S1 Dataset -

BackgroundRepeated sub-concussive head impacts are a growing brain health concern, but their possible biomarkers remain elusive. One impediment is the lack of a randomised controlled human experimental model to study their effects on the human brain.ObjectivesThis work had two objectives. The first one was to provide a randomised controlled human experimental model to study the acute effects of head impacts on brain functions. To achieve this, this work’s second objective was to investigate if head impacts from heading footballs acutely alter brain excitability by increasing corticospinal inhibition as compared to a control group.MethodsIn practised and unpractised young healthy adults, transcranial magnetic stimulation was used to assess corticospinal silent period (CSP) duration and corticospinal excitability (CSE) before and immediately after performing headings by returning 20 hand-thrown balls directed to the head (Headings; n = 30) or the dominant foot (Control; n = 30). Moreover, the Rivermead Post-Concussion Questionnaire (RPQ) was used to assess the symptoms of head impacts. Head acceleration was also assessed in subgroups of participants.ResultsThe intervention lengthened CSP duration in both the Headings (6.4 ± 7.5%) and Control groups (4.6 ± 2.6%), with no difference in lengthening between the two groups. Moreover, CSE was not altered by the intervention and did not differ between groups. However, performing headings increased headaches and dizziness symptoms and resulted in greater head acceleration upon each football throw (12.5 ± 1.9g) as compared to the control intervention (5.5 ± 1.3g).ConclusionsThe results suggest that head impacts from football headings do not acutely alter brain excitability as compared to a control intervention. However, the results also suggest that the present protocol can be used as an experimental model to investigate the acute effects of head impacts on the human brain.

背景重复性脑震荡性头部撞击已成为日益关注的大脑健康问题，但其潜在的生物标志物仍难以寻觅。一项障碍在于，缺乏随机对照的人体实验模型以研究其对人类大脑的影响。目标本项研究旨在实现两个目标。其一是提供一项随机对照的人体实验模型，用以研究头部撞击对大脑功能的急性影响。为实现此目标，研究的第二个目标是探究通过头顶足球，头部撞击是否能够急性地改变大脑兴奋性，即通过增加皮质脊髓抑制（Corticospinal Inhibition）与对照组成员相比。方法在经过训练和未经训练的年轻健康成年人中，运用经颅磁刺激（Transcranial Magnetic Stimulation）技术评估皮质脊髓静息期（Corticospinal Silent Period, CSP）的持续时间及皮质脊髓兴奋性（Corticospinal Excitability, CSE），在执行头顶球动作前后进行（头顶球组；n = 30）或以优势足部触球（对照组；n = 30）。此外，采用Rivermead脑震荡后问卷（Rivermead Post-Concussion Questionnaire, RPQ）评估头部撞击的症状。同时，对参与者的小组进行了头部加速度的评估。结果干预措施延长了头顶球组（6.4 ± 7.5%）和对照组（4.6 ± 2.6%）的CSP持续时间，两组之间的延长程度无显著差异。此外，干预措施并未改变CSE，且两组间无显著差异。然而，执行头顶球动作增加了头痛和眩晕症状，并且与对照干预相比，每次足球投掷导致的头部加速度更大（12.5 ± 1.9g）。结论结果表明，与对照干预相比，足球头顶球产生的头部撞击并未急性地改变大脑兴奋性。然而，这些结果亦表明，当前方案可作为实验模型，用以研究头部撞击对人类大脑的急性影响。