Blood lactate threshold differences between arterialized and venous blood

The purpose of this study was to investigate the differences between lactate thresholds determined from venous and arterialized blood. Seven endurance-trained college males performed an incremental bicycle ergometer exercise test until exhaustion. At the end of each 3 min stage, blood was sampled simultaneously from a hyperemized ear-lobe and an antecubital vein for the measurement of blood lactate (La-). Two-minute rest intervals separated each stage. Arterialized blood La-concentrations ([La-]) were significantly higher than venous blood at 350 W (14.5 and 9.7 mmol·l-1), maximal exercise (15.5 and 11.39 mmol·l-1), and throughout recovery. Arterialized [La-] was significantly higher than venous blood at the onset of blood La- accumulation (OBLA) (4.0 and 2.8±0.1 mmol·l-1), the individual anaerobic threshold (IAT) (3.4+0.3 and 2.1±0.1 mmol·l-1), and the ventilatory threshold (VT) (4.7±0.9 and 3.2±0.6 mmol·l-1). No significant differences were found between either La-threshold for arterialized or venous blood. The oxygen consumption (V̇O2) at OBLA was significantly lower when determined from arterialized blood La (2.3±0.2 and 2.8±0.2 l·min-1). No significant differences existed between the LT, OBLA, and IAT threshold-V̇O2 determinations from arterialized blood; however, significant differences were found between IAT-OBLA (2.1±0.2 and 2.8±0.2 l·min-1) and LT (2.2±0.2 l·min-1)-OBLA from venous blood. These results indicate that differences between venous and arterialized blood [La-] need to be considered when comparing different anaerobic threshold determinations