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Mental load and fatigue are important causes of performance decreases and accidents in different activities. However, a robust systematic review, detailing the instruments used to quantify them, is currently lacking. The purpose of this study was to summarize and classify by derivations the validated instruments used to quantify mental load and fatigue. The most representative electronic databases in the scope of this review, PubMed, WOS, Scopus, SPORTDiscus, and PsycINFO (until September 2020) were searched for studies that included instruments to analyze mental load and fatigue. The quality of the selected studies was scored using a quality assessment checklist. A total of 40 papers were included. Most of the papers used subjective scales (75%) to quantify mental load and fatigue, with a small presence of behavioral (n = 5) and objective techniques (n = 5). Less is known about the analysis of mental load and fatigue using a combination of derivations. Despite the high cost and complexity of objective techniques, research that applies these measures is important for further analysis of brain processes in mental load and fatigue. The design of a battery of tests that include the three types of derivations also seems necessary.

Fatigue is usually defined as a subjective perception of lacking energy, mentally or physically, with a difficulty sustaining voluntary activities. It is a common symptom of many diseases and most likely has a multifactorial cause. In myasthenia gravis (MG), fatigue has a high prevalence and is correlated with female sex and disease severity. However, no large scale studies have been performed. Therefore, we aimed to evaluate fatigue in the Dutch participants (n = 420) of the Dutch-Belgian Myasthenia Patient Registry using an online survey. Additional information was obtained on mood, sleep, coping, quality of life, disease severity, physical activities and medication. Severe fatigue was present in 62% with a mean score of 37.1 +/- 13.2 points. Fatigue severity and prevalence increased significantly with disease severity. A positive correlation was found for female gender, BMI, disease severity and depressive symptoms. A negative correlation was found for strenuous physical activities and older age. The strong association with disease severity suggests that fatigue should be recognized as an element of the symptomatology of MG. The observed association between strenuous activity and fatigue and differences in coping style between fatigued and non-fatigued patients warrant future clinical trials on exercise and cognitive behavioral therapy. (C) 2021 The Authors. Published by Elsevier B.V.

Introduction Although fatigue is a well-studied concept in neurological disease, cognitive fatigability (CF) is less understood. While most studies measure fatigue using subjective self-report, fewer have measured CF objectively. Given the negative impact of CF on quality-of-life, there is a need for targeted interventions. The objective of this review was to determine which procedural, behavioural and pharmacological treatments for objectively measured CF are available to people living with neurological conditions. Methods In accordance with the PRISMA guidelines, systematic searches for randomized control trials (RCTs), case-controlled studies and case reports/series were conducted across the Ovid Medline, PsycInfo, EMBASE and Cochrane Library databases. English-language articles published between 1980 and February 2019 were considered for eligibility. Included were those that objectively measured CF in individuals with neurological disease/disorder/dysfunction between the ages of 18 and 65 years. Studies were reviewed using a modified Cochrane Data Extraction Template. Risk of bias was assessed using the Cochrane Risk of Bias tool. The review process was facilitated using Covidence software (www.covidence.org). Two authors reviewed articles independently, with a third resolving conflicts regarding article inclusion. Results The search identified 450 records. After duplicates were removed and remaining titles/abstracts were screened for eligibility, 28 full-text articles were assessed, and two studies were included in the qualitative synthesis. Studies were a priori divided into those with pharmacological, procedural or behavioural interventions. Two studies met eligibility criteria; both of these included participants with multiple sclerosis. One study utilized a procedural intervention (i.e. transcranial direct current stimulation), while the other utilized a pharmacological intervention (i.e. fampridine-SR). Studies were evaluated for risk of bias, and evidence from both eligible studies was discussed. Conclusion Despite the positive results of the procedural intervention, the paucity of eligible studies and the nascent nature of the field suggests that more studies are required before firm conclusions can be drawn regarding the amenability of CF to treatment. Trial registration The review was registered with PROSPERO (CRD42019118706). Electronic supplementary material The online version of this article (10.1007/s40120-019-00158-3) contains supplementary material, which is available to authorized users.

Background: The importance of the serve in tennis players’ performance is well known but no previous studies have analyzed the effects of both physical and cognitive fatigue on the speed and accuracy of the serve. This study analyzed the effect of a High-Intensity Interval Training (HIIT) with and without cognitive load on serve speed and accuracy, spirometry, and strength manifestation. Methods: 32 recreational players (25 men and 7 women, aged 21.40 ± 1.52 years) performed a HIIT and a HIIT with a Stroop in recovery phases before performing a series of tennis services. Speed and accuracy of the services, spirometry, and strength manifestations were registered. Results: The main findings of the study showed that strength manifestations and spirometry were not affected by either protocol. A decrease in serve speed was observed in both protocols (p &lt, 0.001) but service accuracy did not show impairments (p = 0.66). Conclusion: A combination of physical and mental fatigue may decrease serve speed but will not affect strength manifestations or spirometry negatively. These results could be caused by a response of the central nervous system to maintain the accuracy of the ball in presence of fatigue.

