Relative Strength and Power and Sprinting Speed by NASEinc

Predictors of Sprint Performance in Professional Rugby Players: Relative strength and power are key factors that affect the speed of athletes during the start, acceleration, and maximum speed phase of a short sprint. The Abstract of a study by Cunningham and colleagues, described below, reinforces this concept.

The ability to accelerate and attain high speed is an essential component of success in team sports; however, the physical qualities that underpin these activities remain unclear. This study aimed to determine some of the key strength and power predictors of speed with professional rugby players.

Methods: Twenty professional players were tested for speed (0-10-meter sprint and a flying 10-meter sprint), strength (3 repetitions maximum squat), lower body power countermovement jumps (CMJ, and drop jumps (DJ), reactive strength and leg spring stiffness. The strength and power variables were expressed as absolute values and relative values for analysis.

Results: Both relative strength (r=.55, P<0.05) and relative power (-.082, P<0.01) were negatively correlated with 10-meter time. Leg spring stiffness and DJ contact time were also related to the flying 10-meter time (r=.046 and 0.47 respectively, P(<0.05) while relative strength index was negatively related to both the 10-meter and flying 10-meter Tims (r=0.60 and r=0.62, P<0.05). Acceleration was significantly related to relative strength, relative power and jump height from a 40 cm DJ. Maximum velocity sprinting was significantly related to relative power, contact time, height and leg stiffness. The study provides an insight into those physical attributes that underpin sprinting performance in professional rugby union players and specifically highlights the importance of relative strength and power in the expression and development of different speed components (e.g. acceleration, maximum velocity). Coaching Application: Findings on “relative strength” reinforce the importance of acquiring a favorable ratio of Ground Reaction Force/Body Weight. Acceleration and maximum speed improve when GRF increases and/or body weight decreases. Team sport athletes should strive to become as strong as possible with minimum body fat. In the above study, absolute strength was not related to 10-meter or flying 10-meter speed. When 1RM strength was expressed relative to body mass, significant relationships wwere identified with jump height and 10-meter speed. In addition, acceleration and maximum speed are separate entities and require different training approaches to improve.

Reference

Cunningham, D.J., West, D.J., Owen, N.J., Shearer, D.A., Finn, C.V., Bracken, R.M., Crewther, B.T., Scott, P., Cook, C.J., and Kilduff, L.P. 2013. Strength and Power Predictors of Sprinting Performance in Professional Rugby Players. The Journal of Sports Medicine and Physical Fitness. 53: 1-2