Reproducibility of VO2-VCO2 relationship during incremental exercise protocol

We examined the effect of two different slope protocols to the reproducibility of the VO2-VCO2 relationship and the lactic acidosis threshold (LAT) during incremental exercise. Two adult male subjects performed a cycle ergometer exercise 2 to 4 times repeatedly in which the increase of work rate was 25 W every 1 or 2 min according to experimental design method. Gas exchange parameters during each exercise was measured every 10 s. The V-slope method was applied to the data which remained after the deletion of the data during the transient phase with the onset of exercise and above respiratory compensation of metabolic acidosis (RCMA), for detecting LAT and summarizing the VO2-VCO2 relationship below and above LAT. LAT had a high reproducibility whichever slope protocol was used. The confidential limit of LAT estimated by a statistical method was about +/- 0.1 l/min in terms of VO2. There were stable and reasonable responses of VO2-VCO2 during incremental exercise in which the work rate increased 25 W every 1 min.