Fatigue induced by sustained cognitive demands often entails decreased behavioural performance and the unavailability of brain resources, either due to reduced levels or impaired access. In the present study, we investigated the neural dynamics underlying preserved behavioural performance after inducing cognitive fatigue (CF) in a sleep deprivation (SD) condition in which resources are naturally compromised. Using functional near infrared spectroscopy (fNIRS), we recorded cortical brain activity during task-related CF induction in the evening, in the middle of the night and early in the morning. Although cortical oxygenation similarly increased over the 3 sessions, decreased intra-hemispheric connectivity between left anterior frontal and frontal areas paralleled a sudden drop in task performance in the early morning. Our data indicate that decreased sustained attention after the induction of cognitive fatigue in a situation of high sleep pressure results from impaired connectivity between left prefrontal cortical areas rather than from a mere modulation in brain resources., SCOPUS: ar.j, info:eu-repo/semantics/published

Purpose This study explored conflicting findings in the literature on the influence of perceived cognitive fatigue on physical performance by testing the effect of the Stroop task (high cognitive load) on an intermittent running test (beep test). Methods In a within-subjects repeated-measures experiment, 13 active athletes performed the beep test on two occasions, in a randomized, counterbalanced order. In each session, a preceding cognitive task was completed for 30 min, with the incongruent Stroop task in the high load condition, and the congruent Stroop task in the low load condition. Perceived cognitive fatigue was measured before testing (baseline) and at 10, 20, and 30 min of the cognitive load manipulation. Perceived effort on the cognitive task and general motivation for the physical task (beep test) were measured before the beep test, and motivation-related perception of the beep test and ratings of perceived exertion were measured after completion of the test. Heart rate and beep test performance (completion stage and time) were also recorded. Results The incongruent Stroop task was perceived as more fatiguing and effortful. Participants also withdrew from the beep test significantly earlier in the high load condition (M = 8:48 min, SD = 2:32 min) compared to the low load condition (M = 9:20 min, SD = 2:28 min), F (1,11) = 21.76, P < 0.01, ŋ2 = 0.67. There were no differences in heart rate or general motivation between the two conditions. Conclusions Whereas previous research shows that active athletes can maintain performance on the beep test after 10 min of the incongruent Stroop task, this study shows that performance is impaired after 30 min. Variables in need of exploration in future investigations include experience with both the physical and cognitive task.

Purpose This study examined the aftereffects of cognitively demanding acute aerobic exercise on working memory in middle-age individuals. Methods In a within-participants design, middle-age males (n = 28) performed a two-back task to assess working memory before, immediately after, and 30 min after the following three interventions: 1) a rest-cognition intervention, in which they performed a cognitive task on a cycle ergometer without exercising; 2) an exercise-cognition intervention, in which they simultaneously exercised on a cycle ergometer and performed a cognitive task; and 3) an exercise-only intervention, in which they only exercised on a cycle ergometer. Results The exercise-only intervention resulted in increased hit rate and decreased reaction times and intraindividual variability on correct rejection trials, suggesting that simple aerobic exercise had a beneficial impact on working memory. By contrast, the exercise-cognition intervention resulted in increased intraindividual variability on correct rejection trials, which is suggestive of cognitive fatigue resulting from the additional cognitive demands. Such a decline was not observed even in the rest-cognition condition. Conclusions Cognitive fatigue caused by additional cognitive demands during aerobic exercise may cancel beneficial postexercise effects on working memory. Cognitively demanding acute aerobic exercise appears to be less effective than simple aerobic exercise in improving executive function.

Background Multiple sclerosis is a chronic disease leading to reduced quality of life. Objectives To investigate whether motor and cognitive fatigue impact differently on aspects of quality of life among patients with multiple sclerosis, independently from bodily disability. Methods 79 patients with multiple sclerosis from Aalborg University Hospital, Denmark were included in an observational, cross-sectional study. Each subject completed two separate questionnaires regarding fatigue (Fatigue Scale for Motor and Cognitive Functions and Modified Fatigue Impact Scale) and one regarding quality of life (Short Form 36). Disability was measured with the Expanded Disability Status Scale (EDSS)-scores obtained from patient records. Results All fatigue scores were significantly correlated to all areas of quality of life (p Conclusion Increased motor and cognitive fatigue lead to a differential reduction in physical and mental quality of life, independently of bodily disability. This underlines the importance of proper assessment and treatment of fatigue among patients with multiple sclerosis.

When we are fatigued, we feel that our performance is worse than when we are fresh. Yet, for over 100 years, researchers have been unable to identify an objective, behavioral measure that covaries with the subjective experience of fatigue. Previous work suggests that the metrics of signal detection theory (SDT)—response bias (criterion) and perceptual certainty (d’)—may change as a function of fatigue, but no work has yet been done to examine whether these metrics covary with fatigue. Here, we investigated cognitive fatigue using SDT. We induced fatigue through repetitive performance of the n-back working memory task, while functional magnetic resonance imaging (fMRI) data was acquired. We also assessed cognitive fatigue at intervals throughout. This enabled us to assess not only whether criterion and d’ covary with cognitive fatigue but also whether similar patterns of brain activation underlie cognitive fatigue and SDT measures. Our results show that both criterion and d’ were correlated with changes in cognitive fatigue: as fatigue increased, subjects became more conservative in their response bias and their perceptual certainty declined. Furthermore, activation in the striatum of the basal ganglia was also related to cognitive fatigue, criterion, and d’. These results suggest that SDT measures represent an objective measure of cognitive fatigue. Additionally, the overlap and difference in the fMRI results between cognitive fatigue and SDT measures indicate that these measures are related while also separate. In sum, we show the relevance of SDT measures in the understanding of fatigue, thus providing researchers with a new set of tools with which to better understand the nature and consequences of cognitive fatigue.

