The mechanism(s) underlying the attenuation of the slow component of pulmonary O₂ uptake (VO₂) by prior heavy intensity exercise is(are) poorly understood, but may be ascribed to either an intramuscular-metabolic or a circulatory modification resulting from 'priming' exercise. We investigated the effects of delayed vagal withdrawal to the circulation induced by the cold face stimulation (CFS) on the VO₂-kinetics during repeated bouts of heavy intensity cycling exercise. Five healthy subjects (aged 21-43 years) volunteered to participate in this study and initially performed two consecutive 6-min leg cycling exercise bouts (work rate: 50 % between LT and VO₂max) separated by 6-min baseline rest without CFS, as a control (N1 and N2). CFS was then applied separately, by gel-filled cold compresses to the face for 2-min spanning the rest-exercise transition, to each of the 1st bout (CFS1) or 2nd bout (CFS2) of repeated heavy intensity exercise. In the control protocol, VO₂ responses in N2 showed a facilitated adaptation compared to those in N1, mainly attributable to the reduction of slow component. CFS application successfully slowed and delayed the heart rate (HR) kinetics (P<0.05) on transition to exercise (HR; N1: 55.6 (±16.0, SD) vs. CFS1: 69.0 (12.8) and N2: 55.5 (11.8) vs. CFS2: 64.0 (17.5)), however it did not affect the 'primary' VO₂ kinetics (VO₂; N1: 23.7 (±7.9, SD) vs. CFS1: 20.9 (3.8) and N2: 23.3 (10.3) vs. CFS2: 17.4 (6.3)). In conclusion, increased vagal withdrawal delayed and slowed the circulatory response, but did not alter the VO₂-kinetics at the onset of supra-LT cycling exercise. As the facilitation of VO₂ subsequent to prior heavy leg cycling exercise is not attenuated by slowing the central circulation, it seems unlikely that this facilitation is exclusively determined by a blood flow-related mechanism.