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 51,768 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Repetitive work in occupational settings often requires a combination of mental and physical demands, but few studies were conducted concerning the relationship between attention and repetitive work. In attentive and cognitive tasks, it is common to observe effort and fatigue without the presence of those neuromuscular modifications that would justify the use of these terms. Therefore, we can talk about mental fatigue in those cases in which it is observed the exhaustion of the necessary resources for the execution of a job that doesn't demand the employment of neuromuscular apparatus. Scientific literature about this argument consists of experimental studies which aim to estimate at what extent attentive demands exspecially cognitive demands can interact with physical ones which are peculiarities of repetitive tasks. Work characterized by the maintenance of high levels of performance for a long time, produce cognitive effort with high level of vigilance, selective attention, decisional ability, automated control mechanisms, such as "eye-hand", and may contribute to the fatigue. Indeed, fatigue plays a important role in a working context since, it may interfere with the work itself by reducing the worker's efficiency and performance and if excessive and extended, it may alter the subject's psycho-physical condition and induce different pathologies. Repetitive work can contribute to the increasing of muscular fatigue by inducing mental fatigue: for example tasks which require high vigilance but low neuromuscular work, may induce a sense of effort and fatigue and cognitive factors and mental stress may cause muscular fatigue. Several intrinsic job factors, including repetitive works, may act as stressors and they can cause mental and physical symptoms such as anxiety, depression and somatic diseases. The European Community has often emphasized the pathogenic value of stress and fatigue with their high social and individual costs. For this purpose, it is opportune to consider the norm UNI EN ISO 10075, which points out the necessity to consider the human component, in term of mental load which implies not only the cognitive component but also the whole psychical sphere of the subject. Training intended like a sort of learning of specific modalities, supplies workers with the necessary instruments for a correct and more aware management of the peculiarities of working activity, contributing to the reduction of fatigue and stress deriving from the job.
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PMID:[Attention, repetitive works, fatigue and stress]. 1708 57

To investigate the relation between plasma amino acid levels and mental fatigue, we measured the plasma concentrations of 20 amino acids in 9 healthy volunteers before and after a fatigue-inducing mental task session for 8 hr. As fatigue-inducing mental tasks, the subjects performed an advanced trail making test, a Japanese KANA pick up test, and a mirror drawing test. As a control, 8-hr relaxation session was performed in the same subjects at an interval of 4 weeks. Immediately after the fatigue session, the plasma levels of branched-chain amino acids, tyrosine, cysteine, methionine, lysine, and arginine were below those after a relaxation session. The values for other blood parameters including total protein, albumin, glucose, and total cholesterol did not show any differences between the 2 sessions. These results indicate that mental fatigue may be characterized by a decrease in the plasma level of these amino acids.
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PMID:Mental fatigue-induced decrease in levels of several plasma amino acids. 1716 Mar 70

An Auditory Vigilance Task (AVT) as a validation criterion for monitoring mental fatigue was proposed in this study. The biological basis of this task design is on the understanding that mental fatigue is a cortical deactivation. This AVT is simple to perform, free of learning curve and independent on acquired skills (aptitude, knowledge). The validity and sensitivity of this task was verified by a scientifically controlled 25-hour fatigue experiment recorded by Electroencephalogram (EEG). Results showed that this AVT is highly sensitive to changes during fatigue process. The effectiveness of this AVT was compared to one subjective rating scale (FSS). The 5-level fatigue EEG datasets (labeled by AVT and FSS respectively) were fed into Support Vector Machines (SVM). SVM test accuracy indicated that AVT is more effective than subject's own estimation. The results demonstrate conclusively that this AVT is suitable for fatigue detection study as a reliable validation criterion.
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PMID:An auditory vigilance task for mental fatigue detection. 1728 42

Electroencephalogram (EEG) might be the most predictive and reliable physiological indicator of mental fatigue. However, the extraction of key features from massive EEG data for mental fatigue identification remains a challenge. The objective of this study is to identify the key EEG features in relationship to mental fatigue, from a broad pool of EEG features generated by quantitative EEG (qEEG) techniques, using Random Forests (RF), which is a recently developed machine learning algorithm. The method is applied to key EEG feature extraction for 5-level mental fatigue identification using the five subjects' EEG data recorded in 25-hour fatigue experiments. RF produces significant feature reduction with little compromise of the classification performance. The identified key EEG features also indicate that electrode locations in frontal and occipital regions of the brain are most important for adequate representation of the deactivation of functional lobes of the brain, which is consistent with the anatomical areas known to be involved in mental fatigue. It is also interesting to discover that the four frequency bands are all important for the mental fatigue identification.
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PMID:Key Feature Extraction for Fatigue Identification using Random Forests. 1728 28

