Subjective Fatigue Level Research Articles

Validation of the Multidimensional Fatigue Inventory with Coronary Artery Disease Patients.

Background: Fatigue is a common distressing symptom in patients with coronary artery disease (CAD). The Multidimensional Fatigue Inventory (MFI) is used for measuring fatigue in various clinical settings. Nevertheless, its multidimensional structure has not been consistent across studies. Thus, we aimed to psychometrically evaluate the MFI in patients with CAD. Methods: In sum, 1162 CAD patients completed questionnaires assessing their subjective fatigue level (MFI-20), mental distress symptoms (HADS, STAI), and health-related quality of life (SF-36). Participants also completed exercise capacity (EC) testing. Results: Confirmatory factor analysis of the four-factor model, showed acceptable fit (CFI = 0.905; GFI = 0.895; NFI = 0.893, RMSEA = 0.077). After eliminating four items, confirmatory factor analysis testing showed improvement in the four-factor model of the MFI-16 (CFI = 0.910; GFI = 0.909; NFI = 0.898, RMSEA = 0.077). Internal consistency values were adequate for the total score and four MFI-16 subscales: General fatigue, physical fatigue, reduced activity, and mental fatigue with Cronbach’s α range: 0.60–0.82. The inadequate value (Cronbach’s α = 0.43) was received for the subscale of reduced motivation in both MFI-20 and MFI-16. Correlations between the MFI-16 and HADS, STAI, SF-36, and EC measures were statistically significant (all p’s < 0.001). Conclusions: The Lithuanian version of the modified MFI of 16 items showed good factorial structure and satisfactory psychometric characteristics, except for reduced motivation subscale.

Characteristics of Victims of Fall-Related Accidents during Mountain Hiking.

The study evaluated characteristics of non-fatal mountain hiking accidents caused by falls. Questionnaires were sent to mountain hikers who suffered a fall-related accident in Tyrol (Austria) during a 3-year period. The questionnaire included details of socio-demographic data, physical activity, medication intake, defective vision, breaks, fluid intake, level of fatigue, muscle soreness, use of backpacks, use of hiking sticks, and type of shoes. Data of 405 individuals (57% females and 43% males) were included in the analyses. Victims were 56 ± 15 years of age, had a body mass index of 24.8 ± 3.5, and indicated 4.2 ± 3.9 h/week regular physical activity. A defective vision was reported by 70% of the victims, breaks were frequent (in 80%), and alcohol intake was rare (4%) among the interviewed hikers. Subjective level of fatigue was low and only 5% reported muscle soreness. A backpack was carried by 83% of the victims and the average weight was higher in males compared to females. The majority (61%) of the victims wore ankle-height hiking shoes with a profiled sole. Victims of non-fatal falls in mountain hiking are older than the general population of mountain hikers and are often afflicted with defective vision.

Prehabilitation may ameliorate depression symptoms before major pancreatic surgery

Background: Depression symptoms are common before major surgery. Some studies have shown an association between psychological health and surgical outcomes. Exercise appears to improve sleep and mental health over a period of 12-24 weeks. Data is lacking to support a shorter intervention time which may be amenable to prehabilitation. Materials & Methods: We prospectively recruited patients with benign or malignant pathology, listed for pancreatic resection. The 4-week prehabilitation intervention comprised: resistance and high intensity interval training x3/week and daily omega-3 fatty acids (2g) and 30ml extra virgin olive oil. At baseline and after 4/52, subjective sleep quality, fatigue levels and depression symptoms were measured using: Pittsburgh Sleep Quality Index (PSQI), Karolinska Sleepiness Scale (KSS), Visual Analogue Scale for Fatigue (VAS-F), Brief Fatigue Inventory (BFI) and WHO-5 Well-Being Index (WHO-5). Sleep behaviour was quantified using 30-second epoch wrist actigraphy. Insulin sensitivity was measured with hyperinsulinaemic-euglycaemic clamp. These cases were compared with contemporaneous non-randomised patients (controls). Results: Within the prehab group, there was a significant improvement in depression symptoms [WHO-5: P = 0.001], with a 25% improvement in mean WHO-5 scores. Global sleep quality scores did not improve [PSQI: P= 0.63; KSS: P= 0.17]. There was no significant change in actigraphy-related parameters [P > 0.05]. Fatigue and energy levels did not change [VAS-F, P = 0.72 ; BFI, P = 0.75]. When compared with controls, a trend towards significance was observed in depression symptoms [P = 0.13]. A strong correlation was identified between sleep quality (PSQI) scores and insulin sensitivity (R= -0.867, P= 0.0003; Spearman's rank correlation coefficient). Conclusion: Prehabilitation was associated with an improvement in depression symptoms. Sleep quality was unchanged in this time-frame. We observed a strong correlation between sleep quality and insulin sensitivity. Larger, controlled studies are required to further evaluate the effect of prehabilitation on psychological health.

