Mental Fatigue Alters Cortical Activation and Psychological Responses, Impairing Performance in a Distance-Based Cycling Trial.

Cayque Brietzke,Tony Meireles Santos,Paulo E. Franco-Alvarenga,Nanci M. de França,Fernando L. Silva-Júnior,Flávio O. Pires,Fabiano A. Pinheiro,Silmar Teixeira

doi:10.3389/fphys.2018.00227

Abstract

Purpose: We sought to verify if alterations in prefrontal cortex (PFC) activation and psychological responses would play along with impairments in pacing and performance of mentally fatigued cyclists.Materials and Methods: Eight recreational cyclists performed two preliminary sessions to familiarize them with the rapid visual information processing (RVP) test, psychological scales and 20 km cycling time trial (TT20km) (session 1), as well as to perform a VO2MAX test (session 2). Thereafter, they performed a TT20km either after a RVP test (30 min) or a time-matched rest control session (session 3 and 4 in counterbalanced order). Performance and psychological responses were obtained throughout the TT20km while PFC electroencephalography (EEG) was obtained at 10 and 20 km of the TT20km and throughout the RVP test. Increases in EEG theta band power indicated a mental fatigue condition. Repeated-measures mixed models design and post-hoc effect size (ES) were used in comparisons.Results: Cyclists completed the trial ~2.7% slower in mental fatigue (34.3 ± 1.3 min) than in control (33.4 ± 1.1 min, p = 0.02, very large ES), with a lower WMEAN (224.5 ± 17.9 W vs. 240.2 ± 20.9 W, respectively; p = 0.03; extremely large ES). There was a higher EEG theta band power during RVP test (p = 0.03; extremely large ES), which remained during the TT20km (p = 0.01; extremely large ES). RPE increased steeper in mental fatigue than in control, together with isolated reductions in motivation at 2th km (p = 0.04; extremely large ES), felt arousal at the 2nd and 4th km (p = 0.01; extremely large ES), and associative thoughts to exercise at the 6th and 16th km (p = 0.02; extremely large ES) of the TT20km.Conclusions: Mentally fatigued recreational cyclists showed impaired performance, altered PFC activation and faster increase in RPE during a TT20km.

Highlights

Mental fatigue is a psychophysiological state caused by a prolonged, high-demanding and sustained cognitive activity that induces a feeling of “tiredness” and “lack of energy” (Boksem and Tops, 2008; Ishii et al, 2014)
Mental fatigue may be considered as a threat to a successful performance as this may decrease the ability to deal with aversive sensations and affect the perceived cost-reward relationship during exercise
Overall results showed that a 30 min rapid visual information processing (RVP) test induced mental fatigue

Summary

Introduction

Mental fatigue is a psychophysiological state caused by a prolonged, high-demanding and sustained cognitive activity that induces a feeling of “tiredness” and “lack of energy” (Boksem and Tops, 2008; Ishii et al, 2014). Even in a relatively simple cycling time trial scenario athletes have to use inhibitory control and attentional location on sensory cues while dealing with aversive sensations, in order to adequately regulate their pace and finish the trial as fast as possible (Brick et al, 2016; Martin et al, 2016; Micklewright et al, 2017) In this scenario, mental fatigue may be considered as a threat to a successful performance as this may decrease the ability to deal with aversive sensations and affect the perceived cost-reward relationship during exercise. An impaired inhibitory control (Martin et al, 2016) and attentional location with mental fatigue (Brick et al, 2016) could be involved in

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Results

Conclusion