What is the effect of vigorous exercise on the brain?

Abstract Aims: This study aimed to verify whether vigorous exercise is capable of generating mental fatigue. Methods: To do so, 16 young adult male (29.4 ± 5.2 years old) cyclists (5.4 ± 4.6 years of training) underwent three visits: 1) control session (rest); 2) session with cognitive demand (20 minutes of AX-CPT); 3) session with vigorous exercise (10km time trial). Mental fatigue was assessed using the visual analog scale of fatigue in the pre-and post-session moments. A two-way ANOVA of repeated measures followed by the Bonferroni posthoc was used to verify the effect of the condition (control, cognitive demand, and exercise) and time (pre and post) interaction. The paired “t” test was used to compare the delta of mental fatigue (post - pre) of the sessions. The partial eta squared was used to determine the effect size of the variance. The significance adopted was p < 0.05. Results: A condition x time interaction was observed (F (2.30) = 5.349, p = 0.010, partial η2 = 0.263). When comparing the deltas, a mean difference was found between the control and vigorous exercise (p = 0.033) conditions and cognitive demand and vigorous exercise (p = 0.017) conditions. Control and cognitive demand sessions showed no difference (p = 0.801). Conclusion: The findings suggest that intense physical exercise seems to cause mental fatigue after practice.摘要 研究目的：本研究旨在验证剧烈运动是否可诱发心理疲劳（mental fatigue）。研究方法：招募16名成年男性自行车运动员（年龄29.4±5.2岁，训练年限5.4±4.6年），完成三次实验环节：1）对照实验（休息状态）；2）认知负荷实验（20分钟AX-CPT任务）；3）剧烈运动实验（10公里计时赛）。分别在各实验环节的前后时刻，采用疲劳视觉模拟量表（visual analog scale of fatigue）评估心理疲劳水平。统计分析方法如下：采用重复测量双因素方差分析（two-way ANOVA of repeated measures）结合Bonferroni事后检验，以验证实验条件（对照、认知负荷、运动）与测量时间（实验前、后）的交互效应；采用配对t检验（paired t test）比较各实验环节间的心理疲劳变化量（post - pre，即实验后得分减去实验前得分）；采用偏Eta平方（partial eta squared）计算方差的效应量。本研究设定显著性水平为p<0.05。研究结果：观察到实验条件与测量时间的交互效应显著（F(2,30)=5.349，p=0.010，偏η²=0.263）。事后比较显示，对照与剧烈运动条件间的疲劳变化量存在均值差异（p=0.033），认知负荷与剧烈运动条件间同样存在显著均值差异（p=0.017）；而对照与认知负荷实验环节间无显著差异（p=0.801）。研究结论：本研究结果提示，剧烈体力运动可在运动后诱发心理疲劳。