Gebel Arnd, Busch Aglaja, Stelzel Christine, Hortobágyi Tibor, Granacher Urs
Division of Training and Movement Sciences, Research Focus Cognition Sciences, University of Potsdam, Potsdam, Germany.
University Outpatient Clinic, Sports Medicine and Sports Orthopedics, University of Potsdam, Potsdam, Germany.
Front Hum Neurosci. 2022 Jun 14;16:871930. doi: 10.3389/fnhum.2022.871930. eCollection 2022.
Physical fatigue (PF) negatively affects postural control, resulting in impaired balance performance in young and older adults. Similar effects on postural control can be observed for mental fatigue (MF) mainly in older adults. Controversial results exist for young adults. There is a void in the literature on the effects of fatigue on balance and cortical activity. Therefore, this study aimed to examine the acute effects of PF and MF on postural sway and cortical activity. Fifteen healthy young adults aged 28 ± 3 years participated in this study. MF and PF protocols comprising of an all-out repeated sit-to-stand task and a computer-based attention network test, respectively, were applied in random order. Pre and post fatigue, cortical activity and postural sway (i.e., center of pressure displacements [CoP], velocity [CoP], and CoP variability [CV CoP, CV CoP]) were tested during a challenging bipedal balance board task. Absolute spectral power was calculated for theta (4-7.5 Hz), alpha-2 (10.5-12.5 Hz), beta-1 (13-18 Hz), and beta-2 (18.5-25 Hz) in frontal, central, and parietal regions of interest (ROI) and baseline-normalized. Inference statistics revealed a significant time-by-fatigue interaction for CoP ( = 0.009, = 0.39, Δ 9.2%) and CoP ( = 0.009, = 0.36, Δ 9.2%), and a significant main effect of time for CoP variability (CV CoP: = 0.001, = 0.84; CV CoP: = 0.05, = 0.62). analyses showed a significant increase in CoP ( = 0.002, = 1.03) and CoP ( = 0.003, = 1.03) following PF but not MF. For cortical activity, a significant time-by-fatigue interaction was found for relative alpha-2 power in parietal ( < 0.001, = 0.06) areas. tests indicated larger alpha-2 power increases after PF ( < 0.001, = 1.69, Δ 3.9%) compared to MF ( = 0.001, = 1.03, Δ 2.5%). In addition, changes in parietal alpha-2 power and measures of postural sway did not correlate significantly, irrespective of the applied fatigue protocol. No significant changes were found for the other frequency bands, irrespective of the fatigue protocol and ROI under investigation. Thus, the applied PF protocol resulted in increased postural sway (CoP and CoP) and CoP variability accompanied by enhanced alpha-2 power in the parietal ROI while MF led to increased CoP variability and alpha-2 power in our sample of young adults. Potential underlying cortical mechanisms responsible for the greater increase in parietal alpha-2 power after PF were discussed but could not be clearly identified as cause. Therefore, further future research is needed to decipher alternative interpretations.
身体疲劳（PF）会对姿势控制产生负面影响，导致年轻人和老年人的平衡能力受损。主要在老年人中，精神疲劳（MF）对姿势控制也有类似影响。而关于年轻人，相关结果存在争议。目前，关于疲劳对平衡和皮层活动影响的文献存在空白。因此，本研究旨在探讨PF和MF对姿势摆动和皮层活动的急性影响。15名年龄在28±3岁的健康年轻人参与了本研究。分别采用由全力重复坐立试验任务组成的PF方案和基于计算机的注意力网络测试组成的MF方案，并随机顺序应用。在疲劳前后，在具有挑战性的双足平衡板任务期间测试皮层活动和姿势摆动（即压力中心位移[CoP]、速度[CoP]和CoP变异性[CV CoP、CV CoP]）。计算额叶、中央和顶叶感兴趣区域（ROI）中θ（4 - 7.5Hz）、α - 2（10.5 - 12.5Hz）、β - 1（13 - 18Hz）和β - 2（18.5 - 25Hz）的绝对频谱功率，并进行基线归一化。推断统计显示，CoP（ = 0.009， = 0.39，Δ 9.2%）和CoP（ = 0.009， = 0.36，Δ 9.2%）存在显著的时间与疲劳交互作用，以及CoP变异性存在显著的时间主效应（CV CoP： = 0.001， = 0.84；CV CoP： = 0.05， = 0.62）。 分析显示，PF后CoP（ = 0.002， = 1.03）和CoP（ = 0.003， = 1.03）显著增加，而MF后未增加。对于皮层活动，在顶叶区域发现相对α - 2功率存在显著的时间与疲劳交互作用（ < 0.001， = 0.06）。 检验表明，与MF（ = 0.001， = 1.03，Δ 2.5%）相比，PF后α - 2功率增加更大（ < 0.001， = 1.69，Δ 3.9%）。此外，无论采用何种疲劳方案，顶叶α - 2功率变化与姿势摆动测量值均无显著相关性。无论疲劳方案和所研究的ROI如何，其他频段均未发现显著变化。因此，所应用的PF方案导致姿势摆动（CoP和CoP）增加以及CoP变异性增加，同时顶叶ROI中的α - 2功率增强，而MF导致我们年轻成人样本中的CoP变异性和α - 2功率增加。讨论了PF后顶叶α - 2功率增加幅度更大的潜在皮层机制，但无法明确确定其原因。因此，未来需要进一步研究来解读其他解释。