Although fatigue is a multidimensional concept, multidimensional fatigue is rarely investigated in hospitalised cancer patients. We determined the levels and correlates of multidimensional fatigue in 100 advanced cancer patients admitted for symptom control. Fatigue dimensions were general fatigue (GF), physical fatigue (PF), reduced activity (RA), reduced motivation (RM) and mental fatigue (MF). Investigated correlates were tumour load, prior anti-tumour treatment, medication use, haemoglobin levels, serum biochemical variables, physical symptoms and mood. Median GF, PF and RA scores were very high; median RM and MF scores were moderate, and differed from the GF, PF and RA scores. Multiple regression analyses showed that symptoms and mood correlated with all fatigue dimensions. Each fatigue dimension had different relationships with other factors. Hospitalised advanced cancer patients differ in fatigue levels depending on the fatigue dimension, and each fatigue dimension has different correlates. The results confirm that fatigue should be regarded as a multidimensional concept.
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PMID:Multidimensional fatigue and its correlates in hospitalised advanced cancer patients. 1733 52

The neural mechanisms underlying feelings of fatigue are poorly understood. The primary purpose of the study was to use functional magnetic resonance imaging (fMRI) to determine the association between feelings of mental fatigue and blood oxygen level dependent (BOLD) brain responses during a mentally fatiguing cognitive task. Healthy, non-fatigued controls and chronic fatigue syndrome (CFS) patients were included to determine the influence of chronic levels of fatigue on brain responses. We hypothesized that mental fatigue would be significantly related to brain activity during a fatiguing cognitive task but not during either a non-fatiguing motor (finger tapping) or cognitive (auditory monitoring) task. Patients (n=9) and controls (n=11) completed a finger tapping task, a simple auditory monitoring task and a challenging working memory task, designed to induce mental fatigue, while undergoing fMRI. Fatigue was measured prior to scanning and following each task during fMRI data collection. Results showed that mental fatigue was significantly related to brain activity during the fatiguing cognitive task but not the finger tapping or simple auditory monitoring tasks. Significant (p< or =0.005) positive relationships were found for cerebellar, temporal, cingulate and frontal regions. A significant (p=0.001) negative relationship was found for the left posterior parietal cortex. CFS participants did not differ from controls for either finger tapping or auditory monitoring tasks, but exhibited significantly greater activity in several cortical and subcortical regions during the fatiguing cognitive task. Our results suggest an association between subjective feelings of mental fatigue and brain responses during fatiguing cognition.
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PMID:Functional neuroimaging correlates of mental fatigue induced by cognition among chronic fatigue syndrome patients and controls. 1740 73

The Multidimensional Fatigue Inventory (MFI-20) scale is widely used for measuring fatigue in cancer care. This questionnaire has been translated into Swedish and used in Swedish cancer populations, and the aim of this study was to test the validity and reliability of the Swedish version in four populations, with a total of 584 patients. The participants were classified into four groups: palliative cancer patients, cancer patients receiving radiation therapy, non-cancer outpatients, and a group of hospital staff. The MFI-20 consists of five subscales of fatigue: General Fatigue (GF), Physical Fatigue (PF), Reduced Motivation (RM), Reduced Activity (RA) and Mental Fatigue (MF). We have tested the convergent validity of the MFI-20 using the Category Ratio instrument (CR-10). The validity and the reliability of MFI-20 were acceptable. All subscales of the MFI-20 were correlated, and all were also correlated with the CR-10 score (p < or = 0.001). General Fatigue was highly correlated with Physical Fatigue for the three patient groups, but this was not the fact for healthy staff. Deleting some items increased Cronbach's alpha of the subscale to which these items belonged (where alpha measures the reliability of the results). The level of non-response was low (less than 1.2%) and there was no pattern to the items omitted. We conclude that the MFI-20 is a valid and reliable instrument for measuring fatigue in patients and in healthy individuals. The results support, to some extent, earlier findings and one item can be removed from the Swedish version of the MFI-20.
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PMID:The psychometric properties of the Swedish Multidimensional Fatigue Inventory MFI-20 in four different populations. 1743 11

