[Blood lactate in the steeplechase horse: triangular and rectangular series of steps during short duration races].

The research investigates the effects of different types of exercises on blood lactate levels in steeplechase horses, seeking to distinguish between the influences of work rate and time. Five horses were subjected to both constant-load and incremental exercises, and blood samples were taken after each exercise stage to assess lactate levels.

Research Design

• The research involved five steeplechase horses who were put through both incremental and constant-load exercises. These exercises were made up of three parts, with each part lasting two minutes. Between these parts, the horses were given a one-minute rest during which jugular blood samples were taken. This was to allow the researchers to observe changes in blood lactate levels.
• The constant-load exercises were designed to evaluate how the horses’ blood lactate levels would respond to a consistent level of exertion over a period of time.
• The incremental exercises, on the other hand, allowed the researchers to observe how increasing the horses’ work rate influenced their blood lactate levels.

Results and Findings

• At the end of the constant-load exercises, blood lactate among the horses remained below 4 mmol.l-1, indicating that a steady level of exertion brought the horses to a state referred to as ‘lactatemia critical velocity’ (LVC). The LVC was not significantly different from the velocity leading to a 4 mmol.l-1 blood lactate level, otherwise known as VS4, during the incremental run tests.
• With regard to the incremental exercises, the rise in blood lactate levels (delta L) within a single short run increased linearly with speed, enabling the determination of a ‘null’ velocity. This ‘null’ velocity was the maximum speed at which there was no significant lactate increase.
• However, for independent runs, delta L increased exponentially with velocity, showing significant differences among the horses. The researchers concluded that this variability in short-term functional adaptation to increasing exercise intensity could be useful for evaluating and monitoring the fitness of racehorses over time.

Implications

• The findings of the research offer several important insights into understanding how different forms of exercise influence lactate levels in the blood of steeplechase horses. Such knowledge is vital in managing the training and performance of such horses.
• Knowing the ‘null’ velocity, or the maximum speed at which there is no significant increase in lactate levels, can be particularly useful in exercise prescription and fitness programming for racehorses.
• Notably, the variability in response to independent runs among horses suggests that individualized exercise programs may be more beneficial to optimize fitness levels and performance.