Effects of intensified training and subsequent reduced training on glucose metabolism rate and peripheral insulin sensitivity in Standardbreds.

The research investigated how intense training and later reduced training affects the body’s glucose metabolism and insulin sensitivity in Standardbred horses. It observed that excessive training can lead to non-insulin-dependent increases in glucose metabolism.

Research Methodology

• The research was conducted using 12 Standardbred gelded horses who were put through four phases of treadmill-based training.
• Phase 1 involved acclimating the horses to the treadmill.
• In phase 2, the horses went through endurance training alternated with high-intensity exercise training.
• For the third phase, the horses were divided into two groups: one underwent the same training regimen as in the previous phase (control group), while the other had their training intensity, duration, and frequency further increased to induce overtraining (intensified training group).
• In the final phase, the training intensity for both groups was reduced.
• After each phase, standardized exercise tests were performed. Hyperinsulinemic euglycemic clamp (HEC) tests, which measure insulin sensitivity, were performed after phases 2, 3, and 4.

Research Results

• 10 out of the 12 horses completed the study.
• A notable dissociation was observed in the intensified training group between the mean glucose metabolism rate and its ratio to plasma insulin concentration at steady state during the HEC testing conducted after the third and fourth phases.
• After phase 4, both mean glucose metabolism rate and the ratio of glucose metabolism rate to plasma insulin concentration significantly decreased in the intensified training group, indicating an impact of excessive training on insulin sensitivity and glucose metabolism.

Conclusion

• The observed dissociation between glucose metabolism rate and its ratio to plasma insulin concentration in the intensified training group suggests that overtraining might lead to non-insulin-dependent increases in glucose metabolism.
• This could potentially serve as a marker for early overtraining in horses, providing critical clues to veterinarians and horse trainers on regulating training regimens.