Previous studies have highlighted that certain cognitive challenges, such as mental fatigue and self-control, may interfere with endurance exercise performance. Although it has been acknowledged that psychological factors could be detrimental for post-exercise recovery, few studies have investigated the role of cognitive challenges in recovery from endurance exercise. Likewise, few investigations have focused on interventions that allow athletes to maintain exercise performance when they deal with external cognitive challenges. The present thesis consisted of four studies with two main aims. Firstly, it investigates mental fatigue in the context of post-exercise recovery. Secondly, it investigates the use of noninvasive brain stimulation (electroencephalogram, EEG, neurofeedback) after a cognitively challenging task to improve endurance exercise performance. The first experiment adopted a multidisciplinary approach to investigate the effect of mental fatigue induced via the performance of 40-min cognitive task on acute post-exercise recovery (90 min) following a 45-min strenuous cycling exercise. Participants completed three randomised laboratory visits, two of which started with the 45-min strenuous cycling task followed by either a 40-min cognitive task or a control condition during which participants viewed a 40-min documentary. In the third visit, participants completed the 40-min cognitive task with no prior 45-min cycling task. Subjective and neurophysiological measures (EEG) indicated that the 40-min cognitive task induced a state of mental fatigue. However, it did not influence the trajectory of the post-exercise recovery markers (e.g., heart rate variability and perceived recovery and cycling time-to-exhaustion test) when compared to the 40-min control documentary. The second study adopted an observational design to investigate the longitudinal effect of daily mental fatigue on perceived post-exercise recovery and morning fatigue and energy dimensions of mood. This time daily self-reported mental fatigue, post-exercise recovery state and mood state were assessed during the two weeks prior to an important race in a sample of 110 amateur endurance
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athletes. A hierarchical linear modelling approach was used to analyse these data. Results indicated that daily mental fatigue and training load were negatively associated with perceived daily post-exercise recovery after controlling for muscle soreness, baseline recovery state and fitness level. Daily mental fatigue and training load also predicted low morning mood state (high fatigue and low energy) after controlling for sleep quality. Despite the impact that mental fatigue may have on athlete’s ability to train and recover, few investigations have highlighted strategies that could counteract this detrimental effect. Hence, the third study consisted of a two-part experiment where participants completed a 12-min EEG-neurofeedback intervention to modify frontal hemispheric asymmetry after a cognitively demanding task. The effect of the intervention was tested on a cycling time-to-exhaustion test. The first part adopted a between-subject design consisting of three experimental groups, two of which received the neurofeedback interventions. The third group acts as a passive control group. The second part adopted a within-subject design. Results indicated that the neurofeedback intervention modified frontal hemispheric asymmetry (p=0.038) and the increased relative left frontal hemispheric activity neurofeedback significantly improved endurance performance (part A: p =.050; part B: p=.028). The second study adopted a multidisciplinary approach to examine the mechanisms of this effect. This time, however, the effect of the intervention on hemispheric asymmetry was not as robust as in the previous study and yielded no significant effect on performance (p=.781). In light of this inconsistency suggestions for how to approach neurofeedback protocols are provided within the discussion of the thesis. Results of this thesis are discussed in relation to motivational processes of mental fatigue and the approach-avoidance motivation model of frontal hemispheric asymmetry.