Training-induced alterations in glucose metabolism during moderate-intensity exercise

Area of Science:

• Equine Exercise Physiology
• Metabolic Adaptations to Training
• Sports Science

Background:

• Physical conditioning alters substrate utilization during exercise in many species.
• Limited quantitative data exists on these effects in horses.
• Understanding these adaptations is crucial for optimizing equine athletic performance.

Purpose of the Study:

• To investigate the impact of a 6-week moderate-intensity training program on plasma glucose kinetics in horses during submaximal exercise.
• To compare glucose metabolism at absolute and relative workloads post-training.
• To examine the influence of training on hormonal responses during exercise.

Main Methods:

• Seven horses underwent a 6-week treadmill training program.
• Exercise trials were conducted pre- and post-training at 55% of maximum aerobic capacity (VO2max).
• Plasma glucose kinetics, hormonal concentrations (glucagon, epinephrine, norepinephrine), and exercise duration were measured at absolute (ABS) and relative (REL) workloads.

Main Results:

• VO2max increased by 14.9% post-training.
• Exercise duration was longer in the ABS trial post-training.
• Plasma glucose concentration, rate of appearance (Ra), and rate of disappearance (Rd) were lower in the ABS trial compared to the untrained (UT) trial.
• Hormonal responses to exercise were blunted in the ABS trial.

Conclusions:

• Six weeks of moderate-intensity training decreases glucose flux during submaximal exercise at an absolute workload in horses.
• This reduction in glucose flux may be attributed to altered glucoregulatory hormone concentrations.
• Training adaptations enhance metabolic efficiency during submaximal exercise, particularly at fixed absolute workloads.