Pro-inflammatory Cytokine Levels and Cancer-related Fatigue in Breast Cancer Survivors: Effects of an Exercise Adherence Program.

PurposeThis study aimed to determine the effect of an exercise intervention on subjective cancer-related fatigue (CRF) and pro-inflammatory cytokine levels in breast cancer survivors (BCS).MethodsBCS with greater than moderate CRF (≥ 4) were recruited and randomly assigned to experimental or control groups. The experimental group participated in a 12-week exercise adherence program (Better Life after Cancer - Energy, Strength, and Support; BLESS). Interleukin (IL)-6 and tumor necrosis factor-α (TNF-α) levels were determined at 3 time points (M1: baseline, M2: post-intervention, and M4: 6 months after intervention). Subjective fatigue was measured using the Korean version of the revised Piper Fatigue Scale.ResultsIn this analysis of participants with physiological fatigue measures available (19 experimental, 21 control), there were no statistically significant differences in IL-6 (F = 1.157, p = 0.341), TNF-α levels (F = 0.878, p = 0.436), and level of fatigue (F = 2.067, p = 0.118) between the 2 groups at baseline. Fatigue in the experimental group showed statistically significant improvement compared to the control only at M2 (p = 0.022). There was no significant relationship between subjective and physiological fatigue at the 3 measurement points.ConclusionThe BLESS intervention improved CRF in BCS immediately at post-intervention, and this study presents clinical feasibility for the management of CRF in BCS in the early survivorship phase who are already experiencing fatigue.

Work related fatigue and sleepiness at work among intern house officers of four hospitals in Sri Lanka

Introduction: Intern house officers (IHOs) are expected to work long duration shifts with frequent on-calls. Lack of adequate sleep due to prolonged duty hours leads to increase in medical errors. United States and European countries have imposed guidelines to restrict duty hours of IHOs, however no such restrictions are implemented in Sri Lanka. Objectives: The aim of this study was to evaluate fatigability and sleepiness at work among IHOs of four main hospitals in Sri Lanka. Method: IHOs of Colombo South Teaching Hospital, National Hospital Sri Lanka, Lady Ridgway Children’s Hospital and De Soysa Maternity Hospital were recruited. Duty rosters were analysed for the length of duty shifts and night on-calls. Questionnaires were used to record fatiguability, sleepiness at work, medical errors, risk at work and daytime sleepiness. Results: Out of 94 IHOs, 73% worked more than 100 hours and 32% worked more than 125 hours a week. Notably, 38% did three night on-calls per week and 31% did more than three. Subjective fatigue level at work was reported as “most of the time” and “always” by more than 80% of IHOs, 32% had severe day time sleepiness. Fatigue risk assessment score indicated that 97% IHOs were in the high-risk group. Female IHOs were found to be more fatigued. One third of doctors reported medical errors due to fatigue and sleepiness which was significantly high in medicine rotation. Conclusions: IHOs were found to be over working. Majority were fatigued and sleepy at work. Self reported medical errors during internship were found to be high.

The effects of different fatigue levels on brain-behavior relationships in driving.

BackgroundIn the past decade, fatigue has been regarded as one of the main factors impairing task performance and increasing behavioral lapses during driving, even leading to fatal car crashes. Although previous studies have explored the impact of acute fatigue through electroencephalography (EEG) signals, it is still unclear how different fatigue levels affect brain–behavior relationships.MethodsA longitudinal study was performed to investigate the brain dynamics and behavioral changes in individuals under different fatigue levels by a sustained attention task. This study used questionnaires in combination with actigraphy, a noninvasive means of monitoring human physiological activity cycles, to conduct longitudinal assessment and tracking of the objective and subjective fatigue levels of recruited participants. In this study, degrees of effectiveness score (fatigue rating) are divided into three levels (normal, reduced, and high risk) by the SAFTE fatigue model.ResultsResults showed that those objective and subjective indicators were negatively correlated to behavioral performance. In addition, increased response times were accompanied by increased alpha and theta power in most brain regions, especially the posterior regions. In particular, the theta and alpha power dramatically increased in the high‐fatigue (high‐risk) group. Additionally, the alpha power of the occipital regions showed an inverted U‐shaped change.ConclusionOur results help to explain the inconsistent findings among existing studies, which considered the effects of only acute fatigue on driving performance while ignoring different levels of resident fatigue, and potentially lead to practical and precise biomathematical models to better predict the performance of human operators.

