Cancer-related fatigue--mechanisms, risk factors, and treatments.

PubMed

Bower, Julienne E

2014-10-01

Fatigue is one of the most common adverse effects of cancer that might persist for years after treatment completion in otherwise healthy survivors. Cancer-related fatigue causes disruption in all aspects of quality of life and might be a risk factor of reduced survival. The prevalence and course of fatigue in patients with cancer have been well characterized and there is growing understanding of the underlying biological mechanisms. Inflammation seems to have a key role in fatigue before, during, and after cancer-treatment. However, there is a considerable variability in the presentation of cancer-related fatigue, much of which is not explained by disease-related or treatment-related characteristics, suggesting that host factors might be important in the development and persistence of this symptom. Indeed, longitudinal studies have identified genetic, biological, psychosocial, and behavioural risk factors associated with cancer-related fatigue. Although no current gold-standard treatment for fatigue is available, a variety of intervention approaches have shown beneficial effects in randomized controlled trials, including physical activity, psychosocial, mind-body, and pharmacological treatments. This Review describes the mechanisms, risk factors, and possible interventions for cancer-related fatigue, focusing on recent longitudinal studies and randomized trials that have targeted fatigued patients.

Cancer-related fatigue: Mechanisms, risk factors, and treatments

PubMed Central

Bower, Julienne E.

2015-01-01

Fatigue is one of the most common and distressing side effects of cancer and its treatment, and may persist for years after treatment completion in otherwise healthy survivors. Cancer-related fatigue causes disruption in all aspects of quality of life and may be a risk factor for reduced survival. The prevalence and course of fatigue in cancer patients has been well characterized, and there is growing understanding of underlying biological mechanisms. Inflammation has emerged as a key biological pathway for cancer-related fatigue, with studies documenting links between markers of inflammation and fatigue before, during, and particularly after treatment. There is considerable variability in the experience of cancer-related fatigue that is not explained by disease- or treatment-related characteristics, suggesting that host factors may play an important role in the development and persistence of this symptom. Indeed, longitudinal studies have begun to identify genetic, biological, psychosocial, and behavioral risk factors for cancer-related fatigue. Given the multi-factorial nature of cancer-related fatigue, a variety of intervention approaches have been examined in randomized controlled trials, including physical activity, psychosocial, mind-body, and pharmacological treatments. Although there is currently no gold standard for treating fatigue, several of these approaches have shown beneficial effects and can be recommended to patients. This report provides a state of the science review of mechanisms, risk factors, and interventions for cancer-related fatigue, with a focus on recent longitudinal studies and randomized trials that have targeted fatigued patients. PMID:25113839

The role of psychological factors in fatigue among end-stage kidney disease patients: a critical review

PubMed Central

Moss-Morris, Rona; Macdougall, Iain C.; Chilcot, Joseph

2017-01-01

Fatigue is a common and debilitating symptom, affecting 42–89% of end-stage kidney disease patients, persisting even in pre–dialysis care and stable kidney transplantation, with huge repercussions on functioning, quality of life and patient outcomes. This paper presents a critical review of current evidence for the role of psychological factors in renal fatigue. To date, research has concentrated primarily on the contribution of depression, anxiety and subjective sleep quality to the experience of fatigue. These factors display consistent and strong associations with fatigue, above and beyond the role of demographic and clinical factors. Considerably less research is available on other psychological factors, such as social support, stress, self-efficacy, illness and fatigue-specific beliefs and behaviours, and among transplant recipients and patients in pre-dialysis care. Promising evidence is available on the contribution of illness beliefs and behaviours to the experience of fatigue and there is some indication that these factors may vary according to treatment modality, reflecting the differential burdens and coping necessities associated with each treatment modality. However, the use of generic fatigue scales casts doubt on what specifically is being measured among dialysis patients, illness-related fatigue or post-dialysis-specific fatigue. Therefore, it is important to corroborate the available evidence and further explore, qualitatively and quantitatively, the differences in fatigues and fatigue-specific beliefs and behaviours according to renal replacement therapy, to ensure that any model and subsequent intervention is relevant and grounded in the experiences of patients. PMID:28638608

Hypoxia Worsens Affective Responses and Feeling of Fatigue During Prolonged Bed Rest

PubMed Central

Stavrou, Nektarios A. M.; Debevec, Tadej; Eiken, Ola; Mekjavic, Igor B.

2018-01-01

Previous research, although limited, suggests that both hypoxia and bed rest influence psychological responses by exaggerating negative psychological responses and attenuating positive emotions. The present study investigated the effect of a 21-day prolonged exposure to normobaric hypoxia and bed rest on affective responses and fatigue. Eleven healthy participants underwent three 21-day interventions using a cross-over design: (1) normobaric hypoxic ambulatory confinement (HAMB), (2) normobaric hypoxic bed rest (HBR) and (3) normoxic bed rest (NBR). Affective and fatigue responses were investigated using the Activation Deactivation Adjective Check List, and the Multidimensional Fatigue Inventory, which were completed before (Pre), during (Day 7, Day 14, and Day 21) and after (Post) the interventions. The most negative psychological profile appeared during the HBR intervention. Specifically, tiredness, tension, general and physical fatigue significantly increased on days 7, 14, and 21, as well as at Post. After the HBR intervention, general and physical fatigue remained higher compared to Pre values. Additionally, a deterioration of psychological responses was also noted following HAMB and NBR. In particular, both hypoxia and BR per se induced subjective fatigue and negative affective responses. BR seems to exert a moderate negative effect on the sensation of fatigue, whereas exercise attenuates the negative effects of hypoxia as noted during the HAMB condition. In conclusion, our data suggest that the addition of hypoxia to bed rest-induced inactivity significantly worsens affective responses and feeling of fatigue. PMID:29628903

Proximal and distal muscle fatigue differentially affect movement coordination

PubMed Central

Cowley, Jeffrey C.

2017-01-01

Muscle fatigue can cause people to change their movement patterns and these changes could contribute to acute or overuse injuries. However, these effects depend on which muscles are fatigued. The purpose of this study was to determine the differential effects of proximal and distal upper extremity muscle fatigue on repetitive movements. Fourteen subjects completed a repetitive ratcheting task before and after a fatigue protocol on separate days. The fatigue protocol either fatigued the proximal (shoulder flexor) or distal (finger flexor) muscles. Pre/Post changes in trunk, shoulder, elbow, and wrist kinematics were compared to determine how proximal and distal fatigue affected multi-joint movement patterns and variability. Proximal fatigue caused a significant increase (7°, p < 0.005) in trunk lean and velocity, reduced humeral elevation (11°, p < 0.005), and increased elbow flexion (4°, p < 0.01). In contrast, distal fatigue caused small but significant changes in trunk angles (2°, p < 0.05), increased velocity of wrench movement relative to the hand (17°/s, p < 0.001), and earlier wrist extension (4%, p < 0.005). Movement variability increased at proximal joints but not distal joints after both fatigue protocols (p < 0.05). Varying movements at proximal joints may help people adapt to fatigue at either proximal or distal joints. The identified differences between proximal and distal muscle fatigue adaptations could facilitate risk assessment of occupational tasks. PMID:28235005

Crew Factors in Flight Operations. 11; A Survey of Fatigue Factors in Regional Airline Operations

NASA Technical Reports Server (NTRS)

Co, Elizabeth L.; Gregory, Kevin B.; Johnson, Julie M.; Rosekind, Mark R.

1999-01-01

This report is the eleventh in a series on the physiological effects of flight operations on flight crews. A 119-question survey was completed by 1,424 flight crewmembers from 26 regional carriers to identify factors contributing to fatigue in regional airline operations. Eighty-nine percent of crewmembers identified fatigue as a moderate or serious concern with 88% reporting that it was a common occurrence and 92% reporting that, when it occurs, fatigue represents a moderate or serious safety issue. However, 86% reported they received no company training addressing fatigue issues. Identified fatigue factors included multiple flight segments, scheduling considerations, varying regulations, and others. The two most commonly cited fatigue factors regarded flying multiple (more than four) segments. Scheduling factors accounted for nine of the ten most common recommendations to reduce fatigue in regional operations. Differing requirements among regulations were cited as contributing to fatigue. Other identified factors were the flight deck environment, automation, and diet. The data suggested specific recommendations, including education of industry personnel about fatigue issues and examination of scheduling practices. Education plays a critical role in any effort to address fatigue. Analyzing scheduling practices and identifying potential improvements may result in reduced fatigue as well as other benefits to operations.

The Effect of Classroom Capacity on Vocal Fatigue as Quantified by the Vocal Fatigue Index.

PubMed

Banks, Russell E; Bottalico, Pasquale; Hunter, Eric J

2017-01-01

Previous research has concluded that teachers are at a higher-than-normal risk for voice issues that can cause occupational limitations. While some risk factors have been identified, there are still many unknowns. A survey was distributed electronically with 506 female teacher respondents. The survey included questions to quantify three aspects of vocal fatigue as captured by the Vocal Fatigue Index (VFI): (1) general tiredness of voice (performance), (2) physical discomfort associated with voicing (pain), and (3) improvement of symptoms with rest (recovery). The effect of classroom capacity on US teachers' self-reported experience of vocal fatigue was analyzed. The results indicated that a classroom's capacity significantly affected teachers' reported amounts of vocal fatigue, while a teacher's age also appeared to significantly affect the reported amount of vocal fatigue. A quadratic rather than linear effect was seen, with the largest age effect occurring at around 40-45 years in all three factors of the VFI. Further factors which may affect vocal fatigue must be explored in future research. By understanding what increases the risk for vocal fatigue, educators and school administrators can take precautions to mitigate the occupational risk of short- and long-term vocal health issues in school teachers. © 2017 S. Karger AG, Basel.

Risk factors for fatigue among airline pilots.

PubMed

van Drongelen, Alwin; Boot, Cécile R L; Hlobil, Hynek; Smid, Tjabe; van der Beek, Allard J

2017-01-01

The objective of this study is to determine risk factors for fatigue among airline pilots, taking into account person-, work-, health-, sleep-, and lifestyle-related characteristics. The study population consisted of 502 pilots who participated in the MORE Energy study. Included risk factors were either measured through an online questionnaire or provided by the company. The outcome of this study, fatigue, was assessed using the Checklist Individual Strength (CIS), and was defined as scoring more than 76 points on this questionnaire. The association of the risk factors with fatigue was determined using univariate and multivariate logistic regression analyses. Of the participating pilots, 29.5 % scored more than 76 points on the CIS and were classified as being fatigued. The fully adjusted regression model showed that person-, work-, health-, and lifestyle-related characteristics were associated with fatigue. Pilots who were aged 31 to 40 (OR 3.36, 95 % CI 1.32-8.53) or 41 to 50 (OR 4.19, 95 % CI 1.40-12.47), an evening type (OR 2.40, 95 % CI 1.38-4.16), scored higher on work-life balance disturbance (OR 1.22, 95 % CI 1.10-1.36), scored higher on need for recovery (OR 1.02, 95 % CI 1.01-1.04), scored lower on general health perception (OR 0.31, 95 % CI 0.20-0.47), were less physically active (OR 0.77, 95 % CI 0.66-0.89), and had a moderate alcohol consumption (OR 3.88, 95 % CI 1.21-12.43), were at higher risk for fatigue. Higher age, being an evening type, disturbance of the work-life balance, more need for recovery, a lower perceived health, less physical activity, and moderate alcohol consumption were shown to be risk factors for fatigue. Further longitudinal research is needed to elucidate the direction of the associations found and to evaluate the effects of possible countermeasures in airline pilots.

Longitudinal risk factors for persistent fatigue in adolescents.

PubMed

Viner, Russell M; Clark, Charlotte; Taylor, Stephanie J C; Bhui, Kam; Klineberg, Emily; Head, Jenny; Booy, Robert; Stansfeld, Stephen A

2008-05-01

To examine whether sedentary behavior, obesity, smoking, and depression are risk factors for persistent fatigue in adolescents. Longitudinal population-based survey. Twenty-eight randomly selected schools in east London, England, in 2001 and 2003. A total of 1880 adolescents (49% male; 81% nonwhite British) aged 11 to 12 years and 13 to 14 years in 2000. Confidential questionnaires completed in class. Persistent fatigue (extreme tiredness twice weekly or more often in the previous month at both surveys), sedentary behavior, physical activity, depressive symptoms, body mass index, and smoking. Severe fatigue was reported in 11% of participants aged 11 to 14 years and 17% of participants aged 13 to 16 years. Eighty-four participants (4%) reported persistent fatigue. Across both surveys, only 3 pupils reported chronic fatigue syndrome. In multivariate logistic regression, risk of persistent fatigue was independently associated with being sedentary for more than 4 hours per day (odds ratio = 1.6; 95% confidence interval, 1.1-2.3; P = .01), being physically active (odds ratio = 1.5; 95% confidence interval, 1.1-2.3; P = .004), and depressive symptoms (odds ratio = 2.0; 95% confidence interval, 1.5-2.7; P < .001) in the first survey, after adjustment for age, sex, and socioeconomic status. Obesity and smoking were not associated with fatigue. Persistent fatigue is common. Being highly sedentary or highly active independently increased the risk of persistent fatigue, suggesting that divergence in either direction from healthy levels of activity increases the risk for persistent fatigue. Mental health is important in the etiology of persistent fatigue. To help define effective preventive strategies, further work is needed on the mechanisms by which these factors contribute to fatigue.

A study into psychosocial factors as predictors of work-related fatigue.

PubMed

Rahman, Hanif Abdul; Abdul-Mumin, Khadizah; Naing, Lin

2016-07-14

To explore and determine relationship between psychosocial factors and work-related fatigue among emergency and critical care nurses in Brunei. Cross-sectional study conducted on all emergency and critical care nurses across Brunei public hospitals from February to April 2016. 201 nurses participated in the study (82% response rate). A total of 36% of the variance of chronic fatigue was explained by stress, trust in management, decision latitude, self-rated health, and work-family conflict. Burnout, self-rated health, commitment to workplace, and trust in management explained 30% of the variance of acute fatigue. Stress, work-family conflict and reward explained 28% of the variance of intershift recovery after controlling for significant sociodemographic variables. Smoking was identified as an important sociodemographic factor for work-related fatigue. Psychosocial factors were good predictors of work-related fatigue. A range of psychosocial factors were established, however more research is required to determine all possible causation factors of nurses' work-related fatigue.

Fatigue, not self-rated motor symptom severity, affects quality of life in functional motor disorders.

PubMed

Gelauff, J M; Kingma, E M; Kalkman, J S; Bezemer, R; van Engelen, B G M; Stone, J; Tijssen, M A J; Rosmalen, J G M

2018-06-02

While fatigue is found to be an impairing symptom in functional motor disorders (FMD) in clinical practice, scientific evidence is lacking. We investigated fatigue severity and subtypes in FMD compared to organic neurological disease. Furthermore, the role of fatigue within FMD and its impact on quality of life and self-rated health were investigated. Data from 181 patients participating in the self-help on the internet for functional motor disorders, randomised Trial were included. Data from 217 neurological controls with neuromuscular disorders (NMD) originated from a historical cohort. Fatigue was measured using the checklist individual strength (CIS). Motor symptom severity, depression and anxiety were correlated to fatigue. For multivariable regression analyses, physical functioning and pain were additionally taken into account. Severe fatigue was, respectively, present in 78 and 53% of FMD and NMD patients (p < 0.001). FMD patients scored higher than NMD patients on all fatigue subdomains (p < 0.001). In the FMD group, fatigue subdomains were correlated to depression, anxiety and partly to motor symptom severity. Quality of life was negatively associated with fatigue [OR 0.93 (0.90-0.96), p < 0.001] and depression [OR 0.87 (0.81-0.93), p < 0.001], but not self-rated motor symptom severity. Self-rated health was negatively associated with fatigue [OR 0.92 (0.88-0.96), p < 0.001] and pain [OR 0.98 (0.97-0.99), p < 0.001]. Fatigue was found to be a prevalent problem in FMD, more so than in organic neurological disease. It significantly affected quality of life and self-rated health, while other factors such as motor symptom severity did not. Fatigue should be taken into account in clinical practice and treatment trials.

Risk factors for fatigue in patients with epilepsy.

PubMed

Yan, Song; Wu, Yuanbin; Deng, Yanchun; Liu, Yonghong; Zhao, Jingjing; Ma, Lei

2016-11-01

Fatigue is highly prevalent in patients with epilepsy and has a major impact on quality of life, but little data is available on its effects and management in epilepsy. To identify the incidence and risk factors of fatigue in patients with epilepsy, 105 epilepsy patients (45 women and 60 men) were enrolled in our study. Demographic and clinical data were collected and psychological variables including fatigue, sleep quality, excess daytime sleepiness, anxiety, and depression were measured by Fatigue Severity Scale, Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale, and Hospital Anxiety and Depression Scale, respectively. Of 105 patients, 29.5% exhibited fatigue (FSS score ⩾4). We found no correlation between the occurrence of fatigue and any of our demographic or clinical variables. Fatigue is correlated with low sleep quality, anxiety, and depression, but not with excess daytime sleepiness. Thus, we concluded that fatigue is highly prevalent in patients with epilepsy, and that low sleep quality, anxiety, and depression are significantly correlated with fatigue in epileptics, while excess daytime sleepiness not. Copyright © 2016. Published by Elsevier Ltd.

Factors associated with work-related fatigue and recovery in hospital nurses working 12-hour shifts.

PubMed

Han, Kihye; Trinkoff, Alison M; Geiger-Brown, Jeanne

2014-10-01

Nurse fatigue threatens both nurse and patient safety; fatigue affects nurses' neurocognitive functioning and hinders their work performance. The authors assessed the association of work and non-work factors with acute and chronic fatigue and intershift recovery among hospital nurses working 12-hour shifts. This study used survey data from 80 nurses who provided full-time direct patient care on medical-surgical and critical care units in a large teaching hospital. Psychological job demands (e.g., work load and social support from supervisor or coworker) were significantly associated with acute and chronic fatigue and intershift recovery. Rotating shifts were significantly related to acute fatigue. Findings suggest the need for a comprehensive approach to fatigue management, including organizational support to provide healthful work schedules and favorable nursing work environments, fewer psychological and physical demands, and assistance to improve nurses' sleep quality and quantity. [Workplace Health Saf 2014;62(10):409-414.]. Copyright 2014, SLACK Incorporated.

Pilot fatigue survey: exploring fatigue factors in air medical operations.

PubMed

Gregory, Kevin B; Winn, William; Johnson, Kent; Rosekind, Mark R

2010-01-01

Humans confront significant physiological challenges with sleep and alertness when working in 24/7 operations. A web-based national survey of air medical pilots examined issues relevant to fatigue and sleep management. Six hundred ninety-seven responses were received, with a majority of rotor wing pilots working 3/3/7 and 7/7 duty schedules. Over 84% of the pilots reported that fatigue had affected their flight performance; less than 28% reported "nodding off" during flight. More than 90% reported a separate work site "rest" room with a bed available. Over 90% reported no company policies restricting on-duty sleep. Approximately half of the pilots reported getting 4 hours or more sleep during a typical night shift. Approximately half reported that sleep inertia had never compromised flight safety. Over 90% reported that it was better to sleep during the night and overcome sleep inertia if necessary. Survey results reflected practices that can mitigate the degrading effects of fatigue, including the availability of designated work-site sleep rooms. As demands continue to evolve, the need remains for sustained efforts to address fatigue-related risks in the air medical transport industry. This includes further study of sleep inertia issues and the need for alertness management programs. Copyright © 2010 Air Medical Journal Associates. Published by Elsevier Inc. All rights reserved.

The reciprocal relationship between daily fatigue and catastrophizing following cancer treatment: Affect and physical activity as potential mediators.

PubMed

Müller, Fabiola; Stephenson, Ellen; DeLongis, Anita; Smink, Ans; Van Ginkel, Robert J; Tuinman, Marrit A; Hagedoorn, Mariët

2018-03-01

Fatigue is a distressing symptom many cancer patients experience even after completion of treatment. Although theory and empirical evidence indicate that negative cognitions perpetuate fatigue after completion of treatment, insight into how this process unfolds in daily life is limited. This study used an intensive longitudinal design to investigate the reciprocal relationship between catastrophizing and fatigue in daily life and whether affective and behavioral processes mediate these relationships. Post-treatment colorectal cancer patients (n = 101) completed daily diaries (14 days, 3 times daily) regarding their fatigue, catastrophizing, positive and negative affect, and physical activity. Multilevel modeling was applied to investigate within-person associations within days. Analyses revealed a positive reciprocal relationship between fatigue and catastrophizing throughout the day. That is, high levels of catastrophizing were associated with increases in fatigue within patients. In turn, but to a lesser extent, high levels of fatigue predicted increases in catastrophizing at the next assessment. Low positive affect and high negative affect mediated the effect of catastrophizing on increases in fatigue. Only negative affect mediated the reverse relationship. Physical activity did not mediate either relationship. This study provides evidence for a mutually reinforcing relationship between catastrophizing and fatigue in daily life, which might explain the perpetuation of fatigue after completion of cancer treatment. Fatigue-specific cognitive behavior therapy could be improved by educating patients about this daily reciprocal relationship, train them to quickly replace catastrophizing thoughts in daily life, and help them to cope with affective changes induced by fatigue. Copyright © 2017 John Wiley & Sons, Ltd.

Objectively measured muscle fatigue in Crohn's disease: correlation with self-reported fatigue and associated factors for clinical application.

PubMed

van Langenberg, D R; Della Gatta, P; Warmington, S A; Kidgell, D J; Gibson, P R; Russell, A P

2014-02-01

The association of fatigue with decreased physical performance and underlying mechanisms are poorly understood in Crohn's disease (CD). We aimed to measure and compare self-reported fatigue with skeletal muscle fatigue in CD subjects and healthy controls, and to identify associated factors that may be amenable to change. Demographic and clinical data were collected and fatigue assessed using the Fatigue Impact Scale (FIS) in 27 consecutive CD patients and 22 matched healthy controls. Circulating cytokines and growth factors were measured. The rate of quadriceps muscle fatigue was assessed using an isokinetic dynamometer as the decrement of force with 30 contractions performed over a 5-minute period. Compared with healthy controls, CD patients reported greater levels of fatigue (mean global FIS score 45.3 vs 10.5, physical dimension score 12.3 vs 2.7 respectively; each p<0.01) and muscle fatigue (-5.2 vs -1.3 Nm min(-1); p<0.05). The two indices were correlated (r = -0.52 in CD; p<0.01). Patients with CD had lower mean serum IGF-1 levels (16.1 vs 25.4 pmol/L, p<0.01) and higher oxidative stress (TBARS assay 4.3 vs 3.9 μM, p<0.05). On multivariate analysis, low serum vitamin D, IGF-1 and magnesium, and higher IL-6 levels were associated with increased muscle fatigue (all p ≤ 0.05). Subjects with CD had more muscle fatigue than matched healthy controls and this correlated well with self-reported fatigue. Of circulating factors that were independently associated with increased muscle fatigue, vitamin D, magnesium and IGF-1 could be targeted in future studies to reduce fatigue and improve physical performance. © 2013.

Carbide factor predicts rolling-element bearing fatigue life

NASA Technical Reports Server (NTRS)

Chevalier, J. L.; Zaretsky, E. V.

1973-01-01

Analysis was made to determine correlation between number and size of carbide particles and rolling-element fatigue. Correlation was established, and carbide factor was derived that can be used to predict fatigue life more effectively than such variables as heat treatment, chemical composition, and hardening mechanism.

The influence of trait-negative affect and compassion satisfaction on compassion fatigue in Australian nurses.

PubMed

Craigie, Mark; Osseiran-Moisson, Rebecca; Hemsworth, David; Aoun, Samar; Francis, Karen; Brown, Janie; Hegney, Desley; Rees, Clare

2016-01-01

For this study, we examined the nature of the unique relationships trait-negative affect and compassion satisfaction had with compassion fatigue and its components of secondary traumatic stress and burnout in 273 nurses from 1 metropolitan tertiary acute hospital in Western Australia. Participants completed the Professional Quality of Life Scale (Stamm, 2010), Depression Anxiety Stress Scale (Lovibond & Lovibond, 2004), and the State-Trait Anxiety Inventory (Spielberger, Gorsuch, Lushene, Vagg, & Jacobs, 1983). Bivariate correlation and hierarchical regression analyses were performed to examine and investigate 4 hypotheses. The results demonstrate a clear differential pattern of relationships with secondary traumatic stress and burnout for both trait-negative affect and compassion satisfaction. Trait-negative affect was clearly the more important factor in terms of its contribution to overall compassion fatigue and secondary traumatic stress. In contrast, compassion satisfaction's unique protective relationship only related to burnout, and not secondary traumatic stress. The results are therefore consistent with the view that compassion satisfaction may be an important internal resource that protects against burnout, but is not directly influential in protecting against secondary traumatic stress for nurses working in an acute-care hospital environment. With the projected nursing workforce shortages in Australia, it is apparent that a further understanding is warranted of how such personal variables may work as protective and risk factors. (c) 2016 APA, all rights reserved).

Factors impacting the illness trajectory of post-infectious fatigue syndrome: a qualitative study of adults' experiences.

PubMed

Stormorken, Eva; Jason, Leonard A; Kirkevold, Marit

2017-12-13

Post-infectious fatigue syndrome (PIFS), also known as post-viral fatigue syndrome, is a complex condition resulting in physical, cognitive, emotional, neurological, vocational and/or role performance disabilities in varying degrees that changes over time. The needs for health care resources are high, and costly, as is the economic burden on the affected individuals. Many factors may impact the trajectory, and frequently PIFS develops into a chronic condition. Health professionals lack understanding and knowledge, which results in delayed diagnosis, lack of recognition, appropriate treatment, support and practical help. The aim of our study was to explore, from the perspective of persons who had lived with PIFS for four years following an outbreak of Giardia l. induced enteritis, factors that may have impacted their illness trajectory and how these factors had played a role during different phases. In this retrospective exploratory qualitative study a group of 26 affected adults between 26 and 59 years old were selected for in-depth interviews. A maximum variation sample was recruited from a physician-diagnosed cohort of persons with PIFS enrolled at a tertiary outpatient fatigue clinic. The interviews were audio-recorded, transcribed verbatim and subjected to qualitative content analysis. Unhelpful and helpful factors were associated with the healthcare system, health professionals and the affected persons were experienced as having an impact on the trajectory. External impacting factors which are related to the health care system, providers and the social security system are misdiagnosis, trivialization of symptoms, unhelpful advice, delayed diagnosis and lack of appropriate help. Internal impacting factors related to the affected individuals were lack of knowledge, overestimating functional capacity, assuming the condition will pass, ignoring body signals and denial. A model of impacting factors in each phase of the trajectory is presented. Unmet needs may

Multidimensional Predictors of Fatigue among Octogenarians and Centenarians

PubMed Central

Cho, Jinmyoung; Martin, Peter; Margrett, Jennifer; MacDonald, Maurice; Johnson, Mary Ann; Poon, Leonard W.

2012-01-01

Background Fatigue is a common and frequently observed complaint among older adults. However, knowledge about the nature and correlates of fatigue in old age is very limited. Objective: This study examined the relationship of functional indicators, psychological and situational factors and fatigue for 210 octogenarians and centenarians from the Georgia Centenarian Study. Methods Three indicators of functional capacity (self-rated health, instrumental activities of daily living, physical activities of daily living), two indicators of psychological well-being (positive and negative affect), two indicators of situational factors (social network and social support), and a multidimensional fatigue scale were used. Blocked multiple regression analyses were computed to examine significant factors related to fatigue. In addition, multi-group analysis in structural equation modeling was used to investigate residential differences (i.e., long-term care facilities vs. private homes) in the relationship between significant factors and fatigue. Results Blocked multiple regression analyses indicated that two indicators of functional capacity, self-rated health and instrumental activities of daily living, both positive and negative affect, and social support were significant predictors of fatigue among oldest-old adults. The multiple group analysis in structural equation modeling revealed a significant difference among oldest-old adults based on residential status. Conclusion The results suggest that we should not consider fatigue as merely an unpleasant physical symptom, but rather adopt a perspective that different factors such as psychosocial aspects can influence fatigue in advanced later life. PMID:22094445

Multidimensional predictors of fatigue among octogenarians and centenarians.

PubMed

Cho, Jinmyoung; Martin, Peter; Margrett, Jennifer; MacDonald, Maurice; Johnson, Mary Ann; Poon, Leonard W; Jazwinski, S M; Green, R C; Gearing, M; Woodard, J L; Tenover, J S; Siegler, I C; Rott, C; Rodgers, W L; Hausman, D; Arnold, J; Davey, A

2012-01-01

Fatigue is a common and frequently observed complaint among older adults. However, knowledge about the nature and correlates of fatigue in old age is very limited. This study examined the relationship of functional indicators, psychological and situational factors and fatigue for 210 octogenarians and centenarians from the Georgia Centenarian Study. Three indicators of functional capacity (self-rated health, instrumental activities of daily living, physical activities of daily living), two indicators of psychological well-being (positive and negative affect), two indicators of situational factors (social network and social support), and a multidimensional fatigue scale were used. Blocked multiple regression analyses were computed to examine significant factors related to fatigue. In addition, multi-group analysis in structural equation modeling was used to investigate residential differences (i.e., long-term care facilities vs. private homes) in the relationship between significant factors and fatigue. Blocked multiple regression analyses indicated that two indicators of functional capacity, self-rated health and instrumental activities of daily living, both positive and negative affect, and social support were significant predictors of fatigue among oldest-old adults. The multiple group analysis in structural equation modeling revealed a significant difference among oldest-old adults based on residential status. The results suggest that we should not consider fatigue as merely an unpleasant physical symptom, but rather adopt a perspective that different factors such as psychosocial aspects can influence fatigue in advanced later life. Copyright © 2011 S. Karger AG, Basel.

Occupational Factors, Fatigue, and Cardiovascular Disease

PubMed Central

2009-01-01

Purpose: Briefly identify the epidemiological evidence, propose pertinent mechanisms, and discuss physical therapy practice as well as research implications of a causal association between occupational factors and cardiovascular disease. Summary of Key Points: There is evidence that occupational metabolic demands and work organizations characterized by reduced worker control are associated with increased risk of cardiovascular disease. It is biologically plausible that these two factors interact to create a preclinical, intermediate state of fatigue (burnout) that is a critical component in the causal path from occupational factors to CVD. Physical therapists are uniquely qualified to contribute to an understanding of these mechanisms and their resultant implications for work organization, rehabilitation, and health promotion. Statement of Recommendations: Physical therapists engaged in ergonomic job analysis should consider work related metabolic demands, worker control, and fatigue in their assessment of risk for injury and illness, in recommendations for return to work, and in the prescription of health promotion leisure time physical activity PMID:20467535

Shift work and employee fatigue: implications for occupational health nursing.

