Application of V200 values for evaluation of training effects in the young thoroughbred under field conditions.

The purpose of this investigation was to study, under field conditions, the usefulness of an incremental exercise test to measure V200 (running velocity [V] at heart rate HR[ of 200 beats/min) for evaluation of training effects in the young Thoroughbred. Five to 112 two-year-old Thoroughbreds were used over 4 years to investigate the correlation between HR and V, the influence of the track and rider's weight to V200, reproducibility of V200 and the changes of V200 as training progresses. The high correlation coefficient between HR and V, and V200 were obtained in horses that exercised smoothly during gait changes and had acceleration during the canter in relaxed and nonexcitable states. The reproducibility of V200 as statistically significant providing the conditions were constant. Furthermore, the regression lines between HR and V gradually declined in parallel as training progressed. The average V200 in 2-year-old Thoroughbreds significantly increased from 623 +/- 55 m/min to 691 +/- 64 m/min after 5 months of training (P < 0.05). We concluded that V200 could easily be measured, that it was useful in evaluating treatment effect and that practical application under field conditions was possible.