Maximal Lactate Steady State Prediction Using Two DMAX Methods in Horses Subjected to Treadmill-Graded Exercise Test

Area of Science:

• Equine exercise physiology
• Sports science
• Animal physiology

Background:

• Maximal lactate steady state (MLSS) and lactate threshold (LT) are crucial for evaluating equine endurance.
• Numerous methods exist to predict MLSS, but their concordance needs further investigation.
• Understanding these metrics aids in training prescription and performance assessment in horses.

Purpose of the Study:

• To compare the accuracy of two DMAX methods against established MLSS in teaching horses.
• To evaluate the reliability of DMAX approaches for determining lactate threshold (LT) and estimating MLSS.
• To assess the concordance between velocities derived from DMAX methods (VMAX, VMAXC) and MLSS (VMLSS).

Main Methods:

• Ten teaching horses underwent graded exercise tests (GXT) on a treadmill to generate lactate-velocity curves (LVC).
• MLSS was determined through multiple 30-minute continuous running sessions.
• Two DMAX methods (traditional and calculated DMAXC) were applied to LVCs, and results were statistically analyzed using Bland-Altman plots and ordinary least products (OLP).

Main Results:

• Average lactatemia at VMLSS, VMAX, and VMAXC were 1.50 ± 0.36 mM, 2.02 ± 0.66 mM, and 1.92 ± 0.65 mM, respectively.
• Speeds at VMLSS, VMAX, and VMAXC were 5.42 ± 0.57 m/s, 6.42 ± 0.71 m/s, and 6.35 ± 0.66 m/s.
• Mean differences (VMAX-VMLSS and VMAXC-VMLSS) were -1.01 ± 0.61 m/s and -0.93 ± 0.67 m/s, with no significant constant or proportional biases.

Conclusions:

• The DMAX methods (VMAX and VMAXC) demonstrate accuracy and reliability in estimating MLSS in teaching horses.
• These DMAX approaches are suitable for lactate threshold determination within the GXT protocol used.
• The findings support the use of DMAX methods for assessing equine endurance capacity and optimizing training regimens.