PubMed

Yumang-Ross, Doreen J; Burns, Candace

2014-06-01

Long work hours and irregular shifts are part of the nation's 24-hour society and contribute to employee fatigue. Factors affecting employee fatigue are circadian rhythm, sleep quality and quantity, individual health, the environment, and work tasks. Employee fatigue contributes to accidents and injuries, and affects occupational performance, safety, and health. These findings should be used by occupational health nurses to address fatigue management and develop comprehensive fatigue management programs. Copyright 2014, SLACK Incorporated.

A Fatigue Life Prediction Method Based on Strain Intensity Factor

PubMed Central

Zhang, Wei; Liu, Huili; Wang, Qiang; He, Jingjing

2017-01-01

In this paper, a strain-intensity-factor-based method is proposed to calculate the fatigue crack growth under the fully reversed loading condition. A theoretical analysis is conducted in detail to demonstrate that the strain intensity factor is likely to be a better driving parameter correlated with the fatigue crack growth rate than the stress intensity factor (SIF), especially for some metallic materials (such as 316 austenitic stainless steel) in the low cycle fatigue region with negative stress ratios R (typically R = −1). For fully reversed cyclic loading, the constitutive relation between stress and strain should follow the cyclic stress-strain curve rather than the monotonic one (it is a nonlinear function even within the elastic region). Based on that, a transformation algorithm between the SIF and the strain intensity factor is developed, and the fatigue crack growth rate testing data of 316 austenitic stainless steel and AZ31 magnesium alloy are employed to validate the proposed model. It is clearly observed that the scatter band width of crack growth rate vs. strain intensity factor is narrower than that vs. the SIF for different load ranges (which indicates that the strain intensity factor is a better parameter than the stress intensity factor under the fully reversed load condition). It is also shown that the crack growth rate is not uniquely determined by the SIF range even under the same R, but is also influenced by the maximum loading. Additionally, the fatigue life data (strain-life curve) of smooth cylindrical specimens are also used for further comparison, where a modified Paris equation and the equivalent initial flaw size (EIFS) are involved. The results of the proposed method have a better agreement with the experimental data compared to the stress intensity factor based method. Overall, the strain intensity factor method shows a fairly good ability in calculating the fatigue crack propagation, especially for the fully reversed cyclic

What paramedics think about when they think about fatigue: contributing factors.

PubMed

Paterson, Jessica L; Sofianopoulos, Sarah; Williams, Brett

2014-04-01

Paramedic fatigue is associated with burnout, attrition, sick leave, work disability, physical and mental health complaints and impaired performance. However, no studies have addressed how fatigue is understood by paramedics. The present study addresses this shortcoming by exploring factors paramedics recognise as contributors to fatigue. Forty-nine (12F; 38 years ± 9.7 years) Australian paramedics completed a survey on perceived causes of performance impairing fatigue. A total of 107 responses were systematically coded following principles common to qualitative data analysis: data immersion, coding, categorisation and theme generation. Six themes emerged: working time, sleep, workload, health and well-being, work-life balance and environment. Consistent with a scientific understanding of fatigue, prior sleep and wake, time of day and task-related factors were often identified as contributing to fatigue. In other cases, paramedics' attributions deviated from a scientific understanding of direct causes of fatigue. These findings demonstrate that paramedics have a broad understanding of fatigue. It is critical to take this into account when discussing fatigue with paramedics, particularly in the case of fatigue education or wellness programmes. These data highlight areas for intervention and education to minimise the experience of paramedic fatigue and the negative health and safety outcomes for paramedics and patients as a result. © 2014 Australasian College for Emergency Medicine and Australasian Society for Emergency Medicine.

Fatigue mechanisms in patients with cancer: effects of tumor necrosis factor and exercise on skeletal muscle

NASA Technical Reports Server (NTRS)

St Pierre, B. A.; Kasper, C. E.; Lindsey, A. M.

1992-01-01

Fatigue is a common adverse effect of cancer and its therapy. However, the specific mechanisms underlying cancer fatigue are unclear. One physiologic mechanism may involve changes in skeletal muscle protein stores or metabolite concentration. A reduction in skeletal muscle protein stores may result from endogenous tumor necrosis factor (TNF) or from TNF administered as antineoplastic therapy. This muscle wasting would require patients to exert an unusually high amount of effort to generate adequate contractile force during exercise performance or during extended periods of sitting or standing. This additional effort could result in the onset of fatigue. Additionally, cancer fatigue may develop or become exacerbated during exercise as a consequence of changes in the concentration of skeletal muscle metabolites. These biochemical alterations may interfere with force that is produced by the muscle contractile proteins. These physiologic changes may play a role in the decision to include exercise in the rehabilitation plans of patients with cancer. They also may affect ideas about fatigue.

The effect of fatigue driving on injury severity considering the endogeneity.

PubMed

Li, Yanyan; Yamamoto, Toshiyuki; Zhang, Guangnan

2018-02-01

Fatigue driving is one of the most risky driving-related behaviors and represented a significant social and economic cost to the community. Several studies have already examined the relationship between fatigue driving behavior and traffic injury severity from different aspects. However, fatigue driving and injury severity in traffic crash may share some common influential factors. Ignoring the impact of these common factors will lead to endogeneity problem and result in biased parameter estimation. Based on 38,564 crash records during 2006-2011 in Guangdong province, China, we apply a bivariate endogenous binary-ordered probit model to examine the relationship between fatigue driving and injury severity considering endogeneity of fatigue driving. We also explore the difference of influential factors between commercial and non-commercial vehicle drivers. This study identifies several common observed influential factors of fatigue driving propensity and fatal injury propensity and reveals a substantial and significant negative correlation of unobserved factors between them. The influence of fatigue driving on injury severity is significantly underestimated if the endogeneity of fatigue driving on fatal injury propensity is ignored. Factors such as vehicle insurance and road types not only affect fatal injury propensity, but also fatigue driving propensity. The findings in this study can help better understand how those factors affect fatigue driving and injury severity, and contributes to more efficient policy for preventing the harmfulness of fatigue-related crashes. Copyright © 2017 National Safety Council and Elsevier Ltd. All rights reserved.

Comparative Physiology of Fatigue.

PubMed

Jones, James H

2016-11-01

This review attempts to provide insights into factors associated with fatigue in human and nonhuman animals by using the two fundamental approaches of comparative physiology: determining common principles that govern structure and function in animals that are relatively invariant between animals and evaluating animals that have been highly adapted by natural selection to demonstrate extreme performance. In this review, I approach the topic of fatigue by considering factors that are associated with its reciprocal or inverse or duration of sustained performance before fatigue sets in to end the performance. The two general factors that I consider that affect endurance time more than any other are body temperature and body mass. The former affects endurance time because of thermodynamic effects on chemical reaction rates and metabolism; the latter acts through the mechanism of allometry or scaling. The examples of extreme animal performance that I discuss are two examples of bird migration, the diving performance of marine mammals, and the unique relationship that governs energy cost of locomotion in hopping kangaroos.

Factors of working conditions and prolonged fatigue among teachers at public elementary and junior high schools.

PubMed

Shimizu, Midori; Wada, Koji; Wang, Guoqin; Kawashima, Masatoshi; Yoshino, Yae; Sakaguchi, Hiroko; Ohta, Hiroshi; Miyaoka, Hitoshi; Aizawa, Yoshiharu

2011-01-01

Prolonged fatigue among elementary and junior high school teachers not only damages their health but also affects the quality of education. The aim of this study was to determine the factors of working conditions associated with prolonged fatigue among teachers at public elementary and junior high schools. We distributed a self-reported, anonymous questionnaire to 3,154 teachers (1,983 in elementary schools, 1,171 in junior high schools) working in public schools in a city in Japan. They were asked to assess 18 aspects of their working conditions using a seven-point Likert scale. Prolonged fatigue was measured using the Japanese version of the checklist individual strength questionnaire. Multiple regression analysis was used to examine the association between working conditions and prolonged fatigue. Gender, age, and school type were introduced as confounders. In all, 2,167 teachers participated in this study. Results showed that qualitative and quantitative workload (time pressure due to heavy workload, interruptions, physically demanding job, extra work at home), communication with colleagues (poor communication, lack of support), and career factors (underestimation of performance by the board of education or supervisors, occupational position not reflecting training, lack of prospects for work, job insecurity) were associated with prolonged fatigue.

Explanatory factors and predictors of fatigue in persons with rheumatoid arthritis: A longitudinal study.

PubMed

Feldthusen, Caroline; Grimby-Ekman, Anna; Forsblad-d'Elia, Helena; Jacobsson, Lennart; Mannerkorpi, Kaisa

2016-04-28

To investigate the impact of disease-related aspects on long-term variations in fatigue in persons with rheumatoid arthritis. Observational longitudinal study. Sixty-five persons with rheumatoid arthritis, age range 20-65 years, were invited to a clinical examination at 4 time-points during the 4 seasons. Outcome measures were: general fatigue rated on visual analogue scale (0-100) and aspects of fatigue assessed by the Bristol Rheumatoid Arthritis Fatigue Multidimensional Questionnaire. Disease-related variables were: disease activity (erythrocyte sedimentation rate), pain threshold (pressure algometer), physical capacity (six-minute walk test), pain (visual analogue scale (0-100)), depressive mood (Hospital Anxiety and Depression scale, depression subscale), personal factors (age, sex, body mass index) and season. Multivariable regression analysis, linear mixed effects models were applied. The strongest explanatory factors for all fatigue outcomes, when recorded at the same time-point as fatigue, were pain threshold and depressive mood. Self-reported pain was an explanatory factor for physical aspects of fatigue and body mass index contributed to explaining the consequences of fatigue on everyday living. For predicting later fatigue pain threshold and depressive mood were the strongest predictors. Pain threshold and depressive mood were the most important factors for fatigue in persons with rheumatoid arthritis.

Depressive symptoms and inflammation are independent risk factors of fatigue in breast cancer survivors.

PubMed

Xiao, C; Miller, A H; Felger, J; Mister, D; Liu, T; Torres, M A

2017-07-01

Psychosocial and inflammatory factors have been associated with fatigue in breast cancer survivors. Nevertheless, the relative contribution and/or interaction of these factors with cancer-related fatigue have not been well documented. This cross-sectional study enrolled 111 stage 0-III breast cancer patients treated with breast surgery followed by whole breast radiotherapy. Fatigue was measured by the total score of the Multidimensional Fatigue Inventory-20. Potential risk factors included inflammatory markers (plasma cytokines and their receptors and C-reactive protein; CRP), depressive symptoms (as assessed by the Inventory of Depressive Symptomatology-Self Reported), sleep (as assessed by the Pittsburgh Sleep Quality Index) and perceived stress (as assessed by the Perceived Stress Scale) as well as age, race, marital status, smoking history, menopause status, endocrine treatment, chemotherapy and cancer stage. Linear regression modeling was employed to examine risk factors of fatigue. Only risk factors with a significance level <0.10 were included in the initial regression model. A post-hoc mediation model using PROCESS SPSS was conducted to examine the association among depressive symptoms, sleep problems, stress, inflammation and fatigue. At 1 year post-radiotherapy, depressive symptoms (p<0.0001) and inflammatory markers (CRP: p = 0.015; interleukin-1 receptor antagonist: p = 0.014; soluble tumor necrosis factor receptor-2: p = 0.009 in separate models) were independent risk factors of fatigue. Mediation analysis showed that depressive symptoms also mediated the associations of fatigue with sleep and stress. Depressive symptoms and inflammation were independent risk factors for cancer-related fatigue at 1 year post-radiotherapy, and thus represent independent treatment targets for this debilitating symptom.

Factors Associated with Fatigue among Men Aged 45 and Older: A Cross-Sectional Study

PubMed Central

Lin, Wei-Quan; Jing, Meng-Juan; Tang, Jie; Wang, Jia-Ji; Zhang, Hui-Shan; Yuan, Le-Xin; Wang, Pei-Xi

2015-01-01

Background and Purpose: Fatigue is one of the most common symptoms reported in several studies; but few studies have concentrated on the male population, especially for the middle-aged and older men who are exposed to greater fatigue risk. The purpose of this study was to explore the prevalence of fatigue and identify the risk factors of fatigue among men aged 45 and older in China. Methods: This study was part of a cross-sectional study on community health in Shunde (Guangdong Province, China). A total sample of 1158 men aged 45 and older were included. Sociodemographic characteristics, health and lifestyle factors and the Chalder Fatigue Scale (CFS) were measured by structured questionnaires through face-to-face interviews. Multivariate logistic regression was applied to determine the risk factors of fatigue. Results: Approximately 30% of participants experienced fatigue. Older age (≥75 years: adjusted OR 3.88, 95% CI 2.09–7.18), single marital status (1.94, 1.04–3.62), unemployed status (1.68, 1.16–2.43), number of self-reported chronic diseases (≥2 chronic diseases: 2.83, 1.86–4.31), number of individuals’ children (≥4 children: 2.35, 1.33–4.15), hospitalization in the last year (1.61, 1.03–2.52) were all significantly associated with increased risk of fatigue, while regular exercise (0.46, 0.32–0.65) was a protective factor against fatigue. Conclusions: Fatigue was usual in males and several factors were associated with the fatigue. These findings may have implication in risk assessment of fatigue and help in developing and implementing targeted interventions in middle-aged and elderly males. PMID:26404346

Prolonged fatigue in Ukraine and the United States: Prevalence and risk factors

PubMed Central

Friedberg, Fred; Tintle, Nathan; Clark, Jake; Bromet, Evelyn J.

2015-01-01

Background Prolonged, severe, unalleviated fatigue may be disabling whether it occurs on its own or in conjunction with medical or psychiatric conditions. This paper compares the prevalence and correlates of prolonged fatigue in general population samples in Ukraine versus the U.S. Methods Population surveys were conducted in 2002 in both Ukraine (Ukraine World Mental Health [WMH] Survey) and the U.S. (National Comorbidity Survey-Replication; NCS-R). Both surveys administered the Composite International Diagnostic Interview (CIDI 3.0), which contained modules assessing: neurasthenia (prolonged fatigue); mood, anxiety, and alcohol/drug use disorders; chronic medical conditions; and demographic characteristics. Multivariable logistic regression was used to examine risk factors in each country. Results The lifetime prevalence of prolonged fatigue was higher in Ukraine (5.2%) than the U.S. (3.7%). In both countries, one-fifth of individuals with prolonged fatigue had no medical or DSM-IV psychiatric condition. Also in both settings, fatigue was significantly associated with sociodemographic characteristics (being female, not working, and married before) as well as early onset and adult episodes of mood/anxiety disorder. Fatigue prevalence in Ukraine increased with age, but decreased in the U.S. at age 70. Unique risk factors for fatigue in Ukraine included lower socio-economic status, Ukrainian vs Russian ethnicity, and cardiovascular disease. Unique risk factors in the U.S. were parental depression/anxiety, adult episodes of alcohol/drugs, pain conditions, and other health problems. Conclusions The lifetime prevalence of prolonged fatigue in Ukraine was 40% higher than that found in U.S. data. In addition, fatigue prevalence increased sharply with age in Ukraine perhaps due to limited social and medical resources and greater comorbidity. PMID:26807341

Biopsychosocial risk factors of persistent fatigue after acute infection: A systematic review to inform interventions.

PubMed

Hulme, Katrin; Hudson, Joanna L; Rojczyk, Philine; Little, Paul; Moss-Morris, Rona

2017-08-01

Fatigue is a prevalent and debilitating symptom, preceded by an acute infectious episode in some patients. This systematic review aimed to identify risk factors for the development of persistent fatigue after an acute infection, to develop an evidence-based working model of post-infectious fatigue. Electronic databases (Medline, PsycINFO and EMBASE) were searched, from inception to March 2016, for studies which investigated biopsychosocial risk factors of on-going fatigue after an acute infection. Inclusion criteria were: prospective design; biological, psychological or social risk factors; standardised measure of post-infectious fatigue (self-report scales or clinical diagnosis). Studies were excluded if the sample had a pre-existing medical condition, infection was conceptualised as 'vaccination' or they were intervention trials. A narrative synthesis was performed. Eighty-one full texts were screened, of which seventeen were included in the review. Over half included glandular fever populations. Other infections included dengue fever, 'general'/'viral' and Q-fever. Risk factors were summarised under biological, social, behavioural, cognitive and emotional subthemes. Patients' cognitive and behavioural responses to the acute illness, and pre-infection or baseline distress and fatigue were the most consistent risk factors for post-infectious fatigue. An empirical summary model is provided, highlighting the risk factors most consistently associated with persistent fatigue. The components of the model, the possible interaction of risk factors and implications for understanding the fatigue trajectory and informing preventative treatments are discussed. Copyright © 2017. Published by Elsevier Inc.

The Factors and Features of Museum Fatigue in Science Centres Felt by Korean Students

NASA Astrophysics Data System (ADS)

Kim, Minchul; Dillon, Justin; Song, Jinwoong

2018-03-01

One of the objectives of science education in science centres has been the enhancement of interest in science. However, museum fatigue has a negative impact on interest. Museum fatigue has been described as physical tiredness or a decrease in visitors' interest in a museum. The learning experience of students in science centres is also influenced by museum fatigue. The purpose of this study is to identify the phenomena of museum fatigue in science centres and to identity how it is manifested. First, we identified the factors causing museum fatigue in science centres using the data from an open-ended questionnaire which was given to 597 primary, middle and high school students in South Korea. From the responses to the questionnaire, 50 factors causing museum fatigue in science centres were identified. A second Likert-type questionnaire with the 50 factors of museum fatigue in science centres was administered to 610 primary, middle and high school students in South Korea. Using reliability and factor analyses, we developed a framework of the factors causing museum fatigue in science centres, which consists of three contexts, 12 categories and 50 factors. Secondly, through statistical analyses including T test and ANOVA analysis, the features of students' museum fatigue in science centres were analysed and compared regarding student gender, school level, interest in science, grade of school science, the number of visits, and type of visit. The results, which were found to be statistically significant, are reported and discussed. The findings of this study are intended to serve for a deeper understanding and practical improvement of science learning in science centres.

Analysis of Crew Fatigue in AIA Guantanamo Bay Aviation Accident

NASA Technical Reports Server (NTRS)

Rosekind, Mark R.; Gregory, Kevin B.; Miller, Donna L.; Co, Elizabeth L.; Lebacqz, J. Victor; Statler, Irving C. (Technical Monitor)

1994-01-01

Flight operations can engender fatigue, which can affect flight crew performance, vigilance, and mood. The National Transportation Safety Board (NTSB) requested the NASA Fatigue Countermeasures Program to analyze crew fatigue factors in an aviation accident that occurred at Guantanamo Bay, Cuba. There are specific fatigue factors that can be considered in such investigations: cumulative sleep loss, continuous hours of wakefulness prior to the incident or accident, and the time of day at which the accident occurred. Data from the NTSB Human Performance Investigator's Factual Report, the Operations Group Chairman's Factual Report, and the Flight 808 Crew Statements were analyzed, using conservative estimates and averages to reconcile discrepancies among the sources. Analysis of these data determined the following: the entire crew displayed cumulative sleep loss, operated during an extended period of continuous wakefulness, and obtained sleep at times in opposition to the circadian disposition for sleep, and that the accident occurred in the afternoon window of physiological sleepiness. In addition to these findings, evidence that fatigue affected performance was suggested by the cockpit voice recorder (CVR) transcript as well as in the captain's testimony. Examples from the CVR showed degraded decision-making skills, fixation, and slowed responses, all of which can be affected by fatigue; also, the captain testified to feeling "lethargic and indifferent" just prior to the accident. Therefore, the sleep/wake history data supports the hypothesis that fatigue was a factor that affected crewmembers' performance. Furthermore, the examples from the CVR and the captain's testimony support the hypothesis that the fatigue had an impact on specific actions involved in the occurrence of the accident.

Factors Modulating Recovery Rate after Intermittent Tetanic Fatigue in Atrophic Soleus

NASA Astrophysics Data System (ADS)

Li, Hui; Jiao, Bo; Yu, Zhibin

2008-06-01

To specify the factors modulating the recovery rate after intermittent tetanic fatigue in soleus, and to seek the reasons for the decrease of recovery rate in atrophic soleus, we observed the recovery time course of different types of fatigue in isolated muscle strips. A 10 % or 50 % decrease in maximal contraction tension of tetani was defined respectively as slight or moderate fatigue. Tetanic tension recovery rates after short-term and long-term of slight or moderate fatigue were observed, some pharmacological intervention were also used. The results showed that slight fatigue only induced an inhibition to myofibril, while moderate fatigue induced an inhibition in myofibril and sarcoplasmic reticulum Ca2+ release channels. There were significant decreases in all of the fatigue groups in one-week tail-suspended rats. These suggest that both slight and moderate fatigue inhibit the myofibrils and the sarcoplasmic reticulum Ca2+ release channels in one-week unloaded soleus.

[Analysis of work-related fatigue characteristics and its influencing factors in scientific and technical personnel].

PubMed

Yang, Ting; Zhou, Dinglun; Song, Mingying; Lan, Yajia

2015-02-01

To investigate the current status and characteristics of work-related fatigue among scientific and technical personnel and its associated factors, and to provide a scientific basis for further interventions. A cross-sectional survey was conducted in the staff from a single scientific institution, using a self-administered questionnaire. Basic information of participants, Fatigue Scale-14, and Job Content Questionnaire were collected. The prevalence of work-related fatigue among the scientific and technical personnel was 54.6%; work-related fatigue was positively correlated with occupational stress (rs = 0.384, P < 0.05). Significant differences in the scores, proportions, and types of fatigue were found between different types of occupational stress. The associated factors of work-related fatigue included occupational stress profiles, social support, and educational status. A higher risk of work-related fatigue was found in the staff under high stress, compared with those under low stress (OR = 8.5, 95%CI = 3.9∼18.7). Social support served as a protective factor for work-related fatigue, while a higher level of education was correlated with more severe work-related fatigue. Work-related fatigue is common and serious among scientific and technical personnel, especially in those under high stress. Effective interventions according to occupational stress are of great importance to reduce work-related fatigue.

Risk factors and visual fatigue of baggage X-ray security screeners: a structural equation modelling analysis.

PubMed

Yu, Rui-Feng; Yang, Lin-Dong; Wu, Xin

2017-05-01

This study identified the risk factors influencing visual fatigue in baggage X-ray security screeners and estimated the strength of correlations between those factors and visual fatigue using structural equation modelling approach. Two hundred and five X-ray security screeners participated in a questionnaire survey. The result showed that satisfaction with the VDT's physical features and the work environment conditions were negatively correlated with the intensity of visual fatigue, whereas job stress and job burnout had direct positive influences. The path coefficient between the image quality of VDT and visual fatigue was not significant. The total effects of job burnout, job stress, the VDT's physical features and the work environment conditions on visual fatigue were 0.471, 0.469, -0.268 and -0.251 respectively. These findings indicated that both extrinsic factors relating to VDT and workplace environment and psychological factors including job burnout and job stress should be considered in the workplace design and work organisation of security screening tasks to reduce screeners' visual fatigue. Practitioner Summary: This study identified the risk factors influencing visual fatigue in baggage X-ray security screeners and estimated the strength of correlations between those factors and visual fatigue. The findings were of great importance to the workplace design and the work organisation of security screening tasks to reduce screeners' visual fatigue.

Fatigue in out-patients with inflammatory bowel disease: Prevalence and predictive factors.

PubMed

Villoria, Albert; García, Víctor; Dosal, Angelina; Moreno, Laura; Montserrat, Antònia; Figuerola, Ariadna; Horta, Diana; Calvet, Xavier; Ramírez-Lázaro, María José

2017-01-01

Fatigue is a common and bothersome symptom in inflammatory bowel disease (IBD) patients. The study was aimed to determine the relationship of biological and psychological factors with IBD-related fatigue. Consecutive clinically inactive IBD outpatients receiving immunosuppressants or biological drugs were enrolled between January and December 2013. Patients completed a Fatigue score (FACIT-F), various psychological, quality of life (IBDQ-9), and IBD activity scores. Biological parameters were assessed, including levels of interleukins (IL-5, IL-8 and IL-12) and micronutrients. We prospectively recruited 202 patients (28% ulcerative colitis and 72% Crohn's disease) for the study. Fatigue measured by FACIT-F score was prevalent in the studied population (54%, 96/177) and higher than in the general population. In the univariate analysis no relation was found between IL levels or micronutrient deficiencies and fatigue. Fatigue was significantly related to female sex, Crohn's disease, joint disorders, body mass index (BMI), psychological tests, thiopurine use, and anti-TNF treatment. All these variables were included in the multivariate analysis. Female sex (OR: 4.8), high BMI (OR:1.2) and higher depression rates (OR:1.2) were predictors of increased fatigue. High IBDQ-9 score (OR: 0.82) was significantly related to lower degrees of fatigue. Fatigue was prevalent in quiescent IBD patients with moderate-to-severe disease. It was associated with high levels of depression, low quality of life, and female sex. No association was found with the other biological and psychological factors evaluated.

Fatigue of Chinese railway employees and its influential factors: Structural equation modelling.

PubMed

Tsao, Liuxing; Chang, Jing; Ma, Liang

2017-07-01

Fatigue is an identifiable and preventable cause of accidents in transport operations. Regarding the railway sector, incident logs and simulation studies show that employee fatigue leads to lack of alertness, impaired performance, and occurrence of incidents. China has one of the largest rail systems in the world, and Chinese railway employees work under high fatigue risks; therefore, it is important to assess their fatigue level and find the major factors leading to fatigue. We designed a questionnaire that uses Multidimensional Fatigue Instrument (MFI-20), NASA-TLX and subjective rating of work overtime feelings to assess employee fatigue. The contribution of each influential factor of fatigue was analysed using structural equation modelling. In total, 297 employees from the rail maintenance department and 227 employees from the locomotive department returned valid responses. The average scores and standard deviations for the five subscales of MFI-20, namely General Fatigue, Physical Fatigue, Reduced Activity, Reduced Motivation, and Mental Fatigue, were 2.9 (0.8), 2.8 (0.8), 2.5 (0.8), 2.5 (0.7), and 2.4 (0.8) among the rail maintenance employees and 3.5 (0.8), 3.5 (0.7), 3.3 (0.7), 3.0 (0.6), and 3.1 (0.7), respectively, among the locomotive employees. The fatigue of the locomotive employees was influenced by feelings related to working overtime (standardized r = 0.22) and workload (standardized r = 0.27). The work overtime control and physical working environment significantly influenced subjective feelings (standardized r = -0.25 and 0.47, respectively), while improper work/rest rhythms and an adverse physical working environment significantly increased the workload (standardized r = 0.48 and 0.33, respectively). Copyright © 2017 Elsevier Ltd. All rights reserved.

The Association between Job-Related Psychosocial Factors and Prolonged Fatigue among Industrial Employees in Taiwan

PubMed Central

Tang, Feng-Cheng; Li, Ren-Hau; Huang, Shu-Ling

2016-01-01

Background and Objectives Prolonged fatigue is common among employees, but the relationship between prolonged fatigue and job-related psychosocial factors is seldom studied. This study aimed (1) to assess the individual relations of physical condition, psychological condition, and job-related psychosocial factors to prolonged fatigue among employees, and (2) to clarify the associations between job-related psychosocial factors and prolonged fatigue using hierarchical regression when demographic characteristics, physical condition, and psychological condition were controlled. Methods A cross-sectional study was employed. A questionnaire was used to obtain information pertaining to demographic characteristics, physical condition (perceived physical health and exercise routine), psychological condition (perceived mental health and psychological distress), job-related psychosocial factors (job demand, job control, and workplace social support), and prolonged fatigue. Results A total of 3,109 employees were recruited. Using multiple regression with controlled demographic characteristics, psychological condition explained 52.0% of the variance in prolonged fatigue. Physical condition and job-related psychosocial factors had an adjusted R2 of 0.370 and 0.251, respectively. Hierarchical multiple regression revealed that, among job-related psychosocial factors, job demand and job control showed significant associations with fatigue. Conclusion Our findings highlight the role of job demand and job control, in addition to the role of perceived physical health, perceived mental health, and psychological distress, in workers’ prolonged fatigue. However, more research is required to verify the causation among all the variables. PMID:26930064

Factors Influencing the Fatigue Strength of Materials

NASA Technical Reports Server (NTRS)

Bollenrath, F

1941-01-01

A number of factors are considered which influence the static and fatigue strength of materials under practical operating conditions as contrasted with the relations obtaining under conditions of the usual testing procedure. Such factors are interruptions in operation, periodically fluctuating stress limits and mean stresses with periodic succession of several groups and stress states, statistical changes and succession of stress limits and mean stresses, frictional corrosion at junctures, and notch effects.

Physiological and psychosocial factors that predict HIV-related fatigue.

PubMed

Barroso, Julie; Hammill, Bradley G; Leserman, Jane; Salahuddin, Naima; Harmon, James L; Pence, Brian Wells

2010-12-01

Fatigue is one of the most common and debilitating symptoms experienced by HIV-infected people. We report the results of our longitudinal analysis of physiological and psychosocial factors that were thought to predict changes in HIV-related fatigue in 128 participants over a 1-year period, in an effort to sort out the complex interplay among a comprehensive set of physiological and psychosocial variables. Physiological measures included hepatic function (aspartate aminotransferase, alanine aminotransferase, gamma glutamyl transpeptidase, alkaline phosphatase, total bilirubin, hepatitis C status), thyroid function (thyroid stimulating hormone, thyroxine), HIV viral load, immunologic function (CD4, CD8, CD4/CD8 ratio, CD16, CD8CD38), gonadal function (testosterone, dehydroepiandrosterone), hematologic function (hemoglobin, hematocrit, serum erythropoietin), and cellular injury (lactic acid). Psychosocial measures included childhood and adult trauma, anxiety, depression, social support, stressful life events, and post-traumatic stress disorder (PTSD). Unemployment, not being on antiretroviral therapy, having fewer years since HIV diagnosis, more childhood trauma, more stressful life events, less social support, and more psychological distress (e.g., PTSD, anxiety and depression) put HIV-infected persons at risk for greater fatigue intensity and fatigue-related impairment in functioning during 1-year follow-up. Physiological variables did not predict greater fatigue. Stressful life events had both direct and indirect effects on fatigue.

Fatigue failure of metal components as a factor in civil aircraft accidents

NASA Technical Reports Server (NTRS)

Holshouser, W. L.; Mayner, R. D.

1972-01-01

A review of records maintained by the National Transportation Safety Board showed that 16,054 civil aviation accidents occurred in the United States during the 3-year period ending December 31, 1969. Material failure was an important factor in the cause of 942 of these accidents. Fatigue was identified as the mode of the material failures associated with the cause of 155 accidents and in many other accidents the records indicated that fatigue failures might have been involved. There were 27 fatal accidents and 157 fatalities in accidents in which fatigue failures of metal components were definitely identified. Fatigue failures associated with accidents occurred most frequently in landing-gear components, followed in order by powerplant, propeller, and structural components in fixed-wing aircraft and tail-rotor and main-rotor components in rotorcraft. In a study of 230 laboratory reports on failed components associated with the cause of accidents, fatigue was identified as the mode of failure in more than 60 percent of the failed components. The most frequently identified cause of fatigue, as well as most other types of material failures, was improper maintenance (including inadequate inspection). Fabrication defects, design deficiencies, defective material, and abnormal service damage also caused many fatigue failures. Four case histories of major accidents are included in the paper as illustrations of some of the factors invovled in fatigue failures of aircraft components.

