Effects of training on blood lactate-running speed relationship in thoroughbred racehorses

In this study the effects of training history on the results of a standardized two-speed test in competing Thoroughbreds were investigated during a racing season. For nine Thoroughbreds, 1,755 training days were recorded. Within the observation period each horse completed a two-speed field test at intervals of 6-8 wk to determine its running velocity (v) eliciting blood lactate concentrations of 4 (v4) and 12 mmol/l (v12). Horses performed 29 two-speed tests. Changes of v4 and v12 in a horse between two consecutive tests were used to assess effects of training history variables calculated for the period between two consecutive tests. The percentage of days with gallop workouts between two consecutive tests showed a significant correlation with changes in v4 (r = 0.71, P < 0.01) and v12 (r = 0.56, P < 0.05). The number of gallop workouts (r = 0.60, P < 0.05) and the total time of training (r = 0.58, P < 0.05) correlated with the change of v4. Furthermore the percentage of days without training was negatively correlated to changes of v4 (r = -0.75, P < 0.01) and v12 (r = -0.56, P < 0.05). Therefore the actual training caused changes in the blood lactate-running speed relationship despite its relatively low volume, intensity, and frequency. Future studies have to evaluate how the training variables can be changed to improve the training effects on the blood lactate-running speed relationship of competing Thoroughbreds.