Electroencephalographic Activity Changes After Prolonged Exercise In A Hyperpyrexia And High Humidity Environment

Objective: The aim of this study was to observe the changes of electroencephalogram(EEG) after exhausted exercise in a hyperpyrexia and high humidity environment, detecting the features of EEG variety and the possible influential factors.Methods: 17 non-athlete students(mean age19.1±0.2 yr, height 177.9±5.2 cm,weight 67.8±7.6 kg, VO2 max 4.6±1.4L·min-1) participated in the study. All experiments have been completed in the Integrated Environments Exercise Lab of China Institute of Sport Science(CISS). Heart rate(HR), core temperature(Tc) and forehead temperature(Tf) were recorded during exercise(running at <60% VO2 max to exhaustion) in a chamber set at 36.0℃, 60.0% relative humidity(RH). And weight,EEG of subjects were measured pre- and post-exercise.Results: Subjects exhausted after 29.88±4.06 min coinciding with a 100% HRmax, a Tc of 39.14±0.32 ℃, a Tf of 39.64±0.71 ℃, a weight loss of 623.53±536.81 g.Increases of spectrum power(SP) have found in almost whole brain regions after exhausted exercise in hot and humid environment. And the number of SP increased regions of α2 and β2 were more than these of α1and β1. Plus, the significant decrease of α/β had be found in the left brain regions(p<0.05), and the significant decrease of α/(α+β) could just be found in the F3, F7, T3(p<0.05). Under the correlation analysis, we found that the physical changes had a moderate correlation with the changes of EEG in many brain regions(r=0.48-0.74). And the δ had a negative correlation with physical changes which did not like any other brainwaves.On the other hand, HR had a positive correlation with θ index and the Tc had positive correlation with α and β index, moreover, the number of correlation brain regions of β index was more than α index.Conclusions: Brain activities would increase after exhausted exercise in a hot and humid environment including not only α brainwave but all brainwaves, and these changes may have a correlation with physical changes. The interaction between physical change and brain electricity change may contribute to the exercise-induced fatigue in a hyperpyrexia and high humidity environment...