Fatigue and its associated factors in liver transplant recipients in Beijing: a cross-sectional study

PubMed Central

Lin, Xiao-Hong; Teng, Sha; Wang, Lu; Zhang, Jing; Shang, Ya-Bin; Liu, Hong-Xia; Zang, Yun-Jin

2017-01-01

Objectives Fatigue is a highly prevalent symptom experienced by patients who underwent the liver transplantation. However, the influencing factors of fatigue are poorly understood by healthcare professionals. The aim of this study was to examine the intensity, interference, duration and prevalence of fatigue in liver transplantation recipients and to explore the influencing factors of post-transplantation fatigue. Design A cross-sectional design was used in this study. Methods A convenience sample of liver transplant recipients was recruited at an outpatient transplant clinic of a general hospital in Beijing, China. Self-report survey data were provided by liver transplant recipients using the Fatigue Symptom Inventory (FSI), the Hospital Anxiety and Depression Scale (HADS), the Perceived Social Support Scale (PSSS) and the Athens Insomnia Scale (AIS). Demographic, clinical and psychosocial parameters were evaluated as fatigue influencing factors. Results Participants (n=285) included 69 women and 216 men. Fatigue was found in 87.0% of liver transplant recipients. Mean scores of fatigue intensity items were 4.47±2.85, 1.93±1.97, 3.15±2.13 and 2.73±2.42 (most fatigue, least fatigue, average fatigue in the week prior to assessment and fatigue at the point of assessment). The mean score of fatigue interference was 2.27±2.09.The number of days fatigued in the week prior to assessment was 2.26±2.02 and the amount of time fatigued each day was 2.75±2.44. Spearman's correlation analysis showed that fatigue intensity was positively associated with anxiety, depression and insomnia (p<0.001 for all), while fatigue interference was positively associated with gender, anxiety, depression and insomnia (p<0.05 for all). In the multiple linear regression analysis, anxiety and insomnia were positively associated with fatigue intensity (p<0.001), and insomnia, depression and anxiety were positively associated with fatigue interference (p<0.001). Conclusions Fatigue is common

Fatigue in out-patients with inflammatory bowel disease: Prevalence and predictive factors

PubMed Central

Villoria, Albert; García, Víctor; Dosal, Angelina; Moreno, Laura; Montserrat, Antònia; Figuerola, Ariadna; Horta, Diana; Ramírez-Lázaro, María José

2017-01-01

Background and Aim Fatigue is a common and bothersome symptom in inflammatory bowel disease (IBD) patients. The study was aimed to determine the relationship of biological and psychological factors with IBD-related fatigue. Methods Consecutive clinically inactive IBD outpatients receiving immunosuppressants or biological drugs were enrolled between January and December 2013. Patients completed a Fatigue score (FACIT-F), various psychological, quality of life (IBDQ-9), and IBD activity scores. Biological parameters were assessed, including levels of interleukins (IL-5, IL-8 and IL-12) and micronutrients. Results We prospectively recruited 202 patients (28% ulcerative colitis and 72% Crohn’s disease) for the study. Fatigue measured by FACIT-F score was prevalent in the studied population (54%, 96/177) and higher than in the general population. In the univariate analysis no relation was found between IL levels or micronutrient deficiencies and fatigue. Fatigue was significantly related to female sex, Crohn’s disease, joint disorders, body mass index (BMI), psychological tests, thiopurine use, and anti-TNF treatment. All these variables were included in the multivariate analysis. Female sex (OR: 4.8), high BMI (OR:1.2) and higher depression rates (OR:1.2) were predictors of increased fatigue. High IBDQ-9 score (OR: 0.82) was significantly related to lower degrees of fatigue. Conclusion Fatigue was prevalent in quiescent IBD patients with moderate-to-severe disease. It was associated with high levels of depression, low quality of life, and female sex. No association was found with the other biological and psychological factors evaluated. PMID:28749985

Fatigue Countermeasures: Alertness Management in Flight Operations

NASA Technical Reports Server (NTRS)

Co, E. L.; Rosekind, M. R.; Johnson, J. M.; Weldon, K. J.; Smith, R. M.; Gregory, K. G.; Miller, D. L.; Gander, P. H.; Lebacqz, J. V.; Statler, Irving C. (Technical Monitor)

1994-01-01

Since 1980, the NASA Ames Fatigue Countermeasures Program has studied the effects and impact of fatigue on flight operations . Sleep loss and circadian disruption are two of the primary physiological factors that underlie fatigue in flight operations. The Program has developed an array of fatigue countermeasure recommendations that can be used to combat the effects of fatigue and continues to research potential new countermeasures. For example, one such strategy involved a NASA/FAA study on the effects of planned cockpit rest to improve crewmember alertness and performance. Based partly on the study results, the FAA is currently reviewing a proposed Advisory Circular for controlled rest on the flight deck. Since there is no simple answer to the issue of fatigue in aviation, an Education and Training Module has been developed to provide the industry with pertinent information on sleep, circadian rhythms, how flight operations affect these physiological factors, and recommendations for fatigue countermeasures. The Module will be updated as the Program's continued research efforts uncover new information and develop new countermeasure strategies,

Risk factors for persistent fatigue with significant school absence in children and adolescents.

PubMed

Bakker, Robert J; van de Putte, Elise M; Kuis, Wietse; Sinnema, Gerben

2009-07-01

To assess children and adolescents with severe fatigue who are referred to pediatricians and to examine whether factors can be identified at their first visit that predict worse outcomes at 1 year. Ninety-one patients, aged 8 to 18 years completed questionnaires about sleep, somatic symptoms, physical activity, and fatigue. They were reassessed 12 months later. Measurements at baseline and outcome were analyzed by using univariable logistic regression with persistent, severe fatigue (yes/no) and persistent school absence (yes/no) as dependent variables and baseline scores as independent variables. After 12 months, 50.6% of the children and adolescents showed improvement; 29.1% had persistent fatigue, and 20.3% had persistent fatigue with significant school absence. Factors associated with the poorest outcome were sleep problems (odds ratio [OR]: 1.4 [95% confidence interval (CI): 1.1-1.8]), initial fatigue score (OR: 1.1 [95% CI: 1.0-1.2]), somatic complaints such as hot and cold spells (OR: 1.9 [95% CI: 1.2-3.0]), blurred vision (OR: 2.1 [95% CI: 1.1-4.0]), pain in arms and legs (OR: 2.0 [95% CI: 1.0-3.2]), back pain (OR: 1.8 [95% CI: 1.0-3.2]), constipation (OR: 1.7 [95% CI: 1.0-2.7]), and memory deficits (OR: 1.8 [95% CI: 1.0-3.2]). Resolved fatigue was associated with male gender (OR: 5.0 [95% CI: 1.6-15.5]) and a physically active lifestyle (OR: 1.3 [95% CI: 1.1-1.5]). Assessment of predictive factors at the first visit enables the pediatrician to identify those patients with severe fatigue who are at risk of a poor outcome. Female gender, poor sleep quality, physically inactive lifestyle, and specific somatic complaints were important predictive factors.

Physiological and Psychosocial Factors that Predict HIV-Related Fatigue

PubMed Central

Hammill, Bradley G.; Leserman, Jane; Salahuddin, Naima; Harmon, James L.; Pence, Brian Wells

2010-01-01

Fatigue is one of the most common and debilitating symptoms experienced by HIV-infected people. We report the results of our longitudinal analysis of physiological and psychosocial factors that were thought to predict changes in HIV-related fatigue in 128 participants over a 1-year period, in an effort to sort out the complex interplay among a comprehensive set of physiological and psychosocial variables. Physiological measures included hepatic function (aspartate aminotransferase, alanine aminotransferase, gamma glutamyl transpeptidase, alkaline phosphatase, total bilirubin, hepatitis C status), thyroid function (thyroid stimulating hormone, thyroxine), HIV viral load, immunologic function (CD4, CD8, CD4/CD8 ratio, CD16, CD8CD38), gonadal function (testosterone, dehydroepiandrosterone), hematologic function (hemoglobin, hematocrit, serum erythropoietin), and cellular injury (lactic acid). Psychosocial measures included childhood and adult trauma, anxiety, depression, social support, stressful life events, and post-traumatic stress disorder (PTSD). Unemployment, not being on antiretroviral therapy, having fewer years since HIV diagnosis, more childhood trauma, more stressful life events, less social support, and more psychological distress (e.g., PTSD, anxiety and depression) put HIV-infected persons at risk for greater fatigue intensity and fatigue-related impairment in functioning during 1-year follow-up. Physiological variables did not predict greater fatigue. Stressful life events had both direct and indirect effects on fatigue. PMID:20352317

Work factors as predictors of persistent fatigue: a prospective study of nurses' aides.

PubMed

Eriksen, W

2006-06-01

To identify work factors that predict persistent fatigue in nurses' aides. The sample comprised 5547 Norwegian nurses' aides, not on leave when they completed a mailed questionnaire in 1999. Of these, 4645 (83.7%) completed a second questionnaire 15 months later. The outcome measure was the occurrence of persistent fatigue, defined as having felt "usually fatigued" or "always fatigued" in daytime during the previous 14 days. In respondents without persistent fatigue at baseline, medium and high work demands, heavy smoking, being single, and having long term health problems were associated with increased risk of persistent fatigue at follow up. Medium and high rewards for well done work, medium levels of leadership fairness, and regular physical exercise were associated with reduced risk of persistent fatigue at follow up. In respondents with persistent fatigue at baseline, medium and high levels of positive challenges at work, high support from immediate superior, medium feedback about quality of one's work, and changes of work or work tasks that resulted in less heavy work or lower work pace were associated with increased odds of recovery (no persistent fatigue at follow up). Working in a nursing home and being intensely bothered by long term health problems were associated with reduced odds of recovery. High demands and lack of rewards at work may cause persistent fatigue in nurses' aides. Reduction of demands, adequate feedback, and mental stimulation in the form of support and positive challenges may facilitate recovery in those who have persistent fatigue. Leaders in the health services may be in a position to regulate factors that influence the level of fatigue in nurses' aides.

Exploring the factors affecting motorway accident severity in England using the generalised ordered logistic regression model.

PubMed

Michalaki, Paraskevi; Quddus, Mohammed A; Pitfield, David; Huetson, Andrew

2015-12-01

The severity of motorway accidents that occurred on the hard shoulder (HS) is higher than for the main carriageway (MC). This paper compares and contrasts the most important factors affecting the severity of HS and MC accidents on motorways in England. Using police reported accident data, the accidents that occurred on motorways in England are grouped into two categories (i.e., HS and MC) according to the location. A generalized ordered logistic regression model is then applied to identify the factors affecting the severity of HS and MC accidents on motorways. The factors examined include accident and vehicle characteristics, traffic and environment conditions, as well as other behavioral factors. Results suggest that the factors positively affecting the severity include: number of vehicles involved in the accident, peak-hour traffic time, and low visibility. Differences between HS and MC accidents are identified, with the most important being the involvement of heavy goods vehicles (HGVs) and driver fatigue, which are found to be more crucial in increasing the severity of HS accidents. Measures to increase awareness of HGV drivers regarding the risk of fatigue when driving on motorways, and especially the nearside lane, should be taken by the stakeholders. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

A study on fatigue strength reduction factor for small diameter socket welded pipe joints

DOE Office of Scientific and Technical Information (OSTI.GOV)

Higuchi, Makoto; Nakagawa, Akira; Hayashi, Makoto

1996-12-01

Factors that may exert influence on the fatigue strength of small diameter socket welded joints of nominal diameter in the 20--50 mm range have been investigated by the fully reversed four-point bending fatigue test with the material, diameter, pipe schedule, throat depth, bead shape, slip-on gap, and root defect as the testing parameters. The fatigue strength of socket joints depended acutely on the diameter. When the diameter is large, the fatigue strength tended to be low and the fracture is of the root-failure mode; when it is small, on the other hand, the fatigue strength is high and the fracturemore » is of the toe-failure mode. Stainless steel proved to be superior to carbon steel; it gave rise to 1.37 times the fatigue strength of the latter for socket joints of nominal diameter 50 mm; the fatigue strength reduction factor determined at 10{sup 7} cycles with respect to the fatigue strength of smooth base metal in the fully reversed fatigue was about 4 for stainless steel and about 5 for carbon steel. The fatigue strength was higher, the larger the Sche number (i.e., the thicker the pipe wall); it was improved markedly by placing one final refinement pass on the toe or by eliminating the slip-on gap. An empirical formula relating the size of the root defect to the fatigue strength reduction has been proposed.« less

Factors related to fatigue after paediatric acquired brain injury (ABI).

PubMed

van Markus-Doornbosch, F; de Kloet, A J; Berger, M A M; Lambregts, S A M; Wolterbeek, R; Vliet Vlieland, T P M

2016-01-01

To assess the degree of fatigue in children and youth after traumatic and non-traumatic brain injury (TBI and NTBI) and related factors. Follow-up study including patients with a hospital-based diagnosis of acquired brain injury (ABI), aged 4-20 years at onset and their parents. Parents and children (dependent on age) completed the Paediatric Quality of Life Inventory™ Multidimensional Fatigue Scale (PedsQL™ MFS), which measures general fatigue (GF), sleep/rest fatigue (SRF) and cognitive fatigue (CF). Additional assessments included the Child & Family Follow-up Survey (CFFS) and PedsQL™ 4.0 General Core Scales and sociodemographic and disease characteristics. Eighty-eight parents completed the PedsQL™ MFS 24-30 months after diagnosis, with 49/88 patients (56%) completing the child version. The median age of the patients was 11 years (interquartile range [IQR] = 7). There were 69 patients with TBI (16% moderate/severe TBI) and 19 patients with NTBI (16% moderate/severe NTBI). The median parent-reported and child-reported PedsQL™ MFS Total Scale Scores were 76.5 (SD = 16.4) and 78.5 (12.9), respectively (Spearman r = 0.450, p = 0.001). Apart from NTBI, increasing age and a single-parent household were significantly associated with more fatigue according to the parent-reported PedsQL™ MFS Total Score (and/or one or more sub-scale scores). Two years after onset, in particular, the parent-reported fatigue after NTBI was considerable. Moreover, older children and children from a single-parent household were found to have higher fatigue levels.

High-strength bolt corrosion fatigue life model and application.

PubMed

Hui-li, Wang; Si-feng, Qin

2014-01-01

The corrosion fatigue performance of high-strength bolt was studied. Based on the fracture mechanics theory and the Gerberich-Chen formula, the high-strength bolt corrosion fracture crack model and the fatigue life model were established. The high-strength bolt crack depth and the fatigue life under corrosion environment were quantitatively analyzed. The factors affecting high-strength bolt corrosion fatigue life were discussed. The result showed that the high-strength bolt corrosion fracture biggest crack depth reduces along with the material yield strength and the applied stress increases. The material yield strength was the major factor. And the high-strength bolt corrosion fatigue life reduced along with the increase of material strength, the applied stress or stress amplitude. The stress amplitude influenced the most, and the material yield strength influenced the least. Low bolt strength and a low stress amplitude level could extend high-strength bolt corrosion fatigue life.

A critical review of the psychophysiology of driver fatigue.

PubMed

Lal, S K; Craig, A

2001-02-01

Driver fatigue is a major cause of road accidents and has implications for road safety. This review discusses the concepts of fatigue and provides a summary on psychophysiological associations with driver fatigue. A variety of psychophysiological parameters have been used in previous research as indicators of fatigue, with electroencephalography perhaps being the most promising. Most research found changes in theta and delta activity to be strongly linked to transition to fatigue. Therefore, monitoring electroencephalography during driver fatigue may be a promising variable for use in fatigue countermeasure devices. The review also identified anxiety and mood states as factors that may possibly affect driver fatigue. Furthermore, personality and temperament may also influence fatigue. Given the above, understanding the psychology of fatigue may lead to better fatigue management. The findings from this review are discussed in the light of directions for future studies and for the development of fatigue countermeasures.

Factors associated with fatigue in acquired immunodeficiency syndrome patients with antiretroviral drug adverse reactions: a retrospective study.

PubMed

Liu, Zhibin; Yang, Jiping; Liu, Huijuan; Jin, Yantao

2013-06-01

To retrospectively study the prevalence of fatigue and factors associated with fatigue among acquired immunodeficiency syndrome (AIDS) patients with antiretroviral drug adverse reactions. Data were collected from case report forms (CRFs) for a project funded by the 11th National 5-year Special Science and Technology Program on Major Infectious Diseases. Fatigue was defined by patient self-report. The outcomes were the prevalence of fatigue and the potential risk factors of fatigue. Univariate and multivariate logistic regression analyses were conducted to identify the factors associated with fatigue. Among the 228 subjects, the prevalence of fatigue was 86.8%. In univariate analysis, the significant differences in demographic characteristics between patients with and without fatigue were: gender [OR = 2.29; 95% CI (1.05-4.98)], education level [OR = 0.40; 95% CI (0.18-0.85)], anemia [OR = 3.80; 95% CI (1.27-11.31)], time of HIV diagnosis [OR = 0.29; 95% CI (0.13-0.65)], and route of infection [OR = 0.14; 95% CI (0.06-0.32)]. Abnormal taste and rapid pulse were more commonly seen in patients with fatigue (P < 0.05), while abdominal distension and lumbar soreness were encountered less often in patients with fatigue (P < 0.05). Multivariate analysis showed that the four main factors associated with fatigue were anemia [OR = 3.50; 95% CI (1.01-12.15)], route of infection [OR = 3.40; 95% CI (1.21-9.58); P = 0.02 < 0.05], lumbar soreness [OR = 0.06; 95% CI (0.02-0.18); P = 0.000 < 0.05], and rapid pulse [OR = 10.58; 95% CI (2.16-51.75); P = 0.004 < 0.05]. This study demonstrated that fatigue is common (86.8% prevalence) in AIDS patients with antiretroviral drug adverse reactions, and that anemia, route of infection (i.e., non-commercial blood donation) and rapid pulse were risk factors, while lumbar soreness was a protective factor related to fatigue. More attention should be paid to fatigue and more efforts should be made to find ways to prevent, control and eliminate

Factors that influence the development of compassion fatigue, burnout, and compassion satisfaction in emergency department nurses.

PubMed

Hunsaker, Stacie; Chen, Hsiu-Chin; Maughan, Dale; Heaston, Sondra

2015-03-01

The purpose of this study was twofold: (a) to determine the prevalence of compassion satisfaction, compassion fatigue, and burnout in emergency department nurses throughout the United States and (b) to examine which demographic and work-related components affect the development of compassion satisfaction, compassion fatigue, and burnout in this nursing specialty. This was a nonexperimental, descriptive, and predictive study using a self-administered survey. Survey packets including a demographic questionnaire and the Professional Quality of Life Scale version 5 (ProQOL 5) were mailed to 1,000 selected emergency nurses throughout the United States. The ProQOL 5 scale was used to measure the prevalence of compassion satisfaction, compassion fatigue, and burnout among emergency department nurses. Multiple regression using stepwise solution was employed to determine which variables of demographics and work-related characteristics predicted the prevalence of compassion satisfaction, compassion fatigue, and burnout. The α level was set at .05 for statistical significance. The results revealed overall low to average levels of compassion fatigue and burnout and generally average to high levels of compassion satisfaction among this group of emergency department nurses. The low level of manager support was a significant predictor of higher levels of burnout and compassion fatigue among emergency department nurses, while a high level of manager support contributed to a higher level of compassion satisfaction. The results may serve to help distinguish elements in emergency department nurses' work and life that are related to compassion satisfaction and may identify factors associated with higher levels of compassion fatigue and burnout. Improving recognition and awareness of compassion satisfaction, compassion fatigue, and burnout among emergency department nurses may prevent emotional exhaustion and help identify interventions that will help nurses remain empathetic and

The Effects of Mental Fatigue on Physical Performance: A Systematic Review.

PubMed

Van Cutsem, Jeroen; Marcora, Samuele; De Pauw, Kevin; Bailey, Stephen; Meeusen, Romain; Roelands, Bart

2017-08-01

Mental fatigue is a psychobiological state caused by prolonged periods of demanding cognitive activity. It has recently been suggested that mental fatigue can affect physical performance. Our objective was to evaluate the literature on impairment of physical performance due to mental fatigue and to create an overview of the potential factors underlying this effect. Two electronic databases, PubMed and Web of Science (until 28 April 2016), were searched for studies designed to test whether mental fatigue influenced performance of a physical task or influenced physiological and/or perceptual responses during the physical task. Studies using short (<30 min) self-regulatory depletion tasks were excluded from the review. A total of 11 articles were included, of which six were of strong and five of moderate quality. The general finding was a decline in endurance performance (decreased time to exhaustion and self-selected power output/velocity or increased completion time) associated with a higher than normal perceived exertion. Physiological variables traditionally associated with endurance performance (heart rate, blood lactate, oxygen uptake, cardiac output, maximal aerobic capacity) were unaffected by mental fatigue. Maximal strength, power, and anaerobic work were not affected by mental fatigue. The duration and intensity of the physical task appear to be important factors in the decrease in physical performance due to mental fatigue. The most important factor responsible for the negative impact of mental fatigue on endurance performance is a higher perceived exertion.

Lower brain-derived neurotrophic factor levels associated with worsening fatigue in prostate cancer patients during repeated stress from radiation therapy.

PubMed

Saligan, L N; Lukkahatai, N; Holder, G; Walitt, B; Machado-Vieira, R

2016-12-01

Fatigue during cancer treatment is associated with depression. Neurotrophic factors play a major role in depression and stress and might provide insight into mechanisms of fatigue. This study investigated the association between plasma concentrations of three neurotrophic factors (BDNF, brain-derived neurotrophic factor; GDNF, glial-derived neurotrophic factor; and SNAPIN, soluble N-ethylmaleimide sensitive fusion attachment receptor-associated protein) and initial fatigue intensification during external beam radiation therapy (EBRT) in euthymic non-metastatic prostate cancer men. Fatigue, as measured by the 13-item Functional Assessment of Cancer Therapy-Fatigue (FACT-F), and plasma neurotrophic factors were collected at baseline (prior to EBRT) and mid-EBRT. Subjects were categorized into fatigue and no fatigue groups using a > 3-point change in FACT-F scores between the two time points. Multiple linear regressions analysed the associations between fatigue and neurotrophic factors. FACT-F scores of 47 subjects decreased from baseline (43.95 ± 1.3) to mid-EBRT (38.36 ± 1.5, P < 0.001), indicating worsening fatigue. SNAPIN levels were associated with fatigue scores (r s = 0.43, P = 0.005) at baseline. A significant decrease of BDNF concentration (P = 0.008) was found in fatigued subjects during EBRT (n = 39). Baseline SNAPIN and decreasing BDNF levels may influence worsening fatigue during EBRT. Further investigations are warranted to confirm their role in the pathophysiology and therapeutics of fatigue.

The NASA Ames Fatigue Countermeasures Program: The Next Generation

NASA Technical Reports Server (NTRS)

Rosekind, Mark R.; Neri, David F.; Miller, Donna L.; Gregory, Kevin B.; Webbon, Lissa L.; Oyung, Ray L.

1997-01-01

Twenty-four hour, global aviation operations pose unique challenges to humans. Physiological requirements related to sleep, the internal circadian clock, and human fatigue are critical factors that are known to affect safety, performance, and productivity. Understanding the human operators' physiological capabilities, and limitations, will be important to address these issues as global demand for aviation activities continues to increase. In 1980, in response to a Congressional request, the National Aeronautics and Space Administration (NASA) Ames Research Center initiated a Fatigue/Jet Lag Program to examine the role of fatigue in flight operations. Originally established by Dr. John K. Lauber and Dr. Charles E. Billings, the Program was designed to address three objectives: (1) determine the extent of fatigue, sleep loss, and circadian disruption in flight operations; (2) determine how fatigue affected flight crew performance; and (3) develop strategies to maximize performance and alertness during flight operations.

Fatigue in osteoarthritis: a qualitative study

PubMed Central

Power, J Denise; Badley, Elizabeth M; French, Melissa R; Wall, Angela J; Hawker, Gillian A

2008-01-01

Background Fatigue is recognized as a disabling symptom in many chronic conditions including rheumatic disorders such as rheumatoid arthritis (RA) and lupus. Fatigue in osteoarthritis (OA) is not routinely evaluated and has only been considered in a very limited number of studies. To date, these studies have focused primarily on patients with OA under rheumatological care, which represent the minority of people living with OA. The purpose of this study was to increase our understanding of the fatigue experience in community dwelling people with OA. Methods In 2004, 8 focus groups were conducted with 28 men and 18 women (mean age 72.3) with symptomatic hip or knee OA recruited from a population-based cohort. Participants completed a self-administered questionnaire, which included demographics, measures of OA severity (WOMAC), depression (CES-D) and fatigue (FACIT). Sessions were audio taped and transcribed verbatim. Two researchers independently reviewed the transcripts to identify themes. Findings were compared and consensus reached. Results Mean pain, disability, depression and fatigue scores were 8.7/20, 27.8/68, 15.4/60, and 30.9/52, respectively. Participants described their fatigue as exhaustion, being tired and "coming up against a brick wall". Participants generally perceived fatigue as different from sleepiness and distinguished physical from mental fatigue. Factors believed to increase fatigue included OA pain and pain medications, aging, various types of weather and poor sleep. Mental health was identified as both affecting fatigue and being affected by fatigue. Participants described fatigue as impacting physical function, and their ability to participate in social activities and to do household chores. Rest, exercise, and avoiding or getting assistance with activities were cited as ways of coping. Participants generally did not discuss their fatigue with anyone except their spouses. Conclusion Participants with OA described experiencing notable amounts

The contribution of clinical and psychosocial factors to fatigue in 182 patients with inflammatory bowel disease: a cross-sectional study.

PubMed

Artom, M; Czuber-Dochan, W; Sturt, J; Murrells, T; Norton, C

2017-02-01

Fatigue is a frequently reported and predominant symptom experienced by patients with inflammatory bowel disease (IBD) and its impact has been associated with poorer quality of life (QoL). The complex interplay between disease-related variables and potentially modifiable psychosocial factors in IBD-fatigue has yet to be unravelled. To evaluate the contribution of clinical, sociodemographic and psychosocial factors to the severity and impact of IBD-fatigue and QoL. In a cross-sectional study, 182 patients with IBD were recruited from three tertiary referral hospitals' out-patient clinics in London. Fatigue was assessed utilising the Inflammatory Bowel Disease-Fatigue Scale (IBD-F), the Multidimensional Fatigue Inventory (MFI); and QoL by the Inflammatory Bowel Disease Questionnaire (IBDQ). Patients completed self-report questionnaires evaluating emotional, cognitive and behavioural factors potentially correlated with fatigue. Sociodemographic data were collected. Disease-related and laboratory data were retrieved from patients' hospital electronic medical records. In hierarchical regression models, disease activity was the only clinical factor consistently associated with severity and impact of fatigue and QoL (P = 0.01). More negative fatigue perceptions were significantly associated with greater IBD-F1 scores (P = 0.01). When controlling for clinical factors (disease activity and anti-TNF therapy), negative perceptions of fatigue, and all-or-nothing and avoidance behaviours explained an additional 41% of the variance in fatigue impact (IBD-F2). Apart from disease activity, emotional and behavioural factors and patients' negative fatigue perceptions may be key factors to be addressed. Further exploration of these factors in longitudinal and intervention studies may help to develop effective models of fatigue management. © 2016 John Wiley & Sons Ltd.

Fatigue in adults with Marfan syndrome, occurrence and associations to pain and other factors.

PubMed

Bathen, Trine; Velvin, Gry; Rand-Hendriksen, Svend; Robinson, Hilde Stendal

2014-08-01

This study aims to investigate how fatigue affects adults with verified Marfan syndrome (MFS) in their daily lives, by examining fatigue levels and prevalence of severe fatigue compared to the general Norwegian population and individuals with other comparable chronic conditions. We investigated associations between socio-demographic characteristics, Marfan-related health problems, pain and fatigue. A cross-sectional study was conducted, using a postal questionnaire including the Fatigue Severity Scale (FSS) and questions on socio-demographic characteristics, Marfan-related health problems and pain. One hundred seventeen persons with MFS were invited to participate, 73 answered (62%). Participants reported significantly higher FSS scores and prevalence of severe fatigue compared to the general Norwegian population and patients with rheumatoid arthritis (RA), but lower than for other chronic conditions. Participants with chronic pain reported higher fatigue scores than those without chronic pain. Participants on disability benefits reported higher fatigue scores than participants who were working or enrolled in higher education. Marfan-related health problems like aortic dissection and use of blood pressure medication were not significantly associated with fatigue. In multivariable regression analyses chronic pain and employment status were significantly associated with fatigue. The final multivariable model explained 24% of the variance in fatigue scores. Our results show that fatigue is common in MFS patients and that it interferes with their daily lives. Chronic pain and employment status show significant associations to fatigue. This implies that fatigue is important to address when meeting MFS patients in clinical practice. There is need for more research on fatigue in Marfan syndrome. © 2014 Wiley Periodicals, Inc.

[Study on relationship between fatigue and work ability in chemistry workers].

PubMed

Wu, Si-Ying; Wang, Mian-Zhen; Wang, Zhi-Ming; Lan, Ya-Jia

2005-01-01

Explore the relationship between fatigue and work ability in 976 chemistry workers. A test of fatigue and work ability was carried out with fatigue scale and work ability index (WAI) for 976 workers, other influence factors of the work ability (such as work environment, labor load, job factors) were investigated with questionnaire. (1) The frequency of fatigue of the unmarried workers was significantly lower than that of the married workers and other marital status workers, while the score of WAI of the unmarried was significantly higher than that of those( P < 0.05); (2) the frequency of fatigue of the mental workers was significantly lower than that of the mixed physical and mental workers, while the score of WAI of the mental workers was significantly higher than that of physical workers and mixed physical and mental workers ( P < 0.05); (3) compared with the workers free of fatigue, the other workers had lower WAI scores; (4) the fatigue score correlated negatively to the WAI score (r = -0.499, P < 0.01); (5) Cumulative odds model analysis showed that after controlling the other risk factors, fatigue was an important risk factor of work ability (OR = 4.005). Fatigue has affected work ability in chemistry workers, the frequency of fatigue is higher, the score of WAI is lower.

[Effect of fatigue on the fitness to drive].

