Effect of acute light aerobic exercise and rest on electroencephalogram after mental tasks

The aim of the present study is to clarify the effect of mental tasks, light aerobic exercise and sustained rest on electroencephalogram in terms of the amplitude and frequency for developing a method for measuring human stresses using electroencephalogram. The present study investigated response of electroencephalogram to acute aerobic exercise with low intensity after performing mental tasks and compared with that to sustained rest for the same duration. The mean amplitude of the alpha wave in the low frequency band (8-10 Hz, low-alpha wave) showed significant decrease between the mental arithmetic and the resting state prior to the mental tasks over the entre scalp with a focus on the occipital lobe, while that of the alpha wave in the high frequency band (10-13 Hz, high-alpha wave) did not show such reduction. The weighted mean frequency with amplitude of the alpha wave (8-13 Hz) was increased at the occipital lobe during the mental tasks due to the increase of the weighted mean frequency of the low-alpha wave. The amplitudes of the alpha, low-alpha and high-alpha waves were beginning to be increased after the onset of an acute exercise; significant difference in the high-alpha wave was seen between the entire duration of the exercise and the resting state prior to the tasks. Moreover, the weighted mean frequency of the high-alpha wave showed the increase during the most of the duration of exercise, whereas that of the low-alpha wave almost stayed during the exercise. Such modulation in amplitude and frequency was immediately deteriorated after the end of the exercise and became comparable to the modulation by the sustained rest in 10 minutes after the exercise. The observation obtained suggests that the mental calculation mainly reduced the amplitude and increased the frequency of the low-alpha wave, while the aerobic exercise increased the amplitude and frequency of the high-alpha wave. Increase of the high-alpha wave during the exercise may reflect an activa- ion of serotonergic system.