Perceived Time Shapes Physical Fatigue Accumulation and Its Neural Oscillatory Correlates.

Recent studies suggest that fundamental physiological processes, such as physical fatigue, rely on perceived rather than actual time. However, the neural correlates underlying this effect and its disentanglement from motivational factors (i.e., performance goals) remain unknown. To investigate the time deception effect on fatigue, we developed a novel EEG design in which participants (N = 24) performed 100 isometric contractions at a fixed pace and resistance in four distinct sessions. The actual contraction duration (short or long) and the calibration of the displayed clock (normal or biased toward acceleration or deceleration) were independently manipulated across sessions to examine whether fatigue and its neural correlates evolved in response to perceived or actual time. Our results showed a slowed-down accumulation of physical fatigue when the clock was slowed down, irrespective of motivational factors, while no symmetric effect was observed when the clock was accelerated. This time-deception effect was accompanied by frontal oscillatory dynamics that closely tracked perceived rather than actual time, while motor-related activity showed no such modulation. Further analyses highlighted the key role of frontal oscillatory dynamics in the effectiveness of the time-deception effect on physical fatigue. deception; electroencephalography; electromyography; false belief; isometric exercise; neuromuscular fatigue; neuroscience; oscillation; psychology; time perception.