Variability of blood lactate during and between given constant prolonged cycling power

Blood lactate concentration (BLC) has been the basis of rational performance diagnostics for almost five decades. Aim of this study was to identify the variability of the BLC during repeated constant power tests (VC-BLC) and to quantify the corresponding variability of changes in the BLC over time (VC-BLC-Difference).

Twelve healthy male subjects (24.8±3-8 years, 182.9±7.5 cm, 75.7±7.1 kg, ·VO2peak: 4.1±0.6 l min-1) performed four series of three constant power tests at exercise intensities of 45% (A), 60% (B), 75% (C) and 90% (D) of VO2peak. Blood sampling was conducted before, at the end of every 5th min and at the end of each test terminated ahead of schedule.

BLC was different at all exercise intensities from minute five onwards. Power output was equivalent to 142.1±18.9 W (A), 196.3±25.2 W (B), 247.9±30.3 W (C) and 302.5±38.4 W (D). VC-BLC varied between 9±2.2% and 21±10.1%. VC-BLC and VC-BLC-Difference between 10th and 30th min correlated inversely with mean BLC level and BLC-Difference respectively.

By providing first data on constant power test VC-BLC and VC-BLC-Difference this study might help to improve performance diagnostics and training control in sports medicine and medical exercise therapy by assisting in selecting and monitoring exercise intensity. Performance monitoring with BLC-Differences is feasible at moderate and high exercise intensities; single BLC measurements at termination of tests might not be sufficient.