Optimal Loading for Maximizing Power During Sled- Resisted Sprinting

Purpose: To ascertain whether force-velocity-power relationships could be compiled from a battery of sled-resisted overground sprints and to clarify and compare the optimal loading conditions for maximizing power production for different athlete cohorts. Methods: Recreational mixed-sport athletes (n = 12) and sprinters (n = 15) performed multiple trials of maximal sprints unloaded and towing a selection of sled masses (20-120% body mass [BM]). Velocity data were collected by sports radar, and kinetics at peak velocity were quantified using friction coefficients and aerodynamic drag. Individual force-velocity and power-velocity relationships were generated using linear and quadratic relationships, respectively. Mechanical and optimal loading variables were subsequently calculated and test-retest reliability assessed. Results: Individual force-velocity and power-velocity relationships were accurately fitted with regression models (R2 >.977, P <.001) and were reliable (ES = 0.05-0.50, ICC =.73-. 97, CV = 1.0-5.4%). The normal loading that maximized peak power was 78% +/- 6% and 82% +/- 8% of BM, representing a resistance of 3.37 and 3.62 N/kg at 4.19 +/- 0.19 and 4.90 +/- 0.18 m/s (recreational athletes and sprinters, respectively). Optimal force and normal load did not clearly differentiate between cohorts, although sprinters developed greater maximal power (17.2-26.5%, ES = 0.97-2.13, P <.02) at much greater velocities (16.9%, ES = 3.73, P <.001). Conclusions: Mechanical relationships can be accurately profiled using common sled-training equipment. Notably, the optimal loading conditions determined in this study (69-96% of BM, dependent on friction conditions) represent much greater resistance than current guidelines (- 7-20% of BM). This method has potential value in quantifying individualized training parameters for optimized development of horizontal power.