title: Changes in EEG activity before and after exhaustive exercise in sedentary women in neutral and hot environments.
abstract: This study examined the effect of hyperthermia on brain electrical activity measured with encephalography during prolonged exhaustive exercise in a group of sedentary women (VO(2)max = 35 +/- 4 mL kg min(-1)). Two strenuous cycling exercises were performed either in neutral (N-Ex) or in heat (H-Ex) conditions. Tympanic temperature (Tty), heart rate (HR), body mass loss (BML), plasma volume decrease, and brain electrical activity [EEG: alpha (8-13 Hz) and beta(13-30 Hz)-band and alpha/beta index of fatigue: the ratio between EEG activity in the alpha band and beta-band] were recorded throughout the cycling sessions. The Tty increase 1.0 degrees C in the N-Ex and 1.8 degrees C in H-Ex. HR increased in both sessions but with significantly higher values during the H-Ex session when compared with the N-Ex session (p < 0.001) (from 85 +/- 4 beats min(-1) to 164 +/- 6 beats min(-1) and from 83 +/- 6 beats min(-1) to 181 +/- 8 beats min(-1), respectively in N-Ex and in H-Ex). This was associated with a significantly higher BML (p < 0.05) and a higher plasma volume decrease in the H-Ex session (p < 0.01). The alpha/beta index increased significantly during both trials particularly during the H-Ex session (p < 0.05). This was associated with a significant decrease of time to exhaustion (-34%). We suggest that exhausting work in the heat induced a change in gross brain activity (alpha/beta ratio) compared to a longer, less thermally demanding exposure. Fatigue in the heat could be attributed to central factors as well as thermal, cardiac and hydro-electrolytic impairment.
authors.affiliation: Institute of Sport and Physical Education, Sfax, Tunisia. ftaiti_foued@yahoo.fr
authors.forename: Foued
authors.initials: F
authors.lastname: Ftaiti
authors.forename: Asma
authors.initials: A
authors.lastname: Kacem
authors.forename: Nadia
authors.initials: N
authors.lastname: Jaidane
authors.forename: Zouhair
authors.initials: Z
authors.lastname: Tabka
authors.forename: Mohamed
authors.initials: M
authors.lastname: Dogui
mesh_terms: D016022:Case-Control Studies; D004569:Electroencephalography; D015444:Exercise / Q000502:physiology / Q000523:psychology*; D005080:Exercise Test; D005221:Fatigue / Q000523:psychology*; D005260:Female; D018882:Heat Stress Disorders / Q000523:psychology*; D006801:Humans; D006979:Hyperthermia, Induced; D010101:Oxygen Consumption; D057185:Sedentary Behavior; D055815:Young Adult