Evaluation of the effectiveness of the sliding sheet in repositioning care in terms of working time and subjective fatigue: A comparative study with an experimental design

BackgroundManual patient handling is a major cause of low back pain among healthcare staff. The sliding sheet is an assistive device designed to aid healthcare staff performing patient repositioning in bed. The use of sliding sheets in healthcare facilities is currently relatively rare because of the perceived additional time required compared with non-assisted handling. However, the details of the time difference between techniques and the barriers to the use of sliding sheets have not been examined in depth. ObjectivesWe sought to evaluate differences in working time and subjective fatigue between the use of sliding sheets and non-assisted handling techniques for patient repositioning, in order to understand the factors preventing the use of sliding sheets among nurses. DesignWe conducted a comparative study with an experimental design. SettingsThe study was conducted in the nursing practice room at a university in Japan. ParticipantsWe recruited 30 pairs of nurses and care receivers. All nurses were under 60 years old, with experience in lateral turning and repositioning in the process of changing diapers in clinical settings. Those with a previous or current medical history of low back pain were excluded. Care receivers were older adults (65–80 years old). We excluded adults with bedsores, body mass index values >30, or restricted joint motion due to femoral trochanteric fracture or compression fracture. Thus, 27 pairs were included in the final analysis. MethodsThe care receivers were instructed to behave as if they were bedridden patients with no limb movement, and as if they had contracture and difficulty communicating. Nurses repositioned the patient using three techniques assigned as interventions in random order: repositioning by one person using a sliding sheet (Sheet), repositioning by two people without a sliding sheet (Double), and repositioning by one person without a sliding sheet (Single). Working time was the primary endpoint for comparative analysis among the three technique conditions. ResultsThe results revealed that the Sheet technique required significantly more time than the non-assisted techniques. However, when total staff time was taken into consideration, the Sheet technique outperformed the Double technique. Moreover, the Sheet technique was associated with significantly lower levels of subjective fatigue, compared with the Double technique. ConclusionsThe use of a sliding sheet can substantially reduce caregiver burden when performing patient repositioning, and requires less staff time than manual techniques involving more than one caregiver.

Neural effects of hand-grip-activity induced fatigue sensation on appetite: a magnetoencephalography study

It has been reported that physical activity not only increases energy expenditure, but also affects appetite. However, little remains known about the effects of physical activity-induced fatigue sensation on appetite. In the present study, classical conditioning related to fatigue sensation was used to dissociate fatigue sensation from physical activity. The participants were 20 healthy male volunteers. After overnight fasting, on day 1, the participants performed hand-grip task trials for 10 min with listening to a sound. The next day, they viewed food images with (target task) and without (control task) listening to the sound identical to that used on day 1, and their neural activity during the tasks were recorded using magnetoencephalography. The subjective levels of appetite and fatigue sensation were assessed using a visual analog scale. The subjective level of fatigue increased and that of appetite for fatty foods showed a tendency toward increase in the target task while the subjective level of fatigue and that of appetite for fatty foods were not altered in the control task. In the target task, the decrease of theta (4–8 Hz) band power in the supplementary motor area (SMA), which was observed in the control task, was suppressed, and the suppression was positively correlated with appetite for fatty foods, suggesting hand grip activity-induced fatigue sensation may increase the appetite for fatty food; this increase could be related to neural activity in the SMA. These findings are expected to contribute to the understanding of the neural mechanisms of appetite in relation to fatigue.

