An Investigation of the Sled Push Exercise: Quantification of Work, Kinematics, and Related Physical Characteristics

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