Precision in Estimating Maximal Lactate Steady State Performance in Running Using a Fixed Blood Lactate Concentration or a Delta Value from an Incremental Lactate Profile Test

Six definitions of blood lactate threshold were used on an incremental lactate profile test (LPT) to ascertain which of them best estimated the Maximal Lactate Steady State (MLSS) velocity when using the Lactate Pro LT-1710 analyser. These definitions included three fixed blood lactate concentrations of 4.0, 3.0 and 2.0 mmol ·L-1, and three dynamic definitions, in which a value of 1.0, 1.5 and 2.0 mmol ·L-1 were added to the resting blood lactate concentration. Fourteen trained men (age 49±12 yrs, mass 74.5±5.7 kg) performed an incremental LPT and a VO2max test on a treadmill. A few days later they performed several MLSS runs of 30 min. duration to find the highest velocity with a stable blood lactate concentration. Threshold definitions that had resting blood lactate concentrations between 3.0 and 4.0 mmol ·L-1 gave threshold velocities not statistically different from the velocity at MLSS when using the LT-1710 blood lactate analyser. The only definition to overestimate the MLSS running velocity was the fixed blood lactate concentrations of 4.0 mmol ·L-1. The closest match was found when adding a delta value of 2.1 (1.1) mmol ·L-1 to the resting blood lactate concentration. When using the LT-1710 analyser for MLSS estimation from incremental LPTs, lactate threshold definitions that gives blood lactate concentrations of 3.0 to 4.0 mmol ·L-1 can be used