Objective Assessments of Mental Fatigue During a Continuous Long-Term Stress Condition

Changes in mental fatigue across preparation and competition periods in elite male Australian football players

This study aimed to measure perceived mental fatigue (MF) across a season in elite male Australian Football (AF) athletes and identify if physical fatigue (PF) or sleep quality (SQ) are associated with perceived MF. Twenty-four elite male AF athletes (25.2 ± 4.4y) rated their MF and PF on visual analogue scales and SQ on a Likert scale each training day of a 38-week season, defined into 7 periods. Linear mixed models determined differences in MF between periods, along with potential relationships of PF and SQ on MF. Repeated measures correlations determined shared variance between MF, PF and SQ. MF was significantly higher Pre-Christmas (baseline) compared to Early In-Season (p < 0.001), Early-Mid In-Season, Late-Mid In-Season and Late In-Season (all p < 0.01). Small effect sizes were observed between Pre-Christmas and Transition, Early In-Season, Early-Mid In-Season, Late-Mid In-Season and Late In-Season MF. Significant interactions were noted between MF and PF (p < 0.001) and MF and SQ (p < 0.01). A positive relationship between MF and PF (r = 0.55, p < 0.001) and inverse relationship between MF and SQ (r=-0.17, p < 0.001) were observed. Perceived MF was highest at the beginning of preparation phase of the season, while increased PF and decreased perceived SQ related to increased perceived MF in elite AF athletes.

The Effects of Mental Fatigue Induced by the Stroop Test on Muscular Endurance Performance and Neuromuscular Activation in Division III Female Athletes

The purpose of this study was to investigate the effect that mental fatigue, as induced by a Stroop test, has on resistance training performance outcomes such as muscular endurance, power output, and neuromuscular activation. Seven female college-aged NCAA Division III student-athletes with at least one year of resistance training experience and were within the 50th percentile for maximal aerobic capacity provided informed consent for participation. During two separate visits, using a within-subject crossover experimental design, subjects completed either the experimental or control condition. Subjects then completed a to-failure leg press test at 50% of their 1-repetition maximum (1RM) followed by an isometric midthigh pull (IMTP) attempt with electromyography (EMG) analysis. The experimental condition consisted of a 30-minute Stroop test, while the control condition consisted of watching 30 minutes of a sitcom. Both activities were completed while cycling at 40% of their aerobic capacity. A NASA Task Load Index (TLX) inventory was administered following the completion of each cycling session to determine the perceived workload and mental fatigue of each activity. While the mentally fatiguing condition was significantly more mentally fatiguing (p = 0.02) than the control condition, mental fatigue did not statistically affect any of the evaluated performance outcomes (p>0.05). These findings suggest that mental fatigue, a common symptom of psychological stress, does not affect resistance-training-related performance outcomes among female athletic populations.

Effects of Covid-19 Emergency and Associated Lockdown Policies on the Normative Expectations for the Personality Assessment Inventory (PAI) and the Rorschach Performance Assessment System (R-PAS)

Standardized personality tests compare the test taker's scores to those of a large sample of individuals representing normative expectations. However, what is psychologically normal in one historical context may not be similarly normal in another, so the recent spread of a new coronavirus, SARS-Cov-2 (COVID-19), may have implications for what should normally be expected of a nonclinical person taking a personality test shortly after this dramatic event. To address this research question, we administered the Personality Assessment Inventory (PAI) and the Rorschach Performance Assessment System (R-PAS) to 60 nonclinical volunteers from Italy and compared their scores with the official normative reference values of the two tests, which had been established before COVID-19. The results of a series of two-sample t-tests indicated that our newly collected sample appeared somewhat less psychologically healthy compared with normative expectations, and these discrepancies were more pronounced on the PAI than on the R-PAS. Implications and future perspectives are discussed.

Fatigue in children using motor imagery and P300 brain-computer interfaces

BACKGROUND

Brain-computer interface (BCI) technology offers children with quadriplegic cerebral palsy unique opportunities for communication, environmental exploration, learning, and game play. Research in adults demonstrates a negative impact of fatigue on BCI enjoyment, while effects on BCI performance are variable. To date, there have been no pediatric studies of BCI fatigue. The purpose of this study was to assess the effects of two different BCI paradigms, motor imagery and visual P300, on the development of self-reported fatigue and an electroencephalography (EEG) biomarker of fatigue in typically developing children.

