Korean J Health Promot.  2019 Mar;19(1):59-67. 10.15384/kjhp.2019.19.1.59.

Effects of Bicycle Ergometer Exercise on Cerebral Blood Flow Velocity and Electroencephalogram Response in Normoxia and Hypoxia

• Kim SD
• Kim MW
• Jeong IG

• KMID: 2442659
• DOI: http://doi.org/10.15384/kjhp.2019.19.1.59

Abstract

BACKGROUND
The cerebral blood flow velocity (CBFV) has been known to increase in response to acute hypoxia. However, how CBFV might respond to exercise in hypoxic conditions and be associated with electroencephalogram (EEG) remains unclear. The purpose of this study was to evaluate the effect of exercise in hypoxic conditions corresponding to altitudes of 4,000 m on CBFV and EEG.
METHODS
In a randomized, double-blind, balanced crossover study, ten healthy volunteers (19.8±0.4 years) were asked to perform the incremental bicycle ergometer exercise twice in hypoxic and control (sea level) conditions with a 1-week interval, respectively. Exercise intensity was set initially at 50 W and increased by 25 W every 2 minutes to 125 W. Acute normobaric hypoxic condition was maintained for 45 minutes using low oxygen gas mixture. CBFV in the middle cerebral artery (MCA) and EEG were measured at rest 5 minutes, rest 15 minutes, immediately after exercise, and 15 minutes recovery using transcranial-Doppler sonography and EEG signal was recorded from 6 scalp sites leading to analysis of alpha and beta wave relative activities. All data were analyzed using two-way repeated-measures analysis of variance and Pearson's correlation.
RESULTS
CBFV in the MCA in the hypoxic condition was significantly higher than that in the control condition at rest 5 minutes (83±9 vs. 69±9 cm/s, P<0.01), rest 15 minutes (87±8 vs. 67±7 cm/s, P<0.001), immediately after exercise (112±9 vs. 97±9 cm/s, P<0.01), and 15 minutes recovery (91±11 vs. 74±7 cm/s, P<0.01). However, no significant correlation was found between the changes of CBFV and EEG wave activities.
CONCLUSIONS
These results suggest that the drastic change of CBFV observed during exercise with hypoxia might appear independently with EEG wave activities.

Keyword

Exercise; Hypoxia; Cerebrovascular circulation; Electroencephalogram

MeSH Terms

Altitude
Anoxia*
Cerebrovascular Circulation*
Cross-Over Studies
Electroencephalography*
Healthy Volunteers
Middle Cerebral Artery
Oxygen
Scalp
Oxygen

Figure

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  Figure 1 Experimental procedures. Abbreviations: CBF, cerebral blood flow; EEG, electroencephalography; HR, heart rate; SaO2, arterial oxygen saturation.

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  Figure 2 Correlation between changes in mean flow velocity of middle cerebral artery (MCA) and changes in Beta activity for resting 15 minutes after hypoxic exposure. P values are calculated by Pearson correlation analysis. r represents a negative correlation of changes in mean flow velocity of MCA and changes in Beta activity.

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