Rugby League Injuries: Injury impact of new rugby rule

A new rule designed to limit the frequent replacement of players during rugby matches has significantly reduced the risk of injury in sub-elite rugby league players, according to a new study from Australia (‘Influence of the limited interchange rule on injury rates in sub-elite rugby league players’, J Sci Med Sport 2005;8;1:111-115).

The ‘limited interchange rule’ was introduced by the National Rugby League in Australia in 2001 and has since been adopted by sub-elite rugby league competitions. Previously, players were replaced frequently during matches, with replacements often made after very short bouts of activity. Under the limited interchange rule teams are permitted a maximum of 12 replacements over the course of the match, leaving less time for recovery and forcing players to compete in a fatigued state.

TJ Gabbett of the Queensland Academy of Sport set out to examine the effects of this rule change in a prospective study of the incidence of injury in one sub-elite rugby league club over three competitive seasons – the first two played under the unlimited interchange rule and the third played under the new rule.

Players participated in 91 matches under the unlimited interchange rule and 44 under the limited interchange rule. Injury was defined as any pain, disability or injury that occurred as a result of a competition game and caused a player to miss a subsequent game.

The beneficial effects of the new rule seemed beyond doubt, with the incidence of injury falling from 72.5 per thousand player hours under the unlimited interchange rule to 51 per thousand under the limited interchange rule – a significant reduction of 30%.

How did a rule change that allowed for less recovery time and generated more fatigue manage to lead to fewer injuries? Gabbett explains: ‘Previous studies have found that match speed and playing intensity contribute to injuries in rugby league. It is likely that match speed decreased during matches played under the limited interchange rule as a result of the reduced recovery afforded to players.’

He concludes: ‘The results of this study suggest that player fatigue associated with the limited interchange rule may act as a protective mechanism against injuries in sub-elite rugby league players… The reduced injury risk may reflect a fatigue-induced reduction in match speed and impact forces associated with physical collisions and tackles.’