Author(s)

Asma Kacem, Foued Ftaiti, Karim Chamari, Mohamed Dogui, Laurent Grélot, Zouhair Tabka

Department of Physiology and Functional Explorations, IBN EL JAZZAR Medicine Faculty, Sousse, Tunisia.
Department of Physio-Neurology, University Hospital of Sahloul, Sousse, Tunisia.
Institute of Movement Sciences, Faculty of Sport Sciences, University of Mediterranean, Marseille, France.
Research Unit “Evaluation, Sport, Health”, National Centre of Medicine and Science in Sport, Tunis, Tunisia.

Purpose: This study examined the possible causal mechanisms of fatigue during intense exercise in the heat in a group of nine sedentary women. Methods: Two strenuous cycling sessions were performed, at 100% of maximal aerobic power, either in neutral (N-Ex, air temperature: 22°C ± 0.4°C, air humidity: 53% ± 8%) or in heat conditions (H-Ex, air temperature: 35°C ± 0.3°C, air humidity: 59 ± 6). Tympanic temperature (Tty), heart rate (HR), body mass loss (BML), lactate concentration [La] and brain electrical activity (EEG: α and β waves and α/β ratio) were recorded. Results: Tty, HR and [La] increases (p < 0.001) did not differ significantly between conditions. However, Tty increase rate was significantly (p < 0.05) higher during H-Ex (0.12 ± 0.03°C·min^﹣1) than that during N-Ex (0.08 ± 0.02°C·min^﹣1), and time to exhaustion (Time Limit at 100%) was significantly (p < 0.01) decreased (﹣18% ± 4%) during H-Ex session. Under both conditions, β waves decreased (p < 0.05) and α/β ratio increased (p < 0.05) significantly immediately before exhaustion. Conclusion: During exercise in the heat, the high rate of core temperature rising might be a critical factor triggering faster brain changes.

Fatigue, Women, Brain, Intense Exercise, Hyperthermia

Kacem, A. , Ftaiti, F. , Chamari, K. , Dogui, M. , Grélot, L. and Tabka, Z. (2014) EEG-Related Changes to Fatigue during Intense Exercise in the Heat in Sedentary Women. Health, 6, 1277-1285. doi: 10.4236/health.2014.611156.