Mental fatigue is a change in psychobiological state caused by prolonged periods of demanding cognitive activity. Although mental fatigue is a common and everyday occurrence, the literature surrounding mental fatigue is almost exclusively limited to its effects on cognitive performance and attention (Lorist 2000,van der Linden, Frese et al. 2003,Boksem,Meijman et al. 2005,van der Linden and Eling 2006,Lorist 2008). In 2009,Samuele Marcora and colleagues published findings suggesting that the effect of mental fatigue extends beyond the impact on cognitive functioning, and impairs the subsequent performance of physical exercise (Marcora, Staiano et al. 2009). The aim of this thesis was therefore to expand on this initial research and further investigate the effect of mental fatigue on physiological, psychological and performance variables during exercise, as well as any possible mechanisms behind the effect. Mental fatigue was experimentally induced and its effect on maximal anaerobic exercise tasks, professional and recreational athletes, and subjects who participated in varying levels of self-regulatory lifestyle behaviours was observed. From these studies, it was determined that maximal anaerobic exercise tasks are largely unaffected by mental fatigue. This finding contrasts the negative effect of mental fatigue on prolonged and submaximal intensity exercise performance. Time trial performance of professional road cyclists was also unaffected by prior mental exertion, whereas recreational cyclists performed worse following mental exertion compared to a control, recording a lower power output and slower average speed. Professional cyclists performed better than recreational cyclists on a mentally fatiguing cognitive task of self-regulation. Following on from this finding, regular performance of self-regulatory lifestyle behaviours including occupational cognitive demand and physical training load were associated with better maintenance of endurance performance with mental fatigue. The findings of the previous three studies, as well as findings from mental fatigue research completed concurrently were then collated to propose a physiological mechanism for the increase in rating of perceived exertion and impaired endurance performance of mentally fatigued participants. This review also sought to explain the apparent increased resistance to mental fatigue of the professional road cyclists. This body of research highlights the individuality of the impact of mental fatigue on physical performance, offers potential protective factors against performance decrements with mental fatigue and proposes a possible physiological mechanism for this effect. This work should be used as a basis for future research investigating the mechanism behind the negative effect of mental fatigue on endurance performance, focusing on neurochemical changes within the brain. Future research may also focus on the efficacy of a training intervention using tasks requiring self-regulation to increase tolerance for those susceptible to performance decrements with mental fatigue.
The impact of mental fatigue on physiological, psychological and performance variables during exercise
Martin, K. M. (Author). 2017
Student thesis: Doctoral Thesis