PubMed

Makowiec-Dabrowska, Teresa; Bortkiewicz, Alicja; Siedlecka, Jadwiga; Gadzicka, Elzbieta

2011-01-01

The 1995 U.S. Department of Transportation files contain a statement that driver fatigue has been a major problem among road vehicle professional drivers, while the consequences of participation in public road traffic of drivers affected by fatigue represent a serious threat to the public safety. Therefore, studies on the causes and consequences of fatigue in drivers are of significant practical value. The authors of this work discuss definitions of fatigue and fatigue classifications relative to the location of the functional changes (physical and mental fatigue, general and local - muscular, ocular, auditory) and relative to intensity (acute, sub-acute, chronic fatigue and weariness), and duration Particular attention has been paid to the factors contributing to fatigue in drivers. These may be classified into two groups: 1. sleep-related (SR), i.e. cumulative sleep deficit, long wake time, and time of the day; 2. task-related (TR), i.e. factors related with vehicle driving and working (driving) time. Studies on the effect of fatigue on driving performance (longer reaction time, poorer vigilance, slower information processing, impaired recent memory) have been analyzed. The major effect of driver fatigue is that he/she becomes gradually diverted from the road and road traffic, with the resultant poorer driving performance. Thus, the effects of fatigue in a driver are comparable to those after alcohol intake. This paper also discusses the methods used to counteract and prevent fatigue.

Factors associated with multidimensional aspect of post-stroke fatigue in acute stroke period.

PubMed

Mutai, Hitoshi; Furukawa, Tomomi; Houri, Ayumi; Suzuki, Akihito; Hanihara, Tokiji

2017-04-01

Post-stroke fatigue (PSF) is a frequent and distressing consequence of stroke, and can be both acute and long lasting. We aimed to investigate multidimensional aspects of acute PSF and to determine the clinical factors relevant to acute PSF. We collected data of 101 patients admitted to the hospital for acute stroke. PSF was assessed using the Multidimensional Fatigue Inventory within 2 weeks of stroke. Measures included Mini-Mental State Examination, Hospital Anxiety and Depression Scale, and Functional Independence Measure. Stroke character, lesion location, and clinical variables that potentially influence PSF were also collected. The prevalence of pathological fatigue is 56.4% within 2 weeks of stroke. Binary logistic regression analysis revealed that anxiety was the only predictor for presence of PSF (OR=1.32, 95% CI: 1.13-1.53, P<0.001). Multivariate stepwise regression analysis showed anxiety, right lesion side, thalamus, and/or brainstem were independently associated with general fatigue, right lesion side, depression, diabetes mellitus, and anxiety with physical fatigue, depression with reduced activity, depression, and BMI with reduced motivation, depression, and diabetes mellitus with mental fatigue. PSF was highly prevalent in the acute phase, and specific factors including lesion location (right side lesion, thalamic and brainstem lesion), anxiety, and depression were independently associated with multidimensional aspects of PSF. Further study is needed to elucidate how specific structural lesions and anxiety symptoms relate to the development of early fatigue following stroke. Copyright © 2016 Elsevier B.V. All rights reserved.

Experimental study of surface integrity and fatigue life in the face milling of inconel 718

NASA Astrophysics Data System (ADS)

Wang, Xiangyu; Huang, Chuanzhen; Zou, Bin; Liu, Guoliang; Zhu, Hongtao; Wang, Jun

2018-06-01

The Inconel 718 alloy is widely used in the aerospace and power industries. The machining-induced surface integrity and fatigue life of this material are important factors for consideration due to high reliability and safety requirements. In this work, the milling of Inconel 718 was conducted at different cutting speeds and feed rates. Surface integrity and fatigue life were measured directly. The effects of cutting speed and feed rate on surface integrity and their further influences on fatigue life were analyzed. Within the chosen parameter range, the cutting speed barely affected the surface roughness, whereas the feed rate increased the surface roughness through the ideal residual height. The surface hardness increased as the cutting speed and feed rate increased. Tensile residual stress was observed on the machined surface, which showed improvement with the increasing feed rate. The cutting speed was not an influencing factor on fatigue life, but the feed rate affected fatigue life through the surface roughness. The high surface roughness resulting from the high feed rate could result in a high stress concentration factor and lead to a low fatigue life.

Diurnal cortisol rhythms, fatigue and psychosocial factors in five-year survivors of ovarian cancer.

PubMed

Cuneo, Michaela G; Schrepf, Andrew; Slavich, George M; Thaker, Premal H; Goodheart, Michael; Bender, David; Cole, Steve W; Sood, Anil K; Lutgendorf, Susan K

2017-10-01

Fatigue is a challenge in ovarian cancer survivorship and greatly impacts quality of life. In other cancer populations, fatigue has been associated with abnormal diurnal cortisol patterns. However, little is known about biological and behavioral factors in 5+-year ovarian cancer survivors and potential mechanisms underlying persistent fatigue have not been investigated in this population. Moreover, relationships between neuroendocrine and psychosocial factors in 5+-year ovarian cancer survivors have not been studied. We addressed these issues by examining relationships between diurnal cortisol rhythms, fatigue, life stress, and social support in 30 survivors of ovarian cancer who were assessed at least 5 years (mean=6.20years) following their primary diagnosis. Flatter diurnal cortisol slopes were associated with higher levels of fatigue, suggesting a role for HPA-axis dysregulation in sustained fatigue experienced by survivors. Moreover, greater cumulative lifetime stressor exposure (p=0.023) and stressor severity (p=0.004) were associated with flatter diurnal cortisol slopes, while higher social attachment (p=0.001) was associated with steeper diurnal cortisol slopes. These findings suggest that ovarian cancer survivors with greater lifetime stress exposure or lower social attachment may be at increased risk for circadian rhythm disruption, which in turn is associated with fatigue. Future research should examine relationships of clinical stage and inflammatory cytokines to cortisol rhythms and fatigue in long-term ovarian cancer survivors, as well as investigating the clinical significance of abnormal diurnal cortisol profiles in this population. Copyright © 2017 Elsevier Ltd. All rights reserved.

Factors influencing healthcare provider respondent fatigue answering a globally administered in-app survey.

PubMed

O'Reilly-Shah, Vikas N

2017-01-01

Respondent fatigue, also known as survey fatigue, is a common problem in the collection of survey data. Factors that are known to influence respondent fatigue include survey length, survey topic, question complexity, and open-ended question type. There is a great deal of interest in understanding the drivers of physician survey responsiveness due to the value of information received from these practitioners. With the recent explosion of mobile smartphone technology, it has been possible to obtain survey data from users of mobile applications (apps) on a question-by-question basis. The author obtained basic demographic survey data as well as survey data related to an anesthesiology-specific drug called sugammadex and leveraged nonresponse rates to examine factors that influenced respondent fatigue. Primary data were collected between December 2015 and February 2017. Surveys and in-app analytics were collected from global users of a mobile anesthesia calculator app. Key independent variables were user country, healthcare provider role, rating of importance of the app to personal practice, length of time in practice, and frequency of app use. Key dependent variable was the metric of respondent fatigue. Provider role and World Bank country income level were predictive of the rate of respondent fatigue for this in-app survey. Importance of the app to the provider and length of time in practice were moderately associated with fatigue. Frequency of app use was not associated. This study focused on a survey with a topic closely related to the subject area of the app. Respondent fatigue rates will likely change dramatically if the topic does not align closely. Although apps may serve as powerful platforms for data collection, responses rates to in-app surveys may differ on the basis of important respondent characteristics. Studies should be carefully designed to mitigate fatigue as well as powered with the understanding of the respondent characteristics that may have higher

Factors influencing healthcare provider respondent fatigue answering a globally administered in-app survey

PubMed Central

2017-01-01

Background Respondent fatigue, also known as survey fatigue, is a common problem in the collection of survey data. Factors that are known to influence respondent fatigue include survey length, survey topic, question complexity, and open-ended question type. There is a great deal of interest in understanding the drivers of physician survey responsiveness due to the value of information received from these practitioners. With the recent explosion of mobile smartphone technology, it has been possible to obtain survey data from users of mobile applications (apps) on a question-by-question basis. The author obtained basic demographic survey data as well as survey data related to an anesthesiology-specific drug called sugammadex and leveraged nonresponse rates to examine factors that influenced respondent fatigue. Methods Primary data were collected between December 2015 and February 2017. Surveys and in-app analytics were collected from global users of a mobile anesthesia calculator app. Key independent variables were user country, healthcare provider role, rating of importance of the app to personal practice, length of time in practice, and frequency of app use. Key dependent variable was the metric of respondent fatigue. Results Provider role and World Bank country income level were predictive of the rate of respondent fatigue for this in-app survey. Importance of the app to the provider and length of time in practice were moderately associated with fatigue. Frequency of app use was not associated. This study focused on a survey with a topic closely related to the subject area of the app. Respondent fatigue rates will likely change dramatically if the topic does not align closely. Discussion Although apps may serve as powerful platforms for data collection, responses rates to in-app surveys may differ on the basis of important respondent characteristics. Studies should be carefully designed to mitigate fatigue as well as powered with the understanding of the

Long-Term Muscle Fatigue After Standing Work.

PubMed

Garcia, Maria-Gabriela; Läubli, Thomas; Martin, Bernard J

2015-11-01

The aims of this study were to determine long-term fatigue effects in the lower limbs associated with standing work and to estimate possible age and gender influences. The progressive accumulation of muscle fatigue effects is assumed to lead to musculoskeletal disorders, as fatigue generated by sustained low-level exertions exhibits long-lasting effects. However, these effects have received little attention in the lower limbs. Fourteen men and 12 women from two different age groups simulated standing work for 5 hr including 5-min seated rest breaks and a 30-min lunch. The younger group was also tested in a control day. Muscle fatigue was quantified by electrically induced muscle twitches (muscle twitch force [MTF]), postural stability, and subjective evaluation of discomfort. MTF showed a significant fatigue effect after standing work that persisted beyond 30 min after the end of the workday. MTF was not affected on the control day. The center of pressure displacement speed increased significantly over time after standing work but was also affected on the control day. Subjective evaluations of discomfort indicated a significant increase in perception of fatigue immediately after the end of standing work; however, this perception did not persist 30 min after. Age and gender did not influence fatigue. Objective measures show the long-term effects of muscle fatigue after 5 hr of standing work; however, this fatigue is no longer perceived after 30 min of rest postwork. The present results suggest that occupational activities requiring prolonged standing are likely to contribute to lower-extremity and/or back disorders. © 2015, Human Factors and Ergonomics Society.

Patient factors related to the presentation of fatigue complaints: results from a women's general health care practice.

PubMed

de Rijk, A E; Schreurs, K M; Bensing, J M

2000-01-01

The aim of this study was to examine which patient-related factors predicted: (1) fatigue, (2) the intention to discuss fatigue and (3) the actual discussion of fatigue during consultation with a GP in a women's general health care practice. Patients were asked to complete two questionnaires: one before and one after consultation. The patient-related factors included: social-demographic characteristics; fatigue characteristics; absence of cognitive representations of fatigue; nature of the requests for consultation; and other complaints. Some 74% of the 155 respondents reported fatigue. Compared to the patients that were not fatigued, the fatigued patients were more frequently employed outside the home, had higher levels of general fatigue, and a higher need for emotional support from their doctor. A minority (12%) intended to discuss fatigue during consultation. Of the respondents returning the second questionnaire (n = 107), 22% reported actually discussing their fatigue with the GP while only 11% had intended to do so. In addition to the intention to discuss fatigue during consultation, the following variables related to actually discussing fatigue: living alone, caring for young children, higher levels of general fatigue, absence of cognitions with regard to the duration of the fatigue, and greater psychological, neurological, digestive, and/or musculoskeletal problems as the reason for consultation. Fatigue was found to be the single reason for consultation in only one case. It is concluded that fatigue does not constitute a serious problem for most patients and that discussion of fatigue with the GP tends to depend on the occurrence of other psychological or physical problems and the patient's social context.

Fatigue Magnification Factors of Arc-Soft-Toe Bracket Joints

NASA Astrophysics Data System (ADS)

Fu, Qiang; Li, Huajun; Wang, Hongqing; Wang, Shuqing; Li, Dejiang; Li, Qun; Fang, Hui

2018-06-01

Arc-soft-toe bracket (ASTB), as a joint structure in the marine structure, is the hot spot with significant stress concentration, therefore, fatigue behavior of ASTBs is an important point of concern in their design. Since macroscopic geometric factors obviously influence the stress flaws in joints, the shapes and sizes of ASTBs should represent the stress distribution around cracks in the hot spots. In this paper, we introduce a geometric magnification factor for reflecting the macroscopic geometric effects of ASTB crack features and construct a 3D finite element model to simulate the distribution of stress intensity factor (SIF) at the crack endings. Sensitivity analyses with respect to the geometric ratio H t / L b , R/ L b , L t / L b are performed, and the relations between the geometric factor and these parameters are presented. A set of parametric equations with respect to the geometric magnification factor is obtained using a curve fitting technique. A nonlinear relationship exists between the SIF and the ratio of ASTB arm to toe length. When the ratio of ASTB arm to toe length reaches a marginal value, the SIF of crack at the ASTB toe is not influenced by ASTB geometric parameters. In addition, the arc shape of the ASTB slope edge can transform the stress flowing path, which significantly affects the SIF at the ASTB toe. A proper method to reduce stress concentration is setting a slope edge arc size equal to the ASTB arm length.

Fatigue in operational settings: Examples from the aviation environment

NASA Technical Reports Server (NTRS)

Rosekind, Mark R.; Gander, Philippa H.; Miller, Donna L.; Gregory, Kevin B.; Smith, Roy M.; Weldon, Keri J.; Co, Elizabeth L.; Mcnally, Karen L.; Lebacqz, J. Victor

1994-01-01

The need for 24-h operations creates nonstandard and altered work schedules that can lead to cumulative sleep loss and circadian disruption. These factors can lead to fatigue and sleepiness and affect performance and productivity on the job. The approach, research, and results of the NASA Ames Fatigue Countermeasures Program are described to illustrate one attempt to address these issues in the aviation environment. The scientific and operational relevance of these factors is discussed, and provocative issues for future research are presented.

Using an innovative multiple regression procedure in a cancer population (Part II): fever, depressive affect, and mobility problems clarify an influential symptom pair (pain-fatigue/weakness) and cluster (pain-fatigue/weakness-sleep problems).

PubMed

Francoeur, Richard B

2015-01-01

Most patients with advanced cancer experience symptom pairs or clusters among pain, fatigue, and insomnia. However, only combinations where symptoms are mutually influential hold potential for identifying patient subgroups at greater risk, and in some contexts, interventions with "cross-over" (multisymptom) effects. Improved methods to detect and interpret interactions among symptoms, signs, or biomarkers are needed to reveal these influential pairs and clusters. I recently created sequential residual centering (SRC) to reduce multicollinearity in moderated regression, which enhances sensitivity to detect these interactions. I applied SRC to moderated regressions of single-item symptoms that interact to predict outcomes from 268 palliative radiation outpatients. I investigated: 1) the hypothesis that the interaction, pain × fatigue/weakness × sleep problems, predicts depressive affect only when fever presents, and 2) an exploratory analysis, when fever is absent, that the interaction, pain × fatigue/weakness × sleep problems × depressive affect, predicts mobility problems. In the fever context, three-way interactions (and derivative terms) of the four symptoms (pain, fatigue/weakness, fever, sleep problems) are tested individually and simultaneously; in the non-fever context, a single four-way interaction (and derivative terms) is tested. Fever interacts separately with fatigue/weakness and sleep problems; these comoderators each magnify the pain-depressive affect relationship along the upper or full range of pain values. In non-fever contexts, fatigue/weakness, sleep problems, and depressive affect comagnify the relationship between pain and mobility problems. Different mechanisms contribute to the pain × fatigue/weakness × sleep problems interaction, but all depend on the presence of fever, a sign/biomarker/symptom of proinflammatory sickness behavior. In non-fever contexts, depressive affect is no longer an outcome representing malaise from the physical

Factorial invariance of pediatric patient self-reported fatigue across age and gender: a multigroup confirmatory factor analysis approach utilizing the PedsQL™ Multidimensional Fatigue Scale.

PubMed

Varni, James W; Beaujean, A Alexander; Limbers, Christine A

2013-11-01

In order to compare multidimensional fatigue research findings across age and gender subpopulations, it is important to demonstrate measurement invariance, that is, that the items from an instrument have equivalent meaning across the groups studied. This study examined the factorial invariance of the 18-item PedsQL™ Multidimensional Fatigue Scale items across age and gender and tested a bifactor model. Multigroup confirmatory factor analysis (MG-CFA) was performed specifying a three-factor model across three age groups (5-7, 8-12, and 13-18 years) and gender. MG-CFA models were proposed in order to compare the factor structure, metric, scalar, and error variance across age groups and gender. The analyses were based on 837 children and adolescents recruited from general pediatric clinics, subspecialty clinics, and hospitals in which children were being seen for well-child checks, mild acute illness, or chronic illness care. A bifactor model of the items with one general factor influencing all the items and three domain-specific factors representing the General, Sleep/Rest, and Cognitive Fatigue domains fit the data better than oblique factor models. Based on the multiple measures of model fit, configural, metric, and scalar invariance were found for almost all items across the age and gender groups, as was invariance in the factor covariances. The PedsQL™ Multidimensional Fatigue Scale demonstrated strict factorial invariance for child and adolescent self-report across gender and strong factorial invariance across age subpopulations. The findings support an equivalent three-factor structure across the age and gender groups studied. Based on these data, it can be concluded that pediatric patients across the groups interpreted the items in a similar manner regardless of their age or gender, supporting the multidimensional factor structure interpretation of the PedsQL™ Multidimensional Fatigue Scale.

Surface Irregularity Factor as a Parameter to Evaluate the Fatigue Damage State of CFRP

PubMed Central

Zuluaga-Ramírez, Pablo; Frövel, Malte; Belenguer, Tomás; Salazar, Félix

2015-01-01

This work presents an optical non-contact technique to evaluate the fatigue damage state of CFRP structures measuring the irregularity factor of the surface. This factor includes information about surface topology and can be measured easily on field, by techniques such as optical perfilometers. The surface irregularity factor has been correlated with stiffness degradation, which is a well-accepted parameter for the evaluation of the fatigue damage state of composite materials. Constant amplitude fatigue loads (CAL) and realistic variable amplitude loads (VAL), representative of real in- flight conditions, have been applied to “dog bone” shaped tensile specimens. It has been shown that the measurement of the surface irregularity parameters can be applied to evaluate the damage state of a structure, and that it is independent of the type of fatigue load that has caused the damage. As a result, this measurement technique is applicable for a wide range of inspections of composite material structures, from pressurized tanks with constant amplitude loads, to variable amplitude loaded aeronautical structures such as wings and empennages, up to automotive and other industrial applications. PMID:28793655

Irregular working hours and fatigue of cabin crew.

PubMed

Castro, Marta; Carvalhais, José; Teles, Júlia

2015-01-01

Beyond workload and specific environmental factors, flight attendants can be exposed to irregular working hours, conflicting with their circadian rhythms and having a negative impact in sleep, fatigue, health, social and family life, and performance which is critical to both safety and security in flight operations. This study focuses on the irregular schedules of cabin crew as a trigger of fatigue symptoms in a wet lease Portuguese airline. The aim was to analyze: what are the requirements of the cabin crew work; whether the schedules being observed and effective resting timeouts are triggering factors of fatigue; and the existence of fatigue symptoms in the cabin crew. A questionnaire has been adapted and applied to a sample of 73 cabin crew-members (representing 61.9% of the population), 39 females and 34 males, with an average age of 27.68 ± 4.27 years. Our data indicate the presence of fatigue and corresponding health symptoms among the airline cabin crew, despite of the sample favorable characteristics. Senior workers and women are more affected. Countermeasures are required. Recommendations can be made regarding the fatigue risk management, including work organization, education and awareness training programmes and specific countermeasures.

Women's experience of SLE-related fatigue: a focus group interview study.

PubMed

Pettersson, Susanne; Möller, Sonia; Svenungsson, Elisabet; Gunnarsson, Iva; Welin Henriksson, Elisabet

2010-10-01

The aim of this study was to describe women's experience of SLE-related fatigue, how they express the feeling of fatigue, impact on life and strategies developed to manage fatigue in daily living. Seven, semi-structured focus group discussions with 33 women were audio-taped, transcribed verbatim and analysed according to qualitative content analysis. Perceptions of SLE-related fatigue were sorted into four themes. Nature of Fatigue, involved the sensation, occurrence and character. Aspects Affected by Fatigue described emotions that arose together with fatigue as well as aspects of work, family life, social contacts and leisure activities that were affected by fatigue. Striving Towards Power and Control concluded the array of ways used to manage daily life and were categorized into the mental struggle, structure, restrict and provide. Factors Influencing the Perception of Fatigue described understanding from their surroundings and pain as strongly influencing the experience and perception of fatigue. SLE-related fatigue was portrayed as an overwhelming phenomenon with an unpredictable character, resulting in the feeling that fatigue dominates and controls most situations in life. The choice of strategies was described as a balance with implications for how fatigue limited a person's life. Health care professionals are advised to take a more active role to empower people with SLE to find their own balance as a way to achieve a feeling of being in control.

Assessment of fatigue life of remanufactured impeller based on FEA

NASA Astrophysics Data System (ADS)

Xu, Lei; Cao, Huajun; Liu, Hailong; Zhang, Yubo

2016-09-01

Predicting the fatigue life of remanufactured centrifugal compressor impellers is a critical problem. In this paper, the S-N curve data were obtained by combining experimentation and theory deduction. The load spectrum was compiled by the rain-flow counting method based on the comprehensive consideration of the centrifugal force, residual stress, and aerodynamic loads in the repair region. A fatigue life simulation model was built, and fatigue life was analyzed based on the fatigue cumulative damage rule. Although incapable of providing a high-precision prediction, the simulation results were useful for the analysis of fatigue life impact factors and fatigue fracture areas. Results showed that the load amplitude greatly affected fatigue life, the impeller was protected from running at over-speed, and the predicted fatigue life was satisfied within the next service cycle safely at the rated speed.

Motor Unit Activity during Fatiguing Isometric Muscle Contraction in Hemispheric Stroke Survivors

PubMed Central

McManus, Lara; Hu, Xiaogang; Rymer, William Z.; Suresh, Nina L.; Lowery, Madeleine M.

2017-01-01

Enhanced muscle weakness is commonly experienced following stroke and may be accompanied by increased susceptibility to fatigue. To examine the contributions of central and peripheral factors to isometric muscle fatigue in stroke survivors, this study investigates changes in motor unit (MU) mean firing rate, and action potential duration during, and directly following, a sustained submaximal fatiguing contraction at 30% maximum voluntary contraction (MVC). A series of short contractions of the first dorsal interosseous muscle were performed pre- and post-fatigue at 20% MVC, and again following a 10-min recovery period, by 12 chronic stroke survivors. Individual MU firing times were extracted using surface EMG decomposition and used to obtain the spike-triggered average MU action potential waveforms. During the sustained fatiguing contraction, the mean rate of change in firing rate across all detected MUs was greater on the affected side (-0.02 ± 0.03 Hz/s) than on the less-affected side (-0.004 ± 0.003 Hz/s, p = 0.045). The change in firing rate immediately post-fatigue was also greater on the affected side than less-affected side (-13.5 ± 20 and 0.1 ± 19%, p = 0.04). Mean MU firing rates increased following the recovery period on the less-affected side when compared to the affected side (19.3 ± 17 and 0.5 ± 20%, respectively, p = 0.03). MU action potential duration increased post-fatigue on both sides (10.3 ± 1.2 to 11.2 ± 1.3 ms on the affected side and 9.9 ± 1.7 to 11.2 ± 1.9 ms on the less-affected side, p = 0.001 and p = 0.02, respectively), and changes in action potential duration tended to be smaller in subjects with greater impairment (p = 0.04). This study presents evidence of both central and peripheral fatigue at the MU level during isometric fatiguing contraction for the first time in stroke survivors. Together, these preliminary observations indicate that the response to an isometric fatiguing contraction differs between the affected and less-affected

Auditory fatigue : influence of mental factors.

DOT National Transportation Integrated Search

1965-01-01

Conflicting reports regarding the influence of mental tasks on auditory fatigue have recently appeared in the literature. In the present study, 10 male subjects were exposed to 4000 cps fatigue toe at 40 dB SL for 3 min under conditions of mental ari...

Psychosocial factors, musculoskeletal disorders and work-related fatigue amongst nurses in Brunei: structural equation model approach.

PubMed

Abdul Rahman, Hanif; Abdul-Mumin, Khadizah; Naing, Lin

2017-09-01

Psychosocial factors, musculoskeletal disorders and work-related fatigue have adverse effects on individual nurses and place a substantial financial burden on health care. Evidence of an association has been reported in the literature, but no theoretical explanation has been published to date. To explore and develop a structural model to provide a theoretical explanation for this relationship. A cross-sectional study using data from 201 valid samples of emergency and critical care nurses across public hospitals in Brunei was performed via self-administered questionnaire. The structural equation model was assessed using partial least squares analysis. A valid and robust structural model was constructed. This revealed that 61.5% of the variance in chronic fatigue could be explained by psychosocial factors and musculoskeletal disorders pathways. Among the psychosocial factors, work-family conflict was identified as a key mediator for progression of musculoskeletal problems and subsequent fatigue through stress and burnout. This report provides a novel theoretical contribution to understanding the relationship between psychosocial factors, musculoskeletal disorders and work-related fatigue. These preliminary results may be useful for future studies on the development of work-related fatigue and musculoskeletal disorders, particularly the central role of work-family conflict. Copyright © 2017 Elsevier Ltd. All rights reserved.

Predictors and Trajectories of Morning Fatigue Are Distinct from Evening Fatigue

PubMed Central

Wright, Fay; Melkus, Gail D’Eramo; Hammer, Marilyn; Schmidt, Brian L.; Knobf, M. Tish; Paul, Steven M.; Cartwright, Frances; Mastick, Judy; Cooper, Bruce A.; Chen, Lee-May; Melisko, Michelle; Levine, Jon D.; Kober, Kord; Aouizerat, Bradley E.; Miaskowski, Christine

2015-01-01

Context Fatigue is the most common symptom in oncology patients during chemotherapy (CTX). Little is known about the predictors of interindividual variability in initial levels and trajectories of morning fatigue severity in these patients. Objectives An evaluation was done to determine which demographic, clinical, and symptom characteristics were associated with initial levels as well as the trajectories of morning fatigue and to compare findings with our companion paper on evening fatigue. Methods A sample of outpatients with breast, gastrointestinal, gynecological, and lung cancer (N=586) completed demographic and symptom questionnaires a total of six times over two cycles of CTX. Fatigue severity was evaluated using the Lee Fatigue Scale. Hierarchical linear modeling (HLM) was used to answer the study objectives. Results A large amount of interindividual variability was found in the morning fatigue trajectories. A piecewise model fit the data best. Patients with higher body mass index (BMI), who did not exercise regularly, with a lower functional status, and who had higher levels of state anxiety, sleep disturbance and depressive symptoms, reported higher levels of morning fatigue at enrollment. Variations in the trajectories of morning fatigue were predicted by the patients’ ethnicity and younger age. Conclusion The modifiable risk factors that were associated with only morning fatigue were BMI, exercise, and state anxiety. Modifiable risk factors that were associated with both morning and evening fatigue included functional status, depressive symptoms, and sleep disturbance. Using this information, clinicians can identify patients at higher risk for more severe morning fatigue and evening fatigue, provide individualized patient education, and tailor interventions to address the modifiable risk factors. PMID:25828559

In situ SEM thermal fatigue of Al/graphite metal matrix composites

NASA Technical Reports Server (NTRS)

Zong, G. S.; Rabenberg, L.; Marcus, H. L.

1990-01-01

Several thermal fatigue-induced failure mechanisms are deduced for unidirectional graphite-reinforced 6061 Al-alloy MMCs subjected to in situ thermal cycling. These thermal cycling conditions are representative of MMC service cycles in aerospace environments, where thermal fatigue is primarily associated with changes in the stress states near the interfaces due to coefficient of thermal expansion mismatch between fiber and matrix. This in situ SEM thermal-cycling study clarified such factors affecting MMCs' thermal fatigue as local fiber content and distribution, void volume, fiber stiffness, thermal excursion magnitude, and number of thermal cycles. MMC microfailure modes in thermal fatigue have been deduced.

Fatigue in people with localized colorectal cancer who do and do not receive chemotherapy: a longitudinal prospective study

PubMed Central

Vardy, J. L.; Dhillon, H. M.; Pond, G. R.; Renton, C.; Dodd, A.; Zhang, H.; Clarke, S. J.; Tannock, I. F.

2016-01-01

Background Fatigue is associated with cancer and chemotherapy and may be sustained. Here, we describe a prospective longitudinal study evaluating fatigue and putative mechanisms in people with colorectal cancer (CRC). Patients and methods People with localized CRC completed the Functional Assessment of Cancer Treatment-Fatigue (FACT-F) questionnaire at baseline (before chemotherapy, if given), 6, 12, and 24 months. Healthy controls (HCs) were assessed at the first three time points. Fatigue was defined by standardized FACT-F scores ≤68/100. Quality-of-life (QoL, assessed by the FACT-G questionnaire), affective, and cognitive symptoms were evaluated. Associations were sought between fatigue, baseline factors, and blood tests (including hemoglobin, cytokines, and sex hormones). Regression analyses, Fisher's exact tests, and Wilcoxon rank-sum tests assessed levels of fatigue at each time point and change in fatigue from baseline. A repeated-measures analysis investigated prognostic factors of fatigue across all time points. Results A total of 289 subjects with localized CRC (173 received chemotherapy) and 72 HCs were assessed. More CRC patients had fatigue than HCs at baseline (52% versus 26%, P < 0.001). Fatigue was increased in the chemotherapy (CTh) group at 6 months [CTh+ 70% versus CTh− 31% (P < 0.001), HCs 22%] and remained more common at 12 [CTh+ 44% versus CTh− 31% (P = 0.079)] and 24 months [CTh+ 39% versus CTh− 24% (P = 0.047)]. There was no significant difference between those not receiving chemotherapy and HCs at follow-up assessments. Fatigue was associated with poor QoL, affective and cognitive symptoms, but not consistently with cytokine levels. Predictors for sustained fatigue were baseline fatigue, treatment group, cognitive and affective symptoms, poorer QoL, and comorbidities. Conclusions CRC patients have more fatigue than HCs at baseline. Fatigue peaks immediately after adjuvant chemotherapy, but remains common for 2 years in those who

Poststroke Fatigue: Who Is at Risk for an Increase in Fatigue?