METHODS

Thirty-seven typically-developing school-aged children were recruited to a prospective, crossover study. Participants attended three sessions: (A) motor imagery-BCI, (B) visual P300-BCI, and (C) video viewing (control). The motor imagery task involved an imagined left- or right-hand squeeze. The P300 task involved attending to one square on a 3 × 3 grid during a random single flash sequence. Each paradigm had respective calibration periods and a similar visual counting game. Primary outcomes were self-reported fatigue and the power of the EEG alpha band both collected during resting-state periods pre- and post-task. Self-reported fatigue was measured using a 10-point visual analog scale. EEG alpha band power was calculated as the integrated power spectral density from 8 to 12 Hz of the EEG spectrum.

RESULTS

Thirty-two children completed the protocol (age range 7-16, 63% female). Self-reported fatigue and EEG alpha band power increased across all sessions (F(1,155) = 33.9, p < 0.001; F = 5.0(1,149), p = 0.027 respectively). No differences in fatigue development were observed between session types. There was no correlation between self-reported fatigue and EEG alpha band power change. BCI performance varied between participants and paradigms as expected but was not associated with self-reported fatigue or EEG alpha band power.

CONCLUSION

Short periods (30-mintues) of BCI use can increase self-reported fatigue and EEG alpha band power to a similar degree in children performing motor imagery and P300 BCI paradigms. Performance was not associated with our measures of fatigue; the impact of fatigue on useability and enjoyment is unclear. Our results reflect the variability of fatigue and the BCI experience more broadly in children and warrant further investigation.

Effect of the period of EEG signals on the decoding of motor information

Decoding movement information from electroencephalogram to construct brain-computer interface has promising applications. The EEG data during the entire motor imagery (MI) period or movement execution (ME) period is generally decoded, and calculation of numerous information and massive dataset is time-consuming. In order to improve decoding efficiency, the joint topographic maps of the brain activation state of 15 subjects were studied during different periods. The results showed that the activation intensity of the preparation period in the motor imagery experiment was higher than during the exercise period, while during the exercise period, the activation intensity was higher than in the preparation period in the movement execution experiment. Hence, the wavelet neural network was used to decode the six-class movements including elbow flexion/extension, forearm pronation/supination and hand open/close in periods of MI/ME. The experimental results show that the accuracy obtained in the preparation period is the highest in the motor imagery experiment, which is 80.77%. On the other hand, the highest accuracy obtained in the exercise period of the movement execution experiment is 79.26%. It further proves that the optimized period is a key decoding factor to reduce the cost of calculation, and this new decoding method is effective to build a more intelligent brain-computer interface system.

Acute combined effects of concurrent physical activities on autonomic nervous activation during cognitive tasks

Backgrounds: The validity of heart rate variability (HRV) has been substantiated in mental workload assessments. However, cognitive tasks often coincide with physical exertion in practical mental work, but their synergic effects on HRV remains insufficiently established. The study aims were to investigate the combined effects of cognitive and physical load on autonomic nerve functions. Methods: Thirty-five healthy male subjects (aged 23.5 ± 3.3 years) were eligible and enrolled in the study. The subjects engaged in n-back cognitive tasks (1-back, 2-back, and 3-back) under three distinct physical conditions, involving isotonic contraction of the left upper limb with loads of 0 kg, 3 kg, and 5 kg. Electrocardiogram signals and cognitive task performance were recorded throughout the tasks, and post-task assessment of subjective experiences were conducted using the NASA-TLX scale. Results: The execution of n-back tasks resulted in enhanced perceptions of task-load feelings and increased reaction times among subjects, accompanied by a decline in the accuracy rate (p < 0.05). These effects were synchronously intensified by the imposition of physical load. Comparative analysis with a no-physical-load scenario revealed significant alterations in the HRV of the subjects during the cognitive task under moderate and high physical conditions. The main features were a decreased power of the high frequency component (p < 0.05) and an increased low frequency component (p < 0.05), signifying an elevation in sympathetic activity. This physiological response manifested similarly at both moderate and high physical levels. In addition, a discernible linear correlation was observed between HRV and task-load feelings, as well as task performance under the influence of physical load (p < 0.05). Conclusion: HRV can serve as a viable indicator for assessing mental workload in the context of physical activities, making it suitable for real-world mental work scenarios.

