EFFECT OF LIGHT-MODERATE EXERCISE AT ACUTE NORMOBARIC HYPOXIA ON ELECTROENCEPHALOGRAM AND PHYSIOLOGICAL RESPONSES

Abstract

It is well known that hypoxic stress causes various physiological responses and/or adaptations. Hypoxia also affects brain activities such as cognition, judgment and exercise performance, and it is thought that the influence on electroencephalogram (EEG) is great. However, there are few researches related to the change of EEG to hypoxia per se and exercise at hypoxia, and it is thought that the mechanisms underlying the physiological responses including brain activity of hypoxic stress per se and exercise at hypoxia were not fully understand. PURPOSE: The purpose of this study was to examine that effect of light-moderate exercise at acute normobaric hypoxia on EEG and physiological responses. METHODS: Eleven college-age male subjects were participated in this study. They completed the light-moderate exercise (50-65%HRmax) at both normoxia and normobaric hypoxia (14.5% hypoxia). We measured EEG of left forehead, heart rate (HR), and oxygen saturation (SpO2) before and after exercise. EEG measurement was carried out in a quiet environment, and subjects measured with their eyes closed. The measured EEG was classified into 3 frequency bands. In other words, it was classified into θ wave 4 to 7.5 Hz, α wave 8 to 13 Hz, β wave 13.5 to 30 Hz. The average value (μV) of the amplitude of the EEG and the total amplitude of the EEG in the entire frequency band (3 to 30 Hz) were obtained for each measurement for 10 minutes. Repeated measures ANOVA were performed across treatments. RESULTS: SpO2 at rest and during moderate exercise in hypoxia was significantly lower than that of normoxia (hypoxia; 89.0±2.2% at rest, 82.1±4.4% during exercise, normoxia; 96.8±1.5% at rest, 96.6±1.5% during exercise, p<0.05). HR at rest and during moderate exercise in hypoxia was significantly higher than that of normoxia (p<0.05). The average value of α wave tended to increase after exercise in normoxia from 3.08±0.79 to 3.26±0.96 μV. On the other hand, α wave tended to slightly decrease after exercise in hypoxia from 2.96±0.85 to 2.84±0.82μV. The average value of θ and β wave did not change after exercise at both environments. CONCLUSIONS: From these results, light-moderate exercise in hypoxia could attenuate α wave expression by decreasing SpO2. It would be affect the exercise performance and acclimatization at altitude, as well as cognition.