Maximal lactate steady state during exercise in blood of horses.

The study examined the maximum lactate steady state (maxLASS) during exercise in the blood of four Thoroughbred horses utilizing a treadmill exercise protocol, as well as the maxLASS of fourteen other horses under field conditions. It concluded that the maxLASS of horses was found to not exceed a speed inducing a blood lactate concentration of 2 mmol/L (v2), which is lower compared to humans.

Research Design and Methodology

• This study involves an exploration of the maximal lactate steady state (maxLASS), defined as maximum speed during which the blood lactate concentration ([LA]) does not increase by more than 1 mmol/L between the 5th and 25th minutes of continuous exercise.
• Four Thoroughbred horses underwent a treadmill-based Standardized Exercise Test (SET) to determine their Blood Lactate-Running Speed (BLRS) relationship and calculate individual v(1.5), v(2), v(2.5), v(3), and v(4) values. These values correspond to the speeds that produce blood LA of 1.5, 2, 2.5, 3, and 4 mmol/L respectively.
• Following this, horses were made to run on the treadmill for 40 minutes at their v(1.5), v(2), and v(2.5) speeds, the practice being repeated every 3 days.
• In a separate part of the study, fourteen other horses underwent a SET in open field conditions to ascertain their BLRS relationship and calculate their v(2).
• Afterwards these fourteen horses ran between 15 and 30 minutes at their v(2) speed.

Research Findings

• In the treadmill test, maxLASS was achieved only at v(1.5) speeds.
• For the horses tested in open field conditions, blood LA concentration did not increase more than 1 mmol/L between the 10th minute to the end of the exercise when they ran at their v(2) speeds.
• Overall, the study demonstrated that the maxLASS of horses is not higher than v(2), suggesting that this value is lower compared to maximum lactate steady state observations in running humans.

Significance of the Study

• The research linked the concept of maxLASS, originally constituted for humans, to measure the aerobic-anaerobic lactate threshold in horses.
• The findings are significant for the physical conditioning and athletic training of horses, especially those participating in endurance-related sports.
• As the maxLASS of horses is found to be lower compared to humans, this differentiating factor should be considered in designing exercise and fitness regimes for equine athletes.