International audience; The effects of mental fatigue on both cognitive and physical performance are well described in the literature, but the recovery aspects of mental fatigue have been less investigated. The present study aimed to fill this gap by examining the persistence of mental fatigue on behavior and electrophysiological mechanisms. Fifteen participants performed an arm-pointing task consisting of reaching a target as fast as possible, before carrying out a 32-min cognitively demanding task [Time Load Dual Back (TLDB) task], and immediately, 10 and 20 min after completion of the TLDB task. During the experiment, electroencephalography was continuously recorded. The significant increase in mental fatigue feeling after the TLDB task was followed by a decrease during the 20 min of recovery without returning to premeasurement values. Brain oscillations recorded at rest during the recovery period showed an increase in both theta and alpha power over time, suggesting a persistence of mental fatigue. Arm-pointing movement duration increased gradually over time during the recovery period, indicating that behavioral performance remained impaired 20 min after the end of the cognitively demanding task. To conclude, subjective measurements indicated a partial recovery of mental fatigue following a cognitively demanding task, whereas electrophysiological and behavioral markers suggested that the effects of mental fatigue persisted for at least 20 min. While the subjective evaluation of mental fatigue is a very practical way to attest the presence of mental fatigue, electrophysiological and behavioral measures seem more relevant to evaluate the time course of mental fatigue effects.Introduction

The advent of mobile electroencephalography (mEEG) has created a means for large scale collection of neural data thus affording a deeper insight into cognitive phenomena such as cognitive fatigue. Cognitive fatigue – a neural state that is associated with an increased incidence of errorful performance – is responsible for accidents on a daily basis which at times can cost human lives. To gain better insight into the neural signature of cognitive fatigue in the present study we used mEEG to examine the relationship between perceived cognitive fatigue and human-event related brain potentials (ERPs) and electroencephalographic (EEG) oscillations in a sample of 1,000 people. As a secondary goal, we wanted to further demonstrate the capability of mEEG to accurately measure ERP and EEG data. To accomplish these goals, participants performed a standard visual oddball task on an Apple iPad while EEG data were recorded from a Muse EEG headband. Counter to traditional EEG studies, experimental setup and data collection was completed in less than seven minutes on average. An analysis of our EEG data revealed robust N200 and P300 ERP components and neural oscillations in the delta, theta, alpha, and beta bands. In line with previous findings we observed correlations between ERP components and EEG power and perceived cognitive fatigue. Further, we demonstrate here that a linear combination of ERP and EEG features is a significantly better predictor of perceived cognitive fatigue than any ERP or EEG feature on its own. In sum, our results provide validation of mEEG as a viable tool for research and provide further insight into the impact of cognitive fatigue on the human brain.

International audience; Recent literature suggests that when prolonged, motor imagery (MI) induces mental fatigue and negatively impacts subsequent physical exercise. The aim of this study was to confirm this possibility with neurophysiological and self-reported measures. Thirteen participants performed 200 imagined isometric knee extension contractions (Prolonged MI condition) or watched a documentary (Control condition), and then performed 150 actual isometric knee extensions. Electroencephalography was continuously recorded to obtain motor-related cortical potential amplitude at Cz electrode (MRCP, index of motor area activity) for each imagined and actual contraction. Electromyography of the vastus lateralis muscle as well as the perceived effort required to perform prolonged MI, watch the documentary, and perform the actual contractions were measured. During prolonged MI, mental fatigue level, the effort required to imagine the contractions and MRCP amplitude increased over time. The increase in the effort required to imagine the contractions was significantly correlated with the MRCP amplitude. During the physical exercise, a significant condition × time interaction revealed a greater increase over time in perceived effort in the prolonged MI condition compared to the control condition, as well as a specific alteration in EMG RMS of the vastus lateralis muscle. These alterations observed in the presence of mental fatigue during actual contractions, combined with those observed during prolonged MI, suggest that prolonged MI may impair the motor command required to perform imagined or actual contractions. While the observed effect of mental fatigue on MRCP amplitude was clear during MI, future studies should tailor the physical exercise to minimize the exercise-induced decrease in force production capacity and control for its confounding effects on MRCP amplitude in the presence of mental fatigue.

Purpose It is well established that mental fatigue impairs performance during lab-based endurance tests lasting less than 45 min. However, the effects of mental fatigue on longer duration endurance events and in field settings are unknown. The aim of this study was to investigate the effect of mental fatigue on performance during a half-marathon race. Methods Forty-six male amateur runners (means ± SD: age 43.8 ± 8.6 years, $$\dot V{O_{2peak}}$$ V ˙ O 2 p e a k 46.0 ± 4.1 ml/kg/min) completed a half-marathon after being randomly allocated to performing a 50-min mentally fatiguing task (mental fatigue group) or reading magazines for 50 min (control group). Running speed, heart rate, and perceived effort were measured during the race. Results Runners in the mental fatigue group completed the half-marathon approximately 4 min slower (106.2 ± 12.4 min) than those in the control group (102.4 ± 10.2 min), but this difference was not statistically significant (Cohen’s d = 0.333; p = 0.265). However, equivalence was not established [t(40.88) = 0.239, p = 0.594] and equivalence testing analysis excluded a beneficial effect of mental fatigue on half-marathon performance. Conclusion Due to its posttest-only design and the achievable sample size, the study did not have enough power to provide evidence that the observed 4-min increase in half-marathon time is statistically significant. However, equivalence testing suggests that mental fatigue has no beneficial effect on half-marathon performance in male amateur runners, and a harmful effect cannot be excluded. Overall, it seems prudent for endurance athletes to avoid mentally fatiguing tasks before competitions.

