Effects of Mental Fatigue Duration on Cortical Activity and Jump Performance

"Mental fatigue is a psychobiological state induced by prolonged demanding cognitive activity, characterized by subjective tiredness and measurable decrements in sustained attention and executive control. While mental fatigue has been linked to impairments in endurance, strength, and anaerobic performance, evidence regarding explosive, single-effort tasks such as the countermovement jump (CMJ) remains sparse and inconsistent, and it remains unclear whether the cortical and behavioral consequences of mental fatigue scale with the duration of the inducing cognitive task.

This study used a single-group, repeated-measures crossover design in which the same twelve participants completed a non-fatiguing control condition and three graded mental-fatigue protocols (10, 15, and 30 minutes of continuous Stroop-task performance), with session order counterbalanced across participants and a minimum 72-hour washout between sessions. All sessions were conducted in the same laboratory within a consistent daily time window (10:00 ± 1 hour) to minimize circadian confounds.

Resting-state EEG (spectral power in delta, theta, alpha, and beta bands; theta/alpha and theta/beta ratios; spectral and sample entropy; frontal theta and posterior alpha) and subjective fatigue (0-10 visual analogue scale) were assessed immediately before and after each condition. Countermovement-jump height and its kinetic/kinematic correlates were then measured to evaluate explosive lower-limb power, the study's primary outcome; EEG parameters were treated as secondary, mechanistic outcomes.

Data were analyzed using repeated-measures ANOVA, Holm-Bonferroni-corrected Friedman/Wilcoxon tests where appropriate, and repeated-measures correlation to examine the relationship between post-intervention EEG parameters and CMJ performance. The study tested the hypothesis that increasing Stroop-task duration would produce progressively larger shifts in EEG-derived cortical activation and parallel reductions in CMJ performance, and that these neurophysiological and performance changes would be significantly associated with one another."

Inclusion criteria

• Healthy male volunteers aged 18-30 years
• Enrolled in the Faculty of Sport Sciences at İnönü University
• Engaged in structured exercise at least three days per week
• Free of any neurological, psychiatric, cardiovascular, or musculoskeletal disorder
• Normal or corrected-to-normal vision
• Physically capable of completing the experimental protocol safely

Exclusion criteria

• Diagnosed neurological, psychiatric, cardiovascular, or musculoskeletal disorder
• Lower-limb injury within the preceding 6 months
• Use of medication known to affect central nervous system function
• Prior diagnosis of a sleep disorder
• Uncorrectable visual impairment or any disturbance of color perception
• Cognitive or sensory limitation likely to interfere with performance of the Stroop task
• Failure to complete a session in full, non-compliance with investigator instructions during testing, inability to produce an EEG recording of analyzable quality for technical reasons, or discontinuation of the experimental procedure for any reason
• Non-compliance with pre-session restrictions (vigorous physical exercise or alcohol consumption within 24 hours before each session; caffeine, energy drinks, or other stimulant substances within 12 hours before each session)