Downsides of downhill: The adverse effects of head vibration associated with downhill mountain biking on visuomotor and cognitive function

振动可以被定义为当人体由振动表面支撑或与振动特征相互作用时围绕稳定点的振荡运动。由于接触振动对健康的负面影响已成为一个令人关注的问题，国际和欧洲标准已经制定，以确定职业接触的阈值和风险预防。一个新出现的问题是，从功能-身体界面到头部水平的振动转移可能与大脑结构和功能的变化有关。大多数研究调查振动对人体的影响是针对生理和肌肉骨骼条件，和相对较少的关注振动引起的认知问题。测量认知功能的细微变化的困难可能是研究数量有限的一个原因。在骑自行车时，由于轮胎表面和地形的持续相互作用，振动是活动固有的。振动能量必须被自行车的机械结构和骑车者的软组织吸收，以保护中轴骨骼和中枢神经系统。有人认为，公路自行车运动中的振动大大超过了职业接触限值（Edwards & Holsgrove，2020），这表明不良健康后果的风险增加。Hurst等人（2020）提出了下坡山地自行车（DH MTB）中头部振动负面影响的初步证据，他们发现四项DH试验足以损害执行功能的各个方面，如心理速度，反应时间，处理准确性和心理灵活性。尽管该研究将DH组的表现与没有头部加速度的运动匹配组和对照组进行了比较，但该研究缺乏对头部加速度的直接量化。然而，作者先前证明，DH MTB期间的旋转和平移头部加速度高于足球、雪地运动、接触性运动和BMX中报道的那些（Hurst等人，2018年）。如果在足球和冰球比赛的一个赛季中，重复的头部加速可能会损害白色物质的完整性和神经认知，那么DH车手在整个比赛赛季中可能会面临持续不可逆脑损伤的风险增加。该项目的主要目的是调查与DH MTB相关的头部振动如何影响认知功能，视力和身体运动控制。第二个目的是阐明振动暴露和脑功能之间的剂量反应关系。为此，将开发一种最先进的VR范例，具有高灵敏度，可靠性和有效性，用于早期识别脑功能障碍。通过了解头部振动的幅度及其对认知健康的潜在影响，我们可以探索减少振动和减轻其有害影响的方法。

Vibration can be defined as an oscillatory movement around a stable point when the human body is supported by a vibrating surface or interacts with a vibrating feature. As the negative health effects of exposure to vibration have become a cause of concern, international and European standards have been developed to define thresholds and risk prevention in occupational exposure. An emerging issue is related to the transference of vibration from the feature-body interface to the level of the head that might be associated with changes in brain structure and function. Most studies investigating the effects of vibration on the human body are directed at physiological and musculoskeletal conditions, and relatively little attention has been given to vibration-induced cognitive problems. Difficulties of measuring subtle alterations in cognitive function might be one factor that could explain the limited number of studies.In cycling, vibration is intrinsic to the activity due to the continuous interaction of the tyre surface and the terrain. Vibrational energy must be absorbed by mechanical structures of the bike and the cyclists' soft tissues to protect the axial skeleton and the central nervous system. It has been suggested that vibration during road cycling substantially exceeds occupational exposure limits (Edwards & Holsgrove, 2020), which indicates an elevated risk of adverse health outcomes. Initial evidence of the negative effect of head vibration experienced in downhill mountain biking (DH MTB) has been presented by Hurst et al, 2020 who found that four DH trials were sufficient to impair aspects of executive function such as psychomotor speed, reaction time, processing accuracy, and mental flexibility. Although the study compared the DH group's performance to an exercise-matched group without head accelerations and a control group, the study lacked direct quantification of head accelerations. Nevertheless, the authors previously demonstrated that rotational and translational head accelerations during DH MTB are higher than those reported in soccer, snow sports, contact sports and BMX (Hurst et al., 2018). Provided that repetitive head accelerations could compromise white matter integrity and neurocognition over the course of a season in football and ice hockey, DH riders might face an increased risk of sustaining irreversible brain injuries over an entire race season. The primary aim of the project is to investigate how head vibrations associated with DH MTB influence cognitive function, oculomotor, and body movement control. A secondary aim is to elucidate the dose-response relationship between vibration exposure and brain function. For this purpose, a state-of-the-art VR paradigm will be developed, with high sensitivity, reliability, and validity for early identification of brain dysfunction. By gaining knowledge on the magnitude of head vibration and its potential influence on cognitive health, we can explore ways to reduce vibration and mitigate its harmful effect.