Lateral prefrontal cortex thickness is associated with stress but not cognitive fatigue in exhaustion disorder

Introduction

Impaired executive functioning, including cognitive fatigue, is a core feature of the long-term stress-related condition exhaustion disorder (ED). Recent research suggests that a key area for executive control, the lateral prefrontal cortex (LPFC), may be mechanistically linked to cognitive fatigue due to stress. Here, we therefore asked if and how stress, the LPFC and cognitive fatigue may be related in ED.

Methods

We used a multimodal cross-sectional study design with high-resolution structural magnetic resonance imaging (MRI), self-reported measures, and path analysis modeling in 300 participants with ED.

Results

We found positive associations between stress and cognitive fatigue, and stress and LPFC thickness,but no association between LPFC thickness and cognitive fatigue. Furthermore, LPFC thickness did not mediate or moderate the association between stress and cognitive fatigue.

Discussion

These findings suggest that LPFC brain morphology is related to perceived stress levels but not cognitive fatigue, expanding previous research on the role of the LPFC in executive functioning. Moreover, the results support the notion that the LPFC may be mechanistically involved in stress-related executive function impairment but prompt further research into if and how this may be related to cognitive symptoms in ED.

Start-of-day oculomotor screening demonstrates the effects of fatigue and rest during a total immersion training program

BACKGROUND

Investigating changes in sleep and fatigue metrics during intensive surgical and trauma skills training, this study explored the dynamic association between oculomotor metrics and fatigue. Specifically, alterations in these relations over extended stress exposure, the influence of time of day, and the impact of fatigue exposure on sleep metrics were examined.

METHODS

Thirty-nine military medical students participated in 6 days of immersion, hyper-realistic, and high-stress experiential casualty training. Participants completed surveys assessing the state of sleepiness with oculomotor tests performed each morning and evening, analyzing eye movement and pupillary change to characterize fatigue. Participants wore Fitbit TM devices to measure overall time asleep and time in each sleep stage during the training.

RESULTS

Fitbit data showed increased average minutes in rapid eye movement, deep sleep, and less time in light sleep from day 1 to day 4. The microsaccade peak velocity-to-displacement ratio exhibited a morning decrease but not in afternoon sessions, indicating repeated but temporary effects of accumulated fatigue. There were no findings regarding pupil reactivity to illumination changes.

CONCLUSION

This study describes characteristics of fatigue measured by rapid and individually calibrated oculomotor tests. It demonstrates oculomotor relationships to fatigue in start-of-day testing, providing a direction for timing for optimal fatigue testing. These data suggest that improved sleep could signal resilience to fatigue during afternoon testing. Further investigation with more participants and longer duration is warranted. A deeper understanding of the interrelationships between training, sleep, and fatigue could improve surgical and military fitness.

A regression model combined convolutional neural network and recurrent neural network for electroencephalogram-based cross-subject fatigue detection

Fatigue, one of the most important factors affecting road safety, has attracted many researchers' attention. Most existing fatigue detection methods are based on feature engineering and classification models. The feature engineering is greatly influenced by researchers' domain knowledge, which will lead to a poor performance in fatigue detection, especially in cross-subject experiment design. In addition, fatigue detection is often simplified as a classification problem of several discrete states. Models based on deep learning can realize automatic feature extraction without the limitation of researcher's domain knowledge. Therefore, this paper proposes a regression model combined convolutional neural network and recurrent neural network for electroencephalogram-based (EEG-based) cross-subject fatigue detection. At the same time, a twofold random-offset zero-overlapping sampling method is proposed to train a bigger model and reduce overfitting. Compared with existing results, the proposed method achieves a much better result of 0.94 correlation coefficient (COR) and 0.09 root mean square error (RMSE) in a within-subject experiment design. What is more, there is no misclassification between awake and drowsy states. For cross-subject experiment design, the COR and RMSE are 0.79 and 0.15, respectively, which are close to the existing within-subject results and better than similar cross-subject results. The cross-subject regression model is very important for fatigue detection application since the fatigue indication is more precise than several discrete states and no model calibration is required for a new user. The twofold random-offset zero-overlapping sampling method can also be used as a reference by other EEG-based deep learning research.

