km marker on Phase C, end of Phase C, and 20 minutes after the completion of Phase D.
• The blood samples were tested for various parameters, including packed cell volume (PCV), total plasma protein [TPP], lactate, ionised calcium, pH, sodium, potassium, chloride, total calcium and glucose concentrations, and enzyme activities including aspartate aminotransferase, creatine kinase and lactate dehydrogenase.

Ambient Conditions During the Test

• The average ambient environmental temperature during the test was 25.3 +/- 1 degrees Celsius.
• The relative humidity averaged 43.8 +/- 2.4%, and the ‘comfort index’ (a measure of how comfortable the environment feels to most human) was at 121.

Results and Findings

• There were no significant differences in the parameters between the groups competing in the Endurance Test, despite the shorter Phase B. However, harmonious changes were observed in biometric measures such as reduced body weight (BW) and total body water (TBW).
• Similarly, noteworthy fluctuations were seen in biochemical attributes like packed cell volume (PCV), total plasma protein (TPP), lactate, and the activities of aspartate aminotransferase, creatine kinase and lactate dehydrogenase.
• There were decreases in some electrolytes (chloride, ionised calcium) and the body’s pH. Sodium and total calcium concentrations, however, remained at near pre-event levels.
• Potassium, glucose and the aforementioned enzymes experienced an increase during the endurance test compared to pre-event values.
• The findings suggest that horses participating in this endurance event experienced significant fluid and electrolyte losses, reduced kidney filtration, increased glucose breakdown, and enzyme leakage from working muscles. These changes could not be mitigated by shortening Phase B and lengthening Phase C.