THE BLOOD LACTATE RESPONSE OF CYCLISTS DURING INCREMENTAL AND FREE RANGE EXERCISE.

411 The aim of the study was to determine whether the blood lactate response of cyclists obtained during a load-incremented exercise test predicts their blood lactate response during typical, daily cycling exercise. 4 Trained and 4 untrained cyclists performed an incremental exercise test to exhaustion, and a 40 minute free range test (a computer simulation of a mountainous cycle competition route). A radial arterial catheter was inserted in the non-dominant arm and blood samples were taken every minute, while cardiorespiratory data were monitored continuously, during both tests. The lactate threshold (LT) was determined as the oxygen consumption (VO2) where there was an abrupt increase in blood [lactate] from baseline values, expressed as %VO2max. Kinetic analysis was performed, using a single-component exponential model, to calculate the time constants for the lactate responses during incremental exercise. The trained and untrained cyclists differed significantly with regards to LT (67±1.0 vs 61±2.2% VO2max) and time constants (5.1±0.3 vs 3.9±0.3 sec), however, there were only minor within group differences during incremental exercise. During the free range test, there were distinct within and between group differences in the blood lactate profiles. The individual responses were not related to the LT or time constants of the incremental exercise test. It would seem them that incremental exercise does not give a true reflection of the blood lactate profile of cyclists engaging in typical, daily cycling exercise.