The pathophysiology of cognitive dysfunction in multiple sclerosis (MS) is still unclear. This magnetoencephalography (MEG) study investigates the impact of MS on brain resting‐state functional connectivity (rsFC) and its relationship to disability and cognitive impairment. We investigated rsFC based on power envelope correlation within and between different frequency bands, in a large cohort of participants consisting of 99 MS patients and 47 healthy subjects. Correlations were investigated between rsFC and outcomes on disability, disease duration and 7 neuropsychological scores within each group, while stringently correcting for multiple comparisons and possible confounding factors. Specific dysconnections correlating with MS‐induced physical disability and disease duration were found within the sensorimotor and language networks, respectively. Global network‐level reductions in within‐ and cross‐network rsFC were observed in the default‐mode network. Healthy subjects and patients significantly differed in their scores on cognitive fatigue and verbal fluency. Healthy subjects and patients showed different correlation patterns between rsFC and cognitive fatigue or verbal fluency, both of which involved a shift in patients from the posterior default‐mode network to the language network. Introducing electrophysiological rsFC in a regression model of verbal fluency and cognitive fatigue in MS patients significantly increased the explained variance compared to a regression limited to structural MRI markers (relative thalamic volume and lesion load). This MEG study demonstrates that MS induces distinct changes in the resting‐state functional brain architecture that relate to disability, disease duration and specific cognitive functioning alterations. It highlights the potential value of electrophysiological intrinsic rsFC for monitoring the cognitive impairment in patients with MS., This MEG study demonstrates that MS induces distinct changes in the resting‐state functional brain architecture that relate specifically to disability, disease duration and specific cognitive functioning alterations. It highlights the potential value of electrophysiological intrinsic rsFC for monitoring the cognitive impairment in patients with MS.

Purpose: The aim of the study was to verify the effect of mental fatigue on tactical actions quality and the intensity of covered distance in soccer players. Methods: Six U-15 male soccer players participated in this study (14.7 ± 0.59 years of age). For data collection, the FUTSAT and GPSports® (SPI-HPU) systems were applied. To induce mental fatigue, the Stroop task was used for 20 minutes. The individuals were evaluated in 2 conditions: mental fatigue and control (with and without the Stroop task). Statistical analysis was performed with the Kolmogorov-Smirnov test, t-test, and Wilcoxon test. Results: The results displayed significant differences in actions related to principles of balance (p = 0.02), defensive unity (p < 0.01), and total defensive actions (p = 0.02), as well as in the covered distance in intensity related to zones 3 (p = 0.03) and 6 (p < 0.01). In mental fatigue, the players revealed a decrease in tactical action quality referring to movements that aimed at numerical stability in relations of opposition and at defending in unity and in block, and covered greater distances in zones 3 and 6. Conclusions: Mental fatigue modified the players' movement dynamics on the pitch with reference to the quality of tactical actions and covered distance intensity.

Introduction: Mental fatigue is associated with a shift of electroencephalography (EEG) power towards low-frequency bands [theta, alpha(a)], which is suggested to be related to a decrease in the level of arousal. In addition a decrease in the amplitude of event related brain potentials like P2 (i.e. an index of activity engaged in selection of relevant information) is also observed with the occurrence of mental fatigue. In order to further elucidate the role of these brain alterations in the occurrence of mental fatigue we sought to prevent them with a caffeine-maltodextrin (CAF-MALT) mouth rinse intervention during a mentally fatiguing task. Methods: Ten active healthy males (age: 23±2y, physical activity: 7.3±4.3h/week), which were all low CAF users (101±97mg/day), performed two experimental trials in a randomized crossover order. In both trials participants first completed a baseline Flanker task (3min). Next they performed a 90-min mentally fatiguing task (Stroop task), that was immediately followed by aFlanker task. Before the start and after each 12.5% of the Stroop task (8 blocks of 11min) subjects received either a CAF-MALT mouth rinse (MR; 0.3g/25ml CAF; 1.6g/25ml MALT) or placebo (PLAC; 25ml artificial saliva). To measure mental fatigue, physiological and psychological measures were assessed. EEG (32 active electrodes) was applied throughout the experiment to record brain activity. Normality was checked, repeated measure ANOVAs were employed to observe interaction and/or main effects of condition and/or time. Follow up tests were performed where necessary (p

Cognitive fatigue is an alteration in central nervous system (CNS) processing due to prolonged performance of mentally demanding tasks. Decreased gait speed and increased stride length variability have been noted in cognitively fatigued older adults (≥ 65 years). Further, cognitive fatigue may weaken the visual, vestibular, and proprioceptive systems of the CNS, contributing to increased postural sway. Detriments in gait and sway caused by cognitive fatigue could increase fall risk. The objective of this literature review was to evaluate the impact of cognitive fatigue on changes in gait and postural sway and its role in fall risk., Highlights • Cognitive fatigue may cause gait disturbances in older adults (≥ 65 years). • Cognitive fatigue may increase postural sway in older adults. • Cognitive fatigue may be considered a fall risk for older adults. • Interventions to attenuate cognitive fatigue should be further explored. • Studies should explore the role of cognitive fatigue in fall risk.

