Relationships between racing times of Standardbreds and v₄ and v

• Published in: Journal of animal science Vol. 88; no. 3; pp. 950 - 954
• Main Author: Lindner, A.E
• Format: Journal Article
• Language: English
• Published: American Society of Animal Science 2010
• Subjects: exercise test; heart rate; racehorses; racing performance; racing times; running; Standardbred; validity; velocity
• ISSN: 0021-8812; 1525-3163

The objective of the study was to examine the validity of v₄ [velocity run under the defined conditions inducing 4 mmol/L of blood lactate concentration ([LA])] and v₂₀₀ (velocity run under the defined conditions inducing a heart rate of 200 beats/min) to differentiate performance level among Standardbred racehorses. For this purpose, 19 Standardbred trotting racehorses with differing racing time records in 2 training yards were submitted to a standardized exercise test to determine their v₄ and v₂₀₀ (6 horses of one yard only). The test consisted of 4 or more consecutive intervals depending on when the blood [LA] of a horse increased above 4 mmol/L. Speed and time trotted in each interval as well as time between consecutive intervals were the same for horses of a training yard. The blood [LA] measured after each interval was plotted exponentially against running speed to derive v₄ from the blood lactate-running speed relationship, and the mean heart rate during the intervals was plotted linearly against running speed to derive v₂₀₀ from the heart rate-running speed relationship. The correlation coefficient between v₄ and the racing time record was 0.77 and 0.75 for horses in racing yard A and B, respectively. There was no correlation between v₂₀₀ and the racing time record. Therefore, v₄ is a valid indicator of performance level of Standardbred trotting racehorses; however, v₂₀₀ may not be or to a lesser extent.