With the concern of concussion risk and repetitive head impacts in youth football, organizations have adopted rules that limit contact during practice. However, rule changes are not ubiquitous among organizations and are challenging to monitor and enforce. Ultimately, football practice activities are determined by coaches, but it is unknown whether providing objective data to coaches relating activities to their athletes' head impact exposure (HIE) would alter practice structure or help reduce HIE. This study evaluated the effect of coach awareness of HIE on practice structure over time. Head impact data from three intervention (56 players) and three control (38 players) teams were collected over two youth football seasons. Athletes were instrumented with the Head Impact Telemetry (HIT) System and time-synchronized video was recorded for practices and games. Impact frequencies and head accelerations were compiled into weekly HIE practice and game reports and shared with the head coach of each intervention team. Time per drill, impact rate, and impact magnitude were compared across three time frames (pre-season, mid-season, and late-season) using generalized linear models. Control teams had higher impact rates than intervention teams in all drills across time frames. Among all teams, 95th percentile linear and rotational accelerations were highest during mid-season. Among intervention teams, more time was spent on scrimmage and skill development from pre-season to late-season, with less time spent on tackling. This study suggests that receiving objective data informing HIE in practice may contribute to changes in practice structure and help inform intervention efforts to improve head impact safety in football.

中文翻译：

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教练反馈和头部撞击暴露意识对青少年足球练习结构的影响

出于对青少年足球中脑震荡风险和重复性头部撞击的担忧，各组织采取了限制练习期间接触的规则。然而，规则变更在组织中并不普遍，并且难以监控和执行。最终，足球练习活动由教练决定，但尚不清楚向教练提供与运动员头部撞击暴露 (HIE) 有关的客观数据是否会改变练习结构或有助于减少 HIE。本研究评估了教练对 HIE 的认识随着时间的推移对练习结构的影响。在两个青少年足球赛季中收集了三支干预队（56 名球员）和三支对照队（38 名球员）的头部撞击数据。运动员配备了头部撞击遥测（HIT）系统，并录制练习和比赛的时间同步视频。撞击频率和头部加速度被编入每周的 HIE 练习和比赛报告中，并与每个干预队的主教练分享。使用广义线性模型在三个时间范围（季前、季中和季末）中比较每次训练的时间、冲击率和冲击强度。在跨时间范围的所有演习中，控制团队的影响率高于干预团队。在所有球队中，95% 的线性和旋转加速度在赛季中期最高。在干预队中，从季前到季末，更多的时间花在混战和技能发展上，而花在抢断上的时间更少。这项研究表明，在实践中接收 HIE 的客观数据可能有助于实践结构的变化，并有助于为干预措施提供信息，以提高足球运动中头部碰撞的安全性。