Evaluating the impact of mental fatigue on construction equipment operators' ability to detect hazards using wearable eye-tracking technology

Abstract Construction equipment related accidents, such as collisions between equipment and pedestrian workers, pose a major challenge to occupational safety at construction sites. Decrement of operators' hazard detection ability resulting from attention failure is a leading cause of these accidents. Although mental fatigue induced by prolonged and monotonous operating tasks is known as the primary cause of this type of failure, little is revealed on how mental fatigue influences operators' ability to detect hazardous situations and associated visual attention features. To address this issue, this study uses wearable eye-tracking technology to evaluate the impact of mental fatigue on operators' ability in hazard detection and the corresponding patterns of visual attention allocation. Twelve healthy participants performed a simulated excavator operating task in a laboratory experiment. Subjective mental fatigue assessment, hazard detection task performance, and eye movement metrics were recorded and analyzed. In the experiment, mental fatigue was effectively induced and manipulated by a Time-On-Operating (TOO) procedure. Results revealed that operators' hazard detection ability decreased with the increase in subjective mental fatigue level, reflected by significant increases in reaction time for hazards and the number of misdetections. Attention allocation-related data were further analyzed to explain the specific manifestations of hazard detection failure in visual attention. The results indicated that the decrease of operators' hazard detection ability is associated with the changes of the distributions of fixation and gaze point while mental fatigue level increases. Consequently, clear observation of surrounding hazards and related details becomes difficult for operators. The findings demonstrate the effectiveness of wearable eye-tracking technology in measuring and quantifying operators' mental fatigue and hazard detection ability. More importantly, the findings offer insights into the impairing effect of mental fatigue on operators' hazard detection ability from a visual attention perspective. Such insights provide a solid basis for developing effective safety interventions and attentional guidance-based safety training methods to mitigate relevant site accidents.

Introducing chaotic codes for the modulation of code modulated visual evoked potentials (c-VEP) in normal adults for visual fatigue reduction.

Code modulated Visual Evoked Potentials (c-VEP) based BCI studies usually employ m-sequences as a modulating codes for their broadband spectrum and correlation property. However, subjective fatigue of the presented codes has been a problem. In this study, we introduce chaotic codes containing broadband spectrum and similar correlation property. We examined whether the introduced chaotic codes could be decoded from EEG signals and also compared the subjective fatigue level with m-sequence codes in normal subjects. We generated chaotic code from one-dimensional logistic map and used it with conventional 31-bit m-sequence code. In a c-VEP based study in normal subjects (n = 44, 21 females) we presented these codes visually and recorded EEG signals from the corresponding codes for their four lagged versions. Canonical correlation analysis (CCA) and spatiotemporal beamforming (STB) methods were used for target identification and comparison of responses. Additionally, we compared the subjective self-declared fatigue using VAS caused by presented m-sequence and chaotic codes. The introduced chaotic code was decoded from EEG responses with CCA and STB methods. The maximum total accuracy values of 93.6 ± 11.9% and 94 ± 14.4% were achieved with STB method for chaotic and m-sequence codes for all subjects respectively. The achieved accuracies in all subjects were not significantly different in m-sequence and chaotic codes. There was significant reduction in subjective fatigue caused by chaotic codes compared to the m-sequence codes. Both m-sequence and chaotic codes were similar in their accuracies as evaluated by CCA and STB methods. The chaotic codes significantly reduced subjective fatigue compared to the m-sequence codes.

Application of autonomic nervous function evaluation to job stress screening

The present study focuses on the evaluation of autonomic nervous function, which is increasingly being used as an objective measure of fatigue state. It has recently been reported that autonomic nervous activity, which is expressed as total heart rate variability (HRV) power, is associated with, and can be used as an objective measure of, mental and physical fatigue. Total HRV power (log (LF + HF)) has been shown to decline with ageing, and thus cannot be utilized as a fatigue index in populations with a different age composition. In the present study, we devised standard scores (deviation value) for autonomic nervous activity corrected for individual age calculated from the distribution of such activity in individual age cohorts. This allowed us to accurately evaluate an individual's autonomic nervous activity, even when that individual was part of a group with members of different ages. Standard scores were quantified using autonomic nervous function data gathered from 1,969 healthy individuals (age range 20–77 years).The efficacy of this method in mental health screening was investigated by evaluating both autonomic nervous function and subjective levels of fatigue among corporate workers. Based on results from the Brief Job Stress Questionnaire recommended by the research team of the Ministry of Health, Labour and Welfare, 103 participants were divided into two groups (a high-stress group [n = 17] and a non–high-stress group [n = 86]). Visual analog scale (VAS) scores for all fatigue-related symptoms were significantly higher among the high-stress than among the non–high-stress group (p < 0.01).The mean standard score for autonomic nervous activity was 56.3 for the non–high-stress group. The score for the high-stress group was significantly lower, at 47.9 (p < 0.01), indicating that autonomic nervous function was reduced among participants who experienced high stress. According to an analysis of raw and standard scores in each domain, autonomic nervous activity did not significantly correlate with stress-causing factors (e.g., overwork) or other factors affecting stress responses (e.g., support from supervisors and colleagues), but did exhibit a significant positive correlation with physical and mental responses to stress (r = 0.334, p < 0.01). Lower raw scores for mental and physical responses to stress represent stronger subjective symptoms. Moreover, greater stress responses were found to be associated with lower standard scores for autonomic nervous activity.In terms of fatigue-related symptoms rated using the VAS, autonomic nervous activity negatively correlated with mental stress, physical stress, fatigue/malaise, depressed mood, anxiety/fear, tension, irritation/anger, cognitive decline, and muscle/joint/general pain, and positively correlated with motivation/vitality. Reduced autonomic nervous activity was observed with high stress, confirming that standard scores for autonomic nervous activity are associated with mental and physical responses to stress and subjective fatigue-related symptoms.These results indicate that the evaluation of autonomic nervous activity using standard scores (deviation value) is a useful tool for the objective measurement of fatigue state, even in groups with members of different ages, and can be applied as a useful objective health index to evaluate industrial fatigue.