Multidisciplinary oncology team meetings (MDMs) or tumor boards, like other MDMs in healthcare, facilitate the incorporation of diverse clinical expertise into treatment planning for patients. Decision-making (DM) in relation to treatment planning in MDMs is carried out repeatedly until all patients put forward for discussion have been reviewed. Despite continuing financial pressure and staff shortages, the workload of cancer MDMs, and therefore meeting duration continue to increase (up to 5 h) with patients often receiving less than 2 min of team input. This begs the question as to whether the current set-up is conducive to achieve optimal DM, which these multi-specialty teams were set out to achieve in the first place. Much of what it is known, however, about the effects of prolonged cognitive activity comes from various subfields of science, leaving a gap in applied knowledge relating to complex healthcare environments. The objective of this review was thus to synthesize theory, evidence and clinical practice in order to bring the current understanding of prolonged, repeated DM into the context of cancer MDMs. We explore how and why time spent on a task affects performance in such settings, and what strategies can be employed by cancer teams to counteract negative effects and improve quality and safety. In the process, we propose a pragmatic framework of repeated DM that encompasses the strength, the process and the cost-benefit models of self-control as applied to real-world contexts of cancer MDMs. We also highlight promising research avenues for closing the research-to-practice gap. Theoretical and empirical evidence reviewed in this paper suggests that over prolonged time spent on a task, repeated DM is cognitively taxing, leading to performance detriments. This deterioration is associated with various cognitive-behavioral pitfalls, including decreased attentional capacity and reduced ability to effectively evaluate choices, as well as less analytical DM and increased reliance on heuristics. As a short to medium term improvement for ensuring safety, consistently high quality of care for all patients, and the clinician wellbeing, future research and interventions in cancer MDMs should address time-on-task effects with a combination of evidence-based cognitive strategies. We propose in this review multiple measures that range from food intake, short breaks, rewards, and mental exercises. As a long term imperative, however, capacity within cancer services needs to be reviewed as well as how best to plan workforce development and service delivery models to achieve population coverage whilst maintaining safety and quality of care. Hence the performance detriments that arise in healthcare workers as a result of the intensity (time spent on a task) and complexity of the workload require not only more research, but also wider regulatory focus and recognition.

Cognitive fatigue (CF) is among the most common and disturbing aging symptoms, and substantially interferes with activities demanding sustained mental effort. Here we examined the relationship between the cortical-striatal network and CF (assessed by the 18-item visual analogue scale) when a group of cognitively and physically healthy older adults participated in a 30-minute cognitively fatiguing task-related fMRI experiment. We also explored whether CF would interfere with the "Posterior-Anterior Shifting in Aging" (PASA) phenomenon, an aging-associated neural reliance on frontal regions to support cognitive capacity. We revealed that decreased connectivity strength of the cortical-striatal network over the course of the task was related to higher CF. Correlation between CF and the cortical-striatal network was more robust in anterior relative to posterior components. Moreover, a positive relationship between reliance on the anterior part of the cortical-striatal network and cognitive performance only existed among older adults experiencing low CF. These findings suggest a crucial role of the cortical-striatal network, especially the anterior component, in linking to CF. The PASA phenomenon may only be applicable to older adults without vulnerability to CF.

Sustained cognitive demands may result in cognitive fatigue (CF), eventually leading to decreased behavioral performance and compromised brain resources. In the present study, we tested the hypothesis that transcranial direct current stimulation (tDCS) would counteract the behavioral and neurophysiological effects of CF. Twenty young healthy participants were tested in a within-subject counterbalanced order across two different days. Anodal tDCS (real vs. sham) was applied over the left prefrontal cortex. In the real tDCS condition, a current of 1.5 mA was delivered for 25 min. Cortical oxygenation changes were measured using functional Near Infrared Spectroscopy (fNIRS) on the frontal cortices. CF was triggered using the TloadDback task, a sustained working memory paradigm that allows tailoring task demands according to each individual's maximal cognitive capacity. Sustained cognitive load-related effects were assessed using pre- versus post-task subjective fatigue and sleepiness scales, evolution of performance accuracy within the task, indirect markers of dopaminergic activity (eye blinks), and cortical oxygenation changes (fNIRS) both during the task and pre- and post-task resting state periods. Results consistently disclosed significant CF-related effects on performance. Transcranial DCS was not effective to counteract the behavioral effects of CF. In the control (sham tDCS) condition, cerebral oxygen exchange (COE) levels significantly increased in the right hemisphere during the resting state immediately after the induction of CF, suggesting a depletion of brain resources. In contrast, tDCS combined with CF induction significantly shifted interhemispheric oxygenation balance during the post-training resting state. Additionally, increased self-reported sleepiness was associated with brain activity in the stimulated hemisphere after recovery from CF during the tDCS condition only, which might reflect a negative middle-term effect of tDCS application., SCOPUS: ar.j, info:eu-repo/semantics/published

International audience; There is growing interest for implementing tools to monitor cognitive performance in naturalistic environments. Recent technological progress has allowed the development of new generations of brain imaging systems such as dry electrodes electroencephalography (EEG) and functional near infrared spec- troscopy (fNIRS) to investigate cortical activity in a variety of human tasks out of the laboratory. These highly portable brain imaging devices offer interesting prospects to implement passive brain computer interfaces (pBCI) and neuroadaptive technology. We developed a fNIRS-EEG based pBCI to monitor cognitive fatigue using engagement related features (EEG engagement ratio and wavelet coherence fNIRS based metrics). This mental state is known to impair cognitive performance and can jeopardize flight safety. In this preliminary study, four participants were asked to perform four identical traffic patterns along with a secondary auditory task in a flight simulator and in an actual light aircraft. The two first traffic patterns were considered as the low cognitive fatigue class, whereas the two last traffic patterns were considered as the high cognitive fatigue class. As expected, the pilots missed more auditory targets in the second part than in the first part of the experiment. Classification accuracy reached 87.2% in the flight simulator condition and 87.6% in the actual flight conditions when combining the two modalities. This study demonstrates that fNIRS and EEG-based pBCIs can monitor mental states in operational and noisy environments.

