Muscular adaptation of horses during intensive training and detraining.

This research study examines the impact of intensive training and subsequent detraining on the muscular adaptions of horses. The findings indicate that such training phases can significantly enhance the muscle’s oxidative capacity and capillary density, which remain elevated even after a period of detraining.

Study Design and Methods

• The researchers used a group of five horses for the study, which was structured around a five-week cycle of intensive daily training, followed by a five-week period of detraining.
• The horses were exercised on a high-speed treadmill for the training portion.
• Throughout both the training and detraining periods, muscle biopsies were taken weekly from different muscles – the right and left gluteus muscle, and the sternocephalicus muscle.
• These biopsies were analyzed both histologically and biochemically, before and after the training and detraining periods, to track any metabolic adaptations.

Findings from the Study

• According to the histological and biochemical analyses, no significant metabolic adaptation was noticed in the sternocephalicus muscle post-training or detraining.
• Similarly, the analysis of the gluteus muscle did not show any major differences in the examined parameters between the contralateral sites.
• However, there was a notable decrease of 10 to 15 per cent in glycogen levels after one to two weeks of training.
• These lowered glycogen levels persisted throughout the training period but bounced back to their usual levels after training ceased for a week.
• Citrate synthase, an enzyme integral to the citric acid cycle, experienced a boost in activity, showing a 27 per cent increase after one week and a 42 per cent increase after five weeks of training.
• Conversely, lactate dehydrogenase, an enzyme regulating lactate metabolism during exercise, saw a decrease in activity by 15 per cent.
• The fluctuations in these enzymes persisted during the detraining period.
• Despite no significant changes to the fibre type composition of the muscles, the areas of type IIA fibres decreased by 19 per cent post five weeks of training.
• Moreover, capillary density, which reflects the muscle’s blood supply and oxygenation, increased by 17 per cent.

Conclusions from the Research

• The research concluded that short, intensive training periods can quickly enhance the oxidative capacity and capillary density of actively working muscles in horses.
• These metabolic adaptations appears to be well-retained over the course of subsequent detraining periods, suggesting the enduring benefits of such training cycles.