The aim of the study was to evaluate the effects of 6-weeks accentuated eccentric training, using a rotary inertial device, on range of motion, assessed with Inter Malleolar Distance test, anthropometry, lower limb explosive and reactive strength, assessed with Squat Jump, Countermovement Jump and 7-Repeated Hop tests, in young elite fencers. Moreover, the effects on hamstring eccentric strength and two technical fencing movements, lunge and advance-advance lunge, were evaluated with motion analysis. The second aim was to evaluate the duration of the accentuated eccentric training residual effects, 6 weeks after the end of the training. Fifty-four male fencers were randomly assigned either to the Inertial Group (IG; n = 26; aged 17.3 ± 1.9 years) such as experimental group, or to the Plyometric Group (PG; n = 28; aged 17.6 ± 2.7 years) such as control group. IG carried out four exercises using the rotary inertial device attached to their waist by a rope. PG carried out several plyometric exercises at the same time in which the IG performed the accentuated eccentric training. MANOVA showed significant improvements in the vertical jumps height post training, with no differences between IG and PG. Significant improvements for technical movements, lunge distance (p = 0.006) and advance-advance lunge distance (p = 0.00005), were found within-group and between-groups (p = 0.00001), with higher improvements in IG than in PG. The univariate analysis showed a significant improvement in lower limb range of motion with higher increase in IG than in PG. The main findings were the significant improvement in lunge and advance-advance lunge distance, maintaining with the same execution time. These results suggested that it is important to apply accentuated eccentric load on specific sport movements.