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?"<br><br>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.<br><br>© The Author(s), CC-BY 4.0

《足球运动中降低球体充气压力是否会减轻头部撞击运动学响应？》一文的补充材料

研究目的：头球导致的脑部健康潜在退行性病变，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. "痛苦令人作呕"——前球员谈头球恐惧. 载于：BBC）。本研究旨在深入探究降低充气压力作为干预手段，能否减轻足球撞击头部时产生的头部运动学响应。实验考察了撞击位置、头部姿态、颈部屈曲角度以及足球型号对该干预效果的影响。

研究方法：采用定制发射装置投射两款现代足球，对Hybrid III型头部颈部假人（Hybrid III）进行正面与斜向撞击。在两种充气压力下，共设置34组撞击变量组合，并计算了峰值线加速度、峰值角速度、峰值角加速度以及DAMAGE指标。

研究结果：90%的撞击工况中，四项指标的幅值均出现下降（82%）或无变化（8%），四项指标的平均幅值变化范围为-2%至-12%。研究结果表明，在多数工况下降低充气压力可有效降低运动学幅值，这一效果在线加速度、角速度及角加速度指标上尤为显著：对应工况中100%、97%及100%的撞击幅值出现下降或无变化。

研究结论：基于上述四项运动学指标，尽管10%的撞击工况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。在MPS的DAMAGE预测指标中，13个工况里有12个出现幅值上升，这表明降低充气压力可能会使角响应衍生指标的运动学幅值升高，提示该干预手段并非普适性解决方案。不过总体来看，所有撞击工况下DAMAGE指标仍呈现净幅值下降。研究发现，指标幅值对头部姿态、撞击位置及足球型号均具有敏感性，印证了本研究中敏感性分析的重要性。推荐选取两次撞击工况作为足球头部撞击的最坏场景，分别对应两种标称姿态。该撞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