The purpose of this study was to examine the effects of muscular power engagement, anaerobic participation, aerobic power level and energy expenditure on post-exercise parasympathetic reactivation. We compared the response of heart rate (HR) following repeated sprinting with that of exercise sessions of comparable net energy expenditure and anaerobic energy contribution. Fifteen moderately-trained athletes performed: 1) 18 maximal all-out 15-m sprints interspersed with 17 s of passive recovery (RS), 2) a moderate isocaloric continuous exercise session (MC) at a similar level of mean oxygen uptake (VO2) to that of the RS trial, and 3) a high-intensity intermittent exercise session (HI) conducted at a similar level of anaerobic energy expenditure to that of the RS trial. Subjects were immediately seated following the exercise trials and beat-to-beat HR was recorded for 10 min. Parasympathetic reactivation was evaluated through 1) immediate post-exercise HR recovery, 2) the time course of the root-mean-square for the successive R-R interval difference between successive 30-s segments (RMSSD_30s) and 3) heart rate variability vagal-related indexes calculated on the last 5-min stationary period of recovery. RMSSD_30s increased during the 10-min period following the MC trial, whereas it remained depressed following both the RS and HI trials. Parasympathetic reactivation indexes were similar for the RS and HI trials, but lower than for the MC trial (P < 0.001). When considering data of the three exercise trials together, only anaerobic contribution was related to HR-derived indexes. Parasympathetic reactivation is highly impaired following RS exercise and appears to be mainly related to anaerobic process participation.