OBJECTIVES Most concussions in rugby union occur during tackles. We investigated whether legislating to lower maximum tackle height would change tackle behaviour, and reduce concussion incidence rate. METHODS In a single group intervention, 12 elite men's teams played in two competitions during the 2019/2020 season. The Championship (control, 90 games) retained standard Laws of Rugby for the tackle; the Championship Cup (intervention, 36 games) used revised laws-the maximum tackle height was lowered from the line of the shoulders on the ball carrier to the line of the armpits. Videos of tackles were analysed for ball carrier and tackler behaviour. Injury data were collected using standardised methods. RESULTS In the intervention setting, there was a significantly lower proportion of tackles; (1) in which ball carriers (rate ratio (RR) 0.83, 95% CI 0.79 to 0.86) and tacklers (RR 0.80, 95% CI 0.76 to 0.84) were upright, (2) in which the tackler's initial contact was to the ball carrier's head or neck (RR 0.70, 95% CI 0.58 to 0.84) and (3) in which initial contact was above the line of the ball carrier's armpit (RR 0.84, 95% CI 0.80 to 0.88). Concussion incidence rate did not differ between conditions (RR 1.31, 95% CI 0.85 to 2.01). Unexpectedly, compared with the control setting, tacklers in the intervention setting were themselves concussed at a higher rate as measured by; (1) incidence (RR 1.90, 95% CI 1.05 to 3.45) and (2) concussions per 1000 tackles (2.09, 95% CI 1.15 to 3.80) than in the control setting. CONCLUSIONS Legislating to lower the height of the tackle meant that tacklers made contact with the ball carrier's head and neck 30% less often. This did not influence concussion incidence rates. Tacklers in the intervention setting-who were aiming to tackle lower-suffered more concussions than did tacklers in the control setting.

中文翻译：

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通过改变精英男子橄榄球联盟（英格兰锦标赛）的法律来降低铲球的高度是否会降低脑震荡的发生率？126场比赛的对照研究

目标 橄榄球联盟中的大多数脑震荡发生在铲球期间。我们调查了立法降低最大铲车高度是否会改变铲车行为并降低脑震荡发生率。方法 在单组干预中，12 支精英男队在 2019/2020 赛季参加了两场比赛。锦标赛（控制，90 场比赛）保留了标准的橄榄球规则进行铲球；冠军杯（干预，36场）使用了修改后的规则——最大铲球高度从持球者的肩膀线降低到腋窝线。分析了铲球视频的持球者和铲球者的行为。使用标准化方法收集伤害数据。结果 在干预环境中，铲球的比例显着降低；（1）其中球载体（比率（RR）0.83，95% CI 0.79 到 0.86) 和铲球者 (RR 0.80, 95% CI 0.76 到 0.84) 是直立的，(2) 铲球者最初接触的是持球者的头部或颈部 (RR 0.70, 95% CI 0.58 到 0.84) ) 和 (3) 其中初始接触位于持球者腋窝线上方（RR 0.84, 95% CI 0.80 至 0.88）。脑震荡发生率在不同情况下没有差异（RR 1.31, 95% CI 0.85 to 2.01）。出乎意料的是，与控制环境相比，干预环境中的铲球者本身的脑震荡率更高，衡量标准是：(1) 发生率 (RR 1.90, 95% CI 1.05 至 3.45) 和 (2) 每 1000 次铲球的脑震荡 (2.09, 95% CI 1.15 至 3.80) 比对照设置。结论 立法降低铲球高度意味着铲球者与持球者头部和颈部的接触频率降低了 30%。这并不影响脑震荡的发生率。干预环境中的抢断者——他们的目标是解决较低的问题——比控制环境中的抢断者遭受更多的脑震荡。