Relationships between racing times of Standardbreds and v4 and v200.

This research study investigates the correlation between the performance levels of Standardbred racing horses and two variables: v(4) – the horse’s running speed under conditions that induce 4 mmol/L of blood lactate concentration, and v(200) – the horse’s running speed under conditions that induce a heart rate of 200 beats per minute. It concluded that the v(4) was a valid indicator of performance, but the v(200) was not or was to a lesser extent.

Objective of the Study

• The main aim of the study was to validate the relevance of the variables v(4) and v(200) in differentiating the performance levels of Standardbred racing horses.

Methodology

• The study involved 19 Standardbred trotting horses from two training yards who had varying racing time records.
• The horses underwent a standardized exercise test to determine their v(4) and v(200) values. Only 6 horses from one yard were used in the calculation of v(200).
• The test consisted of four or more consecutive intervals which increased until a horse’s blood lactate concentration rose above 4 mmol/L.
• The speed and time trotted at each interval, and the time between consecutive intervals, were uniformly maintained for all the horses in a yard.
• After each interval, the blood lactate concentration measured was plotted exponentially against the horse’s running speed to derive the v(4) variable from the obtained blood lactate-running speed relationship.
• Similarly, the mean heart rate measured during the intervals was plotted linearly against the running speed to derive the v(200) variable from the heart rate-running speed relationship.

Findings

• The correlation between v(4) and the racing time record was found to be significant for both yards with correlation coefficients of 0.77 for yard A and 0.75 for yard B, respectively.
• Conversely, no correlation was found between v(200) and the racing time record, indicating that this particular variable may not be a valid indicator of performance ability, or it might be to a lesser extent.

Conclusion

• The study concluded that the v(4) variable, which measures a horse’s running speed under conditions that cause a rise in blood lactate concentration to 4 mmol/L, is a valid indicator of the performance of Standardbred trotting racehorses.
• However, v(200), the measure of a horse’s speed under conditions that cause a heart rate of 200 beats per minute, may not be as useful in predicting performance level.