Progressive hyperthermia during prolonged exercise increased perceived exertion, which was associated with altered frontal EEG activity and core temperature rather than changes in muscle EMG.
Does submaximal exercise in a hot environment alter cerebral electrical activity and correlate with perceived exertion compared to a normal environment?
Fatigue during prolonged exercise in hot environments is associated with altered cerebral activity rather than changes in muscle activation.
The present study tested the hypothesis that perceived exertion during prolonged exercise in hot environments is associated with changes in cerebral electrical activity rather than changes in the electromyogram (EMG) of the exercising muscles. Therefore, electroencephalogram (EEG) in three positions (frontal, central, and occipital cortex), EMG, rating of perceived exertion (RPE), and core temperature were measured in 14 subjects during submaximal exercise in normal (18 degrees C, control) and hot (40 degrees C, hyperthermia) environments. RPE increased from 11 +/- 1 units at 5 min to 20 +/- 0 units at exhaustion (50 +/- 3 min) in the trial with progressive hyperthermia, whereas exercise in the control trial was maintained with a stable core temperature for 1 h without exhausting the subjects. Altered EEG activity was observed in all electrode positions, and stepwise forward-regression analysis identified core temperature and a frequency index of the EEG over the frontal cortex as the best predictors of RPE. In contrast, there were no significant correlations between RPE and any of the measured EMG parameters (median spectral frequency, root mean square, or amplitude), and the EMG parameters were not different in hyperthermia compared with control. Thus hyperthermia does not seem to affect the activation pattern of the muscles. Rather, the linear correlation among core temperature, EEG frequency index, and RPE indicates that alterations in cerebral activity may be associated with the hyperthermia-induced development of fatigue during prolonged exercise in hot environments.
Nybo et al. (Thu,) reported a other. Progressive hyperthermia (40 degrees C environment) vs. Normal environment (18 degrees C) was evaluated on Rating of perceived exertion (RPE) and its predictors (EEG, EMG, core temperature). Progressive hyperthermia during prolonged exercise increased perceived exertion, which was associated with altered frontal EEG activity and core temperature rather than changes in muscle EMG.