PURPOSE: Forwards are regularly substituted within the sport of rugby union. There is currently limited information on how this effects movement patterns in rugby union match play. This study investigated how the movement patterns and pacing strategies of forwards that play the whole game in contrast with forwards inserted as substitutes in the second half. METHODS: Global positioning system (GPS) data were collected during professional rugby union match play. Second half data for 19 whole game (WG) players and 17 substitute (sub) players were compared in terms of relative total and high-intensity (>4m.s-1) distance, maximum speed (m.sec-1), sprint (>6 m.s-1) and acceleration (>2.75 m.s-1) frequency. Given the practical nature of this study, likelihood of effects being true was assessed via magnitude-based inference and the size of effect was assessed using Cohen’s effect size (ES) statistic. Effect sizes of 0.2, 0.6, 1.2 and 2.0 were considered small, medium, large and very large respectively. RESULTS: Substitute forwards displayed increased high intensity running distance (12 ± 6 vs. 9 ± 4 m.min-1, likely medium), sprint frequency (1 every 13 ± 25 min vs. 1 every 20 ± 25 min, likely medium), acceleration frequency (1 every 7 ± 9 min vs. 1 every 13 ± 7 min, likely small) vs. whole game players. Differences in movement variables were larger when substitutes were first introduced, but decreased were not different in later quartiles. CONCLUSIONS: Whole game players adopted a “flat” pacing strategy in the second half, while substitutes adopted a “one bout, all out” approach. The impact if substitutes on game movement patterns is meaningful, but short-lived. Differences between whole game and substitute players were were negligible in the latter phases of the game. PRACTICAL APPLICATION: The introduction of forward substitutes increases match intensity temporarily. This effect could be accentuated by introducing multiple substitutes at once, and ay have tactical applications with coaches saving their substitutes for critical moments within the game.
ORCID: 
CORE (COnnecting REpositories)
CORE (COnnecting REpositories)