Author(s): HAUSENDORF, J., GONZALEZ, C., RAKOBOWCHUK, M., Institution: THOMPSON RIVERS UNIVERSITY, Country: CANADA, Abstract-ID: 1960

Introduction
Central fatigue (CF) and exercise-induced peripheral fatigue (PF) have a detrimental effect on cognitive and sport-specific performance [1,2]. Yet, in past research, the exercise stimulus was based on relative intensities related to VO2peak or maximal heart rates, which often induce vastly different muscle metabolic stresses between participants [3].The purpose of this study was to control the metabolic stress within the heavy exercise domain across participants whilst assessing whether the concomitant mental fatigue potentiates sport performance and inhibitory control declines, and whether these declines relate to changes in gaze behaviour.

Methods
In 10 varsity soccer players, we initially identified ventilatory thresholds using a ramp incremental protocol to individually tailor the 45 minute of cycling within the heavy exercise domain. Participants simultaneously performed four continuous blocks of a modified Stroop task which causes subjective mental fatigue with deteriorating task performance after 45 minutes [4]. Before and after exercise, participants completed a Flanker task, measuring response-inhibition accuracy and reaction time. They also performed an interceptive soccer task (ball control) wearing a mobile eye-tracking device to measure gaze. Two external cameras were used to assess qualitative performance of the soccer-specific task.

Results
There was no significant difference in response-inhibition accuracy on the Flanker task before compared to after exercise (Pre: 117, SD=3; Post: 116, SD=3, p=.32). Also, reaction time before exercise did not differ significantly from reaction time after (Pre: 612, SD=100; Post: 567, SD=25, p=.22). Accuracy on the Stroop task was maintained throughout the exercise bout (F (3,24)=1.31, p=.295). Reaction time on the Stroop task did also not change significantly (F(3,24)=0.07, p=.971). Performance on the interceptive soccer task significantly worsened after compared to before mental and physical exercise (Pre: 0.80, SD=0.35; Post: 0.68, SD=0.29, p=.012, d=0.856). Whereas, with exercise only, performance did not decline (Pre: 0.74, SD=0.31; Post: 0.75, SD=0.24, p=.506).

Conclusion
This study effectively induced a similar metabolic stress and similar peripheral fatigue magnitudes across participants. This reduced performance of the interceptive task when combined with a CF stimulus suggesting CF as an important factor contributing to sport performance deterioration. Subsequent, analysis of kinematics and gaze behaviour may explain underlying mechanisms.

References
Dambroz et al. (2022) PLOS ONE 17(7): e0270099
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Van Cutsem et al. (2020) Medicine & Science in Sports & Exercise, 52(1), 120–130