This study aimed to investigate the impact of mental fatigue on soccer-specific decision-making. Twelve well-trained male soccer players performed a soccer-specific decision-making task on two occasions, separated by at least 72 h. The decision-making task was preceded in a randomised order by 30 min of the Stroop task (mental fatigue) or 30 min of reading from magazines (control). Subjective ratings of mental fatigue were measured before and after treatment, and mental effort (referring to treatment) and motivation (referring to the decision-making task) were measured after treatment. Performance on the soccer-specific decision-making task was assessed using response accuracy and time. Visual search behaviour was also assessed throughout the decision-making task. Subjective ratings of mental fatigue and effort were almost certainly higher following the Stroop task compared to the magazines. Motivation for the upcoming decision-making task was possibly higher following the Stroop task. Decision-making accuracy was very likely lower and response time likely higher in the mental fatigue condition. Mental fatigue had unclear effects on most visual search behaviour variables. The results suggest that mental fatigue impairs accuracy and speed of soccer-specific decision-making. These impairments are not likely related to changes in visual search behaviour.

Patients with multiple sclerosis (MS) disease frequently experience fatigue as their most debilitating symptom. Fatigue in MS partially refers to a cognitive component, cognitive fatigue (CF), characterized by a faster and stronger than usual development of the subjective feeling of exhaustion that follows sustained cognitive demands. The feeling of CF might result from supplementary task-related brain activity following MS-related demyelination and neurodegeneration. Besides, CF in MS disease might also stem from disrupted sleep. The present study investigated the association between the triggering of CF, task-related brain activity and sleep features. In a counterbalance mixed design, 10 patients with MS and 11 healthy controls were exposed twice for 16 min to a CF-inducing dual working memory updating task (TloadDback) under low or high cognitive demands conditions, counterbalanced. Considering known inter-individual differences and potential cognitive deficits in MS, the maximal cognitive load of the task was individually adapted to each participant's own upper limits. During the experimental sessions, cortical brain activity was measured using near-infrared spectroscopy (NIRS) during the CF-induction task, and in a resting state immediately before and after. Ambulatory polysomnography recordings were obtained on the nights preceding experimental sessions. When cognitive load was individually adapted to their processing capabilities, patients with MS exhibited similar than healthy controls levels of subjectively perceived CF, evolution of performance during the task, and brain activity patterns. Linear mixed models indicate a negative association between oxygenation level changes in the dorsolateral prefrontal cortex (DLPFC) and the triggering of subjective CF in patients with MS only. Longer total sleep time was also associated with higher CF in MS patients. These results suggest that controlling for cognitive load between individuals with and without MS results in a similar task-related development of subjective CF. Besides comparable performance and cortical brain activity between groups, mixed model analyses suggest a possible association between CF, DLPFC activity and sleep duration in MS disease., SCOPUS: ar.j, info:eu-repo/semantics/published

A lack of task workload can lead to drivers' cognitive fatigue and vigilance decrement during a prolonged drive. This study examined the effects of speed variability on driving fatigue in a monotonous drive. Twenty-one participants participated in a 60-min simulated driving task. All participants' cognitive fatigue was assessed using psychological and physiological measurements. Results showed that among all participants, variability of vehicle speed was negatively correlated with sleepiness and hypo-vigilance during the driving task. Further, drivers in the large variability group reported less sleepiness, less fatigue, and more vigilance than those in the small variability group did during the driving task. These drivers also presented a smaller electroencephalogram spectral index (𝜃+α)/β during the task, where 𝜃, α, and β are the power spectra of three different frequency bands: theta (𝜃, 4∼8 Hz), alpha (α, 8∼13 Hz), and beta (β, 13∼30 Hz). Our findings suggested that the larger variability of speed within the speed limit may have a deterrent effect on drivers' cognitive fatigue.

Fatigue is such a multifaceted construct it has sprouted specific research fields and experts in domains as different as exercise physiology, cognitive psychology, human factors and engineering, and medical practice. It lacks a consensus definition: it is an experimental concept, a symptom, a risk, a cause (e.g. of performance decrement) and a consequence (e.g. of sleep deprivation). This fragmentation of knowledge leads to slower dissemination of novel insights, and thus to a poorer research. Indeed, what may seem as a novel result in one field, may very well be old news in another, hence leading to this "innovation" being a scientific equivalent to the emperor's new clothes. The current paper aims to describe the common denominator in the different areas of expertise where fatigue is investigated. Indeed, rather than focusing on the differences in semantics and conceptualization, we hope that identifying common concepts may be inductive of easier multidisciplinary research. Considering the vastness of fatigue research in all areas identified as relevant-cognitive science, exercise physiology, and medical practice, this analysis has not the ambition to be an exhaustive review in all domains. We have reviewed the fatigue concepts and research in these areas and report the ones that are used to describe the proposed common model to be further investigated. The most promising common feature to cognitive science, exercise physiology and clinical practice is the notion of "perceived effort." This allows to account for interindividual differences, as well as for the situational variations in fatigue. It is applicable to both mental and physical constructs. It integrates motivational and emotional dimensions. It overcomes current polemics in various research fields, and it does not draw on any semantic ambiguity. We thus suggest a new model of fatigue and performance, whether this performance is mental or physical; and whether it is in a clinical range or relates to optimal functioning., SCOPUS: ar.j, info:eu-repo/semantics/published

