Supplementary information files for "Does reduced ball inflation pressure in association football decrease head impact kinematics?"

Supplementary files for article "Does reduced ball inflation pressure in association football decrease head impact kinematics?"

Purpose: Apparent degeneration in brain health due to heading the football is amongst the most pressing and contentious health-related questions in sport (Keogh F, Pirks N (2024) “Pain was sickening”—Ex-players on heading fears. In: BBC). The purpose of this study was to thoroughly explore the effectiveness of reduced inflation pressure as an intervention to reduce head kinematics from a ball to head impact. The influence of impact location, head orientation, neck flexion angle and ball type on the intervention were experimentally investigated.
Method: A Hybrid III head and neck was impacted in frontal and oblique locations with two modern footballs that were projected using a bespoke launch device. Peak linear acceleration, peak angular velocity, peak angular acceleration and DAMAGE metrics were calculated for a total of 34 permutations of impact variables at two inflation pressures.
Results: Magnitude was decreased (82%) or unchanged (8%) for 90% of impacts with average magnitude changes between − 2 and − 12% across the four metrics. Findings indicated that decreased inflation pressure was a positive intervention towards decreasing kinematic magnitudes in most cases. This was especially true for linear acceleration, angular velocity and angular acceleration, where 100, 97 and 100% of impacts were reduced or unchanged, respectively.
Conclusions: Reduced inflation pressure was overall an effective mitigation to reduce the kinematic magnitude of heading in football based upon these four kinematic metrics despite 10% of impacts exhibiting an increase in kinematic magnitude. The DAMAGE predictor of MPS exhibited 12 out of 13 cases where magnitude increased demonstrating the capacity for decreased inflation pressure to result in increased kinematics for an angular response derived metric, indicating that reducing inflation pressure is not a universal solution. Nonetheless DAMAGE still saw a net decrease in magnitude across all impacts. Metric magnitude was found to be sensitive to head orientation, impact location and ball type, demonstrating the importance of the sensitivity analysis in this study. Two impacts were recommended to represent the worst-case ball to head impact, one in each nominal orientation. These locations contrasted with those commonly used in literature, a finding pertinent to future experimental design in football heading research.

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论文《足球运动中降低足球充气压力是否可减轻头部冲击运动学特征？》的补充材料

研究背景与目的：头球引发的大脑健康显性退化，是体育领域最受关注且颇具争议的健康相关议题之一（Keogh F、Pirks N，2024：《“疼痛令人作呕”——前球员谈头球恐惧》，载于英国广播公司（BBC））。本研究旨在全面评估降低充气压力作为干预手段，以减轻足球头球过程中球-头部冲击带来的头部运动学变化的有效性，并通过实验考察冲击位置、头部姿态、颈部屈曲角度及用球类型对该干预措施的影响。

研究方法：采用定制发射装置投射两款现代足球，分别在正面与斜向冲击位置对Hybrid III型头颈假人（Hybrid III head and neck）进行冲击测试。在两种充气压力条件下，针对共34组冲击变量组合，计算得到峰值线加速度、峰值角速度、峰值角加速度及DAMAGE指标（DAMAGE metrics）四项运动学参数。

研究结果：90%的冲击测试中，四项指标的幅值均出现下降（占比82%）或无变化（占比8%），四项指标的平均幅值变化范围为-2%至-12%。研究结果显示，在多数场景下，降低充气压力可有效降低头部运动学幅值，属于正向干预措施。这一效果在线加速度、角速度及角加速度指标上尤为显著：对应冲击中分别有100%、97%与100%出现幅值下降或无变化。

研究结论：基于上述四项运动学指标，尽管有10%的冲击出现运动学幅值上升，但总体而言，降低充气压力仍是减轻足球头球运动学幅值的有效缓解手段。针对MPS的DAMAGE预测指标中，13个测试案例有12个出现幅值上升，这表明降低充气压力可能会导致基于角响应的指标出现运动学幅值升高，说明该干预手段并非普适性解决方案。不过，所有冲击测试的DAMAGE指标仍整体呈现幅值下降趋势。研究发现，指标幅值对头部姿态、冲击位置及用球类型均较为敏感，凸显了本研究中敏感性分析的重要性。本研究推荐选取两次冲击作为最恶劣的球-头部冲击场景，分别对应两种标称姿态。该两类冲击位置与现有文献中常用的测试位置存在差异，这一发现对未来足球头球相关研究的实验设计具有参考价值。

© 作者，CC-BY 4.0协议