Mental Fatigue and Sport-Related Performance: Proposed Psychobiological Pathways and Task-Demand Constraints

Mental fatigue is often invoked to explain performance changes after sustained cognitive engagement, yet the antecedent cognitive-demand protocols used in sport research are heterogeneous and do not invariably elicit an equivalent fatigue state. This narrative review synthesizes 84 publications to clarify the distinction between antecedent cognitive demand and mental fatigue, classify major antecedent cognitive-demand pathways, and develop a mechanism-based framework for sport-related performance. The framework distinguishes the antecedent exposure, the fatigue-related state that the exposure is intended to elicit, the candidate regulatory processes through which that state may become behaviorally relevant, and the subsequent task-specific expression. Evidence for the proposed processes is calibrated as direct process-level evidence, indirect task-based support, or theory-guided inference. The framework’s central proposition is conditional rather than universal: observable performance decrements should be most likely when an antecedent cognitive demand elicits a supported fatigue-related state and when the regulatory process implicated by that state overlaps with the control requirements of the subsequent task. Heterogeneous findings are therefore used to generate candidate boundary-condition hypotheses rather than treated as proof that particular moderators are established. Across endurance, reaction-time, technical, decision-making, and open-skill outcomes, the available evidence is more consistent with task-specific than with uniform performance effects. For sport science, the framework provides a basis for testing more precise induction protocols, manipulation checks, process measures, and task-specific monitoring hypotheses. For general psychology, sport provides a high-demand model system for examining when fatigue becomes behaviorally consequential under real task constraints.