Exploring physical and biological manifestations of burnout and post-traumatic stress disorder symptoms in healthcare workers: a scoping review protocol

INTRODUCTION

The COVID-19 pandemic has strained the mental and physical well-being of healthcare workers (HCW). Increased work-related stress and limited resources have increased symptoms of anxiety, depression, insomnia and post-traumatic stress disorder (PTSD) in this population. Stress-related disorders have been strongly associated with long-term consequences, including cardiometabolic disorders, endocrine disorders and premature mortality. This scoping review aims to explore available literature on burnout, PTSD, and other mental health-associated symptoms in HCW to synthesise relationships with physiological and biological biomarkers that may be associated with increased risk of disease, creating an opportunity to summarise current biomarker knowledge and identify gaps in this literature.

METHODS AND ANALYSIS

This scoping review uses the Arksey and O'Malley six-step scoping review methodology framework. The research team will select appropriate primary sources using a search strategy developed in collaboration with a health sciences librarian. Three reviewers will initially screen the title and abstracts obtained from the literature searches, and two reviewers will conduct independent reviews of full-text studies for inclusion. The research team will be reviewing literature focusing on which burnout and/or PTSD-associated physiological and biological biomarkers have been studied, the methodologies used to study them and the correlations between the biomarkers and HCW experiencing burnout/PTSD. Data extraction forms will be completed by two reviewers for included studies and will guide literature synthesis and analysis to determine common themes.

ETHICS AND DISSEMINATION

This review does not require ethical approval. We expect results from this scoping review to identify gaps in the literature and encourage future research regarding improving biological and physiological biomarker research in HCW. Preliminary results and general themes will be communicated back to stakeholders. Results will be disseminated through peer-reviewed publications, policy briefs and conferences as well as presented to stakeholders to an effort to invest in HCW mental and physical health.

Exploring Physical and Biological Manifestations of Burnout and Post-Traumatic Stress Disorder Symptoms in Healthcare Workers: A Scoping Review Protocol

Introduction

The COVID-19 pandemic has strained the mental and physical well-being of healthcare workers (HCW). Increased work-related stress and limited resources has increased symptoms of anxiety, depression, insomnia, and post-traumatic stress disorder (PTSD) in this population. Stress-related disorders have been strongly associated with long-term consequences including cardiometabolic disorders, endocrine disorders and premature mortality. This scoping review aims to explore available literature on burnout, PTSD, and other mental health-associated symptoms in HCW to synthesize relationships with physiological and biological biomarkers that may be associated with increased risk of disease, creating an opportunity to summarize current biomarker knowledge and identify gaps in this literature.

Methods and Analysis

This scoping review uses the Arksey and O'Malley six-step scoping review methodology framework. The research team will select appropriate primary sources using a search strategy developed in collaboration with a health sciences librarian. Three reviewers will initially screen the title and abstracts obtained from the literature searches, and two reviewers will conduct independent reviews of full-text studies for inclusion. The research team will be reviewing literature focusing on which burnout and/or PTSD-associated physiological and biological biomarkers have been studied, the methodologies used to study them and the correlations between the biomarkers and HCW experiencing burnout/PTSD. Data extraction forms will be completed by two reviewers for included studies and will guide literature synthesis and analysis to determine common themes.

Ethics and Dissemination

This review does not require ethical approval. We expect results from this scoping review to identify gaps in the literature and encourage future research regarding improving biologic and physiologic biomarker research in HCW. Preliminary results and general themes will be communicated back to stakeholders. Results will be disseminated through peer-reviewed publications, policy briefs, and conferences, as well as presented to stakeholders to an effort to invest in HCW mental and physical health.