Automation Detection of Driver Fatigue Using Visual Behavior Variables

AbstractTo examine the correlation of driver visual behaviors and subjective levels of fatigue, a total of 36 commercial drivers were invited to participate in 2-h, 3-h, and 4-h naturalistic driving tests during which their eye fixation, saccade, blinking variables, and self-awareness of their fatigue levels were recorded. Then, one-way ANOVA was applied to analyze the variations of each variable among different age groups over varying time periods. The statistical analysis revealed that driving duration had a significant effect on the variation of visual behaviors and feelings of fatigue. After 2h of driving, only the average closure duration value and subjective level of fatigue had an increase of one-fifth or more. After 4h of driving, however, all these variables had a significant change except for the number of saccades and pupil diameter measurements. Particularly, driver saccadic eye movement was more sensitive to driving fatigue, and the elderly were more likely to be affected by the duration of the drive. Finally, a predictor of driver fatigue was determined to detect the real-time level of fatigue and alert at the critical moment.

An event-related potential objective evaluation study of mental fatigue based on 2-back task

The electroencephalographic characteristics of mental fatigue, which was induced by long-term working memory task of 2-back, were studied by event-related potential (ERP) technology in order to obtain objective evaluation indicators for mental fatigue. Thirty-two healthy male subjects, 22-28 years old, were divided into two groups evenly, one is un-fatigue group and the other is fatigue group. The fatigue group performed a 2-back task for 100 min continuously, while the un-fatigue group just performed a 2-back task at the first and last 10 min respectively, and rested during the middle 80 min. The subjective levels of fatigue, task performance and electroencephalogram were recorded. The impaired thought and attention states, enhanced sleepy and fatigue feeling were found in the fatigue group, meanwhile their reaction time to 2-back task extended, and the accuracy decreased significantly. These results verified the validity of mental fatigue model induced by 2-back task, and then the ERP characteristic parameters were compared and analyzed between fatigue group and un-fatigue group. The results showed that the fatigue group's amplitudes of P300 ( F = 2.539, P < 0.05) and error-related negativity (ERN) ( F = 10.040, P < 0.05) decreased significantly along with the increase of fatigue comparing with the un-fatigue group, however, there were no significant change in other parameters (all P > 0.05). These results demonstrate that P300 and ERN can be considered as potential evaluation indictors for mental fatigue induced by long-term working memory task, which will provide basis for the future exploring of countermeasure for mental fatigue.

Havacılıkta Yorgunluk: Ölçümler ve Karşı-Önlemlerin bir Gözden Geçirilmesi

Fatigue is a crucial and cumulative factor for aviation safety causing human errors via decrease in the abilities to conduct tasks that require higher-order intellectual processing. Chronic form of fatigue is more insidious and subjective. Factors causing fatigue are lack of sleep, crew scheduling, a long duty period, Jet or shift lag, high workload, and lacking of physical or mental fitness. There are subjective and objective measurements to estimate fatigue levels. Subjective techniques are based on self-report of the sleep and tiredeness whereas objective interventions are built on the basis the physiological features of the subject (brain waves, eye gaze, facial feature recognition) or their physical manifestations (muscle tone, wrist inactivity, head orientation) and support to maintain alertness and performance during long or uneventful duty period. Fatigue contermeasures are mainly based on self-reported data and there is a need for “safety” factor for self-reports.