PubMed Central

van Eijsden, Hanna Maria; van de Port, Ingrid Gerrie Lambert; Visser-Meily, Johanna Maria August; Kwakkel, Gert

2012-01-01

Background. Several studies have examined determinants related to post-stroke fatigue. However, it is unclear which determinants can predict an increase in poststroke fatigue over time. Aim. This prospective cohort study aimed to identify determinants which predict an increase in post-stroke fatigue. Methods. A total of 250 patients with stroke were examined at inpatient rehabilitation discharge (T0) and 24 weeks later (T1). Fatigue was measured using the Fatigue Severity Scale (FSS). An increase in post-stroke fatigue was defined as an increase in the FSS score beyond the 95% limits of the standard error of measurement of the FSS (i.e., 1.41 points) between T0 and T1. Candidate determinants included personal factors, stroke characteristics, physical, cognitive, and emotional functions, and activities and participation and were assessed at T0. Factors predicting an increase in fatigue were identified using forward multivariate logistic regression analysis. Results. The only independent predictor of an increase in post-stroke fatigue was FSS (OR 0.50; 0.38–0.64, P < 0.001). The model including FSS at baseline correctly predicted 7.9% of the patients who showed increased fatigue at T1. Conclusion. The prognostic model to predict an increase in fatigue after stroke has limited predictive value, but baseline fatigue is the most important independent predictor. Overall, fatigue levels remained stable over time. PMID:22028989

Demographic factors, fatigue, and driving accidents: An examination of the published literature.

PubMed

Di Milia, Lee; Smolensky, Michael H; Costa, Giovanni; Howarth, Heidi D; Ohayon, Maurice M; Philip, Pierre

2011-03-01

This article reviews the literature pertaining to the association between demographic variables (e.g., age, sex, race, socio-economic status) with fatigue, and when feasible, accident risk. It also explores their potential influence and interaction with some working arrangements, commute time, personality characteristics, and circadian chronotype. Fatigue has been implicated in a range of impairments that can have detrimental effects on individuals, and it is differentially associated with conventional demographic variables. However, several major methodological limitations prevent clear conclusions. First, there is absence of a shared definition both within and across disciplines. Second, although fatigue has been investigated using a variety of diverse designs, they have either been too weak to substantiate causality or lacked ecological validity. Third, while both subjective and objective measures have been used as dependent variables, fatigue has been more often found to be more strongly linked with the former. Fourth, with the exception of age and sex, the influence of other demographic variables is unknown, since they have not yet been concomitantly assessed. In instances when they have been assessed and included in statistical analyses, they are considered as covariates or confounders; thus, their contribution to the outcome variable is controlled for, rather than being a planned aspect of investigation. Because the interaction of demographic factors with fatigue is largely a neglected area of study, we recommend greater interdisciplinary collaborations, incorporation of multiple demographic variables as independent factors, and use of within-participant analyses. These recommendations would provide meaningful results that may be used to inform public policy and preventive strategies. Copyright © 2009 Elsevier Ltd. All rights reserved.

Exertion fatigue and chronic fatigue are two distinct constructs in people post-stroke.

PubMed

Tseng, Benjamin Y; Billinger, Sandra A; Gajewski, Byron J; Kluding, Patricia M

2010-12-01

Post-stroke fatigue is a common and neglected issue despite the fact that it impacts daily functions, quality of life, and has been linked with a higher mortality rate because of its association with a sedentary lifestyle. The purpose of this study was to identify the contributing factors of exertion fatigue and chronic fatigue in people post-stroke. Twenty-one post-stroke people (12 males, 9 females; 59.5 ± 10.3 years of age; time after stroke 4.1 ± 3.5 years) participated in the study. The response variables included exertion fatigue and chronic fatigue. Participants underwent a standardized fatigue-inducing exercise on a recumbent stepper. Exertion fatigue level was assessed at rest and immediately after exercise using the Visual Analog Fatigue Scale. Chronic fatigue was measured by the Fatigue Severity Scale. The explanatory variables included aerobic fitness, motor control, and depressive symptoms measured by peak oxygen uptake, Fugl-Meyer motor score, and the Geriatric Depression Scale, respectively. Using forward stepwise regression, we found that peak oxygen uptake was an independent predictor of exertion fatigue (P = 0.006), whereas depression was an independent predictor of chronic fatigue (P = 0.002). Exertion fatigue and chronic fatigue are 2 distinct fatigue constructs, as identified by 2 different contributing factors.

The Effect of Porosity on Fatigue of Die Cast AM60

NASA Astrophysics Data System (ADS)

Yang, Zhuofei; Kang, Jidong; Wilkinson, David S.

2016-07-01

AM60 high-pressure die castings are known to contain significant porosity which can affect fatigue life. We have studied this using samples drawn from prototype AM60 shock towers by conducting strain-controlled fatigue tests accompanied by X-ray computed tomography analysis. The results show that the machined surface is the preferential location for fatigue crack development, with pores close to these surfaces serving as initiation sites. Fatigue life shows a strong inverse correlation with the size of the fatigue-crack-initiating pore. Pore shape and pore orientation also influence the response. A supplemental study on surface roughness shows that porosity is the dominant factor in fatigue. Tomography enables the link between porosity and fatigue crack initiation to be clearly identified. These data are complemented by SEM observations of the fracture surfaces which are generally flat and full of randomly oriented serration patterns but without long-range fatigue striations.

Driver fatigue and highway driving: a simulator study.

PubMed

Ting, Ping-Huang; Hwang, Jiun-Ren; Doong, Ji-Liang; Jeng, Ming-Chang

2008-06-09

Long duration of driving is a significant cause of fatigue-related accidents on motorways or major roadways. The fatigue caused by driving for extended periods acutely impairs driver alertness and performance and can compromise transportation safety. This study quantitatively measured the progression of driver fatigue and identified the conservative safe duration of continuous highway driving. Thirty young male subjects were analyzed during 90 min of laboratory-simulated highway driving. Sleepiness ratings (SSS) and reaction time (RT) tests were used to assess impairment of driver alertness and vigilance. Additionally, various measures of driving performance recorded throughout the experiment were used to measure temporal deterioration of driver performance from alert to fatigued using principal component analysis (PCA). The analytical results revealed that SSS scores, reaction times (RTs) and unstable driving performance significantly increased over time, indicating that excessive driving time is a significant fatigue factor and potential cause of fatigue-related accidents. Moreover, the analytical results indicated that 80 min was the safe limit for monotonous highway driving. Based on the experimental findings of this study, public awareness of the adverse affects of driver fatigue during long-distance driving should be enhanced. This study provides explicit information of fatigue development that can be used to prevent fatigue-related accidents.

Customizing treatment of chronic fatigue syndrome and fibromyalgia: the role of perpetuating factors.

PubMed

Van Houdenhove, Boudewijn; Luyten, Patrick

2008-01-01

Syndromes characterized by chronic, medically unexplained fatigue, effort- and stress-intolerance, and widespread pain are highly prevalent in medicine. In chronic fatigue syndrome (CFS) and fibromyalgia (FM), various perpetuating factors may impair patients' quality of life and functioning and impede recovery. Although cognitive-behavioral and graded-exercise therapy are evidence-based treatments, the effectiveness and acceptability of therapeutic interventions in CFS/FM may largely depend on a customized approach taking the heterogeneity of perpetuating factors into account. Further research should clarify the aim and outcome of different treatment strategies in CFS/FM, as well as the underlying mechanisms of change, including those facilitating neurobiological recovery.

Prevalence of Fatigue and Associated Factors in a Spinal Cord Injury Population: Data from an Internet-Based and Face-to-Face Surveys.

PubMed

Cudeiro-Blanco, Javier; Onate-Figuérez, Ana; Soto-León, Vanesa; Avendaño-Coy, Juan; Mordillo-Mateos, Laura; Brocalero-Camacho, Angela; Esclarin-Ruz, Ana; Rotondi, Mario; Aguilar, Juan; Arias, Pablo; Oliviero, Antonio

2017-08-01

Fatigue has a profound impact on patients with spinal cord injury (SCI), but only limited treatments are available. The aim of this study was to determine the prevalence of fatigue in SCI and its association with clinical and demographic factors. We used an internet-based survey and a face-to-face interview to estimate the prevalence of fatigue in a SCI population. Fatigue was measured using the Fatigue Severity Scale (FSS). Clinically significant fatigue was defined as FSS scores greater than or equal to four. A total of 253 participants with SCI were included in the study. Clinically significant fatigue was present in one third of our sample. There was no relationship between fatigue and injury level or completeness. We found significant correlations between depression, pain, and level of injury. The relation of fatigue with completeness of injury and spasticity is less clear. Moreover, the online survey and the standard face-to-face interview showed similar results concerning fatigue evaluation. Several factors may contribute to fatigue, however. Future studies should be conducted to clarify which are the most relevant ones and, if possible, to determine which factors are modifiable.

Fatigue design procedure for the American SST prototype

NASA Technical Reports Server (NTRS)

Doty, R. J.

1972-01-01

For supersonic airline operations, significantly higher environmental temperature is the primary new factor affecting structural service life. Methods for incorporating the influence of temperature in detailed fatigue analyses are shown along with current test indications. Thermal effects investigated include real-time compared with short-time testing, long-time temperature exposure, and stress-temperature cycle phasing. A method is presented which allows designers and stress analyzers to check fatigue resistance of structural design details. A communicative rating system is presented which defines the relative fatigue quality of the detail so that the analyst can define cyclic-load capability of the design detail by entering constant-life charts for varying detail quality. If necessary then, this system allows the designer to determine ways to improve the fatigue quality for better life or to determine the operating stresses which will provide the required service life.

Electrically-induced muscle fatigue affects feedforward mechanisms of control.

PubMed

Monjo, F; Forestier, N

2015-08-01

To investigate the effects of focal muscle fatigue induced by electromyostimulation (EMS) on Anticipatory Postural Adjustments (APAs) during arm flexions performed at maximal velocity. Fifteen healthy subjects performed self-paced arm flexions at maximal velocity before and after the completion of fatiguing electromyostimulation programs involving the medial and anterior deltoids and aiming to degrade movement peak acceleration. APA timing and magnitude were measured using surface electromyography. Following muscle fatigue, despite a lower mechanical disturbance evidenced by significant decreased peak accelerations (-12%, p<.001), APAs remained unchanged as compared to control trials (p>.11 for all analyses). The fatigue signals evoked by externally-generated contractions seem to be gated by the Central Nervous System and result in postural strategy changes which aim to increase the postural safety margin. EMS is widely used in rehabilitation and training programs for its neuromuscular function-related benefits. However and from a motor control viewpoint, the present results show that the use of EMS can lead to acute inaccuracies in predictive motor control. We propose that clinicians should investigate the chronic and global effects of EMS on motor control. Copyright © 2014 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Prevalence and factors associated with fatigue in female patients with systemic lupus erythematosus.

PubMed

Carrión-Barberà, Irene; Salman-Monte, Tarek Carlos; Castell, Sonia; Castro, Francisco; Ojeda, Fabiola; Carbonell, Jordi

2018-02-10

To determine the prevalence of fatigue in our cohort as well as the factors to which it is associated, its relationship with demographic variables, vitamin D levels, treatment, systemic lupus erythematosus (SLE) symptoms and disease activity. A cross-sectional study was carried out including 102 consecutive female patients with SLE (American College of Rheumatology 1997 criteria) who attended the Parc de Salut Mar between January 2012 and May 2014. Variables collected were: sociodemographic data, vitamin D supplementation, fatigue VAS, pharmacological treatment, main serological markers of SLE, and plasma levels of 25(OH)-vitD. The association between fatigue and the different variables was evaluated by the Spearman's Rho correlation coefficient for the continuous variables, the Mann-Whitney U test for the categorical and the Kruskal-Wallis test for the seasons of the year. The fatigue variable was evaluated through a fatigue VAS with a mean score of 52.84 (range 0-100), a median of 59 and a standard deviation of 29.86. A statistically significant relationship was found between fatigue and age, MHAQ, SLICC, summer and photosensitivity. As for the relationship between fatigue and vitamin D insufficiency (defined as 25-(OH)-vitD≤30 levels), the sample was divided into patients receiving vitamin D supplements (n=60) and patients without supplements (n=40), finding a significant relationship in that last group. A statistically significant association was found between the presence of fatigue and age, MHAQ, SLICC, photosensitivity, fibromyalgia and summer, and with vitamin D insufficiency in the group of patients without supplements (n=40). Copyright © 2018 Elsevier España, S.L.U. All rights reserved.

Factors affecting sexual life during pregnancy in eastern Turkey.

PubMed

Eryilmaz, Gülşen; Ege, Emel; Zincir, Handan

2004-01-01

This is a descriptive and cross-sectional study aiming to determine the factors affecting sexual life in pregnant women. The study was carried out in 238 women in Malatya, Turkey. It was found that 61.4% regarded coitus as a risk during pregnancy, 31.9% did not have any knowledge about this matter. In 81.5% sexual life was affected during pregnancy. The mean frequency of intercourse was 2.02 +/- 0.7/week before pregnancy and decreased to 1.51 +/- 0.6/week during pregnancy. The reasons for this decline are: exhaustion and fatigue (64.3%); waning of sexual desire (55.9%); harmful to the fetus (49.2%); causing abortions in early pregnancy (45%), and inducing preterm labor (34%). There was a significant relationship between changes in sexual life during pregnancy and the duration of marriage (chi2=10.8, p<0.05), education level (chi2=18.1, p<0.05), parity (chi2=11.1, p<0.05), and gravidity (chi2=6.8, p<0.05). The variables such as age, employment status, and number of abortions did not affect sexual life during pregnancy. Copyright 2004 S. Karger AG, Basel

Sleep assessment in a population-based study of chronic fatigue syndrome

PubMed Central

Unger, Elizabeth R; Nisenbaum, Rosane; Moldofsky, Harvey; Cesta, Angela; Sammut, Christopher; Reyes, Michele; Reeves, William C

2004-01-01

Background Chronic fatigue syndrome (CFS) is a disabling condition that affects approximately 800,000 adult Americans. The pathophysiology remains unknown and there are no diagnostic markers or characteristic physical signs or laboratory abnormalities. Most CFS patients complain of unrefreshing sleep and many of the postulated etiologies of CFS affect sleep. Conversely, many sleep disorders present similarly to CFS. Few studies characterizing sleep in unselected CFS subjects have been published and none have been performed in cases identified from population-based studies. Methods The study included 339 subjects (mean age 45.8 years, 77% female, 94.1% white) identified through telephone screen in a previously described population-based study of CFS in Wichita, Kansas. They completed questionnaires to assess fatigue and wellness and 2 self-administered sleep questionnaires. Scores for five of the six sleep factors (insomnia/hypersomnia, non-restorative sleep, excessive daytime somnolence, sleep apnea, and restlessness) in the Centre for Sleep and Chronobiology's Sleep Assessment Questionnaire© (SAQ©) were dichotomized based on threshold. The Epworth Sleepiness Scale score was used as a continuous variable. Results 81.4% of subjects had an abnormality in at least one SAQ© sleep factor. Subjects with sleep factor abnormalities had significantly lower wellness scores but statistically unchanged fatigue severity scores compared to those without SAQ© abnormality. CFS subjects had significantly increased risk of abnormal scores in the non-restorative (adjusted odds ratio [OR] = 28.1; 95% confidence interval [CI]= 7.4–107.0) and restlessness (OR = 16.0; 95% CI = 4.2–61.6) SAQ© factors compared to non-fatigued, but not for factors of sleep apnea or excessive daytime somnolence. This is consistent with studies finding that, while fatigued, CFS subjects are not sleepy. A strong correlation (0.78) of Epworth score was found only for the excessive daytime somnolence

Muscle Fatigue Affects the Interpolated Twitch Technique When Assessed Using Electrically-Induced Contractions in Human and Rat Muscles.

PubMed

Neyroud, Daria; Cheng, Arthur J; Bourdillon, Nicolas; Kayser, Bengt; Place, Nicolas; Westerblad, Håkan

2016-01-01

The interpolated twitch technique (ITT) is the gold standard to assess voluntary activation and central fatigue. Yet, its validity has been questioned. Here we studied how peripheral fatigue can affect the ITT. Repeated contractions at submaximal frequencies were produced by supramaximal electrical stimulations of the human adductor pollicis muscle in vivo and of isolated rat soleus fiber bundles; an extra stimulation pulse was given during contractions to induce a superimposed twitch. Human muscles fatigued by repeated 30-Hz stimulation trains (3 s on-1 s off) showed an ~80% reduction in the superimposed twitch force accompanied by a severely reduced EMG response (M-wave amplitude), which implies action potential failure. Subsequent experiments combined a less intense stimulation protocol (1.5 s on-3 s off) with ischemia to cause muscle fatigue, but which preserved M-wave amplitude. However, the superimposed twitch force still decreased markedly more than the potentiated twitch force; with ITT this would reflect increased "voluntary activation." In contrast, the superimposed twitch force was relatively spared when a similar protocol was performed in rat soleus bundles. Force relaxation was slowed by >150% in fatigued human muscles, whereas it was unchanged in rat soleus bundles. Accordingly, results similar to those in the human muscle were obtained when relaxation was slowed by cooling the rat soleus muscles. In conclusion, our data demonstrate that muscle fatigue can confound the quantification of central fatigue using the ITT.

Physiological and psychological correlates of fatigue in HIV disease.

PubMed

Phillips, Kenneth D; Sowell, Richard L; Rojas, Michelle; Tavakoli, Abbas; Fulk, Laura J; Hand, Gregory A

2004-07-01

Fatigue is a frequent symptom reported by persons living with HIV disease and one that affects all aspects of quality of life. To improve quality of care of persons with HIV disease, it is important to address all factors that contribute to fatigue. The purpose of this study was to determine the associations of physiological, psychological, and sociological factors with fatigue in an HIV-infected population. With Piper's integrated fatigue model guiding selection, factors examined in this study were hemoglobin, hematocrit, CD4+ cell count, HIV-RNA viral load, total sleep time, sleep quality, daytime sleepiness, HIV-related symptoms, anxiety, depression, and perceived stress. The sample (N = 79) for this descriptive correlational study was recruited from a primary health care association in South Carolina and consisted of 42 (53.2%) HIV-infected women and 37 (46.8%) HIV-infected men between the ages of 24 and 63 years (x = 39.9, s = 7.9). Of the participants, 70 (90%) were African American, 5 (6%) were Caucasian, and 3 (4%) were Hispanic. Using Pearson's r, significant relationships were observed between fatigue and sleep quality, daytime sleepiness, HIV-related symptoms, state anxiety, trait anxiety, depression, and perceived stress. Sleep quality (F5,65 = 12.02, P = 0.0009), state anxiety (F5,65 = 8.28, P = 0.0054), HIV-related symptoms (F5,65 = 4.87, P = 0.0308), and depression (F5,65 = 7.31, P = 0.0087) retained significance in a 3-step, backward stepwise elimination model and accounted for 67% of the variance in fatigue. These findings underscore the need for addressing psychosocial stressors and sleep quality in developing effective care for HIV-infected individuals who experience fatigue.

Persistent fatigue in young athletes: measuring the clinical course and identifying variables affecting clinical recovery.

PubMed

Locke, S; Osborne, M; O'Rourke, P

2011-02-01

The objective of this paper is to measure the clinical course (months) in young athletes with persistent fatigue and to identify any covariates affecting the duration of recovery. This was a prospective longitudinal study of 68 athletes; 87% were elite (42 males, 26 females), aged 20.5±3.74 years (SD), who presented with the symptom of persistent fatigue. The collective duration to full clinical recovery was estimated using Kaplan-Meier product-limit curves, and covariates associated with prolonging recovery were identified from Cox proportional hazard models. The median recovery was 5 months (range 1-60 months). The range of presenting symptom duration was 0.5-36 months. The covariates identified were an increased duration of presenting symptoms [hazard ratio (HR), 1.06; 95% confidence interval (CI), 1.02-1.12; P=0.005] and the response of serum cortisol concentration to a standard exercise challenge (HR, 1.92; 95% CI, 1.09-3.38; P=0.03). Delay in recovery was not associated with categories of fatigue that included medical, training-related diagnoses, or other causes. In conclusion, the fatigued athlete represents a significant clinical problem with a median recovery of 5 months, whose collective clinical course to recovery can be estimated by Kaplan-Meier curves and appears to be a continuum. © 2009 John Wiley & Sons A/S.

Chronic pain and fatigue: Associations with religion and spirituality

PubMed Central

Baetz, Marilyn; Bowen, Rudy

2008-01-01

BACKGROUND: Conditions with chronic, non-life-threatening pain and fatigue remain a challenge to treat, and are associated with high health care use. Understanding psychological and psychosocial contributing and coping factors, and working with patients to modify them, is one goal of management. An individual’s spirituality and/or religion may be one such factor that can influence the experience of chronic pain or fatigue. METHODS: The Canadian Community Health Survey (2002) obtained data from 37,000 individuals 15 years of age or older. From these data, four conditions with chronic pain and fatigue were analyzed together – fibromyalgia, back pain, migraine headaches and chronic fatigue syndrome. Additional data from the survey were used to determine how religion and spirituality affect psychological well-being, as well as the use of various coping methods. RESULTS: Religious persons were less likely to have chronic pain and fatigue, while those who were spiritual but not affiliated with regular worship attendance were more likely to have those conditions. Individuals with chronic pain and fatigue were more likely to use prayer and seek spiritual support as a coping method than the general population. Furthermore, chronic pain and fatigue sufferers who were both religious and spiritual were more likely to have better psychological well-being and use positive coping strategies. INTERPRETATION: Consideration of an individual’s spirituality and/or religion, and how it may be used in coping may be an additional component to the overall management of chronic pain and fatigue. PMID:18958309

Effects of human fatigue on speech signals

NASA Astrophysics Data System (ADS)

Stamoulis, Catherine

2004-05-01

Cognitive performance may be significantly affected by fatigue. In the case of critical personnel, such as pilots, monitoring human fatigue is essential to ensure safety and success of a given operation. One of the modalities that may be used for this purpose is speech, which is sensitive to respiratory changes and increased muscle tension of vocal cords, induced by fatigue. Age, gender, vocal tract length, physical and emotional state may significantly alter speech intensity, duration, rhythm, and spectral characteristics. In addition to changes in speech rhythm, fatigue may also affect the quality of speech, such as articulation. In a noisy environment, detecting fatigue-related changes in speech signals, particularly subtle changes at the onset of fatigue, may be difficult. Therefore, in a performance-monitoring system, speech parameters which are significantly affected by fatigue need to be identified and extracted from input signals. For this purpose, a series of experiments was performed under slowly varying cognitive load conditions and at different times of the day. The results of the data analysis are presented here.

Cross-Cultural Validation of the Korean Version of the Chalder Fatigue Scale.

PubMed

Ha, Hyeju; Jeong, Donghee; Hahm, Bong-Jin; Shim, Eun-Jung

2018-06-01

University students are vulnerable to fatigue. If not adequately dealt with, fatigue might develop into various health problems and negatively affect quality of life (QOL). The present study examined psychometric properties of the Korean version of the Chalder Fatigue Scale (K-CFQ) in university students. Data were obtained from two samples of undergraduate students in Korea. The first dataset (N = 557) was collected in a cross-sectional survey in 2015 and the second dataset (N = 338) from a longitudinal survey with three time points over a semester period in 2016. Participants completed measures of fatigue, QOL, depression, anxiety, and sleep quality. Three-factor model (physical fatigue, low energy, and mental fatigue) rather than the original two-factor model (physical and mental fatigue) provided a better goodness of fit indices to the data. Internal consistency of the K-CFQ was satisfactory, with Cronbach's α value of 0.88 for the total scale and those of subscales ranging from 0.73 to 0.87. Its convergent validity was supported by its significant association with anxiety, depression, sleep quality, and QOL. Significant association between T1 K-CFQ with physical QOL at T2 and T3 supported its predictive validity. Its known-group validity was proven with higher K-CFQ scores observed in the participants with depression and those with poor sleep quality. Current results suggest that K-CFQ is a valid and reliable measure of fatigue, and a better model fit of the three-factor structure of the K-CFQ implies potential cross-cultural differences in the dimensionality of fatigue.

The prevalence of fatigue and associated health and safety risk factors among taxi drivers in Singapore

PubMed Central

Lim, See Ming; Chia, Sin Eng

2015-01-01

INTRODUCTION Driver fatigue is one of the biggest health and safety concerns within the road transport sector. This study aimed to determine the prevalence of fatigue among taxi drivers in Singapore, to better understand the general working and health conditions of this group of people, and to determine the risk factors associated with fatigued driving. METHODS A total of 340 taxi drivers were randomly selected for participation in a self-administered questionnaire survey, which included height and weight measurements. The response rate was 68.2%. The survey consisted of four main categories: personal particulars; social habits; work patterns; and sleep profile. The Epworth Sleepiness Scale was used to estimate the level of daytime sleepiness and fatigue. Multiple logistic regression analysis was used to estimate the adjusted odd ratios and 95% confidence intervals associated with risk factors related to fatigue among taxi drivers. RESULTS A high proportion of taxi drivers were obese and had self-reported hypertension, diabetes mellitus and high cholesterol. Driver fatigue was associated with very poor/poor self-rating of quality of sleep, having an additional part-time job, drinking three or more caffeinated drinks daily, and driving more than 10 hours a day. CONCLUSION We hope that the findings of the present study will improve awareness of the work and health conditions of taxi drivers, and contribute toward efforts to achieve a healthier workforce. A lower prevalence of fatigued driving may lead to lower risks of road traffic accidents, decreased economic loss, increased productivity, and safer roads for all. PMID:25532512

The prevalence of fatigue and associated health and safety risk factors among taxi drivers in Singapore.

PubMed

Lim, See Ming; Chia, Sin Eng

2015-02-01

Driver fatigue is one of the biggest health and safety concerns within the road transport sector. This study aimed to find out the prevalence of fatigue among taxi drivers in Singapore, to better understand the general working and health conditions of this group of people and to determine the risk factors associated with fatigued driving. A total of 340 taxi drivers were randomly selected for participation in this self-administered questionnaire survey, with height and weight measurements. The response rate was 68.2%. The survey consisted of four main categories: personal particulars; social habits; work patterns and sleep profile; and Epworth Sleepiness Scale, which was used to estimate the level of daytime sleepiness and fatigue. Multiple logistic regression analysis was used to estimate the adjusted odd ratios and 95% confidence intervals associated with the risk factors related to fatigue among the taxi drivers. A high proportion of the taxi drivers were obese and had self-reported hypertension, diabetes mellitus and high cholesterol. Driver fatigue was associated with very poor/poor self-rating of the quality of sleep, having an additional part-time job, drinking three or more caffeinated drinks daily, and driving more than 10 hours a day. We hope that the findings of the present study will improve the awareness regarding the work and health conditions of taxi drivers, and contribute toward the effort to achieve a healthier workforce. A lower prevalence of fatigued driving will lead to lower risks of road traffic accidents, decreased economic loss, increased productivity, and safer roads for all.

Ecological momentary assessment of fatigue, sleepiness, and exhaustion in ESKD.

PubMed

Abdel-Kader, Khaled; Jhamb, Manisha; Mandich, Lee Anne; Yabes, Jonathan; Keene, Robert M; Beach, Scott; Buysse, Daniel J; Unruh, Mark L

2014-02-06

Many patients on maintenance dialysis experience significant sleepiness and fatigue. However, the influence of the hemodialysis (HD) day and circadian rhythms on patients' symptoms have not been well characterized. We sought to use ecological momentary assessment to evaluate day-to-day and diurnal variability of fatigue, sleepiness, exhaustion and related symptoms in thrice-weekly maintenance HD patients. Subjects used a modified cellular phone to access an interactive voice response system that administered the Daytime Insomnia Symptom Scale (DISS). The DISS assessed subjective vitality, mood, and alertness through 19 questions using 7- point Likert scales. Subjects completed the DISS 4 times daily for 7 consecutive days. Factor analysis was conducted and a mean composite score of fatigue-sleepiness-exhaustion was created. Linear mixed regression models (LMM) were used to examine the association of time of day, dialysis day and fatigue, sleepiness, and exhaustion composite scores. The 55 participants completed 1,252 of 1,540 (81%) possible assessments over the 7 day period. Multiple symptoms related to mood (e.g., feeling sad, feeling tense), cognition (e.g., difficulty concentrating), and fatigue (e.g., exhaustion, feeling sleepy) demonstrated significant daily and diurnal variation, with higher overall symptom scores noted on hemodialysis days and later in the day. In factor analysis, 4 factors explained the majority of the observed variance for DISS symptoms. Fatigue, sleepiness, and exhaustion loaded onto the same factor and were highly intercorrelated. In LMM, mean composite fatigue-sleepiness-exhaustion scores were associated with dialysis day (coefficient and 95% confidence interval [CI] 0.21 [0.02 - 0.39]) and time of day (coefficient and 95% CI 0.33 [0.25 - 0.41]. Observed associations were minimally affected by adjustment for demographics and common confounders. Maintenance HD patients experience fatigue-sleepiness-exhaustion symptoms that demonstrate

The role of psychological factors in oncology nurses' burnout and compassion fatigue symptoms.

PubMed

Duarte, Joana; Pinto-Gouveia, José

2017-06-01

This study explored the role of several psychological factors in professional quality of life in nurses. Specifically, we tried to clarify the relationships between several dimensions of empathy, self-compassion, and psychological inflexibility, and positive (compassion satisfaction) and negative (burnout and compassion fatigue) domains of professional quality of life. Using a cross-sectional design, a convenience sample of 221 oncology nurses recruited from several public hospitals filling out a battery of self-report measures. Results suggested that nurses that benefit more from their work of helping and assisting others (compassion satisfaction) seem to have more empathic feelings and sensibility towards others in distress and make an effort to see things from others' perspective. Also, they are less disturbed by negative feelings associated with seeing others' suffering and are more self-compassionate. Nurses more prone to experience the negative consequences associated with care-providing (burnout and compassion fatigue) are more self-judgmental and have more psychological inflexibility. In addition, they experience more personal feelings of distress when seeing others in suffering and less feelings of empathy and sensibility to others' suffering. Psychological factors explained 26% of compassion satisfaction, 29% of burnout and 18% of compassion fatigue. We discuss the results in terms of the importance of taking into account the role of these psychological factors in oncology nurses' professional quality of life, and of designing nursing education training and interventions aimed at targeting such factors. Copyright © 2017 Elsevier Ltd. All rights reserved.

Crew Factors in Flight Operations. 8; A Survey of Fatigue Factors in Corporate/Executive A Viation Operations

NASA Technical Reports Server (NTRS)

Rosekind, Mark R.; Co, Elizabeth L.; Gregory, Kevin B.; Miller, Donna L.