Strengths and Limitations of This Study

This will be the first scoping review to assess the current understanding of the biologic and physiological impact of burnout on healthcare workers. The target population is restricted to healthcare workers; however, identified research gaps may be used to guide future studies in other high-burnout occupations and industries.This scoping review will be guided by the Arksey and O'Malley six-step methodological framework and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Review checklist.Both peer reviewed manuscript and pre-prints/abstracts will be evaluated, but studies that have not been peer reviewed will be notated in the summary table. Conference abstracts are excluded.Preliminary and final themes and results identified by this scoping review will be communicated to stakeholders, including hospital staff and HCW, to ensure agreement with our interpretation and to convey knowledge gained with our population of interest.This review will advance the field's current understanding of mechanisms connecting the burnout and pathogenic stress to biologic and physiologic outcomes in healthcare workers and provide researchers with gaps in the literature to inform opportunities for future research.

Assessing the development of mental fatigue during simulated flights with concurrent EEG-fNIRS measurement

Mental fatigue (MF) can impair pilots' performance and reactions to unforeseen events and is therefore an important concept within aviation. The physiological measurement of MF, especially with EEG and, in recent years, fNIRS, has gained much attention. However, a systematic investigation and comparison of the measurements is seldomly done. We induced MF via time on task during a 90-min simulated flight task and collected concurrent EEG-fNIRS, performance and self-report data from 31 participants. While their subjective MF increased linearly, the participants were able to keep their performance stable over the course of the experiment. EEG data showed an early increase and levelling in parietal alpha power and a slower, but steady increase in frontal theta power. No consistent trend could be observed in the fNIRS data. Thus, more research on fNIRS is needed to understand its possibilities and limits for MF assessment, and a combination with EEG is advisable to compare and validate results. Until then, EEG remains the better choice for continuous MF assessment in cockpit applications because of its high sensitivity to a transition from alert to fatigued, even before performance is impaired.

Mental fatigue decreases complexity: Evidence from multiscale entropy analysis of instantaneous frequency variation in alpha rhythm

Mental fatigue (MF) jeopardizes performance and safety through a variety of cognitive impairments and according to the complexity loss theory, should represent "complexity loss" in electroencephalogram (EEG). However, the studies are few and inconsistent concerning the relationship between MF and loss of complexity, probably because of the susceptibility of brain waves to noise. In this study, MF was induced in thirteen male college students by a simulated flight task. Before and at the end of the task, spontaneous EEG and auditory steady-state response (ASSR) were recorded and instantaneous frequency variation (IFV) in alpha rhythm was extracted and analyzed by multiscale entropy (MSE) analysis. The results show that there were significant differences in IFV in alpha rhythm either from spontaneous EEG or from ASSR for all subjects. Therefore, the proposed method can be effective in revealing the complexity loss caused by MF in spontaneous EEG and ASSR, which may serve as a promising analyzing method to mark mild mental impairments.

Opposite effect of basic combat training on mood state of recruits with different physical fitness: A study from perspective of fatigue

Objective

Basic combat training (BCT) is a kind of necessary high-intensity training to help each military recruit convert into a qualified soldier. In China, both the physical fatigue and passive psychological state have been observed in new recruits during BCT. However, after same-intensity training, the degree of fatigue and passive mood vary among recruits. Therefore, this study aimed to explore the effect of BCT on mood state of recruits with different physical fitness levels from a perspective of fatigue.

Materials and methods

Before and after BCT, the degree of fatigue and mood state of participants were evaluated via the Borg Rating of Perceived Exertion Scale and Profile of Mood States Questionnaire immediately after 20 push-ups as RPE and POMS scores [total mood disturbance (TMD), passive mood (T_tension, T_anger, T_fatigue, T_depression, and T_confusion) and positive mood (T_vigour and T_esteem)]. The participants were divided into two groups according to the RPE score measured after BCT: (1) group 1: RPE score after BCT < 13 and (2) group 2: RPE score after BCT ≥ 13.

