The correlation of running ability and physiological variables in thoroughbred racehorses.

This research examines the relationship between several physiological variables and the running speed of Thoroughbred racehorses, finding that there are significant correlations between running performance and oxygen utilization, blood lactate levels, and heart rates, especially during longer distance runs.

Understanding Running Ability of Thoroughbred Racehorses

In this study, the running speeds of 25 Thoroughbred racehorses were measured at 1200, 1600, and 20000m distances to understand their running abilities. The researchers then measured several physiological variables while the horses were on a treadmill and attempted to find correlations between these variables and running speed.

• Among the variables assessed were blood lactate levels at a steady-state concentration of 4 mmol/litre, peak plasma lactate levels, heart rates (HR), and maximum oxygen consumption (VO2max).
• The velocity (VLa4) and work rate (WLa4) at which each horse achieved a steady-state concentration of 4 mmol/litre of blood lactate was found to correlate negatively with running speed. This suggests that horses with higher speeds have faster and greater increases in plasma lactate levels.
• A contrastingly positive correlation was noted with peak plasma lactate levels, again signifying that blood lactate concentrations of faster horses rise more rapidly and reach higher levels compared to those of slower horses.
• The comparison between running speeds and heart rates showed a stronger correlation in unfit horses than in fit ones. This indicates that cardiovascular training might have a more significant impact on enhancing the running speed of slower horses.

Investigating the Impact of Cardiovascular Activity and Blood Lactate Levels

• A noteworthy correlation was observed between running speeds and V200 – an index used to evaluate the horse’s fitness. It implies that the heart rates of quicker horses increase faster than those of slower ones under similar exercise circumstances.
• Researchers also found a connection between running speeds and maximum oxygen usage during exercise, indicating that faster horses use more oxygen during high-intensity exercise.
• Additionally, researchers discovered a correlation between running speeds, minimum pH, and minimum bicarbonate (HCO3-) levels, indicating that quicker horses maintain their speed even when their blood has higher hydrogen ion concentrations.
• The correlations between running speeds and the tested variables were consistently stronger for longer-distance runs, possibly due to the increased demands of endurance performance.
• The study concluded that VLa4 and WLa4—indicative of a horse’s lactate threshold—are the best correlates of running performance in racehorses as their measurements were obtained during sub-maximal exercise.