The associations between unilateral leg strength, asymmetry and injury in sub-elite Rugby League players

The aim of this study was to analyse the relationship between unilateral leg strength, associated asymmetries and the injuries suffered by sub-elite Rugby League (RL) players in one competitive season. A prospective cohort design was used. Unilateral leg strength was measured using the rear foot elevated split squat five repetition maximum test. Injuries were recorded using the Orchard classification system and were used to quantify relative risk (RR), mean severity, burden, player availability and survival time. No measures of leg strength were related to RR, relative leg strength was found to have a significant, but not meaningful correlation with total time lost to lower body injury, lower body injury burden and lower body injury survival time. The data from the current study indicates a possible positive effect of increasing relative leg strength for injury outcomes in sub-elite RL players. This supports a heuristic that multi-joint lower body strength training for RL players has a potential dual effect of enhancing physical performance and reducing injury time loss, with minimal risk of harm. •First study to examine unilateral leg strength and asymmetry for injuries in UK sub-elite Rugby League.•A comprehensive analysis and novel approach of analysing injury.•Injuries were not related to either absolute unilateral leg strength or asymmetry between legs.•Increasing relative strength showing possible benefits and limited probability of harm.