Abstract Aim was to investigate the effects of heavy resisted and unresisted sprint training protocols and see its effects on sprint time, vertical and horizontal jumping and sprint mechanics. Youth male soccer players [n=27] participated in this study, they were all individually assessed for the horizontal force-velocity profile using two unresisted sprints and load-velocity profile using four progressively resisted sprints (25%, 50%, 75% and 100% body mass). For all sprints an isotonic braking device was used. They also performed vertical and horizontal jumps, counter-movement jump (CMJ) was used for the former and standing long jump (SLJ) for the latter. They were put in three groups (RST: resisted sprint training; UST: unresisted sprint training and TAU: control group – “training as usual”). Athletes performed a 4-week training intervention (5x20m resisted sprint group; 8x20m unresisted sprint group) and were tested 7 days after completing their final training session. Only RST improved all sprint times (T30, T20, T10, T5) substantially (-4.2% to -7.9% in split times) and provided trivial or small changes in sprint mechanics. The small changes were seen in sprint mechanical parameters of RFmax, Pmax and F0. UST only showed trivial effects in those parameters, while TAU showed a small decrease in both Pmax and Vmax. Regarding the jumps, RST and UST both showed a small increase in standing long jump and a trivial effect in counter-movement jump, while TAU decreased in both. Main conclusion is that resisted sprinting has proven to be a worthwhile method to improve acceleration and sprint performance and can be used by practitioners across a wide array of sports. It also improved jumping performance and sprint mechanical outputs, which point toward an improvement in better application of force in a horizontal direction.