Physiological responses of young Thoroughbreds during their first year of race training.

This research investigates how the physiology of young Thoroughbred horses changes during their first year of race training, focusing on the metabolism, oxygen transport, and heart function. The main findings suggest that properly trained horses have increased aerobic capacity and heart output compared to untrained horses at the same time.

Study Design and Participants

• The researchers conducted a study on ten young Thoroughbred horses. Five of them were trained regularly while the other five were kept at pasture and boxes, serving as untrained controls. The trained and untrained horses were matched in sex, size, and age, ensuring a fair comparison.

Methodology

• The physical measurements and testing were carried out at three different stages: before the commencement of training (T1), after six months of training (T2), and following an additional four months of training (T3).
• Various evaluations were conducted including the analysis of metabolism, oxygen transport (O2), and echocardiograms of the horses.
• Satellite telemetry was used to monitor the daily distance movement of the horses in both conditions.

Findings

• Untrained horses moved less total daily distance than trained ones during winter but more during summer. However, the untrained horses majorly walked (80%), while the trained horses only walked for 25% of their distance.
• The body mass of untrained horses increased by 13% after T1, making them significantly heavier and fatter than the trained horses.
• The specific aerobic capacity (VO2max/Mb) increased by 16% in both groups at T2. However, by T3, the aerobic capacity in the untrained group returned to its initial state while it remained higher in the trained group.
• In the trained horses, the specific cardiac output (Q/Mb) increased by 13% at T2. They also exhibited an increased stroke volume (V(S)/Mb) at the T2 and T3 stages compared to T1 and the untrained horses at the same stages.

Conclusion

• The study confirms that trained horses adapt better to exercise with sustained improvement in aerobic capacity and cardiovascular efficiency.
• The significant increases in stroke volume and maximum aerobic capacity had occurred by T2 and were maintained to T3, demonstrating the impacts of consistent training.