This study examined inhibitory control performance and cardiac reactivity (pre-ejection period: PEP) using a within-subject design. Thirty young (18-27 years) and 30 middle-aged adults (55-65 years) performed variants of a flanker task requiring different levels of inhibition control and involving neutral, congruent and incongruent conditions as well as conditions requiring a response (Go) or requiring not to respond (No-Go). Reaction times (RT) and response accuracy were recorded. After a training phase, the protocol involved experimental blocks lasting 4 min and 30 sec, each preceded and followed by a 3-min rest period. During the experiment, participants were monitored for their cardiac activity using electrocardiogram(ECG) and impedance cardiogram (ICG). Blood pressure (BP) was also recorded during each rest period. PEP was calculated as the time interval between R-onset (ECG signal) and B-point (ICG signal) andwas averaged over one-min epochs. To examine the dynamic of the cardiac activity during task blocks, mean PEP in ms was calculated on four successivewindows of onemin. For eachwindow, PEP reactivity (ΔPEP) in ms was calculated as PEPtask minus PEPresting. The behavioral results showed that responses were significantly slower and less accurate for the flanker No-Go block comparatively to the flanker block and the neutral block. Furthermore, RT and accuracy for the incongruent trials were significantlyworse than the ones for the congruent trials. Also, overall, the older adultswere significantly slower but more accurate than the younger ones for each experimental condition. The inhibition cost was globally comparable between the two groups. Concerning cardiac measures, the results revealed that mean PEP values were higher for the older than the younger adults, both at rest and during the tasks. However, importantly, for both groups, PEP reactivity was significantly lower than 0 only during the first minute of each experimental task, going back to baseline level afterward. PEP reactivity values were comparable between the two groups andwere significantlymore important during the flanker No-Go block (-5.6 ms) comparatively to the flanker block (-3,3 ms) and the neutral block (-3,9 ms). In this study, PEP reactivity was shown to be sensitive to different levels of inhibitory control requirement, to be equivalent between young and middle-aged adultswith comparable cognitive performance, and to be a short lasting phenomenon, demonstrating a possible rapid dynamic adaptation of the cardiac activity to task constraints or a form of habituation.