Purpose: Research on mental fatigue and its impact on sport performance has gained significant attention in sport science. A reoccurring observation in these studies is the variation among participants in terms of mental-fatigue perception, as well as impact on performance. Thus, this study investigated personality traits as moderators of these interindividual differences. Methods: Athlete self-report measures of mental fatigue and well-being were recorded throughout the 2023 season of 1 female Australian Rules Football team using a 5-point Likert scale, alongside a personality-trait questionnaire assessing levels of openness, conscientiousness, extraversion, agreeableness, and neuroticism. Results: Mental-fatigue levels fluctuated across the season, with game days presenting significantly (P < .05) lower levels than training days. Repeated-measurements correlations indicated that mental fatigue was positively correlated with wellness ratings of stress (r = .27), sleep (r = .20), soreness (r = .07), and readiness (r = .10). The personality traits of extraversion and openness moderated mental-fatigue levels with a significant negative association for extraversion (P < .001) and a positive association for openness (P < .001). Conclusion: The findings suggest that mental fatigue is a considerable factor in the elite athletic environment. Extraversion and openness moderate perceived mental fatigue across a season. These findings underscore the importance of considering individual differences when interpreting subjective fatigue and when designing support strategies for athletes.
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