International audience; This study aimed at evaluating the effects of mental and muscle fatigue on table tennis performance. Mental fatigue (MF) was induced by completion of 90minutes of the AX-CPT; muscle fatigue was induced by completion of an eccentric exercise performed with the elbow flexors (biceps fatigue, BF) or the knee extensors (quadriceps fatigue, QF). The control condition consisted of watching a movie. Stroke parameters (speed and accuracy of the ball), as well as feelings of fatigue and force production capacity of the elbow flexors (BF, MF and control conditions) and knee extensors (QF condition), were assessed pre and post fatigue protocols. Feelings of fatigue increased post fatigue protocols. Force production capacity decreased only in the BF and QF conditions. BF and MF induced a decrease in accuracy. This decrease in accuracy was associated with an increased ball speed in the BF condition, and a decreased ball speed in the MF condition. QF had a negligible effect on stroke performance. Our results suggest that both mental fatigue, and muscle fatigue, significantly impair table tennis performance and therefore coaches should take into account both the physical and mental state of table tennis players to optimize performance.

The present study explores the cause of cognitive fatigue in persons with traumatic brain injury (TBI), as also in persons with Multiple Sclerosis (MS). Since cognitive fatigue shares many symptoms with chronic sleep deprivation (best described as cumulative excess wakefulness), it was hypothesized that cognitive fatigue is caused by cumulative excess wakefulness because of an impaired sleep efficacy. Recent results about the nature of sleep advocate that sleep aims primarily to replenish the efficiency of cortical inhibitory synapses.We extensively researched in the TBI and MS literature on cognitive fatigue facts that sustained, or invalidate, our hypothesis.We primary focused on TBI, but cognitive fatigue has received much more interest from the MS research community. We therefore used results from the MS literature to consolidate our TBI findings.There are objective reasons related to TBI and MS disease to suppose that NonREM sleep's efficacy is impaired (despite a normal duration of sleep).Strategies providing a more efficient NonREM sleep could demonstrate some therapeutic action against cognitive fatigue.

We examined the effects of aging and cognitive fatigue on working memory (WM) related brain activation using functional magnetic resonance imaging. Age-related differences were investigated in 13 young and 16 middle-aged male school teachers. Cognitive fatigue was induced by sustained performance on cognitively demanding tasks (compared to a control condition). Results showed a main effect of age on left dorsolateral prefrontal and superior parietal cortex activation during WM encoding; greater activation was evident in middle-aged than young adults regardless of WM load or fatigue condition. An interaction effect was found in the dorsomedial prefrontal cortex (DMPFC); WM load-dependent activation was elevated in middle-aged compared to young in the control condition, but did not differ in the fatigue condition due to a reduction in activation in middle-aged in contrast to an increase in activation in the young group. These findings demonstrate age-related activation differences and differential effects of fatigue on activation in young and middle-aged adults. © 2013 Elsevier B.V.

Cognitive fatigue is one of the most frequent symptoms in multiple sclerosis (MS), associated with significant impairment in daily functioning and quality of life. Despite its clinical significance, progress in understanding and treating fatigue is still limited. This limitation is already caused by an inconsistent and heterogeneous terminology and assessment of fatigue. In this review, we integrate previous literature on fatigue and propose a unified schema aiming to clarify the fatigue taxonomy. With special focus on cognitive fatigue, we survey the significance of objective behavioral and electrophysiological fatigue parameters and discuss the controversial literature on the relationship between subjective and objective fatigue assessment. As MS-related cognitive fatigue drastically affects quality of life, the development of efficient therapeutic approaches for overcoming cognitive fatigue is of high clinical relevance. In this regard, the reliable and valid assessment of the individual fatigue level by objective parameters is essential for systematic treatment evaluation and optimization. Transcranial electrical stimulation (tES) may offer a unique opportunity to manipulate maladaptive neural activity underlying MS fatigue. Therefore, we discuss evidence for the therapeutic potential of tES on cognitive fatigue in people with MS.

Prior investigations have shown measurable performance impairments on continuous physical performance tasks when preceded by a cognitively fatiguing task. However, the effect of cognitive fatigue on bodyweight resistance training exercise task performance is unknown. In the current investigation 18 amateur athletes completed a full body exercise task preceded by either a cognitive fatiguing or control intervention. In a randomized repeated measure design, each participant completed the same exercise task preceded by a 52 minute cognitively fatiguing intervention (vigilance) or control intervention (video). Data collection sessions were separated by 1 week. Participants rated the fatigue intervention as being significantly more mentally demanding than the control intervention (p < .001). Additionally, participants self-reported significantly greater energetic arousal for cognitively fatiguing task (p = .02). Cognitive fatigue did not significantly impact number of repetitions completed during the exercise task (p = .77); however, when cognitively fatigued, participants had decreased percent time-on-task (57%) relative to the no fatigue condition (60%) (p = .04). RPE significantly changed over time (p < .001), but failed to show significant differences between the cognitive fatigue intervention and control intervention (p > .05). There was no statistical difference for heart rate or metabolic expenditure as a function of fatigue intervention during exercise. Cognitively fatigued athletes have decreased time-on-task in bodyweight resistance training exercise tasks.