We determined biopsychosocial correlates of general, physical, and mental fatigue in MS patients, by evaluating the additional contribution of potentially modifiable factors after accounting for non-modifiable disease-related factors. Fifty-three ambulatory MS patients, along with 28 normal controls were recruited for a cross-sectional study. Subjects completed the Multidimensional Fatigue Inventory (MFI) and Fatigue Severity Scale. Potential correlates evaluated were: disease-related factors (disease duration and type, immunomodulating treatment, muscle strength, pain, forced vital capacity (FVC), respiratory muscle strength, body mass index, disability, fibromyalgia), behavioural factors (physical activity, sleep quality) and psychosocial factors (depression, stress, self-efficacy). Multivariate models were calculated for MFI General, Physical, and Mental Fatigue. Age-adjusted multivariate models with non-modifiable factors included the following predictors (P < or = 0.10) of 1) MFI General and Mental Fatigue: none; and 2) MFI Physical Fatigue: FVC and disability. The following potentially modifiable predictors (P < or = 0.10) made an additional contribution to the models 1) MFI General Fatigue: sleep quality, self-efficacy, pain; 2) MFI Physical Fatigue: self-efficacy, physical activity; and 3) MFI Mental Fatigue: stress, self-efficacy. Fatigue in MS is multidimensional. Correlates of general and physical fatigue are disease-related, behavioural and psychosocial factors. Correlates of mental fatigue are psychosocial factors. Potentially modifiable factors account for a considerable portion of fatigue.
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PMID:Fatigue in multiple sclerosis: association with disease-related, behavioural and psychosocial factors. 1746 48

It was the aim of the present study to develop a synoptic multidimensional test system for assessment of fatigue in multiple sclerosis (MS) patients objectifying physical and mental fatigue as well as the subjective and objective standpoint in these two fatigue forms. Seventy nine patients with relapsing remitting multiple sclerosis (RRMS) and 51 age-matched healthy controls (H) were analysed by means of the physical fatigue test (hand dynamometer) and an objective mental fatigue test (vigilance test from the computerised Test Battery for Attentional Performance). Furthermore, subjective tiredness caused by test procedures, subjective persisting tiredness (Modified Fatigue Impact Scale; MFIS: physical and cognitive scale) and mood (Beck Depression Inventory; BDI-18) were analysed.MS patients differed significantly from the controls in their objective physical and mental performance under fatigue, as well as in their subjective estimation of tiredness. MS patients showed an inverse relationship between below-average objective performance and high subjective feeling of tiredness when compared to controls. Subjectively severely tired MS patients achieved clearly poorer performances on the hand dynamometer test and slightly poorer performances on the vigilance test when compared to subjectively rarely tired MS patients. Depressed MS patients estimated their subjective tiredness in the MFIS significantly higher than non-depressed MS patients, but attained the same objective performance. This set of standardised tests enables meaningful comparisons between objective fatigue performance and subjective fatigue estimations in the physical and mental sphere and considers the influence of depression. Depression affects the subjective tiredness but not the objective fatigue performance.
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PMID:Qualitative and quantitative assessment of fatigue in multiple sclerosis (MS). 1750 31

Dried-bonito broth is commonly employed as a soup and sauce base in Japanese cuisine and is considered to be a nutritional supplement that promotes recovery from fatigue. Previous human trials suggest that the ingestion of dried-bonito broth improves several mood states; however, its effect on fatigue has not yet been clarified. The aim of this study was to clarify the effects of daily ingestion of dried-bonito broth on fatigue and cognitive parameters by a placebo-controlled double blind crossover trial. Forty-eight subjects with fatigue symptoms ingested the dried-bonito broth or a placebo solution every day for 4 weeks. Mood states were evaluated by the Profile of Mood States (POMS), and mental task performance was evaluated by the Uchida-Kraepelin psychodiagnostic (UKP) test. Fatigue and total mood disturbance (TMD) scores on the POMS test decreased significantly during the dried-bonito broth ingestion (p<0.05), but did not change significantly during placebo ingestion. The change in vigor score during dried-bonito broth ingestion was significantly higher than that during placebo ingestion at 2 weeks (p<0.05). The results of the UKP test indicate that the numbers of both total answers and correct answers significantly increased during dried-bonito broth ingestion (p<0.05), while no significant changes were observed in the placebo ingestion. These results suggest that the daily ingestion of dried-bonito broth may improve the mood states, may reduce mental fatigue and may increase performance on a simple calculation task.
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PMID:Effect of dried-bonito broth on mental fatigue and mental task performance in subjects with a high fatigue score. 1765 88


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