[P3] Poster: Day 3

[P3-10] Perceived time shapes the course of physical fatigue

*Pierre-Marie Matta^1,2,3, Robin Baurès^1,2, Julien Duclay^1,3, Andrea Alamia^1,2 (1. University of Toulouse (France), 2. Centre de Recherche Cerveau et Cognition, CNRS (France), 3. Toulouse NeuroImaging Center, INSERM (France))

Keywords:

Time deception,False-clock paradigm,Fatigue,Electroencephalography,Electromyography

While numerous studies have documented the influence of bodily states on time perception, the reverse relationship has received less attention. Recent findings suggest that some psychophysiological processes, such as physical fatigue, may follow a subjective rather than an objective temporal evolution. However, the underlying neural mechanisms and the role of motivational confounds remain unclear. To investigate whether physical fatigue can be influenced by perceived time, we asked 24 participants to perform 100 isometric knee extensions in four separate sessions. While the rest time between contractions was constant (5s), the real (R) and perceived (P) durations of each contraction were independently manipulated, unbeknownst to the participants. In each session, contraction duration was either short (10s) or long (12s), and the displayed time was either Normal (N) or Biased (B), yielding four counterbalanced conditions: N10 (10s P, 10s R), N12 (12s P, 12s R), B10 (10s P, 12s R), and B12 (12s P, 10s R). Using force and EMG recordings, we showed that the increase in physical fatigue over contractions was larger in N12 compared to N10 and B12, but also B10, in which the real workload was the same as in N12. This finding demonstrates that, irrespective of motivational factors, physical fatigue follows the perceived time when the clock is slowed down, but not when it is accelerated. EEG analyses further revealed significant power differences in theta and beta bands over frontal (but not motor) areas between N10 and N12, with no difference between conditions sharing the same perceived time, hence highlighting a frontal oscillatory dynamic that thoroughly follows the perceived rather than the real time. All in all, our findings suggest a bidirectional relationship between time perception and bodily states: while prior models mostly emphasize how bodily states can affect time perception, our findings show that perceived time can, in turn, shape physiological processes.