Author(s): JULIAN, R., GUTHARDT, Y., WIRTZ, S., MACMAHON, C., Institution: UNIVERSITY OF MÜNSTER, Country: GERMANY, Abstract-ID: 846

INTRODUCTION:
Mental fatigue has been identified as a significant factor influencing both cognitive and physical performance. While its detrimental effects on cognitive tasks are well-established, its impact on endurance exercise remains debated. This study aimed to examine the influence of mental fatigue on running performance, with a particular focus on how individual differences in personality traits and cognitive inhibition may modulate these effects.
METHODS:
A randomised, counterbalanced crossover design was employed. Thirty recreationally active participants completed two experimental sessions: one involving an intervention using the Mackworth Clock Task and the other involving a control condition with a neutral documentary. Each session was completed by a 3 km self-paced run on an indoor running track at maximal effort, with heart rate and rating of perceived exertion (RPE) measured at multiple time points. Additionally, participants completed assessments of inhibitory control and the Big Five Inventory to explore potential moderating effects. Linear mixed models were used for statistical analysis to account for repeated measures and inter-individual variability. Fixed effects included condition (intervention vs. control), time, and their interaction. Random intercepts were included for each participant to control for baseline differences, and random slopes were incorporated where appropriate to model individual variations in response to the fatigue conditions.
RESULTS:
The intervention condition led to significantly higher subjective mental fatigue ratings (p = .044, eta_p^2 = .13) earlier in the protocol; however, subjective fatigue ratings did not differ between conditions immediately before the physical performance task (p = .202). Despite this, participants in the intervention condition exhibited significantly longer time-to-completion in the physical performance task compared to the control condition (p = .015, eta_p^2 = .18), with an average increase of 21.8 seconds. No significant differences were observed between conditions in RPE (p = .217) or heart rate (p = .820). Personality traits, particularly neuroticism (p = .005, eta_p^2 = .23) and openness (p = .006, eta_p^2 = .23), significantly influenced susceptibility to mental fatigue.
CONCLUSION:
Previous research has indicated a distinction between mental fatigue induced by boredom and that resulting from high cognitive demands. The findings of this study support this distinction. Subjective assessments of mental fatigue revealed no significant differences between conditions before undertaking the endurance task; however, a notable disparity in performance was detected, which could not be attributed to variations in heart rate, RPE, or sleep quality. This implies that different forms of mental fatigue might affect endurance performance in unique ways, regardless of perceived exertion or physiological indicators.