The purpose of this dissertation was to describe the basic characteristics of performing resisted sprint training using a push sled for the enhancement of sport performance. Specifically, this dissertation served to: 1.) quantify the frictional forces involved between a push sled and an AstroTurf® surface at 6 loads, 2.) derive an estimation of mechanical work performed during sled push training, 3.) outline the velocity characteristics of 3 sled pushing loads scaled to the athletes body mass for comparison against their sprinting ability and 4.) determine the interrelations of fitness characteristics to the ability to sprint under heavy resistance. The following are major findings of this dissertation. 1.) Coefficients of static friction (0.53 – 0.37) and dynamic friction (0.35 – 0.28) were calculated at multiple loads for the AstroTurf® surface. 2.) A direct near perfect relationship exists between total system load of the sled and the forces required to initiate and maintain movement of the sled. Although a direct measurement of force would be more precise and account for changes in velocity, the total system load may be a more practical alternative for daily use. 3.) Statistically significant changes in velocity characteristics were observed within each sled pushing load as well as when comparing each load to sprinting. Decrements in peak velocity ranged from about 40%-51% when comparing resisted to unresisted sprinting. Load increments of 25% body mass were heavy enough to cause statistically significant differences in velocity characteristics. 4.) Statistically significant correlations were observed in anthropometry, sprinting ability, jumping ability, and strength to sled pushing. The results indicate that larger athletes, who can not only produce greater force but produce those forces rapidly, in addition to excelling at jumping and sprinting compared to their peers demonstrate the ability to move faster against heavy loads and slow down less from unresisted conditions. The strongest athletes demonstrated statistically nonsignificant differences in peak velocity drop off when compared to their weaker counterparts; however, small to moderate effect sizes (d = 0.27 – 1.02) were observed indicating a practical difference between strength levels in peak velocity and peak velocity drop off.

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.