Changes in EEG during graded exercise on a recumbent cycle ergometer

Abstract

Previous studies have shown changes in brain activity as a result of exercise; however, few studies have examined changes during exercise. The purpose of this study was to examine brain activity during a graded exercise test. Twenty male participants performed a graded exercise test on a recumbent cycle ergometer. Exercise intensity was set initially at 50W and was increased by 50W every 2 minutes until volitional fatigue was reached. Electroencephalography (EEG) was measured prior to the onset of exercise, during the last minute of each stage of exercise, immediately post-exercise, and 10 minutes into recovery. EEG was recorded from 8 scalp sites leading to analysis of alpha 1, alpha 2, beta 1, beta 2, and theta activities. Expired air was collected and analyzed for ventilation rate (VE), VO2, % of peak VO2, and Respiratory Exchange Ratio (RER). No differences were seen in EEG between the hemispheres of the brain. There was, however, a significant increase in brain activity across the spectrum occurring at 200 W through immediately post-exercise. Brain activity returned to pre- exercise levels by 10 minutes post. VO2, % of peak VO2 and RER increased linearly with exercise intensity. VE increased linearly through 200 W; however, a disproportionate increase was seen in VE from 200 W to peak exercise. The results of this investigation demonstrate that brain activity may be related to exercise intensity. Future research will want to examine how these changes in brain activity influence affective, perceptual and cognitive changes often associated with exercise. Efforts will also need to be made to determine if changes in brain activity during exercise are mediated by central (within the brain) or peripheral mechanisms. Key pointsEEG can be recorded during exercise.Brain EEG activity increases during exercise and may be related to exercise intensity.Brain EEG activity returns to resting levels quickly after the cessation of exercise.

Keywords: EEG; Exercise; brain activity.

Figures

Figure 1.

Topographical depiction of relative changes in EEG activity in 21 electrode sites during graded exercise to fatigue.

Figure 2.

Changes in Theta activity during graded exercise to fatigue at several EEG sites. * indicates difference from Pre. # indicates difference from 50 Watts.

Figure 3.

Changes in Alpha 1 activity during graded exercise to fatigue at several EEG sites. * indicates difference from Pre, 50 Watts, 100 Watts, 150 Watts and Post 10 min. # indicates difference from Pre, 50 Watts and 100 Watts.

Figure 4.

Changes in Alpha 2 activity during graded exercise to fatigue at several EEG sites. * indicates difference from Pre, 50 Watts, 100 Watts, 150 Watts and Post 10 min. # indicates difference from Pre, 50 Watts and 100 Watts.

Figure 5.

Changes in Beta 1 activity during graded exercise to fatigue at several EEG sites. * indicates difference from Pre, 50 Watts, 100 Watts, 150 Watts and Post 10 min. # indicates difference from Pre and Post 10 min.

Figure 6.

Changes in Beta 2 activity during graded exercise to fatigue at several EEG sites. * indicates difference from Pre, 50 Watts, 100 Watts, 150 Watts and Post 10 min. # indicates difference from Pre and Post 10 min.

Figure 7.

Changes in Alpha-Beta ratio during graded exercise to fatigue at several EEG sites. * indicates difference from Pre. # indicates difference from 50 Watts and 100 Watts. † indicates difference from 50 watts, 100, watts, 150 watts and 200 watts.