School of Biomedical Sciences, University of Leeds, UK.
School of Kinesiology, University of British Columbia, Canada.
J Biomech. 2020 Sep 18;110:109969. doi: 10.1016/j.jbiomech.2020.109969. Epub 2020 Jul 27.
The contact nature of American football has made head acceleration exposure a concern. We aimed to quantify the head kinematics associated with direct helmet contact and inertial head loading events in collegiate-level American football. A cohort of collegiate-level players were equipped with instrumented mouthguards synchronised with time-stamped multiple camera-view video footage of matches and practice. Video-verified contact events were identified as direct helmet contact or inertial head loading events and categorised as blocking, blocked, tackling, tackled or ground contact. Linear mixed-effects models were utilised to compare peak head kinematics between contact event categories. The timestamp-based cross-verification of the video analysis and instrumented mouthguard approach resulted in 200 and 328 direct helmet contact and inertial head loading cases, respectively. Median linear acceleration, angular acceleration and angular velocity for inertial head loading cases was greater than direct helmet contact events by 8% (p = 0.007), 55% (p < 0.001) and 4% (p = 0.007), respectively. Median head kinematics for all contact event categories appeared similar with no pairwise comparison resulting in statistical significance (p > 0.05). The study highlights the potential of combining qualitative video analysis with in-vivo head kinematics measurements. The findings suggest that a number of direct helmet contact events sustained in American football are of lower magnitude to what is sustained during regular play (i.e. from inertial head loading). Additionally, the findings illustrate the importance of including all contact events, including direct helmet contact and inertial head loading cases, when assessing head acceleration exposure and player load during a season of American football.
美式橄榄球的接触性质使得头部加速暴露成为人们关注的焦点。我们旨在量化与大学水平美式橄榄球中直接头盔接触和惯性头部加载事件相关的头部运动学。一队大学水平的球员配备了带有仪器的牙套，与比赛和练习的时间戳记多相机视频片段同步。视频验证的接触事件被确定为直接头盔接触或惯性头部加载事件，并分类为阻挡、被阻挡、擒抱、被擒抱或地面接触。线性混合效应模型用于比较接触事件类别的峰值头部运动学。基于时间戳的视频分析和仪器化牙套方法的交叉验证分别产生了 200 个和 328 个直接头盔接触和惯性头部加载案例。惯性头部加载案例的线性加速度、角加速度和角速度中位数大于直接头盔接触事件的 8%（p = 0.007）、55%（p < 0.001）和 4%（p = 0.007）。所有接触事件类别的中位数头部运动学似乎相似，没有任何两两比较具有统计学意义（p > 0.05）。该研究强调了将定性视频分析与体内头部运动学测量相结合的潜力。研究结果表明，在美国橄榄球中承受的许多直接头盔接触事件的量级低于正常比赛中承受的量级（即来自惯性头部加载）。此外，研究结果说明了在评估美式橄榄球赛季中的头部加速暴露和球员负荷时，包括所有接触事件（包括直接头盔接触和惯性头部加载案例）的重要性。
