EQUIFINALITY OF BLOOD LACTATE STEADY STATE DURING PROLONGED EXERCISE OF LOW AND HIGH INTENSITY

Abstract

1557 It is known that during constant load steady state lactate concentration(CLass) can approach 2 to 10 mmol/l. The purpose of the present study was to investigate whether CLass is independent of a preload activity and preexisting blood lactate (PLaex) concentration. We investigated 11 male middle and long distance runners (age 24.3 ± 3.4 years, LBM 63.72 ± 5.4 kg, 4-mmol-threshold 4.38 ± 0.35 m/s) by two exercise tests of a constant load (20-30 minutes duration) near the aerobic threshold (3.64 ± 0.33 m/s) and near the maximal lactate steady state (4.47 ± 0.26 m/s) with and without a 3-minute preload of supramaximal intensity (5.38 ± 0.28 m/s) on a treadmill. Arterialized capillary blood lactate concentration(sample of ear lobe), VO2, VCO2 (by open spirometry), PaCO2 and pH were measured. TableTableOur results show the change of preexisting lactate concentration by accumulation or elimination to the equifinal blood lactate steady state concentration (CLass) in 15 to 25 minutes during exercise of low intensity(minimal CLass:1.08 mmol/l) and high intensity (maximal CLass:11.16 mmol/l). These data correspond to the theory of metabolic origin of anaerobic threshold by MADER et al. 1986. We suggest following conclusion: Even at higher intensity a time and preload independent CLass exists under true oxidative steady state conditions caused by a balance between gross lactate formation and lactate elimination.