2000-01-01

Corporate flight crews face unique challenges including unscheduled flights, quickly changing schedules, extended duty days, long waits, time zone changes, and peripheral tasks. Most corporate operations are regulated by Part 91 FARs which set no flight or duty time limits. The objective of this study was to identify operationally significant factors that may influence fatigue, alertness, and performance in corporate operations. In collaboration with the National Business Aircraft Association and the Flight Safety Foundation, NASA developed and distributed a retrospective survey comprising 107 questions addressing demographics, home sleep habits, flight experience, duty schedules, fatigue during operations, and work environment. Corporate crewmembers returned 1,488 surveys. Respondents averaged 45.2 years of age, had 14.9 years of corporate flying experience, and 9,750 total flight hours. The majority (89%) rated themselves as 'good' or 'very good' sleepers at home. Most (82%) indicated they are subject to call for duty and described an average duty day of 9.9 h. About two-thirds reported having a daily duty time limit and over half (57%) reported a daily flight time limit. Nearly three-quarters (71%) acknowledged having 'nodded off' during a flight. Only 21% reported that their flight departments offer training on fatigue issues. Almost three-quarters (74%) described fatigue as a 'moderate' or 'serious' concern, and a majority (61%) characterized it as a common occurrence. Most (85%) identified fatigue as a 'moderate' or 'serious' safety issue.

Study of fatigue behavior of longitudinal welded pipes

NASA Astrophysics Data System (ADS)

Simion, P.; Dia, V.; Istrate, B.; Hrituleac, G.; Hrituleac, I.; Munteanu, C.

2016-08-01

During transport and storage of the various fluids, welded pipes are subjected to cyclic loading due to pressure fluctuations that often exceed the prescribed values for normal operation. These cyclic loading can significantly reduce the life of the pipes; as a result the design should be based on the fatigue strength not only on static resistance. In general the fatigue strength of pipes is dependent by strength, pipe geometry and surface quality. In case of the electric longitudinal welded pipes, the fatigue strength is significantly limited by concentration of residual stress and the size of existing defects in the weld seam. This paper presents the fatigue behaviour of the electric welded pipes by high frequency, under conditions that simulate real operating conditions pipes. Fatigue testing was performed on welded pipes made of micro alloyed carbon steels. Some of these pipes were previously subjected to a heat treatment of normalization, in order to also determine the influence of heat treatment on the fatigue strength of welded pipes. To determine and correlate the different factors affecting the fatigue strength, welded pipes were also subjected to various tests: tensile tests, impact tests, measurement of micro hardness, microstructural analysis by optical microscopy and scanning electron microscopy.

Psychological distress, iron deficiency, active disease and female gender are independent risk factors for fatigue in patients with ulcerative colitis

PubMed Central

Jonefjäll, Börje; Simrén, Magnus; Lasson, Anders; Öhman, Lena; Strid, Hans

2017-01-01

Background Patients with ulcerative colitis often report fatigue. Objectives To investigate prevalence of and risk factors for fatigue in patients with ulcerative colitis with active disease and during deep remission. Methods In this cross-sectional study, disease activity was evaluated with endoscopy and calprotectin, and patients were classified as having active disease (n = 133) or being in deep remission (n = 155). Blood samples were analysed to assess anaemia, iron deficiency and systemic immune activity. Patients completed questionnaires to assess fatigue, psychological distress, gastrointestinal symptoms and quality of life. Results The prevalence of high fatigue (general fatigue ≥ 13, Multidimensional Fatigue Inventory) was 40% in the full study population. Among patients with high fatigue, female gender and iron deficiency were more prevalent, and these patients had more severe disease activity and reported higher levels of anxiety, depression and decreased quality of life compared with patients with no/mild fatigue. A logistic regression analysis identified probable psychiatric disorder (odds ratio (OR) (confidence interval) 6.1 (3.1–12.2)), iron deficiency (OR 2.5 (1.2–5.1)), active disease (OR 2.2 (1.2–3.9)) and female gender (OR 2.1 (1.1–3.7)) as independent risk factors for high fatigue. Similar results were found concerning psychological distress, gender and quality of life, but immune markers did not differ in patients in deep remission with high vs. no/mild fatigue. Conclusions Probable psychiatric disorder, iron deficiency, active disease and female gender are independent risk factors for high fatigue in patients with ulcerative colitis. Low-grade immune activity does not seem to be the cause of fatigue among patients in deep remission. PMID:29435325

A Model of Fatigue Following Traumatic Brain Injury.

PubMed

Ponsford, Jennie; Schönberger, Michael; Rajaratnam, Shantha M W

2015-01-01

Fatigue is one of the most frequent sequelae of traumatic brain injury (TBI), although its causes are poorly understood. This study investigated the interrelationships between fatigue and sleepiness, vigilance performance, depression, and anxiety, using a structural equation modeling approach. Seventy-two participants with moderate to severe TBI (78% males) were recruited a median of 305 days postinjury. They completed the Fatigue Severity Scale, a vigilance task, the Epworth Sleepiness Scale, and Hospital Anxiety and Depression Scale. A model of the interrelationships between the study variables was developed, tested, and modified with path analysis. The modified model had a good overall fit (χ2 = 1.3, P = .54; comparative fit index = 1.0; root-mean square error of approximation = 0.0; standardized root-mean square residual = 0.02). Most paths in this model were significant (P < .05). Fatigue predicted anxiety, depression, and daytime sleepiness. Depression predicted daytime sleepiness and poor vigilance, whereas anxiety tended to predict reduced daytime sleepiness. This model confirms the complexity of fatigue experience. It supports the hypothesis that fatigue after TBI is a cause, not a consequence, of anxiety, depression, and daytime sleepiness, which, in turn (especially depression), may exacerbate fatigue by affecting cognitive functioning. These findings suggest that to alleviate fatigue, it is important to address each of these factors. However, the findings need to be confirmed with a longitudinal research design.

A Study on the Impact of Fatigue on Human Raters When Scoring Speaking Responses

ERIC Educational Resources Information Center

Ling, Guangming; Mollaun, Pamela; Xi, Xiaoming

2014-01-01

The scoring of constructed responses may introduce construct-irrelevant factors to a test score and affect its validity and fairness. Fatigue is one of the factors that could negatively affect human performance in general, yet little is known about its effects on a human rater's scoring quality on constructed responses. In this study, we compared…

Fatigue and related factors among hotel workers: the effects of emotional labor and non-standard working hours.

PubMed

Lee, Ju Jong; Moon, Hyun Jey; Lee, Kyung-Jae; Kim, Joo Ja

2014-01-01

This study assessed fatigue and its association with emotional labor and non-standard working hours among hotel workers. A structured self-administered questionnaire was distributed to 1,320 employees of five hotels located in Seoul. The questionnaire survey included questions concerning the participants' sociodemographics, health-related behaviors, job-related factors, emotional labor, and fatigue. Fatigue was assessed using the Multidimensional Fatigue Scale (MFS). Multiple logistic regression modeling was used to determine the associations between fatigue and emotional labor. Among male workers, there was a significant association between fatigue and both emotional disharmony (OR=5.52, 95% CI=2.35-12.97) and emotional effort (OR=3.48, 95% CI=1.54-7.86). These same associations were seen among the female workers (emotional disharmony: OR=6.91, 95% CI=2.93-16.33; emotional effort: OR=2.28, 95% CI=1.00-5.16). These results indicate that fatigue is associated with emotional labor and, especially, emotional disharmony among hotel workers. Therefore, emotional disharmony management would prove helpful for the prevention of fatigue.

The role of cognitive, emotional and personality factors in the experience of fatigue in a university and community sample.

PubMed

Kangas, Maria; Montgomery, Guy H

2011-05-01

The aim of this study was to investigate the contribution of cognitive, emotional and personality factors to the experience of fatigue severity in healthy adult individuals. Specifically, the study examined whether fatigue catastrophising and emotional distress mediated the relationships between neuroticism, general irrational and rational thoughts to fatigue severity. One hundred and eighty nine university students and community volunteers completed self-report questionnaires assessing fatigue catastrophising and symptom severity, neuroticism, general rational and irrational thoughts and emotional distress. A series of correlational and path analyses were conducted to test the study hypotheses. Neuroticism and more general negative, irrational cognitions were associated with elevated fatigue catastrophising and fatigue severity, whereas more adaptive, rational cognitions were related to lower fatigue catastrophising and fatigue severity. Both elevated fatigue catastrophising and emotional distress uniquely and simultaneously mediated the relationships between irrational and rational cognitions and neuroticism to fatigue severity. These findings demonstrate that cognitions play a role in fatigue severity. The results have implications in the assessment and treatment of fatigue disturbances in the general community.

Defining the Focus of Attention: Effects of Attention on Perceived Exertion and Fatigue

PubMed Central

Lohse, Keith R.; Sherwood, David E.

2011-01-01

This manuscript presents two experiments designed to explore the effects of attention on perceived exertion and time to failure in a fatiguing athletic task. There were two major motivating factors for these experiments. First, there are few studies evaluating attentional focus effects in endurance tasks and, second, there is a lack of integration between studies of attentional focus as external/internal (e.g., Wulf, 2007a) compared to associative/dissociative (e.g., Stevinson and Biddle, 1998). In Experiment 1, we used a fatiguing wall-sit posture (essentially a complex, isometric task) to compare two different types of external attention with an internal focus on the position of the legs. An external focus (regardless of type) increased the time taken to failure and reduced perceived exertion. In Experiment 2, we manipulated subjects’ expectancy of fatigue to test the interaction of attention and expectancy (both top-down factors) in this highly fatiguing task. Previous theories of attention during endurance tasks have suggested that as fatigue/pain increase, bottom-up factors begin to dominate subjects’ attention. While this may be true, Experiment 2 showed that even in a highly fatiguing task, attentional strategies, and expectancies affected the time to failure and perceived exertion. PMID:22102843

[Epidemiology of fatigue in general practice].

PubMed

Fuhrer, R

1994-11-01

The epidemiology of fatigue is not well known in France, and this study reports on factors associated with fatigue in a sample of 3,784 general practice patients. Prevalence rates according to several definitions of fatigue are presented and factors are examined that have been reported to be associated with fatigue. Although 41.2% of the sample report having experienced symptoms of fatigue for at least three days, only 7.6% declare fatigue as a reason for consulting a doctor. Women report more symptoms of fatigue, but they do not consult more often than men for this reason. Age is strongly correlated with fatigue, but this is found only for men. Socioprofessional category bears no relationship to fatigue as a reason for consultation, however, the diagnosis of fatigue is more often attributed to professionals and upper management than it is to office staff or skilled and unskilled workers. We do find a strong relationship between depressive symptomatology as measured by the Center for Epidemiologic Studies (CES-D) and fatigue; nonetheless, fatigue is neither sensitive nor specific to the diagnosis of depression.

Low cycle fatigue of PM/HIP astroloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Choe, S.J.; Stoloff, N.S.; Duquette, D.J.

Low cycle fatigue and creep-fatigue-environment interactions of PM/HIP Astrology were studied at 650 C and 725 C. Total strain range was varied from 1.5% to 2.7% at a frequency of 0.3Hz. Creep-fatigue tests were performed with 2 min. or 5 min. tensile hold times. All tests were run in high purity argon in an attempt to minimize environmental effects. Employing a tensile hold was more damaging than raising temperature by 75 C. Slopes of Coffin-Manson plots were nearly independent of temperature and hold time. Raising temperature from 650 C to 725 C did not change the transgranular (TG) crack propagationmore » mode, whereas employing hold times caused TG+IG propagation. All samples displayed multiple fracture origins associated with inclusions located at the specimen surface; pre-existing pores did not affect fatigue crack initiation. Examination of secondary cracks showed no apparent creep damage. Oxidation in high purity argon appeared to be the major factor in LCF life degradation due to hold times.« less

A Preliminary Review of Fatigue Among Rail Staff

PubMed Central

Fan, Jialin; Smith, Andrew P.

2018-01-01

Background: Fatigue is a severe problem in the rail industry, which may jeopardize train crew's health and safety. Nonetheless, a preliminary review of all empirical evidence for train crew fatigue is still lacking. The aim of the present paper is, therefore, to provide a preliminary description of occupational fatigue in the rail industry. This paper reviews the literature with the research question examining the risk factors associated with train crew fatigue, covering both papers published in refereed journals and reports from trade organizations and regulators. It assesses the progress of research on railway fatigue, including research on the main risk factors for railway fatigue, the association between fatigue and railway incidents, and how to better manage fatigue in the railway industry. Methods: Systematic searches were performed in both science and industry databases. The searches considered studies published before August 2017. The main exclusion criterion was fatigue not being directly measured through subjective or objective methods. Results: A total of 31 studies were included in the main review. The causes of fatigue included long working hours, heavy workload, early morning or night shifts, and insufficient sleep. Poor working environment, particular job roles, and individual differences also contributed to fatigue. Conclusion: Fatigue in the rail industry includes most of the features of occupational fatigue, and it is also subject to industry-specific factors. The effect of fatigue on well-being and the fatigued population in the railway industry are still not clear. Future studies can consider associations between occupational risk factors and perceived fatigue by examining the prevalence of fatigue and identifying the potential risk factors in staff within the railway industry. PMID:29867630

Pilot Fatigue and Circadian Desynchronosis

NASA Technical Reports Server (NTRS)

1981-01-01

Pilot fatigue and circadian desynchronosis, its significance to air transport safety, and research approaches, were examined. There is a need for better data on sleep, activity, and other pertinent factors from pilots flying a variety of demanding schedules. Simulation studies of flight crew performance should be utilized to determine the degree of fatigue induced by demanding schedules and to delineate more precisely the factors responsible for performance decrements in flight and to test solutions proposed to resolve problems induced by fatigue and desynchronosis. It was concluded that there is a safety problem of uncertain magnitude due to transmeridian flying and a potential problem due to fatigue associated with various factors found in air transport operations.

Perceived Fatigue Interference and Depressed Mood: Comparison of Chronic Fatigue Syndrome/Myalgic Encephalomyelitis Patients with Fatigued Breast Cancer Survivors.

PubMed

Hall, Daniel L; Antoni, Michael H; Lattie, Emily G; Jutagir, Devika R; Czaja, Sara J; Perdomo, Dolores; Lechner, Suzanne C; Stagl, Jamie M; Bouchard, Laura C; Gudenkauf, Lisa M; Traeger, Lara; Fletcher, MaryAnn; Klimas, Nancy G

Persistent fatigue and depressive symptoms are both highly prevalent among patients with Chronic Fatigue Syndrome/Myalgic Encephalomyelitis (CFS/ME) as well as breast cancer survivors. This study aimed to assess and directly compare perceptions of fatigue as highly interfering in one's daily functioning in both patient populations to better understand their relationships with depressed mood. Participants were 95 female CFS/ME patients and 67 females who were approximately 5 years post-treatment for stage 0-III breast cancer presenting with clinically elevated fatigue severity. Self-report measures were obtained on participants' fatigue-related interference in daily functioning and fatigue severity as well as depressed mood. Hierarchical regression was used to test effects controlling for relevant demographic, psychosocial, and medical covariates. CFS/ME patients endorsed greater depressed mood and fatigue interference than did fatigued breast cancer survivors, p's <.001. These factors were significantly positively correlated among CFS/ME patients (β=.36, p <.001), but not the fatigued breast cancer survivors (β=.18, p =.19). CFS/ME patients reported elevated fatigue symptoms and depression relative to fatigued breast cancer survivors. In the former group, greater depressed mood was highly and significantly associated with greater fatigue-related inference in daily activities. Potential targets for cognitive behavioral interventions are discussed.

Perceived Fatigue Interference and Depressed Mood: Comparison of Chronic Fatigue Syndrome/Myalgic Encephalomyelitis Patients with Fatigued Breast Cancer Survivors

PubMed Central

Hall, Daniel L.; Antoni, Michael H.; Lattie, Emily G.; Jutagir, Devika R.; Czaja, Sara J.; Perdomo, Dolores; Lechner, Suzanne C.; Stagl, Jamie M.; Bouchard, Laura C.; Gudenkauf, Lisa M.; Traeger, Lara; Fletcher, MaryAnn; Klimas, Nancy G.

2015-01-01

Objective Persistent fatigue and depressive symptoms are both highly prevalent among patients with Chronic Fatigue Syndrome/Myalgic Encephalomyelitis (CFS/ME) as well as breast cancer survivors. This study aimed to assess and directly compare perceptions of fatigue as highly interfering in one’s daily functioning in both patient populations to better understand their relationships with depressed mood. Methods Participants were 95 female CFS/ME patients and 67 females who were approximately 5 years post-treatment for stage 0-III breast cancer presenting with clinically elevated fatigue severity. Self-report measures were obtained on participants’ fatigue-related interference in daily functioning and fatigue severity as well as depressed mood. Hierarchical regression was used to test effects controlling for relevant demographic, psychosocial, and medical covariates. Results CFS/ME patients endorsed greater depressed mood and fatigue interference than did fatigued breast cancer survivors, p’s<.001. These factors were significantly positively correlated among CFS/ME patients (β=.36, p<.001), but not the fatigued breast cancer survivors (β=.18, p=.19). Conclusions CFS/ME patients reported elevated fatigue symptoms and depression relative to fatigued breast cancer survivors. In the former group, greater depressed mood was highly and significantly associated with greater fatigue-related inference in daily activities. Potential targets for cognitive behavioral interventions are discussed. PMID:26180660

The mediating role of emotional symptomatology between anticipatory fatigue and the perception of fatigue.

PubMed

Rodríguez Testal, Juan F; Fuentes Márquez, Sandra; Senín Calderón, Cristina; Carrasco, Miguel A

2016-05-01

Clinical research stresses the importance of cognitive variables for predisposition, onset, and especially, perpetuation of perceived fatigue. The aim was to analyze the mediating effects of emotional symptomatology (somatic, depressive and anxiety) between anticipatory fatigue and perception of physical and cognitive fatigue. The sample was composed of 317 participants (29% from a clinical population) aged 18 to 76. Anticipatory fatigue and perception of fatigue were measured by fatigue scales. Emotional symptoms were assessed by the General Health Questionnaire, GHQ-28.  Results : Depressive symptomatology mediated the relationship between anticipatory fatigue and cognitive fatigue in both groups, and also somatic symptoms/somatization in patients. The indirect effect of physical fatigue was observed only in the clinical group, with depressive symptoms partially mediating the anticipatory fatigue and cognitive fatigue relationship. Anticipatory fatigue has a partial indirect effect on total physical fatigue, and full indirect effect on cognitive fatigue, mediated by depressive and somatic symptoms. Anticipatory fatigue is a relevant cognitive factor in the design of psychological intervention for improvement of cognitive and physical fatigue.

Quality Factor and Microslipping of Fatigue Cracks in Thin Plates at Resonant Vibration

NASA Technical Reports Server (NTRS)

Wincheski, B.; Namkung, M.; Fulton, J. P.

1993-01-01

Resonant vibrations have been stimulated in thin metal plates using a non-contacting electromagnetic driver. A sinusoidal force was applied in a swept frequency fashion and the resulting surface displacements were monitored through the use of an acoustic microphone. It has been found that the presence of a fatigue crack in the sample causes a broadening of the second resonance peak. The Q factors of the resonance curves were determined and are directly correlated with the presence of fatigue cracks in the samples. The broadening of the curves is explained in terms of a microslipping at the crack face walls which reduces the amplitude of the resonant vibration by increasing the damping of the system. A comparison is made between the resonance characteristics of fatigue damaged and notched samples, where the stiffness of the two systems is nearly constant while the interaction between crack face walls is eliminated in the latter.

Corrosion Effects on the Fatigue Crack Propagation of Giga-Grade Steel and its Heat Affected Zone in pH Buffer Solutions for Automotive Application

NASA Astrophysics Data System (ADS)

Lee, H. S.

2018-03-01

Corrosion fatigue crack propagation test was conducted of giga-grade steel and its heat affected zone in pH buffer solutions, and the results were compared with model predictions. Pure corrosion effect on fatigue crack propagation, particularly, in corrosive environment was evaluated by means of the modified Forman equation. As shown in results, the average corrosion rate determined from the ratio of pure corrosion induced crack length to entire crack length under a cycle load were 0.11 and 0.37 for base metal and heat affected zone, respectively, with load ratio of 0.5, frequency of 0.5 and pH 10.0 environment. These results demonstrate new interpretation methodology for corrosion fatigue crack propagation enabling the pure corrosion effects on the behavior to be determined.

Increased Incidence of Fatigue in Patients with Primary Immunodeficiency Disorders: Prevalence and Associations Within the US Immunodeficiency Network Registry.

PubMed

Hajjar, Joud; Guffey, Danielle; Minard, Charles G; Orange, Jordan S

2017-02-01

Patients with primary immunodeficiency (PID) often report fatigue, yet this symptom has not been studied in PID. Fatigue affects 6-7.5% of healthy adults. The goal of this study is to estimate the prevalence of fatigue in patients with PID and investigate its associated factors. We analyzed 2537 PID patients registered in USIDNET to determine responses to the field "fatigue" in the core registry form. Demographics, immune phenotypes, and comorbid conditions were compared between fatigued and non-fatigued patients to identify relevant associations and potential drivers. A focused analysis was performed for patients with predominantly antibody deficiency disorders (PADs). Fatigue was reported in 25.9% (95% CI 23.7-28.3) of PAD patients, compared to 6.4% (95% CI 4.9-8.2) of non-PAD. Patients with common variable immunodeficiency (CVID) had the highest prevalence of fatigue (p < 0.001) among all PID diagnoses. Other factors that were associated with a higher rate of fatigue among PAD patients included female sex, higher BMI, depression, bronchiectasis, and autoimmunity. Additionally, fatigued PAD patients had lower absolute lymphocyte, CD3, CD4, and CD8 counts compared to non-fatigued patients. Our findings suggest that fatigue is overrepresented in PAD patients. Prospective studies to estimate prevalence, risk factors, and fatigue etiology in PID are warranted, so therapeutic interventions can be considered.

Relations between muscle endurance and subjectively reported fatigue, walking capacity, and participation in mildly affected adolescents with cerebral palsy.

PubMed

Eken, Maaike M; Houdijk, Han; Doorenbosch, Caroline A M; Kiezebrink, Francisca E M; van Bennekom, Coen A M; Harlaar, Jaap; Dallmeijer, Annet J

2016-08-01

To investigate the relation between muscle endurance and subjectively reported fatigue, walking capacity, and participation in mildly affected adolescents with cerebral palsy (CP) and peers with typical development. In this case-control study, knee extensor muscle endurance was estimated from individual load-endurance curves as the load corresponding to a 15-repetition maximum in 17 adolescents with spastic CP (six males, 11 females; age 12-19y) and 18 adolescents with typical development (eight males, 10 females; age 13-19y). Questionnaires were used to assess subjectively reported fatigue (Pediatric Quality of Life Inventory Multidimensional Fatigue Scale) and participation (Life-Habits questionnaire). Walking capacity was assessed using the 6-minute walk test. Relations were determined using multiple regression analyses. Muscle endurance related significantly to subjectively reported fatigue and walking capacity in adolescents with CP, while no relations were found for adolescents with typical development (subjectively reported fatigue: regression coefficient β [95% confidence intervals] for CP=23.72 [6.26 to 41.18], for controls=2.72 [-10.26 to 15.69]; walking capacity β for CP=125m [-87 to 337], for controls=2m [-86 to 89]). The 15-repetition maximum did not relate to participation in adolescents with CP. Subjectively reported fatigue and reduced walking capacity in adolescents with CP are partly caused by lower muscle endurance of knee extensors. Training of muscle endurance might contribute to reducing the experience of fatigue and improving walking capacity. Reduced muscle endurance seems to have no effect on participation. © 2016 Mac Keith Press.

Taltirelin alleviates fatigue-like behavior in mouse models of cancer-related fatigue.

PubMed

Dougherty, John P; Wolff, Brian S; Cullen, Mary J; Saligan, Leorey N; Gershengorn, Marvin C

2017-10-01

Fatigue affects most cancer patients and has numerous potential causes, including cancer itself and cancer treatment. Cancer-related fatigue (CRF) is not relieved by rest, can decrease quality of life, and has no FDA-approved therapy. Thyrotropin-releasing hormone (TRH) has been proposed as a potential novel treatment for CRF, but its efficacy against CRF remains largely untested. Thus, we tested the TRH analog, taltirelin (TAL), in mouse models of CRF. To model fatigue, we used a mouse model of chemotherapy, a mouse model of radiation therapy, and mice bearing colon 26 carcinoma tumors. We used the treadmill fatigue test to assess fatigue-like behavior after treatment with TAL. Additionally, we used wild-type and TRH receptor knockout mice to determine which TRH receptor was necessary for the actions of TAL. Tumor-bearing mice displayed muscle wasting and all models caused fatigue-like behavior, with mice running a shorter distance in the treadmill fatigue test than controls. TAL reversed fatigue-like behavior in all three models and the mouse TRH 1 receptor was necessary for the effects of TAL. These data suggest that TAL may be useful in alleviating fatigue in all cancer patients and provide further support for evaluating TAL as a potential therapy for CRF in humans. Published by Elsevier Ltd.

Fatigue in Adolescents With Cancer Compared to Healthy Adolescents

PubMed Central

Daniel, Lauren C.; Brumley, Lauren D.; Schwartz, Lisa A.

2015-01-01

Background Cancer-related fatigue is one of the most pervasive and debilitating side-effects of cancer treatment and adolescents consistently rate cancer-related fatigue as one of the most distressing aspects of treatment. Because fatigue is also high in adolescents without cancer, the current study aims to describe fatigue in adolescents with cancer relative to a control group and to identify associates of such fatigue. Knowing this is important for understanding the extent of the problem in adolescents with cancer relative to healthy adolescents and for understanding who is most at risk for fatigue and related distress. Procedure Adolescents with cancer and their caregivers (n =102) and adolescents without a history of chronic health conditions and their caregivers (n =97) completed the Multidimensional Fatigue Scale and measures of depression, quality of life (QoL), affect, coping, and family functioning. Results Adolescents with cancer and their caregivers reported significantly more adolescent fatigue across all domains (with the exception of adolescent reports of cognitive fatigue) relative to adolescents without chronic health conditions. Higher fatigue was significantly related to adolescent report of more symptoms of depression, poorer QoL, higher negative affect, less positive affect, and behavioral disengagement coping style. Fatigue was not related to active coping or family functioning. Conclusions Adolescents with cancer experience significantly more fatigue than peers without chronic health conditions. Reports of fatigue are closely related to multiple indicators of psychosocial well-being, suggesting that fatigue may be an important cancer-related symptom to assess and manage to improve adolescent QoL. PMID:23897651

Effect of stress concentration on the fatigue strength of A7N01S-T5 welded joints

NASA Astrophysics Data System (ADS)

Zhang, Mingyue; Gou, Guoqing; Hang, Zongqiu; Chen, Hui

2017-07-01

Stress concentration is a key factor that affects the fatigue strength of welded joints. In this study, the fatigue strengths of butt joints with and without the weld reinforcement were tested to quantify the effect of stress concentration. The fatigue strength of the welded joints was measured with a high-frequency fatigue machine. The P-S-N curves were drawn under different confidence levels and failure probabilities. The results show that butt joints with the weld reinforcement have much lower fatigue strength than joints without the weld reinforcement. Therefore, stress concentration introduced by the weld reinforcement should be controlled.

Increased Incidence of Fatigue in Patients with Primary Immunodeficiency Disorders: Prevalence and Associations Within the US Immunodeficiency Network Registry

PubMed Central

Guffey, Danielle; Minard, Charles G.; Orange, Jordan S.

2017-01-01

Introduction Patients with primary immunodeficiency (PID) often report fatigue, yet this symptom has not been studied in PID. Fatigue affects 6–7.5% of healthy adults. The goal of this study is to estimate the prevalence of fatigue in patients with PID and investigate its associated factors. Methods We analyzed 2537 PID patients registered in USIDNET to determine responses to the field “fatigue” in the core registry form. Demographics, immune phenotypes, and comorbid conditions were compared between fatigued and non-fatigued patients to identify relevant associations and potential drivers. A focused analysis was performed for patients with predominantly antibody deficiency disorders (PADs). Results Fatigue was reported in 25.9%(95% CI 23.7–28.3) of PAD patients, compared to 6.4% (95% CI 4.9–8.2) of non-PAD. Patients with common variable immunodeficiency (CVID) had the highest prevalence of fatigue (p < 0.001) among all PID diagnoses. Other factors that were associated with a higher rate of fatigue among PAD patients included female sex, higher BMI, depression, bronchiectasis, and autoimmunity. Additionally, fatigued PAD patients had lower absolute lymphocyte, CD3, CD4, and CD8 counts compared to non-fatigued patients. Conclusion Our findings suggest that fatigue is overrepresented in PAD patients. Prospective studies to estimate prevalence, risk factors, and fatigue etiology in PID are warranted, so therapeutic interventions can be considered. PMID:28124237

[The prevalence of low back pain in hospital staff and its relationship with chronic fatigue syndrome and occupational factors].

PubMed

Terzi, Rabia; Altın, Firuzan

2015-01-01

This study aimed to investigate the occurrence of low back pain in hospital employees during the previous year and its correlation with demographic data, occupational factors and chronic fatigue syndrome. All participants provided information on their socio-demographic background, occupational characteristics, their experience of low back pain during the previous year, and chronic fatigue syndrome. The study included 365 volunteers (221 male and 144 female). The mean age was 33.1 ± 7.2. Of the 365 participants, 218 (59.7%) had experienced low back pain in the last year. No statistically significant difference was detected in age, height, weight, level of education, smoking habits, occupation, professional working hours, shift work or levels of income between the groups with and without low back pain. Low back pain was more frequent (p<0.05) in male workers. Chronic fatigue syndrome was statistically significant in the group suffering from low back pain (p<0.05), of whom 21.5% had chronic fatigue syndrome. We detected a statistically significant relationship (p<0.05) between chronic fatigue syndrome, occupational duration and shift work. To the best of our knowledge, this is the first to show the relationship between low back pain and chronic fatigue syndrome in hospital employees. Shift work and length of time in occupation are risk factors for chronic fatigue syndrome.

The Effect of Hole Quality on the Fatigue Life of 2024-T3 Aluminum Alloy Sheet

NASA Technical Reports Server (NTRS)

Everett, Richard A., Jr.

2004-01-01

This paper presents the results of a study whose main objective was to determine which type of fabrication process would least affect the fatigue life of an open-hole structural detail. Since the open-hole detail is often the fundamental building block for determining the stress concentration of built-up structural parts, it is important to understand any factor that can affect the fatigue life of an open hole. A test program of constant-amplitude fatigue tests was conducted on five different sets of test specimens each made using a different hole fabrication process. Three of the sets used different mechanical drilling procedures while a fourth and fifth set were mechanically drilled and then chemically polished. Two sets of specimens were also tested under spectrum loading to aid in understanding the effects of residual compressive stresses on fatigue life. Three conclusions were made from this study. One, the residual compressive stresses caused by the hole-drilling process increased the fatigue life by two to three times over specimens that were chemically polished after the holes were drilled. Second, the chemical polishing process does not appear to adversely affect the fatigue life. Third, the chemical polishing process will produce a stress-state adjacent to the hole that has insignificant machining residual stresses.

Factors Influencing Dwell Fatigue Cracking in Notches of Powder Metallurgy Superalloys

NASA Technical Reports Server (NTRS)

Gabb, T. P.; Telesman, J.; Ghosn, L.; Garg, A.; Gayda, J.

