Do Force–Time and Power–Time Measures in a Loaded Jump Squat Differentiate between Speed Performance and Playing Level in Elite and Elite Junior Rugby Union Players?

Abstract

The purpose of this study was to investigate the discriminative ability of rebound jump squat force-time and power-time measures in differentiating speed performance and competition level in elite and elite junior rugby union players. Forty professional rugby union players performed 3 rebound jump squats with an external load of 40 kg from which a number of force-time and power-time variables were acquired and analyzed. Additionally, players performed 3 sprints over 30 m with timing gates at 5, 10, and 30 m. Significant differences (p < 0.05) between the fastest 20 and slowest 20 athletes, and elite (n = 25) and elite junior (n = 15) players in speed and force-time and power-time variables were determined using independent sample t-tests. The fastest and slowest sprinters over 10 m differed in peak power (PP) expressed relative to body weight. Over 30 m, there were significant differences in peak velocity and relative PP and rate of power development. There was no significant difference in speed over any distance between elite and elite junior rugby union players; however, a number of force and power variables including peak force, PP, force at 100 milliseconds from minimum force, and force and impulse 200 milliseconds from minimum force were significantly (p < 0.05) different between playing levels. Although only power values expressed relative to body weight were able to differentiate speed performance, both absolute and relative force and power values differentiated playing levels in professional rugby union players. For speed development in rugby union players, training strategies should aim to optimize the athlete's power to weight ratio, and lower body resistance training should focus on movement velocity. For player development to transition elite junior players to elite status, adding lean mass is likely to be most beneficial.

Movement Demands of Elite Under-20s and Senior International Rugby Union Players

“…Interestingly Barr et al, [19] found no significant differences between senior and U20s internationals for initial and maximal sprint velocity, however, when initial and maximal sprint momentum was calculated there were significant differences between the groups. These findings are further corroborated by the work of Hansen and colleagues [23] who reported significant differences between elite senior and junior players for mass and measures of strength and power, but not for speed times over 5, 10 and 30m.…”

Roles of Maximal Strength and Rate of Force Development in Maximizing Muscular Power

“…Different levels of strength exist ranging from submaximal to maximal, with maximal strength being a major factor influencing performance (57). Research has shown that stronger athletes are found at higher levels of competition in a variety of sports compared with weaker athletes (4,9,25,27,30). This information begins to illuminate the importance of maximal strength in sports competition.…”

“…However, multiple studies have shown that the average power output for the duration of a distance event, and even peak power during the final sprint, may play a critical role in determining the outcome of a race (42,44,58). Additionally, literature exists suggesting that levels of peak power outputs can differentiate athletic performance (4,6,7,9,21,25,30). As such, the development of muscular power is critical across the spectrum of sport from aerobic to anaerobic sports.…”

Training Principles for Power

“…For example, Hansen et al (33) reported that peak power outputs are significantly (p , 0.001) higher in Elite Rugby Union players compared with their junior counterparts. Similarly, Baker (4) suggested that professional Rugby League players (National Rugby League) produce significantly higher power outputs in both upper-and lower-body movements compared with college-aged players (Student Rugby League).…”