Author(s): DEBARNOT, U., GÉLÉBART, J., DIGONET, G., JACQUET, T., RUFFINO, C., Institution: UNIVERSITÉ CLAUDE BERNARD LYON1, Country: FRANCE, Abstract-ID: 449

INTRODUCTION:
Mental fatigue (MF) arises from sustained cognitive load and manifests as a multisystem state encompassing subjective experience, behavioral regulation, cortical oscillatory activity, and oculomotor dynamics (Schampheleer et al., 2025). While moderate aerobic exercise (EXO) is known to facilitate recovery from MF (Oberste et al., 2021), its capacity to shape the emergence and expression of MF when performed prior to prolonged cognitive effort remains unexplored. This study aimed to provide a fine-grained multimodal and temporal characterization of MF, assess its impact on declarative memory and creative cognition, and determine whether prior EXO modulates these effects.
METHODS:
Twenty-nine healthy adults completed either 15 min of EXO or a resting control condition (REST) before performing a 35-min Time Load Dual Back task designed to induce MF. Subjective fatigue and perceived effort, behavioral performance, electroencephalographic (EEG) activity, and eye-blink rate were continuously monitored throughout task execution. Declarative memory and divergent creativity were assessed before the intervention and immediately after MF induction.
RESULTS:
In both groups, subjective MF and perceived effort increased early during task performance (from the first assessment at 7 min), while accuracy and response times remained stable, indicating sustained behavioral compensation. MF was characterized by a progressive increase in parieto-central alpha power emerging around 18 min, reflecting growing cognitive load. Prior EXO did not attenuate subjective MF nor alter behavioral stability or alpha dynamics. However, EXO selectively modulated neurophysiological and oculomotor markers, with consistently higher frontal-medial theta power and stable blink rates, whereas blink rate increased later in REST (≈21 min). Declarative memory performance was preserved in both groups. In contrast, creative flexibility increased after MF in REST but not in EXO, suggesting MF-related disinhibition in the former and preserved inhibitory control following EXO.
CONCLUSION:
These findings delineate a coherent temporal cascade of MF across subjective, neural, and oculomotor domains, even in the absence of overt performance decline. Acute moderate exercise performed beforehand does not prevent MF but selectively reshapes its neurophysiological expression and downstream cognitive effects. By refining the temporal and multimodal signature of MF, this work underscores the importance of exercise timing and task demands for designing targeted interventions to mitigate cognitive fatigue.