2011-01-01

The influences of heat treatment and cyclic dwells on the notch fatigue resistance of powder metallurgy disk superalloys were investigated for low solvus high refractory (LSHR) and ME3 disk alloys. Disks were processed to produce material conditions with varied microstructures and associated mechanical properties. Notched specimens were first subjected to baseline dwell fatigue cycles having a dwell at maximum load, as well as tensile, stress relaxation, creep rupture, and dwell fatigue crack growth tests at 704 C. Several material heat treatments displayed a bimodal distribution of fatigue life with the lives varying by two orders-of-magnitude, while others had more consistent fatigue lives. This response was compared to other mechanical properties, in search of correlations. The wide scatter in baseline dwell fatigue life was observed only for material conditions resistant to stress relaxation. For selected materials and conditions, additional tests were then performed with the dwells shifted in part or in total to minimum tensile load. The tests performed with dwells at minimum load exhibited lower fatigue lives than max dwell tests, and also exhibited early crack initiation and a substantial increase in the number of initiation sites. These results could be explained in part by modeling evolution of peak stresses in the notch with continued dwell fatigue cycling. Fatigue-environment interactions were determined to limit life for the fatigue cycles with dwells.

The nature of self-regulatory fatigue and “ego depletion”: Lessons from physical fatigue

PubMed Central

Evans, Daniel R.; Boggero, Ian A.; Segerstrom, Suzanne C.

2016-01-01

Self-regulation requires overriding a dominant response, and leads to temporary self-regulatory fatigue. Existing theories of the nature and causes of self-regulatory fatigue highlight physiological substrates such as glucose or psychological processes such as motivation, but these explanations are incomplete on their own. Historically, theories of physical fatigue demonstrate a similar pattern of useful but incomplete explanations, as recent views of physical fatigue emphasize the roles of both physiological and psychological factors. In addition to accounting for multiple inputs, these newer views also explain how fatigue can occur even in the presence of sufficient resources. Examining these newer theories of physical fatigue can serve as a foundation on which to build a more comprehensive understanding of self-regulatory fatigue that integrates possible neurobiological underpinnings of physical and self-regulatory fatigue, and suggests the possible function of self-regulatory fatigue. PMID:26228914

The Nature of Self-Regulatory Fatigue and "Ego Depletion": Lessons From Physical Fatigue.

PubMed

Evans, Daniel R; Boggero, Ian A; Segerstrom, Suzanne C

2015-07-30

Self-regulation requires overriding a dominant response and leads to temporary self-regulatory fatigue. Existing theories of the nature and causes of self-regulatory fatigue highlight physiological substrates such as glucose, or psychological processes such as motivation, but these explanations are incomplete on their own. Historically, theories of physical fatigue demonstrate a similar pattern of useful but incomplete explanations, as recent views of physical fatigue emphasize the roles of both physiological and psychological factors. In addition to accounting for multiple inputs, these newer views also explain how fatigue can occur even in the presence of sufficient resources. Examining these newer theories of physical fatigue can serve as a foundation on which to build a more comprehensive understanding of self-regulatory fatigue that integrates possible neurobiological underpinnings of physical and self-regulatory fatigue, and suggests the possible function of self-regulatory fatigue. © 2015 by the Society for Personality and Social Psychology, Inc.

Fatigue in Arthritis: A Multidimensional Phenomenon with Impact on Quality of Life : Fatigue and Quality of Life in Arthritis.

PubMed

Alikari, Victoria; Sachlas, Athanasios; Giatrakou, Stavroula; Stathoulis, John; Fradelos, Evagelos; Theofilou, Paraskevi; Lavdaniti, Maria; Zyga, Sofia

2017-01-01

An important factor which influences the quality of life of patients with arthritis is the fatigue they experience. The purpose of this study was to assess the relationship between fatigue and quality of life among patients with osteoarthritis and rheumatoid arthritis. Between January 2015 and March 2015, 179 patients with osteoarthritis and rheumatoid arthritis completed the Fatigue Assessment Scale and the Missoula-VITAS Quality of Life Index-15 (MVQoLI-15). The study was conducted in Rehabilitation Centers located in the area of Peloponnese, Greece. Data related to sociodemographic characteristics and their individual medical histories were recorded. Statistical analysis was performed using the IBM SPSS Statistics version 19. The analysis did not reveal statistically significant correlation between fatigue and quality of life neither in the total sample nor among patients with osteoarthritis (r = -0.159; p = 0.126) or rheumatoid arthritis. However, there was a statistically significant relationship between some aspects of fatigue and dimensions of quality of life. Osteoarthritis patients had statistically significant lower MVQoLI-15 score than rheumatoid arthritis patients (13.73 ± 1.811 vs 14.61 ± 1.734) and lower FAS score than rheumatoid patients (26.14 ± 3.668 vs 29.94 ± 3.377) (p-value < 0.001). The finding that different aspects of fatigue may affect dimensions of quality of life may help health care professionals by proposing the early treatment of fatigue in order to gain benefits for quality of life.

Pre-Surgery Psychological Factors Predict Pain, Nausea and Fatigue One Week Following Breast Cancer Surgery

PubMed Central

Montgomery, Guy H.; Schnur, Julie B.; Erblich, Joel; Diefenbach, Michael A.; Bovbjerg, Dana H.

2010-01-01

Prior to scheduled surgery, breast cancer surgical patients frequently experience high levels of distress and expect a variety of post-surgery symptoms. Previous literature has supported the view that pre-surgery distress and response expectancies are predictive of post-surgery outcomes. However, the contributions of distress and response expectancies to post-surgical side effect outcomes have rarely been examined together within the same study. Furthermore, studies on the effects of response expectancies in the surgical setting have typically focused on the immediate post-surgical setting rather than the longer term. The purpose of the present study was to test the contribution of pre-surgery distress and response expectancies to common post-surgery side effects (pain, nausea, fatigue). Female patients (n=101) undergoing breast cancer surgery were recruited to a prospective study. Results indicated that pre-surgery distress uniquely contributed to patients’ post-surgery pain severity (P<0.05) and fatigue (P<0.003) one week following surgery. Response expectancies uniquely contributed to pain severity (P<0.001), nausea (P<0.012) and fatigue (P<0.010) one week following surgery. Sobel tests indicated that response expectancies partially mediated the effects of distress on pain severity (P<0.03) and fatigue (P<0.03). Response expectancies also mediated the effects of age on pain severity, nausea and fatigue. Results highlight the contribution of pre-surgery psychological factors to post-surgery side effects, the importance of including both emotional and cognitive factors within studies as predictors of post-surgery side effects, and suggest pre-surgical clinical targets for improving patients’ postoperative experiences of side effects. PMID:20538186

Saccadic eye movement metrics reflect surgical residents' fatigue.

PubMed

Di Stasi, Leandro L; McCamy, Michael B; Macknik, Stephen L; Mankin, James A; Hooft, Nicole; Catena, Andrés; Martinez-Conde, Susana

2014-04-01

Little is known about the effects of surgical residents' fatigue on patient safety. We monitored surgical residents' fatigue levels during their call day using (1) eye movement metrics, (2) objective measures of laparoscopic surgical performance, and (3) subjective reports based on standardized questionnaires. Prior attempts to investigate the effects of fatigue on surgical performance have suffered from methodological limitations, including inconsistent definitions and lack of objective measures of fatigue, and nonstandardized measures of surgical performance. Recent research has shown that fatigue can affect the characteristics of saccadic (fast ballistic) eye movements in nonsurgical scenarios. Here we asked whether fatigue induced by time-on-duty (~24 hours) might affect saccadic metrics in surgical residents. Because saccadic velocity is not under voluntary control, a fatigue index based on saccadic velocity has the potential to provide an accurate and unbiased measure of the resident's fatigue level. We measured the eye movements of members of the general surgery resident team at St. Joseph's Hospital and Medical Center (Phoenix, AZ) (6 males and 6 females), using a head-mounted video eye tracker (similar configuration to a surgical headlight), during the performance of 3 tasks: 2 simulated laparoscopic surgery tasks (peg transfer and precision cutting) and a guided saccade task, before and after their call day. Residents rated their perceived fatigue level every 3 hours throughout their 24-hour shift, using a standardized scale. Time-on-duty decreased saccadic velocity and increased subjective fatigue but did not affect laparoscopic performance. These results support the hypothesis that saccadic indices reflect graded changes in fatigue. They also indicate that fatigue due to prolonged time-on-duty does not result necessarily in medical error, highlighting the complicated relationship among continuity of care, patient safety, and fatigued providers. Our data

Effects of EVA gloves on grip strength and fatigue under low temperature and low pressure.

PubMed

Tian, Yinsheng; Ding, Li; Liu, Heqing; Li, Yan; Li, Deyu; Wang, Li

2016-03-01

To study the effects of wearing extravehicular activity (EVA) gloves on grip strength and fatigue in low temperature, low pressure and mixing of two factors (low temperature and low pressure). The maximum grip strength and fatigue tests were performed with 10 healthy male subjects wearing gloves in a variety of simulated environments. The data was analysed using the normalization method. The results showed that wearing gloves significantly affected the maximum grip strength and fatigue. Pressure (29.6, 39.2 kPa) had more influence on the maximum grip compared with control group while low temperatures (-50, -90, -110 °C) had no influence on grip but affected fatigue dramatically. The results also showed that the maximum grip strength and fatigue were influenced significantly in a compound environment. Space environment remarkably reduced strength and endurance of the astronauts. However, the effects brought by the compound environment cannot be understood as the superimposition of low temperature and pressure effects. Copyright © 2015 Elsevier Ltd and The Ergonomics Society. All rights reserved.

Workplace aggression as cause and effect: Emergency nurses' experiences of working fatigued.

PubMed

Wolf, Lisa A; Perhats, Cydne; Delao, Altair M; Clark, Paul R

2017-07-01

Emergency nursing requires acute attention to detail to provide safe and effective care to potentially unstable or critically ill patients; this requirement may be significantly impaired by physical and mental fatigue. There is a lack of evidence regarding the effects of fatigue caused by factors other than a sleep deficit (e.g., emotional exhaustion). Fatigue affects nurses' ability to work safely in the emergency care setting and potentially impacts their health and quality of life outside of work. This was the qualitative arm of a mixed methods study; we used a qualitative exploratory design with focus group data from a sample of 16 emergency nurses. Themes were identified using an inductive approach to content analysis. The following themes were identified: "It's a weight on your back;" "Competitive nursing;" "It's never enough;" "You have to get away;" and "Engagement as a solution." Our participants reported high levels of fatigue, which compromised patient care, had a negative effect on their personal lives, and created a toxic unit environment. They reported lateral violence as both the cause and effect of mental and emotional fatigue, suggesting that unit culture affects nurses and the patients they care for. Copyright © 2016 Elsevier Ltd. All rights reserved.

Fatigue Fractures

PubMed Central

Morris, James M.

1968-01-01

Fatigue (or stress) fracture of bone in military recruits has been recognized for many years. Most often it is a metatarsal bone that is involved but the tarsal bones, calcaneus, tibia, fibula, femur, and pelvis are occasionally affected. Reports of such fractures in the ribs, ulna and vertebral bodies may be found in the literature. In recent years, there has been increasing awareness of the occurrence of fatigue fractures in the civilian population. Weekend sportsmen, athletes in an early phase of training, and persons engaged in unaccustomed, repetitive, vigorous activity are potential victims of such a fracture. The signs and symptoms, roentgenographic findings, treatment and etiology of fatigue fractures are dealt with in this presentation. ImagesFigure 1.Figure 2.Figure 3.Figure 4.Figure 5.Figure 6. PMID:5652745

A phenomenological study of fatigue in patients with primary biliary cirrhosis.

PubMed

Jorgensen, Roberta

2006-09-01

This paper reports the findings of research on the lived experience of fatigue in patients with primary biliary cirrhosis - a type of chronic liver disease. Fatigue is a universal phenomenon, commonly associated with both acute and chronic illness, but also seen in healthy individuals. However, it is not often addressed in healthcare encounters despite its disabling nature, perhaps because of the multitude of contributing factors and the lack of effective treatments. It is a common and debilitating symptom in patients with primary biliary cirrhosis. Despite the prevalence of fatigue in this condition, patients' experiences of this symptom have not been researched. An interpretive-phenomenological approach developed by van Manen was chosen and this combines features of descriptive and interpretive phenomenology. Eight participants were interviewed during 2005 about their fatigue experience. Thematic analysis was conducted. Five themes were identified: an unreliable body, fatigue as always present yet insidious, planning a life to conserve energy, struggling to maintain normality and emotional consequences. These themes reflected the unrelenting, intrusive nature of fatigue into the lives of those affected. This research will provide empathic insight into the fatigue experience in this condition and generate communication about coping strategies. It will add to the body of research on fatigue in chronic conditions and may generate ideas for intervention research.

Fatigue: a distressing symptom for patients with irritable bowel syndrome.

PubMed

Frändemark, Å; Jakobsson Ung, E; Törnblom, H; Simrén, M; Jakobsson, S

2017-01-01

Fatigue is a frequent symptom in patients with irritable bowel syndrome (IBS), and is associated with poor quality of life. However, few studies have evaluated its impact on daily life or the perceived distress it can cause. Using a multi-methods approach, this study describes the impact and manifestations of fatigue in patients with IBS and investigates the relationship between fatigue severity and illness-related and health-promoting factors. A total of 160 patients with IBS completed self-reported questionnaires assessing fatigue, gastrointestinal symptoms, psychological distress, and sense of coherence. Fatigue was assessed with the Fatigue Impact Scale, which also includes structured and open-ended questions which were analyzed with a deductive qualitative analysis. Patients were classified as having severe, moderate, or mild fatigue based on frequency, distress and impact on daily life. The open-ended questions revealed a multidimensional impact on life. Fatigue mainly interfered with the ability to perform physical activities, work, and domestic work, and the ability to interact socially. Decreased stamina was evident, along with strategies to limit the bodily consequences of tiredness. Severe fatigue was accompanied by more severe IBS symptoms, anxiety and depression and lower sense of coherence. Fatigue is a distressing symptom which occurs in a sizeable proportion of patients with IBS. It affects life in a multidimensional way, with poor bodily stamina being the most prominent feature. Fatigue, along with sense of coherence, depression and anxiety, needs to be assessed, confirmed and targeted for interventions. © 2016 John Wiley & Sons Ltd.

What Is Orofacial Fatigue and How Does It Affect Function for Swallowing and Speech?

PubMed Central

Solomon, Nancy Pearl

2012-01-01

Speech-language pathologists are likely to encounter patients who report symptoms of fatigue, but there are few clinical procedures to assess this phenomenon. Furthermore, it is difficult to determine whether fatigue contributes to a patient's dysphagia or dysarthria. This article reviews orofacial muscles, including the muscles of the tongue, lips, and cheeks, highlighting in particular their role in swallowing and speaking. It provides definitions of fatigue and describes assessment procedures. The author's research has focused on assessing fatigue, especially of the tongue, and elucidating the effects of exercising the tongue on speech and nonspeech tasks. Most of this work involves people who have Parkinson's disease and neurologically normal adults; results generally support heightened fatigue in Parkinson's disease. However, the effect of fatigue on functional activities remains unclear. Literature regarding the effects of orofacial fatigue on swallowing and speaking is notably sparse, but preliminary evidence indicates that these functions are rather robust. PMID:17117353

Assessing fatigue in inflammatory bowel disease: comparison of three fatigue scales.

PubMed

Norton, C; Czuber-Dochan, W; Bassett, P; Berliner, S; Bredin, F; Darvell, M; Forbes, A; Gay, M; Ream, E; Terry, H

2015-07-01

Fatigue is commonly reported by patients with inflammatory bowel disease (IBD), both in quiescent and active disease. Few fatigue scales have been tested in IBD. To assess three fatigue assessment scales in IBD and to determine correlates of fatigue. Potential participants (n = 2131) were randomly selected from an IBD organisation's members' database; 605 volunteered and were posted three fatigue scales: Inflammatory Bowel Disease Fatigue scale, Multidimensional Fatigue Inventory and Multidimensional Assessment Fatigue scale and questionnaires assessing anxiety, depression, quality of life (QoL) and IBD activity. The questionnaires were tested for stability over time with another group (n = 70) of invited participants. Internal consistency was measured by Cronbach's alpha and test-retest reliability by the intraclass correlation coefficient (ICC). Four hundred and sixty-five of 605 (77%) questionnaires were returned; of 70 invited, 48/70 returned test (68.6%) and 41/70 (58.6%) returned retest. The three scales are highly correlated (P < 0.001). Test-retest suggests reasonable agreement with ICC values between 0.65 and 0.84. Lower age, female gender, IBD diagnosis, anxiety, depression and QoL were associated with fatigue (P < 0.001) on univariable analysis. However, on multivariable analysis only depression and low QoL were consistently associated with fatigue, while female gender was associated on most scales. IBD diagnosis, age and other factors were not consistently associated with severity or impact of fatigue once other variables were controlled for. All three fatigue scales are likely to measure IBD fatigue adequately. Responsiveness to change has not been tested. Depression, poorer QoL and probably female gender are the major associations of fatigue in IBD. © 2015 John Wiley & Sons Ltd.

Oral Colostrum Macrophage-activating Factor for Serious Infection and Chronic Fatigue Syndrome: Three Case Reports.

PubMed

Inui, Toshio; Kubo, Kentaro; Kuchiike, Daisuke; Uto, Yoshihiro; Nishikata, Takahito; Sakamoto, Norihiro; Mette, Martin

2015-08-01

Gc protein-derived macrophage-activating factor (GcMAF) immunotherapy has been steadily advancing over the last two decades. Oral colostrum macrophage-activating factor (MAF) produced from bovine colostrum has shown high macrophage phagocytic activity. GcMAF-based immunotherapy has a wide application for use in treating many diseases via macrophage activation or for use as supportive therapy. Three case studies demonstrate that oral colostrum MAF can be used for serious infection and chronic fatigue syndrome (CFS) without adverse effects. We demonstrate that colostrum MAF shows promising clinical results in patients with infectious diseases and for symptoms of fatigue, which is common in many chronic diseases. Copyright© 2015 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

Chronic Fatigue Syndrome (CFS) and Cancer Related Fatigue (CRF): two "fatigue" syndromes with overlapping symptoms and possibly related aetiologies.

PubMed

Rovigatti, Ugo

2012-12-01

In July 2010, at the Muscle Fatigue Meeting, I presented an overview of Chronic Fatigue Syndrome and Cancer Related Fatigue, emphasizing a critical interpretation of the potential association between Chronic Fatigue Syndrome and Cancer Related Fatigue and a newly discovered retrovirus: Xenotropic Murine Related Virus. Since this association was hotly debated at that time, I suggested at the Meeting that it was wrong and most likely due to the identification of the wrong virus culprit. Today, 20 months after the Meeting, the first part of our prediction has turned out to be correct, as Xenotropic Murine Related Virus was shown to be a laboratory-created artefact. Still, the potential association of fatigue-syndromes with an infection (most likely viral) is sustained by a plethora of evidence and this overview will initially summarize data suggesting prior viral infection(s). The principal hypothesized mechanisms for both peripheral and central Chronic Fatigue Syndrome/Cancer Related Fatigue will be then summarized, also indicating plausible associations and triggering factors. All evidence accrued so far suggests that further research work should be performed in this interesting area and in order to identify an infectious agent for Chronic Fatigue Syndrome/Cancer Related Fatigue. One candidate RNA virus, Micro-Foci inducing Virus, will be described in this overview. Copyright © 2012 Elsevier B.V. All rights reserved.

Prevalence and predictors of fatigue in glioblastoma: a prospective study

PubMed Central

Valko, Philipp O.; Siddique, Asim; Linsenmeier, Claudia; Zaugg, Kathrin; Held, Ulrike; Hofer, Silvia

2015-01-01

Background The main goal of this study was to assess frequency, clinical correlates, and independent predictors of fatigue in a homogeneous cohort of well-defined glioblastoma patients at baseline prior to combined radio-chemotherapy. Methods We prospectively included 65 glioblastoma patients at postsurgical baseline and assessed fatigue, sleepiness, mean bedtimes, mood disturbances, and clinical characteristics such as clinical performance status, presenting symptomatology, details on neurosurgical procedure, and tumor location and diameter as well as pharmacological treatment including antiepileptic drugs, antidepressants, and use of corticosteroids. Data on fatigue and sleepiness were measured with the Fatigue Severity Scale and the Epworth Sleepiness Scale, respectively, and compared with 130 age- and sex-matched healthy controls. Results We observed a significant correlation between fatigue and sleepiness scores in both patients (r = 0.26; P = .04) and controls (r = 0.36; P < .001). Only fatigue appeared to be more common in glioblastoma patients than in healthy controls (48% vs 11%; P < .001) but not the frequency of sleepiness (22% vs 19%; P = .43). Female sex was associated with increased fatigue frequency among glioblastoma patients but not among control participants. Multiple linear regression analyses identified depression, left-sided tumor location, and female sex as strongest associates of baseline fatigue severity. Conclusions Our findings indicate that glioblastoma patients are frequently affected by fatigue at baseline, suggesting that factors other than those related to radio- or chemotherapy have significant impact, particularly depression and tumor localization. PMID:25006033

Work-family conflict and prolonged fatigue among Japanese married male physicians.

PubMed

Ohta, Hiroshi; Wada, Koji; Kawashima, Masatoshi; Arimatsu, Mayuri; Higashi, Toshiaki; Yoshikawa, Toru; Aizawa, Yoshiharu

2011-12-01

Fatigue experienced by physicians may not only endanger their own health but may also affect the safety of patients. Such fatigue may be associated with the work environment and personal factors such as work-family conflict (WFC). This study aimed to determine the association between WFC and prolonged fatigue among Japanese married male physicians. Physicians who graduated from a Japanese medical school answered a mailed anonymous self-report questionnaire. For assessment of WFC and prolonged fatigue, the Japanese versions of the WFC scale and the Checklist of Individual Strength questionnaire (CIS) were used. Prolonged fatigue was defined as the upper quartile of total CIS scores. The WFC scale comprises six dimensions. Total scores were divided into tertiles: low, intermediate, and high levels of WFC. A multiple logistic regression analysis was performed to examine the association between WFC and prolonged fatigue. A total of 540 male physicians answered the questionnaire, and the data of 444 married male physicians were analyzed. The data were then adjusted for age and work condition factors. Prolonged fatigue was significantly associated with high strain-based work interference with family (WIF; corrected odds ratio, 5.56; 95% confidence interval, 2.55-12.1), intermediate strain-based WIF (2.53, 1.25-5.10), high time-based family interference with work (FIW; 1.92, 1.08-3.40), and there was a weak association with high strain-based FIW (1.93, 0.98-3.83). Employers should take measures to improve working conditions in hospitals, and give physicians the opportunity to learn how to cope with WFC. These measures could ultimately help prevent prolonged fatigue.

Causes and consequences of fatigue in rheumatoid arthritis.

PubMed

Katz, Patricia

2017-05-01

To review current information on the causes, treatments, and consequences of fatigue in rheumatoid arthritis. Disease activity (inflammation, pain, joint symptoms) is associated with greater fatigue. However, disease activity per se accounts for only a small portion of fatigue, and rheumatoid arthritis medications that reduce disease activity have small effects on fatigue. Instead, factors outside the direct effects of rheumatoid arthritis, such as obesity, physical inactivity, sleep disturbance, and depression, explain the majority of variation in fatigue. Some of these factors may be indirect effects of disease (e.g. pain can lead to sleep disturbance). Rheumatoid arthritis has significant effects on the quality of life of individuals with rheumatoid arthritis. The most effective approaches to reducing rheumatoid arthritis fatigue appear to be behavioral, such as increasing physical activity, or cognitive, such as cognitive behavioral interventions. Fatigue in rheumatoid arthritis appears to be largely because of factors outside the direct effects of the disease, such as behavioral and psychological factors. In spite of the tremendous impact of fatigue on patient health and quality of life, effective treatments remain elusive, but existing data show that behavioral and cognitive approaches may be most effective.

Fatigue: an overview.

PubMed

Rosenthal, Thomas C; Majeroni, Barbara A; Pretorius, Richard; Malik, Khalid

2008-11-15

Fatigue, a common presenting symptom in primary care, negatively impacts work performance, family life, and social relationships. The differential diagnosis of fatigue includes lifestyle issues, physical conditions, mental disorders, and treatment side effects. Fatigue can be classified as secondary to other medical conditions, physiologic, or chronic. The history and physical examination should focus on identifying common secondary causes (e.g., medications, anemia, pregnancy) and life-threatening problems, such as cancer. Results of laboratory studies affect management in only 5 percent of patients, and if initial results are normal, repeat testing is generally not indicated. Treatment of all types of fatigue should include a structured plan for regular physical activity that consists of stretching and aerobic exercise, such as walking. Caffeine and modafinil may be useful for episodic situations requiring alertness. Short naps are proven performance enhancers. Selective serotonin reuptake inhibitors, such as fluoxetine, paroxetine, or sertraline, may improve energy in patients with depression. Patients with chronic fatigue may respond to cognitive behavior therapy. Scheduling regular follow-up visits, rather than sporadic urgent appointments, is recommended for effective long-term management.

Mental Fatigue Impairs Intermittent Running Performance.

PubMed

Smith, Mitchell R; Marcora, Samuele M; Coutts, Aaron J

2015-08-01

The purpose of the study was to investigate the effects of mental fatigue on intermittent running performance. Ten male intermittent team sports players performed two identical self-paced, intermittent running protocols. The two trials were separated by 7 d and preceded, in a randomized-counterbalanced order, by 90 min of either emotionally neutral documentaries (control) or the AX-continuous performance test (AX-CPT; mental fatigue). Subjective ratings of fatigue and vigor were measured before and after these treatments, and motivation was recorded before the intermittent running protocol. Velocity, heart rate, oxygen consumption, blood glucose and lactate concentrations, and ratings of perceived exertion (RPE) were measured throughout the 45-min intermittent running protocol. Session RPE was recorded 30 min after the intermittent running protocol. Subjective ratings of fatigue were higher after the AX-CPT (P = 0.005). This mental fatigue significantly reduced velocity at low intensities (1.28 ± 0.18 m·s vs 1.31 ± 0.17 m·s; P = 0.037), whereas high-intensity running and peak velocities were not significantly affected. Running velocity at all intensities significantly declined over time in both conditions (P < 0.001). Oxygen consumption was significantly lower in the mental fatigue condition (P = 0.007). Other physiological variables, vigor and motivation, were not significantly affected. Ratings of perceived exertion during the intermittent running protocol were not significantly different between conditions despite lower overall velocity in the mental fatigue condition. Session RPE was significantly higher in the mental fatigue condition (P = 0.013). Mental fatigue impairs intermittent running performance. This negative effect of mental fatigue seems to be mediated by higher perception of effort.

Evaluation of prolonged fatigue post-West Nile virus infection and association of fatigue with elevated antiviral and proinflammatory cytokines.

PubMed

Garcia, Melissa N; Hause, Anne M; Walker, Christopher M; Orange, Jordan S; Hasbun, Rodrigo; Murray, Kristy O

2014-09-01

This study aimed to characterize fatigue postinfection among study participants with a history of West Nile virus (WNV) infection and determine whether antiviral and pro-inflammatory cytokines were significantly elevated in those reporting prolonged fatigue. We found that 31% (44/140) of study participants experienced prolonged (more than 6 months) fatigue postinfection, with an average length of fatigue duration of 5 years. Females, those younger than 50 years of age, and those with symptomatic clinical WNV disease were significantly more likely to report fatigue. Pro-inflammatory and antiviral cytokines (granulocyte macrophage colony stimulating factor, interferon-γ, interferon-γ inducing protein 10, interleukin 2, interleukin 6, and interleukin 12p70) were significantly elevated in those reporting fatigue postinfection compared to those not reporting fatigue. Clinicians should consider history of WNV infection as a possible factor when evaluating causes of prolonged fatigue following a febrile viral illness in their patients.

An Investigation of the Combined Effect of Stress, Fatigue and Workload on Human Performance: Position Paper

NASA Technical Reports Server (NTRS)

Mock, Jessica

2005-01-01

Stress, fatigue, and workload affect worker performance. NSF reported that 61% of respondents state losing concentration at work while 79% occasionally or frequently made errors as a result of being fatigued. Shift work, altered work schedules, long hours of continuous wakefulness, and sleep loss can create sleep and circadian disruptions that degrade waking fundions causing stress and fatigue. Review of the literature has proven void of information that links the combined effects of fatigue, stress, and workload to human performance. This paper will address which occupational factors within stress, fatigue, and workload were identified as occupational contributors to performance changes. The results of this research will be apglied to underlying models and algorithms that will help predict performance changes in control room operators.

Fatigue in the general population of Colombia - normative values for the multidimensional fatigue inventory MFI-20.

PubMed

Hinz, Andreas; Barboza, Carolyn Finck; Barradas, Susana; Körner, Annett; Beierlein, Volker; Singer, Susanne

2013-01-01

Fatigue is a frequent symptom in cancer patients. In Europe and Northern America fatigue questionnaires were developed and tested, but their generalizability to other cultural contexts is largely unknown. The aim of this study is to provide normative values for the Multidimensional Fatigue Inventory (MFI-20) based on a representative sample of the general population in Colombia and to test psychometric properties. 1,500 individuals completed a questionnaire that contained the MFI-20, as well as other questionnaires, and questions on sociodemographic variables and chronic diseases. The mean values of the scales were marginally higher than those for 2 European samples. The mean value of the total score was 44.3 ± 14.1. Women were affected by fatigue more than men, and there was an almost linear age trend, with higher mean scores for older subjects. People with chronic diseases were affected by fatigue more than people without chronic conditions. The best psychometric properties were obtained for the total scale (sum score) of the MFI-20. The normative values presented here can help us to assess the individual burden of fatigue in a Latin American context. Psychometric properties of the MFI-20 in Colombia are similar to those obtained in Europe. © 2013 S. Karger GmbH, Freiburg.

A Subject-Independent Method for Automatically Grading Electromyographic Features During a Fatiguing Contraction

PubMed Central

Jesunathadas, Mark; Poston, Brach; Santello, Marco; Ye, Jieping; Panchanathan, Sethuraman

2014-01-01

Many studies have attempted to monitor fatigue from electromyogram (EMG) signals. However, fatigue affects EMG in a subject-specific manner. We present here a subject-independent framework for monitoring the changes in EMG features that accompany muscle fatigue based on principal component analysis and factor analysis. The proposed framework is based on several time- and frequency-domain features, unlike most of the existing work, which is based on two to three features. Results show that latent factors obtained from factor analysis on these features provide a robust and unified framework. This framework learns a model from EMG signals of multiple subjects, that form a reference group, and monitors the changes in EMG features during a sustained submaximal contraction on a test subject on a scale from zero to one. The framework was tested on EMG signals collected from 12 muscles of eight healthy subjects. The distribution of factor scores of the test subject, when mapped onto the framework was similar for both the subject-specific and subject-independent cases. PMID:22498666

Fatigue in aviation activities.

