Ventilatory, lactate-derived and catecholamine thresholds during incremental treadmill running:: Relationship and reproducibility

Anaerobic threshold as a basic criterion of training recommendation can be estimated by various parameters. The purpose of this study was to investigate the relationship and the reproducibility of ventilatory, lactate-derived and catecholamine thresholds of an incremental treadmill exercise. Therefore, 11 male subjects underwent two incremental treadmill tests within 7 days. The lactate threshold (LT) was determined at the lowest Value of the lactate-equivalent (ratio lactate/performance). The individual anaerobic threshold (IAT) was calculated at LT + 1.5 mmol/L lactate. The ventilatory thresholds, using mass-spectrometry, were defined by the V-slope method (AT) and at the deflection point of end-tidal CO2 (ET-CO2) concentration (RCP). The thresholds of epinephrine (TE) and norepinephrine (TNE) were calculated in the manner of LT. The running velocities were highly reproducible at LT (test-retest correlation coefficient r = 0.90), IAT (r = 0.97), AT (r = 0.88) and RCP (r = 0.95). By contrast TE (r = 0.49) and TNE (r = 0.46) showed a poor reproducibility. TE and TNE occurred 5 - 11 % below LT and AT with a low correlation to LT and AT. LT was found 4 % below AT, both were correlated with r = 0.70 (p < 0.01, test 1) and r = 0.95 (p < 0.01, test 2). IAT occurred 7 - 8% above RCP, in both tests a close correlation was found between IAT and RCP of r = 0.97 (p < 0.01). In summary, the ventilatory and lactate-derived thresholds show a high and similar reproducibility, but the catecholamine threshold does not. In the present exercise protocol, there are systematic differences between the lactate-derived and ventilatory thresholds, in spite of a close relationship, and these must be taken into account in recommendations derived for training.