Effect of lowering the maximum tackle height in English Schoolboy rugby union on tackle characteristics, and all-injury and concussion rates

OBJECTIVES: This study compared tackle characteristics and injury incidence in schoolboy rugby union before and after a law change that lowered the maximum legal tackle height. DESIGN: Prospective cohort study. METHODS: Match injuries and game exposures were reported by U15 and U18 schoolboy teams over three seasons (2017/18 to 2019/20) when the legal tackle height was at the line of the shoulder and one season (2021/22) at the line of the armpit. Matches were filmed pre- (U15:11; U18:16 matches) and post- (U15:10; U18:10 matches) tackle height change and tackles were coded for tackler and ball carrier techniques. Tackle characteristic propensities and injury incidences were compared pre- and post-tackle height change using rate ratios (95 % confidence intervals). RESULTS: Pre- to post-tackle height change, the propensity of shoulder height tackles reduced at U15 (rate ratio: 0.62, 95 % confidence interval: 0.51-0.75) and U18 (rate ratio: 0.77, 95 % confidence interval: 0.65-0.92). Post-change, tacklers were more often bent at the waist when tackling at U15 (rate ratio: 1.34, 95 % confidence interval: 1.21-1.49) and U18 (rate ratio: 1.18, 95 % confidence interval: 1.08-1.29). Overall injury incidence pre- and post-tackle height change was not significantly different for U15 (rate ratio: 0.79, 95 % confidence interval: 0.53-1.17) or U18 (rate ratio: 1.11, 95 % confidence interval: 0.89-1.37). Pre- to post-tackle height change, neither all concussions at U15 (rate ratio: 1.43, 95 % confidence interval: 0.73-2.70) and U18 (rate ratio: 0.95, 95 % confidence interval: 0.59-1.47) or tackle-related concussions at U15 (rate ratio: 1.39, 95 % confidence interval: 0.55-3.25) and U18 (rate ratio: 0.92, 95 % confidence interval: 0.48-1.65) were different. CONCLUSIONS: Following a lowering of the permitted tackle height, tackler and ball carrier tackle techniques changed, without changing the incidence of all injuries or concussions. Further lowering of the tackle height may be explored to invoke the necessary technique changes to reduce injury.