The effects of an 8-week off-season period on the mechanical properties of sprinting in professional rugby league players: implications for training recommendations

Abstract

To determine the change in mechanical properties of sprinting performance across an 8-week off-season period in professional rugby league players. Design: Repeated measuresMethods: Twenty-six professional rugby league players from a single rugby league team competing in Super League completed two assessments of linear sprint performance during final week of the season and second week of preseason. Linear split times were used to model the horizontal force-velocity profile and determine theoretical maximal force (F0), velocity (V0) and power (Pmax). Results:Our result indicated moderate-to-large increases in split times at each distance across the off-season period (ES = 0.86 to 1.24; most likely), indicative of a reduced sprinting ability. Furthermore, small reductions in F0 (ES -0.34 to -0.57; likely to very likely) were observed, whilst the reduction in V0 (ES = -0.81; most likely) and Pmax (ES = -0.62 to -1.03; most likely) were considered moderate in magnitude. Conclusions:An 8-week off-season period elicited negative changes in linear sprint times and the horizontal force-velocity profile of professional rugby league players. Such findings might have implications for preseason training loads and therefore, the off-season period requires careful consideration by practitioners and clinicians with regards to content and monitoring.

Deteriorations in physical qualities during a 10-week unsupervised off-season period in academy rugby union players

“…Conversley, Jensen et al (2018) reported improvements in _ VO 2max , squat strength and vertical jump, alongside increases in body fat percentage in collegiate rugby players after a 4-week unsupervised training break. These findings are in contrast to professional adult male rugby league players (Dobbin et al 2020) and national league male adult rugby union players (Nirmalendran and Ingle 2010) who reported reductions in strength, power, speed and aerobic endurance after 8-and 6-week unsupervised off-seasons, respectively. It remains to be elucidated what effects longer periods of unsupervised training would have on the physical qualties of young rugby players.…”

“…Further, studies exploring the positional variations in physical qualties to an off-season period are required in rugby union given forwards and backs have different qualities (Wood et al 2018). Dobbin et al (2020) reported a high variablity in the change in sprint mechanical properties in rugby league players, with backs reporting a larger decrease in force and power, and forwards reporting a larger decrease in velocity. Reductions in young rugby players' physical qualities towards the end of the in-season period (Dobbin et al 2019) implies the effect of baseline fitness (i.e.…”

Sprint and Jump Mechanical Profiles in Academy Rugby League Players: Positional Differences and the Associations between Profiles and Sprint Performance

“…The mechanical profiles provide the only reference data for academy rugby league players building upon research in senior players [ 14 , 15 , 16 ]. Jump profiles in senior NRL professional rugby league players [ 14 ] (measured using GymAware, Canberra, ACT, Australia) showed greater F V0rel (64.7 ± 16.9 vs. 31.3 ± 5.2 N·kg −1 ) and P Vmaxrel (44.7 ± 6.7 vs. 31.5 ± 9.6 W·kg −1 ) than the current findings.…”

“…The sprint profiles of academy players presented were lower than super league professional players [ 16 ], including F H0 (761.8 ± 112.5 vs. 672.3 ± 121.2 N), F H0rel (8.8 ± 1.1 vs. 7.4 ± 1.1 N·kg −1 ), v H0 (9.1 ± 0.6 vs. 8.8 ± 0.7 m·s −1 ), P Hmax (1727 ± 277 vs. 1471 ± 246 W) and P Hmaxrel (19.8 ± 2.2 vs. 16.3 ± 9.6 W·kg −1 ). This is consistent with the mean sprint profiles in male international rugby league players [ 15 ].…”

“…Thus, mechanical profiling provides valuable diagnostic information for athlete profiling, monitoring, and programming [ 2 , 7 ]. Within rugby league, a plethora of studies have evaluated the physical qualities of rugby league players (e.g., [ 12 , 13 ]), however, only three studies have presented the mechanical profiles from jumping [ 14 ] and sprinting [ 15 , 16 ] in senior elite rugby league cohorts. To date, no study in rugby league has included both methods in one cohort, profiled academy rugby league players, or provided comparisons between playing positions.…”