Muscular and metabolic responses to moderate-intensity short-term training.

The paper investigates the impact of a 10-day moderate-intensity exercise routine on the metabolic responses in horses. The study found that this type of training led to reductions in muscle glycogen depletion and anaerobic metabolism during high-intensity exercises.

Study Objective and Method

• The objective of this study was to examine the effects of 10-day moderate-intensity training on horses’ muscular metabolic response during high-intensity exercise, and on the markers of mitochondrial enzyme oxidative capacity in their gluteal muscle.
• Six unfit Thoroughbred horses were included in the study. They followed a 10-day exercise regime at 55% VO2max (peak oxygen consumption) for 60 minutes per day, covering 13-14 km daily.
• Both incremental and high-intensity exercises were performed before (HI1) and after (HI2) training. The high-intensity workout included a 10-minute warm-up session, followed by an exercise of 100% of pre-training VO2max until exhaustion.

Results of the Study

• The study found a significant improvement in the horses’ performance post-training. Their VO2max increased by approximately 8.9%, and their running time until exhaustion rose by about 24% during high-intensity exercise.
• Contrastingly, training did not alter the VO2 during the high-intensity workout, but significantly reduced peak values for carbon dioxide production (VCO2) and respiratory quotient (R).
• The glycogen breakdown rate in the muscle during the high-intensity workout decreased by 45% in the post-training session (HI2) compared to the pre-training (HI1). Likewise, the peak lactate concentrations in plasma and muscle after exercise fell by 22 and 23% respectively, after training.
• Training also resulted in a lower rise in plasma norepinephrine levels during exercise. However, there was no alteration in the concentration of plasma epinephrine.
• The maximum activities of citrate synthase (CS), succinate dehydrogenase (SDH), and 3-hydroxy-acyl-CoA dehydrogenase (HAD), the markers of oxidative capacity, were unaffected by the training.

Conclusions

• According to the study, 10 consecutive days of moderate-intensity training resulted in improved metabolic efficiency during high-intensity workouts in horses, characterized by decreased muscle glycogen depletion and anaerobic metabolism.
• The study also concluded that measurable increases in mitochondrial oxidative potential might not be necessary for the manifestation of these metabolic adaptations in the early training phase.