Comparison of yearling, two-year-old and adult Thoroughbreds using a standardised exercise test.

The study aims to explore the differences in exercise measurements between yearling, two-year-old, and adult Thoroughbred horses by applying a standardized treadmill exercise test. The research deduced that both aerobic power and exercise capacity enhances with age and training, while anaerobic power is well established during the early horse years.

Methodology

• The participants of the study included yearling, two-year-old, and adult Thoroughbred horses.
• All participants were subjected to a standardized incremental exercise test on the treadmill.
• The researchers measured multiple factors during the exercise test, including peak oxygen consumption (VO2 peak), peak packed cell volume (PCV peak), and the maximum number of steps completed in the exercise test (STEPmax). Other variables like peak venous lactate concentration (LACpeak), peak respiratory exchange ratio (Rpeak), peak heart rate (HRpeak), and the rate of change of VO2 between steps (VO2trans) were also observed.

Results

• The study found VO2 peak, PCV peak, and STEPmax significantly increased with the horse’s age and degree of physical activity.
• LACpeak and Rpeak were significantly higher in both yearlings and two-year-olds when compared to adult racehorses – signalling superior anaerobic development in younger horses.
• HRpeak did not show significant changes with age or training.
• The adult racehorses exhibited a lower rate of change of VO2 at high exercise intensities, which signifies better aerobic performance with age and training.
• The adult horses recorded a quicker decrease in venous lactate and a faster return to initial R values post-exercise, suggesting better exercise recovery.
• The study also examined the relationship between several variables and velocity, revealing trained adult racehorses had significantly lower slopes, implying improved physiological effectiveness.

Conclusion

• The research concludes that the aerobic power and exercise capacity of Thoroughbred horses improved with age and training.
• However, anaerobic power was found to be well-developed even in young horses, as illustrated by higher LACpeak and Rpeak levels.
• The results bring valuable insights into the physiological development of racehorses, contributing to more efficient training programs and performance strategies for Thoroughbred horses of different age groups.