Plasma lactate response to submaximal and maximal exercise tests with training, and its relationship to performance and muscle characteristics in standardbred trotters.

The research focuses on the plasma lactate response in seven young Standardbred trotters to submaximal and maximal workouts and its correlation to their performance and muscle characteristics.

Study Methodology

• The subject of the study were seven young Standardbred trotters that were all born, raised, and trained in the same location.
• These horses underwent various submaximal and maximal workout tests on a track.
• The submaximal test consisted of four 1,000 meters runs at increasing speed for each run.
• Each horse performed these submaximal tests at different stages in their lifetime: 24, 26, 29, and 40 months old.
• The maximal test was performed when the horses were 24 and 29 months old, covering a distance of 1,600 meters.
• Blood samples were taken from the horses after each run during the submaximal test and after the maximal test for the analysis of plasma lactate.
• The muscle biopsy samples were taken from the horses at 24 and 29 months of age to study their muscle characteristics.

Findings

• The results indicated significant differences in lactate response to submaximal efforts among individual horses.
• Early training only seemed to influence the plasma lactate response in some horses.
• When the horses reached 40 months old, their lactate response to the final submaximal test was significantly lower (7.2 mmol/l) compared to when they were 29 months (14.5 mmol/l).
• The study found a negative correlation between lactate concentrations after all runs in the submaximal test and the horses’ speed over 1,600 meters.

Muscle Characteristics and Performance

• The activity of citrate synthase, which is a marker for muscle oxidative capacity, increased as the horses aged from 24 to 29 months.
• The proportion of Type IIB fibers, which are fast-twitch fibers, decreased as the horses aged, while the Type I fibers, which are slow-twitch fibers, increased. This hints that their muscles adapted over time to the exercise regime, developing a better oxidative capacity and efficiency.
• There was no correlation found between lactate concentration after the maximal test and the horses’ speed, indicating that the horses’ speed during a maximal test might not be linked to their lactate concentration post-test.

Conclusion

• In conclusion, the researchers proposed that the lactate response to a submaximal work test could be an important tool for assessing an individual horse’s performance capacity.