Does the initial level of horizontal force determine the magnitude of improvement in acceleration performance in rugby?

Abstract

This study aimed to observe the effect of 8 weeks of resisted sled training (RST), with optimal loading for maximal power output production and initial levels of force, on the magnitude of improvement in sprint performance and individual sprint mechanical outputs in female amateur rugby union players. The study examined the horizontal Power-Force-Velocity profile (P-F-V profile), which provides a measure of the athlete's individual balance between force and velocity capabilities (S fv ), theoretical maximum force (F 0 ), theoretical maximum velocity (V 0 ), maximum power (P max ), the maximum ratio of force (Rf max ) and rate of decrease in ratio of force (D rf ). Thirty-one participants (age = 23.7 ± 3.3years, BM = 69 ± 9Kg, height = 167.5 ± 5.2 cm) were divided into a control group and two experimental groups; forwards (FG) and backs (BG). For 8 consecutive weeks (16 sessions), all groups performed the same training programme: 2 sets of 5 × 30 m, but athletes assigned to FG and BG ran towing a resisted sled attached to their waists, with optimal loading for maximal power output production. Both FG and BG significantly improved (p ≤ 0.05) in 5 and 20 m sprint performance, and in the mechanical properties related to the horizontal P-F-V profile. The correlation between the initial level of horizontal strength and the magnitude of improvement in P max also suggests that higher levels of horizontal force may lead to greater adaptations in RST. The P-F-V profile is a useful field method for identifying the weakest mechanical variable in rugby players during sprinting and enabling the prescription of individualized training programmes according to specific running performance.

The Effects of Heavy Resisted Sled Pulling on Sprint Mechanics and Spatiotemporal Parameters

“…Accordingly, the increase of P max in the same group exhibits an increased ability to transfer higher amounts of horizontal force throughout the early and late acceleration phases posttraining (21). Our results confirm that heavy sled towing selectively improves F 0 , RF max (20), and P max (3,8,11,15,19). Conversely, no significant changes in v 0 and D rf were found postintervention in any of the groups.…”

“…The L 50%vdec is defined as a load, which corresponds to a decrement of v 0 of 50% (50%v dec ), based on the parabolic velocity-power relationship (7). Escobar Álvarez et al (11) examined the effect of 8 weeks of sled pulling with loads corresponding to 50%v dec on sprint acceleration performance, as well as on sprint mechanics. They found significant performance improvements in 5 and 20 m and in mechanical properties related to sprinting (F 0, v 0 , P max , RF max ).…”

Applied sports science and sports medicine in women’s rugby: systematic scoping review and Delphi study to establish future research priorities

“…In amateur women’s rugby union, improvements in 5 m and 20 m sprint performance and mechanical properties related to the horizontal power–force–velocity profile were observed over the course of an 8-week sled training intervention. 141 In international women’s rugby sevens, asymmetry of running mechanical variables was investigated, and symmetry angle remained mostly constant across all kinetic, kinematic, spring-mass characteristics and horizontal force production variables. 140 Finally, machine scrummaging forces were described in club and international rugby union, and women’s peak compressive force was 8.7 kN.…”

“…One of these studies was performed in rugby sevens with an international cohort (33% of 3 studies) 140. In comparison, the other two were performed in rugby union (67%) with amateur141 and combined (club and international)142 cohorts. In amateur women’s rugby union, improvements in 5 m and 20 m sprint performance and mechanical properties related to the horizontal power–force–velocity profile were observed over the course of an 8-week sled training intervention 141.…”

“…In comparison, the other two were performed in rugby union (67%) with amateur141 and combined (club and international)142 cohorts. In amateur women’s rugby union, improvements in 5 m and 20 m sprint performance and mechanical properties related to the horizontal power–force–velocity profile were observed over the course of an 8-week sled training intervention 141. In international women’s rugby sevens, asymmetry of running mechanical variables was investigated, and symmetry angle remained mostly constant across all kinetic, kinematic, spring-mass characteristics and horizontal force production variables 140.…”