Impact of lowering the legal tackle height on tackle behaviour, match events, and suspected injury rates in adolescent female rugby union.

OBJECTIVES: To investigate whether lowering the legal tackle height from below the armpit to below the sternum influenced tackle behaviour, match events, suspected injury and concussion rates, and concussion-related tackle characteristics in adolescent female rugby union. DESIGN: Case-control video analysis of 49 matches across two seasons, before and after the law change. METHODS: Tackle behaviour, match events, and suspected concussion characteristics were compared between seasons. Associations between tackle characteristics and suspected concussion were assessed using 37 cases and 222 control tackles. RESULTS: Head-high tackles were 83% lower (incidence rate ratio 0.17, 95% confidence interval 0.09-0.34) and shoulder-to-armpit tackles 46% lower (incidence rate ratio 0.54, 95% confidence interval 0.40-0.72) after the law change. Offloads, penalties, and open-play kicks increased. Suspected injury rates were 27% lower (rate ratio 0.73, 95% confidence interval 0.53-0.90; p = 0.05). Tackle-related suspected concussion rates were unchanged (incidence rate ratio 0.94, 95% confidence interval 0.49-1.79; p = 0.85). Ruck-related suspected concussions were higher but based on small numbers (incidence rate ratio 9.83, 95% confidence interval 1.26-76.77; p = 0.03). High-intensity head contacts were strongly associated with suspected concussion (odds ratio 52.6, 95% confidence interval 9.2-301.3; p < 0.001), as was lower-leg versus torso or hip head contact (odds ratio 17.22, 95% confidence interval 2.85-103.97; p < 0.001). CONCLUSIONS: Lowering the legal tackle height changed tackle behaviour and was associated with lower overall suspected injury rates, but tackle-related suspected concussion rates and concussion-related tackle characteristics did not differ. Additional head-safe contact strategies may be required.