Effects of mental fatigue on sport-related reaction-time, technical, and decision-making performance: a systematic review and meta-analysis

BACKGROUND: Mental fatigue has been proposed to affect sport-related performance, but previous syntheses have often combined heterogeneous outcomes or insufficiently distinguished response speed, technical execution, and decision-making. This review examined the association between experimentally induced mental fatigue and three sport-specific or sport-relevant performance domains: sport-specific reaction-time outcomes, technical performance, and decision-making performance. METHODS: This systematic review and meta-analysis followed PRISMA 2020 guidance and was registered in PROSPERO. Web of Science, PsycINFO, SPORTDiscus, Embase, and PubMed were searched from inception to 19 January 2026. Eligible studies were experimental studies comparing a mental-fatigue condition with a control or lower cognitive-load condition in healthy participants performing sport-specific or sport-relevant tasks. Hedges' g was calculated so that positive values indicated poorer performance under mental fatigue. Random-effects models were fitted separately for each outcome domain. Risk of bias was assessed using design-specific RoB 2 tools, and certainty of evidence was assessed using GRADE. RESULTS: Nineteen study records contributed 20 study-domain results to the primary meta-analysis. Mental fatigue was associated with poorer sport-specific reaction-time performance (k = 4; g = 0.496, 95% CI 0.171 to 0.822; I² = 47.4%), technical performance (k = 9; g = 0.613, 95% CI 0.411 to 0.815; I² = 86.6%), and decision-making performance (k = 7; g = 0.671, 95% CI 0.546 to 0.796; I² = 9.6%). Sensitivity and dependency analyses generally supported the direction of these findings, although uncertainty was greater for reaction-time outcomes. CONCLUSIONS: Mental fatigue is associated with poorer sport-related performance, but the evidence differs across domains. Decision-making outcomes showed the most consistent pattern, technical performance showed substantial heterogeneity, and sport-specific reaction-time outcomes were limited by a small evidence base. Future studies should predefine primary sport-performance outcomes, report paired statistics for crossover designs, and distinguish reaction-time, technical, and decision-making outcomes more clearly. TRIAL REGISTRATION: PROSPERO CRD420251180776.