Nearly 2 million traumatic brain injuries occur annually, most of which are mild (mTBI). One debilitating sequela of mTBI is cognitive fatigue: fatigue following cognitive work. Cognitive fatigue has proven difficult to quantify and study, but this is changing, allowing models to be proposed and tested. Here, we review evidence for four models of cognitive fatigue, and relate them to specific treatments following mTBI. The evidence supports two models: cognitive fatigue results from the increased work/effort required for the brain to process information after trauma-induced damage; and cognitive fatigue results from sleep disturbances. While there are no evidence-based treatments for fatigue after mTBI, some pharmacological and nonpharmacological treatments show promise for treating this debilitating problem. Future work may target the role of genetics, neuroinflammation and the microbiome and their role in complex cognitive responses such as fatigue.

There is growing evidence to suggest that exposure to natural environments can be associated with mental health benefits. Proximity to greenspace has been associated with lower levels of stress (Thompson et al., 2012) and reduced symptomology for depression and anxiety (Beyer et al., 2014), while interacting with nature can improve cognition for children with attention deficits (Taylor and Kuo, 2009) and individuals with depression (Berman et al., 2012). A recent epidemiological study has shown that people who move to greener urban areas benefit from sustained improvements in their mental health (Alcock et al., 2014). In this paper we critically review evidence indicating that such mental health benefits are associated with the so-called “restorative” properties of natural environments. In particular we focus on the claim that interaction with (or just passive perception of) natural scene content can be linked to the restoration of limited-capacity attentional resources, in comparison to similar exposure to urban or built scene content.

Safe work behaviours rely on accurate perceptions of injury risks, and workers who have a misperception of risk can be injured. Despite the importance of perception-action coupling, little is known about modification of those perceptions with changing physical or cognitive STATE. It is hypothesized that changing values for perceived affordances could evidence these modifications. A better understanding of how worker characteristics (e.g., level of fatigue) affect perceptions of affordance and their corresponding behaviours, may help when developing strategies for ergonomic best practices, particularly in manual material handling (MMH) activities. The aim of this study was to compare safe perceptions of affordance from workers that completed repetitive STATE loading. Seventy-five novice MMH workers (23 male; mean age = 21.43, SD = 3.24) made perceived affordances of their safest horizontal reaching distance (acceptable limit) to complete a model task. STATE loading consisted of physical or cognitive fatigue or a control. The levels of fatigue were assessed at five-minute intervals using Ratings of Perceived Exertion (RPE) values and Multi-Fatigue Inventory (MFI) values, respectively. A significant main effect of TIME indicated a decrease of perceived safest reaching distance observed from baseline through subsequent measurements (p

BACKGROUND: Fatigue is a common complaint in multiple sclerosis (MS) and often interferes with daily functioning. Both clinicians and researchers may need to detect high levels of fatigue impact using a time and effort efficient tool. This study evaluates the psychometric properties of a rapid screening instrument for fatigue impact in multiple sclerosis. METHODS: Three visual analogue scales (VAS) for assessing the impact of fatigue were developed. Sixty two subjects with definite MS (mean age 52 +/- 10.5 years; 29 women) and 24 healthy controls (mean age 52 +/- 14 years; 13 women) completed all VAS scales (range 0-100), the Fatigue Severity Scale (FSS) (range 7-63), the Modified Fatigue Impact Scale (MFIS) (range 0-84) and the Guy's Neurological Disability Scale (GNDS) (range 0-5). All tests were repeated with an interval of maximum three days. To evaluate the reproducibility, intraclass correlations (ICC) were calculated, based on one-way analysis of variance for repeated measurements. Validity was considered by means of correlation coefficients. ROC analysis was used to determine the accuracy of the VAS scales. RESULTS: The ICC of the VAS scales ranged from 0.68 to 0.69. VAS scales showed low to moderate correlation with FSS, MFIS and GNDS (Kendall's tau 0.23-0.45) and were not related with physical or cognitive performance, or with depression. All VAS scales were able to discriminate between subjects with MS and controls. Twenty five subjects with MS had a Fatigue Severity Scale score of 36 or more and were classified into the "fatigue" group. ROC analysis showed that VAS_1 is most useful to classify subjects in the "fatigue" group. A cut-off value of VAS_1 of 59 displayed 76% sensitivity and 72% specificity. When using the MFIS score of 40 or more to classify the groups, VAS_1 remained the strongest tool, with 81% sensitivity and 77% specificity at a cut-off value of 59. CONCLUSION: The VAS for the impact of fatigue on daily life (VAS_1) is a moderately reliable, though valid and useful tool to screen rapidly for fatigue impact in multiple sclerosis. A cut-off value of 59 satisfactorily classifies individuals having severe fatigue with a high impact on daily life. In clinical practice, a more comprehensive assessment of fatigue and the impact on daily life is recommended. ispartof: BMC Neurology vol:6 issue:7032 ispartof: location:AUSTRIA, Vienna status: published