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

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

doi:10.3389/fphys.2018.00227

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

Front Physiol. 2018 Mar 16:9:227. doi: 10.3389/fphys.2018.00227. eCollection 2018.

Authors

Flávio O Pires^{1

2}, Fernando L Silva-Júnior³, Cayque Brietzke¹, Paulo E Franco-Alvarenga¹, Fabiano A Pinheiro¹, Nanci M de França⁴, Silmar Teixeira³, Tony Meireles Santos^{1

5}

Affiliations

¹ Exercise Psychophysiology Research Group, School of Arts, Sciences and Humanities, University of São Paulo, São Paulo, Brazil.
² Human Movement Science and Rehabilitation Program, Federal University of São Paulo, Santos, Brazil.
³ Brain Mapping and Plasticity Laboratory (LAMPLACE), Federal University of Piauí (UFPI), Parnaíba, Brazil.
⁴ Physical Education Program, Catholic University of Brasilia, Brasília, Brazil.
⁵ Research Center for Performance and Health, Physical Education Program, Federal University of Pernambuco, Pernambuco, Brazil.

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 (TT_20km) (session 1), as well as to perform a VO_2MAX test (session 2). Thereafter, they performed a TT_20km 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 TT_20km while PFC electroencephalography (EEG) was obtained at 10 and 20 km of the TT_20km 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 W_MEAN (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 TT_20km (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 TT_20km.Conclusions: Mentally fatigued recreational cyclists showed impaired performance, altered PFC activation and faster increase in RPE during a TT_20km.

Keywords: EEG; fatigue; motivation; pacing strategy; prefrontal cortex.