Result

A total of 564 recruits were included (group 1: 456/564, 80.85%; group 2: 108/564, 19.15%). After BCT, in group 1, TMD (from 95.65 ± 17.89 to 87.52 ± 17.63) and passive mood T_tension (from 4.46 ± 3.18 to 3.79 ± 3.14), T_fatigue (from 4.94 ± 3.58 to 3.12 ± 3.04), T_depression (from 2.86 ± 3.41 to 2.01 ± 2.75), T_confusion (3.12 ± 2.72 to 2.42 ± 2.57) declined significantly (all within-group p < 0.001), but positive mood both increased significantly (T_vigour: from 13.21 ± 4.59 to 15.44 ± 5.42, T_esteem: from 9.18 ± 3.36 to 11.04 ± 3.67; both within-group p < 0.001); while in group 2, only T_anger (from 4.27 ± 4.16 to 6.22 ± 5.94, within-group p = 0.001) and T_esteem (from 8.36 ± 3.15 to 9.07 ± 3.67, within-group p = 0.031) increased significantly.

Conclusion

BCT could alleviate passive mood and add to positive mood for recruits with better physical fitness, while had no ameliorative effects on or even deteriorate most of the passive mood for recruits with worse physical fitness.

The neuroelectrophysiological and behavioral effects of transcranial direct current stimulation on executive vigilance under a continuous monotonous condition

A prolonged period of vigilance task will lead to vigilance decrement and a drop in cognitive efficiency. Although transcranial direct current stimulation (tDCS) can be used to improve cognitive performance following vigilance decrement, the findings in this area of study are inconsistent. This study aims to identify the neuroelectrophysiological and behavioral effects of tDCS over the left dorsolateral prefrontal cortex (DLPFC) on executive vigilance under a continuous monotonous condition. We recruited 29 participants who randomly received 30 min active or sham tDCS before the vigilance task (anode electrode at the left DLPFC, cathode electrode at the right supraorbital area). Participants completed four sessions of vigilance task and five sessions of self-report sleepiness, Oddball task, and Go/Nogo task, for a total of about 5 h. EEG was acquired in real-time throughout the experiment. Repeated measures of ANOVA were utilized to analyze the evolution of each metric with task-on-time. The results demonstrated that subjective arousal state, vigilance performance, event-related potentials (ERPs), and EEG power were significantly affected by time on task. Brain stimulation did not significantly affect the evolution of subjective and objective executive vigilance performance, but significantly modulated spontaneous activity in the alpha and beta bands across the entire brain. The continuous enhancement of the prefrontal cortex increased P2 amplitude for the Oddball task, which was associated with the enhancement of the early stage of information processing. P3 amplitude had a temporary enhancement effect, which significantly decreased following a cognitive fatigue. tDCS had a continuous enhancement effect on N2 amplitude for the Go/Nogo task, which was associated with the enhanced inhibition of distracting stimuli. Together, the current data suggest that anodal tDCS over left DLPFC possibly enhances the early stage of relevant information processing and the inhibitory control of distracting stimuli during a continuous and monotonous vigilance task.

Predictors of Functional School Outcome in Children With Pediatric Acquired Brain Injury

Objective

Among the variety of domains that may be impacted after pediatric acquired brain injury (pABI) are functional school outcomes. The purpose of this study was to identify demographic, medical, and psychological factors associated with impairments in functional school outcomes, defined as school absence, need of educational and psychological services, quality of life (QoL) in the school setting, and academic performance in children with pABI, with a specific emphasis on the significance of fatigue.

Materials and Method

We used baseline data from a randomized controlled trial. The sample consisted of seventy-six children aged 10 to 17 (M = 13 yrs) with pABI in the chronic phase (>1 year). All completed assessments of school-related QoL, academic performance, global functioning, fatigue, IQ, behavioral problems, and executive function.

Results

Fatigue, IQ, global functioning, behavioral problems, and sex emerged as potential predictors for functional school outcomes. Of note, overall fatigue emerged as the strongest potential predictor for parent-reported QoL in school (β = 0.548; p < 0.001) and self-reported QoL in school (β = 0.532; p < 0.001).

Conclusions

Following pABI, specific psychological, medical, and demographic factors are associated with functional school outcomes. Neither of the injury-related variables age at insult and time since insult were associated with functional school outcomes. Overall, our findings may suggest that a reintroduction to school with personalized accommodations tailored to the child's specific function and symptoms, such as fatigue, is recommended.