Effect of Supplementation of a Whey Peptide Rich in Tryptophan-Tyrosine-Related Peptides on Cognitive Performance in Healthy Adults: A Randomized, Double-Blind, Placebo-Controlled Study.

Background: Previous epidemiological and clinical studies have shown that dairy products have beneficial effects on cognitive decline and dementia. Enzymatic digestion of whey protein produces a whey peptide rich in tryptophan-tyrosine-related peptides which improve cognitive performance in mice. We evaluated the effects of whey peptides on cognitive functions in healthy adults in a randomized, double-blind, placebo-controlled design. Methods: 101 healthy adults (45 to 64 years), with a self-awareness of cognitive decline received either whey peptide or placebo supplements for 12 weeks. Changes in cognitive function were assessed using neuropsychological tests at 6 and 12 weeks after the start of supplementation. Results: Verbal fluency test (VFT) score changes tended to be higher in the whey peptide group compared with the placebo at 12 weeks. Subgroup analysis classified by the degree of subjective fatigue showed that changes in the VFT as well as the Stroop and subjective memory function tests between baseline and 6 weeks of intervention were significantly better in subjects with high-level fatigue from the whey peptide group as compared to the placebo group. Conclusions: Intake of whey peptide might improve cognitive function in healthy middle- and older-aged adults with high subjective fatigue levels. Further studies will elucidate the relationship among cognitive improvement, whey peptides, and psychological fatigue.

Age Modulates the Effects of Mental Fatigue on Typewriting.

In the present study, we examined whether age influences the effects of mental fatigue on task performance, and if we could validate the use of measures based on typing behavior as an index of the effects of mental fatigue on different aspects of cognition. Young (N = 24, 18–30 years) and middle-aged (N = 24, 50–67 years) participants performed a typewriting task and a mouse targeting task for 120 min. At the beginning and at the end of the experiment the level of subjective fatigue was assessed. During task performance measures based on typing behavior and EEG were recorded. Results showed that subjective fatigue increased over the experiment in both the young and the middle-aged group. Typing speed decreased with time-on-task (ToT) in both age groups, reflected in larger general interkey intervals and in an increase in typing time. In addition, typing accuracy decreased with ToT in the young group, however, not in the middle-aged group, reflected by an increase in typing errors. Moreover, the young group used the backspace key more often with ToT due to delayed error-correction, reflected in larger backspace sequences, resulting in larger interkey intervals and increased typing time. This effect was absent in the middle-aged group. In the young group, the P3 brain potential amplitude decreased over the experiment, which was related to an increase in typing time, longer general interkey intervals, and an increase in typing errors, suggesting that decreased task engagement was related to less efficient typewriting, at least in the young group. These results indicate that measures based on typing behavior could give information about the process of mental fatigue, and in addition suggest that age influences the effect of mental fatigue on typewriting. More specifically, younger adults more often adopt a strategy that emphasizes speed, while middle-aged adults act more error-aversive than younger adults.

The neural effects of positively and negatively re-experiencing mental fatigue sensation: a magnetoencephalography study.

Fatigue sensation is an essential biological alarm that urges us to take rest to avoid disrupting homeostasis and thus plays an important role in maintaining well-being. However, there are situations in which the anticipation of unpleasant fatigue sensation undesirably reduces motivation for activity. The aim of this study was to examine whether thinking positively about the fatigue sensation would increase motivation to accomplish the workload. Fourteen healthy male volunteers participated in this study and performed a two-back test for 30min to induce mental fatigue sensation. After their subjective level of fatigue had recovered to the baseline level, they re-experienced the fatigue sensation experienced in the two-back test positively, negatively, and without any modification (i.e., re-experienced the fatigue sensation as it was). The level of motivation to perform another two-back test they felt during the re-experiencing was assessed. The neural activity related to the re-experiencing was recorded using magnetoencephalography. The level of the motivation to perform another two-back test was increased by positively re-experiencing the fatigue sensation. The increase in delta band power in Brodmann area 7 was positively associated with the increase in motivation. These results show that positive thinking about fatigue sensation can enhance motivation and suggest that this enhanced motivation may have some effects on visual attention system.

