The Reproducibility and External Validity of a Modified Rugby League Movement Simulation Protocol for Interchange Players.

PURPOSE: The study assessed the reliability and external validity of a rugby league movement simulation protocol for interchange players that was adapted to include physical contact between participants.

METHODS: Eighteen rugby players performed two trials of a modified rugby league movement simulation protocol for interchange players (RLMSP-i), seven days apart. The simulation was conduced outdoors on artificial turf with movement speeds controlled using an audio signal. Micro-technology was used to measure locomotive and accelerometer (i.e. PlayerLoadTM ) metrics for both bouts (~23 min each) alongside heart rate and RPE.

RESULTS: Reported for each bout, total distance (102 ± 3 and 101 ± 3 m·min-1 ), low-speed distance (77 ± 3 and 79 ± 4 m·min-1 ), high-speed distance (25 ± 3 and 22 ± 4 m·min-1 ), PlayerLoadTM (10 ± 1 and 10 ± 1 AU·min-1 ), PlayerLoadTM slow (3.2 ± 0.6 and 3.2 ± 0.6 AU·min-1 ), PlayerLoadTM 2D (6.0 ± 0.9 and 5.7 ± 0.8 AU·min-1 ) and heart rate (86 ± 5 and 84 ± 6 %HR max) were similar to match play. The coefficient of variation (%CV) for locomotive metrics ranged from 1.3 to 14.4%, accelerometer CV% 4.4 to 10.0%, and internal load 4.8 to 13.7%. All variables presented a CV% less than the calculated moderate change during one or both bouts of the simulation except high-speed distance (m·min-1 ), %HRpeak and RPE (AU).

CONCLUSION: The modified RLMSP-i offers a reliable simulation to investigate influences of training and nutrition interventions on the movement and collision activities of rugby league interchange players.