The ability to generate force and power is conditioned by muscle properties, which can be improved through eccentric training. While vastus lateralis (VL) reported to be a major contributor of sprinting performance, its muscle architecture and subsequent impact on strength performance following an eccentric training cycle in elite sprinters remain unknown. Seven elite sprinters (2 females) were involved in the study. Before and after a 3-week eccentric training cycle, during which in addition to their four habitual sprint training sessions, athletes performed two eccentric strength and conditioning sessions, muscle architecture of the VL (ultrasound measurements), and half-squat performance (isokinetic device) were assessed. The results reported that muscle architecture characteristics (i.e., fascicle length, pennation angle and muscle thickness) were unchanged following the eccentric training cycle (all p ≥ 0.41), as well as squat performance (i.e., power, force and explosiveness;​ all p ≥ 0.09). Therefore, this study highlights that, in elite sprinters, the inclusion of a 3-week eccentric training cycle during the season did not induce any modification of VL muscle architecture, nor lower-limb performance.