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Mental fatigue reduces exercise performance through an impaired psychological response such as increased perceived exertion. Carbohydrate (CHO) mouth rinses improve exercise performance and perceived exertion likely due to an improved activation in cerebral reward areas, then we investigated if the CHO mouth rinse-improved exercise performance in mentally fatigued individuals was associated with ameliorated reward-related psychological responses. We hypothesised that CHO mouth rinse would be beneficial for mentally fatigued cyclists mainly in high-metabolic disturbance intensities. After familiarization and baseline sessions, well trained cyclists (n = 20) performed a maximal incremental test (MIT) after mental fatigue induction. They completed the MIT either without mouth rinse (MF) or rinsing their mouth with CHO (MF+CHO) or placebo (FM+PLA) solutions at every 25 % of the MIT. Psychological responses such as ratings of perceived exertion (RPE), affective valence, emotional arousal, and motivation were assessed throughout the MIT, while performance was assessed as peak power output and time of exercise. Mental fatigue reduced MIT performance (P < 0.05), but CHO mouth rinse was effective to counteract this deleterious mental fatigue effect (P < 0.05). However, we found null effects of CHO mouth rinses in psychological responses above the VT 2 (P > 0.05) such as RPE, affective valence, emotional arousal, and motivation. Correlational analysis showed a significant, but moderate negative correlation between motivation and time of exercise above the VT 2 when participants used CHO mouth rinse. In conclusion, the ergogenic CHO mouth rinse effects on MIT performance of mentally fatigued cyclists were irrespective of ameliorated psychological responses to exercise., Competing Interests: Declaration of Competing Interest The authors declare no conflict of interest., (Copyright © 2023. Published by Elsevier Inc.)

Background: Studies have shown a relationship between prefrontal cortex (PFC) activation asymmetry and psychological responses to exercise, so that a higher rest activation in left rather than right PFC has been associated with positive psychological responses to exercise such as an improved affect, anxiety and multidimensional arousal states., Purpose: To review: 1) evidence that PFC activation asymmetry before exercise is associated with psychological responses to exercise; 2) protocols of PFC asymmetry determination., Methods: A systematic review (SR) was performed on studies retrieved from the PubMed and Web of Science database up to 04-30-2019. Eligibility criteria were: 1) studies investigating participants submitted to aerobic exercises; 2) including cerebral activation measures through electroencephalography (EEG) before the exercise bout; 3) and psychological measures during or after the exercise bout; 4) original studies., Results: A number of 1901 studies was retrieved from the databases and 1 study was manually inserted. Thereafter, 1858 studies were excluded during the screening stage so that 30 studies remained for the SR. After full reading, 22 studies were excluded and 8 studies composed the final SR. Methodological assessment revealed that 62.5% of the studies showed a low risk of bias, while 34.37% and 3.12% showed either an unclear or a high risk of bias, respectively. Protocols of PFC activation asymmetry used EEG at F3-F4-P3-P4 (3 studies), F3-F4 (2 studies), F3-F4-T3-T4 (1 study), F3-F4-F7-F8-T5-T6-P3-P4 (1 study) and Fp1-Fp2-Fz-F3-F4-F7-F8-Cz-C3-C4-T3-T4-T5-T6-Pz-P3-P4-Oz-O1-O2 (1 study) positions. Most studies (75%) found a higher left PFC activation associated with a greater affect (n = 2), energetic arousal (n = 2), lower anxiety (n = 2) as well as calmness and tired arousal, simultaneously (n = 1)., Conclusions: Although the heterogeneity of PFC asymmetry protocols, reviewed studies showed a low risk of bias, suggesting that a higher left PFC activation is associated with a positive psychological response to exercise., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Purpose: To verify whether caffeine (CAF) could increase the prefrontal cortex (PFC) activation and improve 20 km cycling time trial (TT 20km ) performance in mentally fatigued cyclists., Methods: After preliminary TT 20km , twelve recreational cyclists (VO 2MAX of 58.9 ± 6.2 mL kg min -1 ) performed a familiarization with a cognitive test to induce mental fatigue (MF) and psychological scales. Thereafter, they performed: 2) a baseline TT 20km ; 3) a mentally fatigued TT 20km (MF); 4 and 5) a mentally fatigued TT 20km after CAF (MF + CAF) or placebo (MF + PLA) ingestion, in a double-blind, counterbalanced design. Performance and psychological responses were obtained throughout the TT 20km , while PFC electroencephalography (EEG) theta wave was obtained before and after the mental fatigue test., Results: The mental fatigue-induced increase in EEG theta wave (↑ ~ 4.8%) was reverted with CAF (↓ 8.8%) and PLA ingestion (↓ 4.8%). CAF improved TT 20km performance in mentally fatigued cyclists by reducing time (p = .00; ↓ ~ 1.7%) and increasing W MEAN (p = .00; ↑ ~ 3.6%), when compared to MF + PLA. The RPE-power output ratio was lower (p = .01), but affect (p = .018), motivation (p = .033) and emotional arousal (p = .001) were greater throughout the TT 20km in MF + CAF than in MF + PLA., Conclusions: CAF ingestion improved TT 20km performance and psychological responses in mentally fatigued cyclists, despite the unaltered PFC activation., (Copyright © 2019 Elsevier Inc. All rights reserved.)