Changes in the subjective fatigue and pupil diameters induced by watching LED TVs

To assess the changes in subjective fatigue and pupil diameters while watching two different videos in different viewing conditions such as the screen luminosity and the display forms. A total of 108 subjects were participated in this study. The pupil diameter of the participants was measured by an eye tracker while the subjects watched one of the two different videos in different viewing conditions. The subjective fatigue of each subject was measured by a questionnaire conducted before and after watching the videos. The relative effects of the viewing conditions on the pupil diameters showed significant correlations in both screen luminosity and display forms (p < 0.05). The levels of subjective fatigue increased after watching the videos, compared to those before watching them, and the young subjects significantly felt more tired (p < 0.05). Changes in the subjective fatigue and pupil diameters during watching videos on LED TVs were different according to the display forms, the screen luminosity and videos. However, the pupil diameters decreased with a pattern of regression in the linear and third-order polynomial expressions in process of viewing time. The present study suggests a further study with a detailed analysis is needed to prove these findings.

Co-variation of fatigue and psychobiological stress in couples’ everyday life

ObjectiveThere is limited knowledge about how fatigue develops and worsens and what influences fluctuations in daily fatigue. Stress was found to influence fatigue, and being in a relationship seems to either increase or decrease stress depending on the couple interaction. In this study, co-variation of fatigue, self-reported stress, and biological stress markers in couples’ everyday lives was investigated. Specifically, we examined a) whether momentary couple interactions moderated dyadic outcomes and b) whether and how stress and relationship measures influenced individual momentary fatigue. MethodsForty heterosexual couples (age: 28 ± 5 years) reported subjective fatigue and stress levels 4 times a day for 5 consecutive days (1600 measures). Furthermore, participants reported whether they had interacted with their partner since the last data entry and, if so, they rated the valence of this interaction. Salivary cortisol (a measure of HPA axis activity) and alpha amylase (a measure of ANS activity) were analyzed as biological stress markers from saliva samples obtained at the same time points. Moment-to-moment data were analyzed using dyadic multilevel models to account for the nested design. ResultsStress (women and men: p ≤ 0.001) and fatigue (women: p = .003, men: p = .020) showed patterns of co-variation within couples, especially if partners had interacted with each other since the previous data entry. Cortisol was also found to co-vary between partners (women: unstandardized coefficient (UC) = 0.12, p ≤ .001, men: UC = 0.18, p ≤ .001), whereas the regulation of alpha-amylase levels depending on the partner’s levels was only present in women (UC = 0.11, p = .002). Valence of couple interaction was negatively associated with fatigue (women: UC = −0.13, p ≤ .001, men: UC = −0.06, p = .011). There was no momentary association of fatigue with an individual’s own or the partner’s subjective or biological stress markers. ConclusionsFatigue and stress levels during the day seem to co-vary within couples. These associations were particularly strong when the partners had interacted with each other since the last measurement. These data underline the importance of social factors in fatigue and stress in everyday life.

Environmental temperature and exercise modality independently impact central and muscle fatigue among people with multiple sclerosis.

BackgroundHeat sensitivity and fatigue limit the ability of multiple sclerosis patients to participate in exercise.ObjectiveThe purpose of this study was to determine the optimal aerobic exercise parameters (environmental temperature and exercise modality) to limit exercise-induced central and muscle fatigue among people with multiple sclerosis.MethodsFourteen people with multiple sclerosis with varying levels of disability completed four randomized exercise sessions at 65% of the maximal volume of oxygen: body-weight supported treadmill cool (16°C), body-weight supported treadmill room (21°C), total-body recumbent stepper cool and total-body recumbent stepper room. Maximum voluntary contraction, electromyography, and evoked contractile properties were collected from the more affected plantar flexors along with subjective levels of fatigue, body temperature and perceived level of exertion.ResultsExercise in cooler room temperature increased maximum voluntary contraction force (p = 0.010) and stabilized body temperature (p = 0.011) compared to standard room temperature. People with multiple sclerosis experienced greater peak twitch torque (p = 0.047), shorter time to peak twitch (p = 0.035) and a longer half relaxation time (p = 0.046) after total-body recumbent stepper suggestive of less muscle fatigue.ConclusionCooling the exercise environment limits the negative effects of central fatigue during aerobic exercise and using total-body recumbent stepper (work distributed among four limbs) rather than body-weight supported treadmill lessens muscular fatigue. Therapists can titrate these two variables to help people with multiple sclerosis achieve sufficient exercise workloads.