Effects of Mental Fatigue Duration on Cortical Activity and Jump Performance

"Mental fatigue is a psychobiological state induced by prolonged demanding cognitiveactivity, characterized by subjective tiredness and measurable decrements in sustainedattention and executive control. While mental fatigue has been linked to impairments inendurance, strength, and anaerobic performance, evidence regarding explosive,single‐effort tasks such as the countermovement jump (CMJ) remains sparse andinconsistent, and it remains unclear whether the cortical and behavioral consequences ofmental fatigue scale with the duration of the inducing cognitive task.This study used a single‐group, repeated‐measures crossover design in which the sametwelve participants completed a non‐fatiguing control condition and three gradedmental‐fatigue protocols (10, 15, and 30 minutes of continuous Stroop‐task performance),with session order counterbalanced across participants and a minimum 72‐hour washoutbetween sessions. All sessions were conducted in the same laboratory within a consistentdaily time window (10:00 ± 1 hour) to minimize circadian confounds.Resting‐state EEG (spectral power in delta, theta, alpha, and beta bands; theta/alpha andtheta/beta ratios; spectral and sample entropy; frontal theta and posterior alpha) andsubjective fatigue (0‐10 visual analogue scale) were assessed immediately before andafter each condition. Countermovement‐jump height and its kinetic/kinematic correlateswere 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‐correctedFriedman/Wilcoxon tests where appropriate, and repeated‐measures correlation to examinethe relationship between post‐intervention EEG parameters and CMJ performance. The studytested the hypothesis that increasing Stroop‐task duration would produce progressivelylarger shifts in EEG‐derived cortical activation and parallel reductions in CMJperformance, and that these neurophysiological and performance changes would besignificantly associated with one another."