Blood lactate responses to submaximal field exercise tests in thoroughbred horses.

This research article investigates how Thoroughbred racehorses’ blood lactate levels respond to submaximal exercise tests. The study analyses the association between the speed at which the horses run during an 800-meter test run and their consequent blood lactate level, with emphasis on comparing results obtained on both grass and sand tracks. The research also evaluates the potential application of the measured and predicted blood lactate concentrations in assessing fitness levels in Thoroughbred horses.

Methodology and Results

• The researchers performed exercise tests on two different types of tracks – sand and grass – to compare the horses’ lactate reaction to varying terrain conditions. The exercise tests involved running at varied speeds ranging from 12.8 meters per second to 16.6 meters per second.
• The variability of speed within the exercise test was measured as the coefficient of variation (CV). The CV represented the differences in times it took for the horses to complete four 200-meter sections within the entire 800-meter test.
• Numerous equations were used to determine the relationship between lactate concentration (measured in millimoles per liter), and the speed of exercise (measured in meters per second). The best-fit formula was different for the two tracks; an exponential regression equation was best suited for the sand track and a second-order polynomial equation for the grass track.
• On the sand track, the correlation between the speed and lactate levels was 0.58 using a coefficient-determination (r(2)) equation, while on the grass track, the coefficient was slightly lower, standing at 0.57.
• The researchers found average differences between the measured and predicted blood lactate concentrations in repeated tests were 1.9 +/- 1.8 (SD) on the sand track and 1.8 +/- 1.7 (SD) on the grass track. This differences were statistically insignificant, verifying the reliability of the chosen equations for predicting lactate concentrations in these conditions.

Key Findings and Implications

• The study found no significant associations between the velocity of exercise and the coefficient of variation on either the sand or the grass track. This suggests that the horses maintained a relatively consistent pace throughout each 800-meter test run, irrespective of their velocity or track type.
• The predicted and measured lactate concentrations showed insignificant differences, implying that the applied formula accurately predicts lactate concentrations for thoroughbred horses running at submaximal speeds on the tested tracks.
• This research contributes valuable insights for using lactate-speed relationships in assessing thoroughbred horses’ fitness. The negligible differences between predicted and actual lactate measurements mean that blood lactate responses to submaximal exercise can be a reliable predictor of a horse’s fitness levels during field studies.