研究目的：脑力疲劳会造成人体主观、生理和行为上的变化，如工作场所的表现下降，思维和反应能力下降。因此，当人们面对危险或者紧急情况时，可能无法及时做出有效反应，可能会造成重大的人生伤害甚至于死亡。本研究从生物力学特性的角度，观察长时间、高强度认知任务诱发的脑力疲劳对青年男性大学生身体摇摆度、稳定极限、步态、落地动作的影响，旨在阐明脑力疲劳后，人体平衡和姿势控制能力的变化特征。

研究方法：选取40名健康成年男性大学生，采用自身对照设计，利用e-prime软件设计90分钟AX连续性能（AX-CPT）认知任务诱导脑力疲劳；利用90分钟中立情绪记录片进行对照干预。采用Vicon三维运动捕捉系统（采样频率250Hz），Kistler三维测力台（采样频率1000Hz），多种运动生物力学研究手段采集平衡指数、运动学、动力学指标。采用SPSS22.0统计软件中单因素方差分析、配对样本T检验对实验数据进行分析。

研究结果：（1）脑力疲劳对静态平衡能力的影响：双脚站立静态测试中，前后、左右、总的移动距离、移动速度、移动面积以及运动椭圆面积均显著增大（P＜0.05）；前后、左右和总的移动速度均显著减小（P＜0.05）。单脚站立静态测试中，总移动距离、总移动面积、左右移动距离、前后移动面积、左右移动面积、运动椭圆面积显著增大（P＜0.05）；总移动速度、前后移动速度、左右移动速度均无显著差异（P＞0.05）。（2）脑力疲劳对动态平衡能力的影响：双脚站立动态测试中，前-最远距离、右-最远距离、左-最远距离均显著减小（P＜0.05）；前-移动偏差角、后-最远距离、后-移动偏差角、右-移动偏差角均无显著差异（P＞0.05）。单脚站立动态测试中，所有指标均无显著差异（P＞0.05）。（3）脑力疲劳对步态姿势控制能力的影响：时空参数以及下肢髋膝踝关节的运动学指标、动力指标变化，均无显著差异（P＞0.05）。（4）脑力疲劳对落地姿势控制能力的影响：总时间和缓冲时间显著增加（P＜0.05）；缓冲阶段，髋、膝、踝的屈曲角度峰值、关节活动范围显著减小（P＜0.05）、峰值力矩显著增大（P＜0.05），踝关节内旋/外旋的角度峰值、关节活动范围显著减小、峰值力矩显著增大（P＜0.05）；稳定阶段，髋关节内收/外展、内旋/外旋峰值角度、关节活动范围显著增大（P＜0.05）、峰值力矩显著减小（P＜0.05）。

研究结论：（1）脑力疲劳增加了人体静态平衡重心晃动的距离和面积，损害了静态平衡控制能力。（2）脑力疲劳造成人体双足动态平衡中身体重心在前、左、右方向上的最远移动距离减小，但对单脚和双脚动态平衡的目标方位的判断和执行均没有显著影响。（3）脑力疲劳对步态行走姿势控制不会产生任何负面影响。（4）脑力疲劳导致落地动作姿势的缓冲阶段下肢关节矢状面内的活动度减小，造成姿势控制模式改变，可能增加运动过程中的损伤风险。

Research purpose: Mental fatigue can cause subjective, physiological and behavioral changes in the human body, such as decreased performance in the workplace, and decreased thinking and responsiveness. Therefore, when people face danger or emergencies, they may not be able to respond effectively in time, which may result in serious personal injury or even death. From the perspective of biomechanical properties, this study observed the effects of mental fatigue induced by long-term, high-intensity cognitive tasks on body sway, stability limit, gait and landing movements of young male college students, aiming to clarify the balance of human body after mental fatigue. and changes in postural control.

Research methods: 40 healthy adult male college students were selected, using self-control design, using e-prime software to design a 90-minute AX-continuous performance cognitive task to induce mental fatigue; using 90-minute neutral emotional recordings for control intervention. Vicon 3D motion capture system , Kistler 3D force platform and various sports biomechanical research methods are used to collect balance index, kinematics, dynamics and other indicators. The experimental data were analyzed by one-way ANOVA and paired sample T test in SPSS22.0 statistical software.

Research results: (1) The effect of mental fatigue on static balance ability: in the static test of standing on both feet, the total movement distance, movement speed, movement area and movement ellipse area increased significantly (P<0.05); Front-back, left-right and total movement speed were significantly decreased (P<0.05). In the static test of standing on one foot, the total movement distance, total movement area, left and right movement distance, front and rear movement area, left and right movement area, and motion ellipse area increased significantly (P<0.05); total movement speed, front and rear movement speed, left and right movement speed There was no significant difference (P>0.05). (2) The effect of mental fatigue on the dynamic balance ability: in the dynamic test of standing on both feet, the front-farthest distance, the right-farthest distance, and the left-farthest distance were significantly reduced (P<0.05); front-movement deviation There was no significant difference in angle, rear-farthest distance, rear-movement deviation angle, and right-movement deviation angle (P>0.05). In the dynamic test of standing on one foot, there was no significant difference in all indicators (P>0.05). (3) The effect of mental fatigue on gait and posture control ability: there was no significant difference in the spatiotemporal parameters, kinematic indexes and dynamic indexes of lower extremity hip, knee and ankle joints (P>0.05). (4) The effect of mental fatigue on the control ability of landing posture: the total time and buffering time increased significantly (P<0.05); in the buffering stage, the peak flexion angle of the hip, knee and ankle, and the range of motion of the joints decreased significantly (P<0.05) , peak torque increased significantly (P<0.05), the peak angle of ankle internal/external rotation, the range of motion of the joint decreased significantly, and the peak torque increased significantly (P<0.05); The extension, internal rotation/external rotation peak angle, joint range of motion increased significantly (P<0.05), and peak torque decreased significantly (P<0.05).

Research conclusions: (1) Brain fatigue increases the distance and area of the body's static balance center of gravity swaying, and impairs the static balance control ability. (2)Brain fatigue reduces the farthest moving distance of the body's center of gravity in the front, left and right directions in the dynamic balance of the human body, but has no significant impact on the judgment and execution of the target orientation of the one-foot and two-foot dynamic balance. (3) Brain fatigue does not have any negative impact on gait and walking posture control. (4) Brain fatigue leads to a decrease in the range of motion in the sagittal plane of the lower extremity joints during the buffering stage of the landing posture, resulting in changes in the posture control mode, which may increase the risk of injury during exercise.