Subconcussive hits to the head and physical fitness both have been associated with alterations in white matter (WM) microstructure in partly overlapping areas of the brain. The aim of the present study was to determine whether WM damage associated with repeated exposure to subconcussive hits to the head in university level contact sports athletes is modulated by high levels of fitness. To this end, 72 students were recruited: 24 athletes practicing a varsity contact sport (A-CS), 24 athletes practicing a varsity non-contact sport (A-NCS), and 24 healthy non-athletes (NA). Participants underwent a magnetic resonance imaging session that included diffusion-weighted imaging. Between-groups, statistical analyses were performed with diffusion tensor imaging measures extracted by tractometry of sections of the corpus callosum and the corticospinal tract. Most significant effects were found in A-NCS who exhibited higher fractional anisotropy (FA) values than A-CS in almost all segments of the corpus callosum and in the corticospinal tract. The A-NCS also showed higher FA compared with NA in the anterior regions of the corpus callosum and the corticospinal tracts. No group difference was found between the A-CS and the NA groups. These data suggest that repeated subconcussive hits to the head lead to anisotropic changes in the WM that may counteract the beneficial effects associated with high levels of fitness.

中文翻译：

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接触式和非接触式大学级体育运动员的扩散张量成像

对头部的次震荡撞击和身体健康都与大脑部分重叠区域的白质 (WM) 微观结构的改变有关。本研究的目的是确定与反复暴露于大学级接触性运动运动员头部的亚脑震荡相关的 WM 损伤是否受到高水平健身的调节。为此，招募了 72 名学生：24 名运动员参加校队接触式运动 (A-CS)，24 名运动员参加校队非接触式运动 (A-NCS)，以及 24 名健康非运动员 (NA)。参与者接受了包括弥散加权成像在内的磁共振成像会议。在组间，使用通过胼胝体和皮质脊髓束切片的牵引测量提取的扩散张量成像测量进行统计分析。在 A-NCS 中发现了最显着的影响，在胼胝体和皮质脊髓束的几乎所有节段中，其分数各向异性 (FA) 值均高于 A-CS。与胼胝体前部和皮质脊髓束的 NA 相比，A-NCS 也显示出更高的 FA。在 A-CS 和 NA 组之间没有发现组差异。这些数据表明，对头部的反复次震荡会导致 WM 的各向异性变化，这可能会抵消与高水平健康相关的有益影响。与胼胝体前部和皮质脊髓束的 NA 相比，A-NCS 也显示出更高的 FA。在 A-CS 和 NA 组之间没有发现组差异。这些数据表明，对头部的反复次震荡会导致 WM 的各向异性变化，这可能会抵消与高水平健康相关的有益影响。与胼胝体前部和皮质脊髓束的 NA 相比，A-NCS 也显示出更高的 FA。在 A-CS 和 NA 组之间没有发现组差异。这些数据表明，对头部的反复次震荡会导致 WM 的各向异性变化，这可能会抵消与高水平健康相关的有益影响。