Objective To assess the incidence, severity and nature of injuries, to determine risk factors for injury and to identify potential injury prevention strategies in men's international Rugby-7s tournaments.

Design A prospective cohort study.

Participants Players from core teams competing in matches at 6 Sevens World Series from 2008/2009 to 2014/2015.

Results The incidence of injury across all Series was 108.3 injuries/1000 player-match-hours (backs: 121.0; forwards: 91.5) with a mean severity of 44.2 days (backs: 46.1; forwards: 40.9) and a median severity of 28 days (backs: 29; forwards: 26). The proportion of injuries sustained in the second half was significantly higher (60%; p<0.001) than the first half of matches and the proportion increased from match to match and day to day in a tournament. The knee (17.4%), ankle (15.9%) and posterior thigh (13.2%) were the most common injury locations for backs and the knee (18.5%), head/face (17.3%) and shoulder/clavicle (13.0%) for forwards. The four most common injuries across all players were knee ligament (13.0%), ankle ligament (12.8%), concussion (10.4%) and posterior thigh muscle strains (9.8%).

Conclusions The incidence of injury in Rugby-7s suggests that teams require squads of around 20 players for a Sevens World Series. The higher incidence of injury in the second half of matches is probably the result of player fatigue; therefore, injury prevention strategies for teams and the Governing Body should address this issue. The results presented support the World Rugby trial allowing ‘rolling substitutes’ during Sevens World Series matches, as this approach may help to mitigate the effects of player fatigue during the second half of matches.