DOT National Transportation Integrated Search

1965-03-01

The report gives a comprehensive survey of work in the field of aviation fatigue. Both current work still in process and earlier work are surveyed. The nature of fatigue itself is discussed, along with all possible factors that contribute to both phy...

Peripheral and Central Mechanisms of Fatigue in Inflammatory and Non-Inflammatory Rheumatic Diseases

PubMed Central

Staud, Roland

2013-01-01

Fatigue is a common symptom in a large number of medical and psychological disorders including many rheumatologic illnesses. A frequent question for health care providers is related to whether reported fatigue is “in the mind” or “in the body” i.e. central or peripheral. If fatigue occurs at rest without any exertion this suggests psychological or central origins. If patients relate their fatigue mostly to physical activities including exercise then their symptoms can be considered peripheral. However, most fatiguing syndromes seem to depend on both peripheral and central mechanisms. Sometimes muscle biopsy with histochemistry may be necessary for the appropriate tissue diagnosis whereas serological tests generally provide little reliable information about the origin of muscle fatigue. Muscle function and peripheral fatigue can be quantified by contractile force and action potential measurements whereas validated questionnaires are frequently used for assessment of mental fatigue. Fatigue is a hallmark of many rheumatologic conditions including fibromyalgia, myalgic encephalitis/chronic fatigue syndrome, rheumatoid arthritis, systemic lupus, Sjogren’s syndrome and ankylosing spondylitis. Whereas many studies have focused on disease activity as a correlate to these patients’ fatigue it has become apparent that other factors including negative affect and pain are some of the most powerful predictors for fatigue. Conversely sleep problems, including insomnia seem to be less important for fatigue. There are several effective treatment strategies available for fatigued patients with rheumatologic disorders including pharmacological and non-pharmacological therapies PMID:22802155

Consolidation of fatigue and fatigue-crack-propagation data for design use

NASA Technical Reports Server (NTRS)

Rice, R. C.; Davies, K. B.; Jaske, C. E.; Feddersen, C. E.

1975-01-01

Analytical methods developed for consolidation of fatigue and fatigue-crack-propagation data for use in design of metallic aerospace structural components are evaluated. A comprehensive file of data on 2024 and 7075 aluminums, Ti-6Al-4V alloy, and 300M steel was established by obtaining information from both published literature and reports furnished by aerospace companies. Analyses are restricted to information obtained from constant-amplitude load or strain cycling of specimens in air at room temperature. Both fatigue and fatigue-crack-propagation data are analyzed on a statistical basis using a least-squares regression approach. For fatigue, an equivalent strain parameter is used to account for mean stress or stress ratio effects and is treated as the independent variable; cyclic fatigue life is considered to be the dependent variable. An effective stress-intensity factor is used to account for the effect of load ratio on fatigue-crack-propagation and treated as the independent variable. In this latter case, crack-growth rate is considered to be the dependent variable. A two term power function is used to relate equivalent strain to fatigue life, and an arc-hyperbolic-tangent function is used to relate effective stress intensity to crack-growth rate.

Psychosocial correlates of fatigue in multiple sclerosis.

PubMed

Schwartz, C E; Coulthard-Morris, L; Zeng, Q

1996-02-01

To explore: (1) the interrelation among the neuropsychological, psychological, and psychosocial factors and fatigue as measured by the Multidimensional Assessment of Fatigue scale, and (2) the impact of fatigue on role performance. Clinical interview with neuropsychological testing and cross-sectional study by mail. Multiple sclerosis (MS) clinic registry of a large Boston teaching hospital. 139 MS patients representing a broad range of disability. The Multidimensional Assessment of Fatigue (MAF) scale, the Extended Disability Status Scale, the Sickness Impact Profile, Rao cognitive battery, the Trailmaking Test, depression, anxiety, and social activity limitations subscales from the Arthritis Impact Measurement Scales, and the Ryff Happiness Scale. Stepwise multiple regression analyses revealed that having a low sense of environmental mastery was the best psychosocial predictor of both global fatigue and fatigue-related distress, after adjusting for sociodemographic and medical factors. Further, people who reported being more depressed tended to report more severe fatigue. Neuropsychological performance was not associated with fatigue. Fatigue was found to limit social, work, and overall role performance, but not physical role performance. People who feel that they can choose or create environments suitable to their psychic or physical conditions report less global fatigue and less fatigue-related distress, and fatigue can have an important impact on role performance. The implications of these findings for designing fatigue management interventions are discussed.

Predicted effect of dynamic load on pitting fatigue life for low-contact-ratio spur gears

NASA Technical Reports Server (NTRS)

Lewicki, David G.

1986-01-01

How dynamic load affects the surface pitting fatigue life of external spur gears was predicted by using the NASA computer program TELSGE. Parametric studies were performed over a range of various gear parameters modeling low-contact-ratio involute spur gears. In general, gear life predictions based on dynamic loads differed significantly from those based on static loads, with the predictions being strongly influenced by the maximum dynamic load during contact. Gear mesh operating speed strongly affected predicted dynamic load and life. Meshes operating at a resonant speed or one-half the resonant speed had significantly shorter lives. Dynamic life factors for gear surface pitting fatigue were developed on the basis of the parametric studies. In general, meshes with higher contact ratios had higher dynamic life factors than meshes with lower contact ratios. A design chart was developed for hand calculations of dynamic life factors.

The role of central and peripheral muscle fatigue in postcancer fatigue: a randomized controlled trial.

PubMed

Prinsen, Hetty; van Dijk, Johannes P; Zwarts, Machiel J; Leer, Jan Willem H; Bleijenberg, Gijs; van Laarhoven, Hanneke W M

2015-02-01

Postcancer fatigue is a frequently occurring problem, impairing quality of life. Little is known about (neuro)physiological factors determining postcancer fatigue. It may be hypothesized that postcancer fatigue is characterized by low peripheral muscle fatigue and high central muscle fatigue. The aims of this study were to examine whether central and peripheral muscle fatigue differ between fatigued and non-fatigued cancer survivors and to examine the effect of cognitive behavioral therapy (CBT) on peripheral and central muscle fatigue of fatigued cancer survivors in a randomized controlled trial. Sixteen fatigued patients in the intervention group (CBT) and eight fatigued patients in the waiting list group were successfully assessed at baseline and six months later. Baseline measurements of 20 fatigued patients were compared with 20 non-fatigued patients. A twitch interpolation technique and surface electromyography were applied, respectively, during sustained contraction of the biceps brachii muscle. Muscle fiber conduction velocity (MFCV) and central activation failure (CAF) were not significantly different between fatigued and non-fatigued patients. Change scores of MFCV and CAF were not significantly different between patients in the CBT and waiting list groups. Patients in the CBT group reported a significantly larger decrease in fatigue scores than patients in the waiting list group. Postcancer fatigue is neither characterized by abnormally high central muscle fatigue nor by low peripheral muscle fatigue. These findings suggest a difference in the underlying physiological mechanism of postcancer fatigue vs. other fatigue syndromes. Copyright © 2015 American Academy of Hospice and Palliative Medicine. Published by Elsevier Inc. All rights reserved.

Fatigue acceptance test limit criterion for larger diameter rolled thread fasteners

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kephart, A.R.

1997-05-01

This document describes a fatigue lifetime acceptance test criterion by which studs having rolled threads, larger than 1.0 inches in diameter, can be assured to meet minimum quality attributes associated with a controlled rolling process. This criterion is derived from a stress dependent, room temperature air fatigue database for test studs having a 0.625 inch diameter threads of Alloys X-750 HTH and direct aged 625. Anticipated fatigue lives of larger threads are based on thread root elastic stress concentration factors which increase with increasing thread diameters. Over the thread size range of interest, a 30% increase in notch stress ismore » equivalent to a factor of five (5X) reduction in fatigue life. The resulting diameter dependent fatigue acceptance criterion is normalized to the aerospace rolled thread acceptance standards for a 1.0 inch diameter, 0.125 inch pitch, Unified National thread with a controlled Root radius (UNR). Testing was conducted at a stress of 50% of the minimum specified material ultimate strength, 80 Ksi, and at a stress ratio (R) of 0.10. Limited test data for fastener diameters of 1.00 to 2.25 inches are compared to the acceptance criterion. Sensitivity of fatigue life of threads to test nut geometry variables was also shown to be dependent on notch stress conditions. Bearing surface concavity of the compression nuts and thread flank contact mismatch conditions can significantly affect the fastener fatigue life. Without improved controls these conditions could potentially provide misleading acceptance data. Alternate test nut geometry features are described and implemented in the rolled thread stud specification, MIL-DTL-24789(SH), to mitigate the potential effects on fatigue acceptance data.« less

Neural Mechanism of Chronic Fatigue Syndrome

DTIC Science & Technology

2004-04-01

Goodwin GM, Lawrie SM. Effects of exercise on cognitive and motor function in chronic fatigue syndrome and depression. J Neurol Neurosurg Psychiatry 1998;65...about how the CNS is affected by CFS. This study will focus on evaluating brain activities of CFS patients during fatigue and non-fatigue muscle exercises ...capacity of brain signal to the working muscle. Post- exercise motor cortical excitability is reduced in CFS patients as compared with healthy volunteers

The factors associated with the burnout syndrome and fatigue in Cypriot nurses: a census report

PubMed Central

2012-01-01

Background Fatigue and burnout are two concepts often linked in the literature. However, regardless of their commonalities they should be approached as distinct concepts. The current and ever-growing reforms regarding the delivery of nursing care in Cyprus, stress for the development of ways to prevent burnout and effectively manage fatigue that can result from working in stressful clinical environments. Methods To explore the factors associated with the burnout syndrome in Cypriot nurses working in various clinical departments. A random sampling method taking into account geographical location, specialty and type of employment has been used. Results A total of 1,482 nurses (80.4% were females) working both in the private and public sectors completed and returned an anonymous questionnaire that included several aspects related to burnout; the MBI scale, questions related to occupational stress, and questions pertaining to self reported fatigue. Two-thirds (65.1%) of the nurses believed that their job is stressful with the majority reporting their job as stressful being female nurses (67.7%). Twelve point eight percent of the nurses met Maslach’s criteria for burnout. The prevalence of fatigue in nurses was found 91.9%. The prevalence of fatigue was higher in females (93%) than in males (87.5%) (p = 0.003). As opposed to the burnout prevalence, fatigue prevalence did not differ among the nursing departments (p = 0.166) and among nurses with a different marital status (p = 0.553). Burnout can be associated adequately knowing if nurses find their job stressful, their age, the level of emotional exhaustion and depersonalization. It has been shown that the fatigue may be thought of as a predictor of burnout, but its influence is already accounted by emotional exhaustion and depersonalization. Conclusion The clinical settings in Cyprus appear as stress generating environment for nurses. Nurses working both in the private and public sector appear to

[Research Progress on the Interaction Effects and Its Neural Mechanisms between Physical Fatigue and Mental Fatigue].

PubMed

Zhang, Lixin; Zhang, Chuncui; He, Feng; Zhao, Xin; Qi, Hongzhi; Wan, Baikun; Ming, Dong

2015-10-01

Fatigue is an exhaustion state caused by prolonged physical work and mental work, which can reduce working efficiency and even cause industrial accidents. Fatigue is a complex concept involving both physiological and psychological factors. Fatigue can cause a decline of concentration and work performance and induce chronic diseases. Prolonged fatigue may endanger life safety. In most of the scenarios, physical and mental workloads co-lead operator into fatigue state. Thus, it is very important to study the interaction influence and its neural mechanisms between physical and mental fatigues. This paper introduces recent progresses on the interaction effects and discusses some research challenges and future development directions. It is believed that mutual influence between physical fatigue and mental fatigue may occur in the central nervous system. Revealing the basal ganglia function and dopamine release may be important to explore the neural mechanisms between physical fatigue and mental fatigue. Future effort is to optimize fatigue models, to evaluate parameters and to explore the neural mechanisms so as to provide scientific basis and theoretical guidance for complex task designs and fatigue monitoring.

Fatigue behavior and encrustation characteristics of nanocrystalline metals

NASA Astrophysics Data System (ADS)

Lai, Li-Chung

The nanocrstalline (NC) metals have been reported to have high mechanical performance owing to it's small grain interior and a large volume fraction of grain boundary (GB) atoms. Small grain leads to the forbidden dislocation activities in grain interior while GB activities become dominant due to a higher volume fraction of GB atoms. Regarding the fatigue response to nanocrstalline metals, it has been reported that decreasing grain led to both significantly improvement on the fatigue-endurance limit and deleterious effect on the resistance to subcritical fatigue crack propagation. The increases endurance limit has been attributed to the greater resistance to fatigue crack initiation at near-surface regions. On the other hand, the less resistance to fatigue crack growth were resulted from less tortuous fatigue crack profiles supported by the deflection/closure theory. However, it has never been studied the influence of proceeding and pre-existing defects on the fatigue performance considering the difference response of NC structure from than coarse grain (CG) structure. In the present work, the influence of electrical discharge machining (EDM) and surface defects on the fatigue behavior of both conventional cold-rolled CG and electro-deposited (ED) NC Ni were investigated. The experimental results revealed considerable influence by EDM on the fatigue strength of NC Ni, while it has little or no affect on that for CG Ni. Specifically, EDM led to a 50 to 75% reduction in fatigue strength for NC Ni despite a relatively small depth of EDM affected material (˜ 1% of width). Rationale for this effect can be attributed to grain growth, microcracks, and a higher sulfur content at the GBs in the EDM affected zone. In addition, the pre-existing surface defects that appear to be due to impurity segregation near the electro-deposition substrate significantly reduced the fatigue resistance of ED NC Ni. In order to understand the fatigued behavior in NC Ni, crack tip grain

Analyses of Fatigue and Fatigue-Crack Growth under Constant- and Variable-Amplitude Loading

NASA Technical Reports Server (NTRS)

Newman, J. C., Jr.

1999-01-01

Studies on the growth of small cracks have led to the observation that fatigue life of many engineering materials is primarily crack growth from micro-structural features, such as inclusion particles, voids, slip-bands or from manufacturing defects. This paper reviews the capabilities of a plasticity-induced crack-closure model to predict fatigue lives of metallic materials using small-crack theory under various loading conditions. Constraint factors, to account for three-dimensional effects, were selected to correlate large-crack growth rate data as a function of the effective stress-intensity factor range (delta K(sub eff)) under constant-amplitude loading. Modifications to the delta K(sub eff)-rate relations in the near-threshold regime were needed to fit measured small-crack growth rate behavior. The model was then used to calculate small- and large-crack growth rates, and to predict total fatigue lives, for notched and un-notched specimens under constant-amplitude and spectrum loading. Fatigue lives were predicted using crack-growth relations and micro-structural features like those that initiated cracks in the fatigue specimens for most of the materials analyzed. Results from the tests and analyses agreed well.

Muscle Deoxygenation Causes Muscle Fatigue

NASA Technical Reports Server (NTRS)

Murthy, G.; Hargens, A. R.; Lehman, S.; Rempel, D.

1999-01-01

Muscle fatigue is a common musculoskeletal disorder in the work place, and may be a harbinger for more disabling cumulative trauma disorders. Although the cause of fatigue is multifactorial, reduced blood flow and muscle oxygenation may be the primary factor in causing muscle fatigue during low intensity muscle exertion. Muscle fatigue is defined as a reduction in muscle force production, and also occurs among astronauts who are subjected to postural constraints while performing lengthy, repetitive tasks. The objectives of this research are to: 1) develop an objective tool to study the role of decreased muscle oxygenation on muscle force production, and 2) to evaluate muscle fatigue during prolonged glovebox work.

Evaluating Fatigue in Operational Settings: The NASA Ames Fatigue Countermeasures Program

NASA Technical Reports Server (NTRS)

Rosekind, Mark R.; Gregory, Kevin; Miller, Donna; Webbon, Lissa; Oyung, Ray

1996-01-01

In response to a 1980 Congressional request, NASA Ames initiated a program to examine fatigue in flight operations. The Program objectives are to examine fatigue, sleep loss, and circadian disruption in flight operations, determine the effects of these factors on flight crew performance, and the development of fatigue countermeasures. The NASA Ames Fatigue Countermeasures Program conducts controlled laboratory experiments, full-mission flight simulations, and field studies. A range of subjective, behavioral, performance, physiological, and environmental measures are used depending on study objectives. The Program has developed substantial expertise in gathering data during actual flight operations and in other work settings. This has required the development of ambulatory and other measures that can be carried throughout the world and used at 41,000 feet in aircraft cockpits. The NASA Ames Fatigue Countermeasures Program has examined fatigue in shorthaul, longhaul, overnight cargo, and helicopter operations. A recent study of planned cockpit rest periods demonstrated the effectiveness of a brief inflight nap to improve pilot performance and alertness. This study involved inflight reaction time/vigilance performance testing and EEG/EOG measures of physiological alertness. The NASA Ames Fatigue Countermeasures Program has applied scientific findings to the development of education and training materials on fatigue countermeasures, input to federal regulatory activities on pilot flight, duty, and rest requirements, and support of National Transportation Safety Board accident investigations. Current activities are examining fatigue in nonaugmented longhaul flights, regional/commuter flight operations, corporate/business aviation, and psychophysiological variables related to performance.

Is the notion of central fatigue based on a solid foundation?

PubMed

Contessa, Paola; Puleo, Alessio; De Luca, Carlo J

2016-02-01

Exercise-induced muscle fatigue has been shown to be the consequence of peripheral factors that impair muscle fiber contractile mechanisms. Central factors arising within the central nervous system have also been hypothesized to induce muscle fatigue, but no direct empirical evidence that is causally associated to reduction of muscle force-generating capability has yet been reported. We developed a simulation model to investigate whether peripheral factors of muscle fatigue are sufficient to explain the muscle force behavior observed during empirical studies of fatiguing voluntary contractions, which is commonly attributed to central factors. Peripheral factors of muscle fatigue were included in the model as a time-dependent decrease in the amplitude of the motor unit force twitches. Our simulation study indicated that the force behavior commonly attributed to central fatigue could be explained solely by peripheral factors during simulated fatiguing submaximal voluntary contractions. It also revealed important flaws regarding the use of the interpolated twitch response from electrical stimulation of the muscle as a means for assessing central fatigue. Our analysis does not directly refute the concept of central fatigue. However, it raises important concerns about the manner in which it is measured and about the interpretation of the commonly accepted causes of central fatigue and questions the very need for the existence of central fatigue. Copyright © 2016 the American Physiological Society.

Is physical behavior affected in fatigued persons with multiple sclerosis?

PubMed

Blikman, Lyan J; van Meeteren, Jetty; Horemans, Herwin L; Kortenhorst, Ilse C; Beckerman, Heleen; Stam, Henk J; Bussmann, Johannes B

2015-01-01

To study physical behavior in detail in fatigued persons with multiple sclerosis (MS). Case-control explorative study. Outpatient rehabilitation department and participants' daily environment. Fatigued persons with MS (n=23) were selected from a randomized controlled trial. Cases were matched by age and sex to healthy, nonfatigued controls (n=23). Eligible persons with MS were severely fatigued (Checklist Individual Strength fatigue domain mean score, 43.2±6.6) and ambulatory (Expanded Disability Status Scale mean score, 2.5±1.5). Not applicable. Measurements were performed using an accelerometer over 7 days. Outcomes included the following: amount of physical activity expressed in counts per day, counts per minute (CPM), and counts per day period (morning, afternoon, evening); duration of activity intensity categories (sedentary, light physical activity, moderate-to-vigorous physical activity [MVPA]); and distribution of MVPA and sedentary periods over the day. Persons with MS had fewer counts per day (mean difference, -156×10(3); 95% confidence interval [CI], -273×10(3) to -39×10(3); P=.010), had fewer CPM (mean difference, -135; 95% CI, -256 to -14; P=.030), and were less physically active in the morning (mean difference, -200; 95% CI, -389 to -11; P=.039) and evening (mean difference, -175; 95% CI, -336 to -14; P=.034) than controls. Persons with MS spent a higher percentage of their time sedentary (mean difference, 5.6; 95% CI, .1-11.1; P=.045) and spent less time at the higher MVPA intensity (mean difference, -2.4; 95% CI, -4.7 to -0.09; P=.042). They had fewer MVPA periods (mean difference, 29; 95% CI, -56.2 to -2.6; P=.032) and a different distribution of sedentary (mean difference, .033; 95% CI, .002 to .064; P=.039) and MVPA periods (mean difference, -.08; 95% CI, -.15 to -.01; P=.023). Detailed analyses of physical behavior showed that ambulatory fatigued persons with MS do differ from healthy controls not only in physical activity level, but also

Preparing Safety Cases for Operating Outside Prescriptive Fatigue Risk Management Regulations.

PubMed

Gander, Philippa; Mangie, Jim; Wu, Lora; van den Berg, Margo; Signal, Leigh; Phillips, Adrienne

2017-07-01

Transport operators seeking to operate outside prescriptive fatigue management regulations are typically required to present a safety case justifying how they will manage the associated risk. This paper details a method for constructing a successful safety case. The method includes four elements: 1) scope (prescriptive rules and operations affected); 2) risk assessment; 3) risk mitigation strategies; and 4) monitoring ongoing risk. A successful safety case illustrates this method. It enables landing pilots in 3-pilot crews to choose the second or third in-flight rest break, rather than the regulatory requirement to take the third break. Scope was defined using a month of scheduled flights that would be covered (N = 4151). These were analyzed in the risk assessment using existing literature on factors affecting fatigue to estimate the maximum time awake at top of descent and sleep opportunities in each break. Additionally, limited data collected before the new regulations showed that pilots flying at landing chose the third break on only 6% of flights. A prospective survey comparing subjective reports (N = 280) of sleep in the second vs. third break and fatigue and sleepiness ratings at top of descent confirmed that the third break is not consistently superior. The safety case also summarized established systems for fatigue monitoring, risk assessment and hazard identification, and multiple fatigue mitigation strategies that are in place. Other successful safety cases have used this method. The evidence required depends on the expected level of risk and should evolve as experience with fatigue risk management systems builds.Gander P, Mangie J, Wu L, van den Berg M, Signal L, Phillips A. Preparing safety cases for operating outside prescriptive fatigue risk management regulations. Aerosp Med Hum Perform. 2017; 88(7):688-696.

Statistical investigation of fatigue crack initiation and growth around chamfered rivet holes in Alclad 2024 T3 as affected by corrosion

NASA Technical Reports Server (NTRS)

Fadragas, M. I.; Fine, M. E.; Moran, B.

1994-01-01

In panel specimens with rivet holes cracks initiate in the blunted knife edge of the chamfered rivet hole and propagate inward as well as along the hole. The fatigue lifetime to dominant crack information was defined as the number of cycles, N500 micrometer, to formation of a 500 micrometer long crack. Statistical data on N500 micrometer and on crack propagation after N500 micrometer were obtained for a large number of uncorroded specimens and specimens corroded in an ASTM B 117 salt spray. Considerable variation in N500 micrometer and crack propagation behavior was observed from specimen to specimen of the same nominal geometry with chamfered rivet holes increased the probability for both early formation and later formation of a propagating 500 micrometer fatigue crack. The growth of fatigue cracks after 500 micrometer size was little affected by prior salt spray.

Parkinson's disease-related fatigue: A case definition and recommendations for clinical research.

PubMed

Kluger, Benzi M; Herlofson, Karen; Chou, Kelvin L; Lou, Jau-Shin; Goetz, Christopher G; Lang, Anthony E; Weintraub, Daniel; Friedman, Joseph

2016-05-01

Fatigue is one of the most common and disabling symptoms in Parkinson's disease (PD). Since fatigue was first described as a common feature of PD 20 years ago, little progress has been made in understanding its causes or treatment. Importantly, PD patients attending the 2013 World Parkinson Congress voted fatigue as the leading symptom in need of further research. In response, the Parkinson Disease Foundation and ProjectSpark assembled an international team of experts to create recommendations for clinical research to advance this field. The working group identified several areas in which shared standards would improve research quality and foster progress including terminology, diagnostic criteria, and measurement. Terminology needs to (1) clearly distinguish fatigue from related phenomena (eg, sleepiness, apathy, depression); (2) differentiate subjective fatigue complaints from objective performance fatigability; and (3) specify domains affected by fatigue and causal factors. We propose diagnostic criteria for PD-related fatigue to guide participant selection for clinical trials and add rigor to mechanistic studies. Recommendations are made for measurement of subjective fatigue complaints, performance fatigability, and neurophysiologic changes. We also suggest areas in which future research is needed to address methodological issues and validate or optimize current practices. Many limitations in current PD-related fatigue research may be addressed by improving methodological standards, many of which are already being successfully applied in clinical fatigue research in other medical conditions (eg, cancer, multiple sclerosis). © 2016 International Parkinson and Movement Disorder Society. © 2016 International Parkinson and Movement Disorder Society.

The Family Experience of Fatigue in Heart Failure.

PubMed

Whitehead, Lisa

2017-02-01

Fatigue is a symptom experienced almost universally by people living with a chronic illness. People diagnosed with heart failure have described experiencing significant levels of fatigue. The family experience of fatigue, that is, how families perceive, respond to, and manage fatigue, is unknown. Semistructured family group interviews with 22 families ( N = 62 family members) were conducted. Thematic analysis was undertaken to explore the family experience of fatigue. Fatigue was described as a significant symptom that affected physical, emotional, and social functioning at a family level. Fatigue was described as difficult to manage, and while most family members interviewed had developed a shared understanding of fatigue, some family members found acceptance of this invisible symptom more difficult. Spouses were more likely to express concern that fatigue, and especially increased fatigue, represented a decline in health. The study highlighted the importance of a shared understanding of fatigue from a family perspective.

Data and methods for studying commercial motor vehicle driver fatigue, highway safety and long-term driver health.

PubMed

Stern, Hal S; Blower, Daniel; Cohen, Michael L; Czeisler, Charles A; Dinges, David F; Greenhouse, Joel B; Guo, Feng; Hanowski, Richard J; Hartenbaum, Natalie P; Krueger, Gerald P; Mallis, Melissa M; Pain, Richard F; Rizzo, Matthew; Sinha, Esha; Small, Dylan S; Stuart, Elizabeth A; Wegman, David H

2018-03-09

This article summarizes the recommendations on data and methodology issues for studying commercial motor vehicle driver fatigue of a National Academies of Sciences, Engineering, and Medicine study. A framework is provided that identifies the various factors affecting driver fatigue and relating driver fatigue to crash risk and long-term driver health. The relevant factors include characteristics of the driver, vehicle, carrier and environment. Limitations of existing data are considered and potential sources of additional data described. Statistical methods that can be used to improve understanding of the relevant relationships from observational data are also described. The recommendations for enhanced data collection and the use of modern statistical methods for causal inference have the potential to enhance our understanding of the relationship of fatigue to highway safety and to long-term driver health. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

The effect of aroma stimulation during isotonic exercise on the rating of perceived exertion and blood fatigue factors of athletes with patellofemoral pain syndrome

PubMed Central

Kim, Sangsoo; Choo, JongHoo; Ju, Sungbum

2018-01-01

[Purpose] The purpose of this study is to examine the effect of aroma stimulation during isotonic exercise on the rating of perceived exertion (RPE) and the blood fatigue factors of athletes who have patellofemoral pain syndrome (PFPS). [Subjects and Methods] The research subjects were seven athletes in their twenties who suffer from PFPS. They were divided into a control group and an aroma stimulation group and performed isotonic exercises repeatedly. After exercising, the RPE and blood fatigue factors, including creatine phosphokinase (CPK), lactate dehydrogenase (LDH), and ammonia, were measured through blood sampling. [Results] The aroma stimulus group showed significantly lower RPE than the control group immediately after exercising, which included leg presses, leg curls, bicep curls, and leg extensions. Among the blood fatigue factors, the change in LDH indicated the effect of aroma stimulation. [Conclusion] We confirmed that aroma stimulation during isotonic exercise has the positive effect of reducing the RPE and blood fatigue factors, such as blood LDH, of the athletes with PFPS. PMID:29545683

Influence of neutron irradiation at 430$deg;C on the fatigue properties of SA 316L steel

NASA Astrophysics Data System (ADS)

Vandermeulen, W.; Hendrix, W.; Massaut, V.; Van de Velde, J.

1988-07-01

Fatigue tests have been carried out at 430°C on hour-glass shaped specimens of the CEC reference heat of SA 316L stainless steel. The tests were performed under constant total axial strain control with a triangular fully reversed wave shape at frequencies of 0.5, 0.05 and 0.005 Hz. Specimens irradiated at 430°C to doses of 9-12 dpa and helium contents of 80 to 145 appm showed a fatigue life reduction by about a factor of two, compared to unirradiated specimens. The cyclic stress is found to be strongly increased by the irradiation. The test frequency influences the fatigue hardening slightly but it does not affect the fatigue life.

Problems of the high-cycle fatigue of the materials intended for the parts of modern gas-turbine engines and power plants

NASA Astrophysics Data System (ADS)

Petukhov, A. N.

2010-10-01

The problems related to the determination of the life of the structural materials applied for important parts in gas-turbine engines and power plants from the results of high-cycle fatigue tests are discussed. Methods for increasing the reliability of the high-cycle fatigue characteristics and the factors affecting the operational reliability are considered.

Physiological and psychological markers associated with HIV-related fatigue.

PubMed

Barroso, Julie; Carlson, John R; Meynell, Janet

2003-02-01

Fatigue is among the most common and debilitating complaints of HIV-positive individuals. These data are part of a larger exploratory study investigating the relationships of selected psychological and physiological factors among 40 participants with HIV-related fatigue. Fatigue severity was measured using the HIV-Related Fatigue Scale. Fatigue was correlated with depression (r = .40, p < .01), state anxiety (r = .40, p <.01), and trait anxiety (r = .46, p <.01). Of the physiological factors, there were three statistically significant correlations: thyroid-stimulating hormone was negatively correlated with fatigue severity (r = -.36, p = .02), and platelets (r = .35, p = .03) and alkaline phosphatase (r = .27, p = .09) were positively correlated with fatigue severity. There were no correlations between fatigue severity and CD4 count (r = -.16, p = .31) or fatigue severity and HIV viral load levels (r = .031, p = .84). Even among the group with excellent viral suppression, fatigue scores were still very high for many participants.

Fatigue in sarcoidosis and idiopathic pulmonary fibrosis: differences in character and severity between diseases.

PubMed

Atkins, Christopher Peter; Gilbert, Daniel; Brockwell, Claire; Robinson, Sue; Wilson, Andrew Malcolm

2016-08-01

Sarcoidosis and idiopathic pulmonary fibrosis (IPF) are two common forms of interstitial lung disease. Fatigue is a recognised feature of sarcoidosis but an association between IPF and fatigue has not been investigated. To investigate the frequency and severity of fatigue in these groups, and variables affecting fatigue scores. A cross-sectional questionnaire study of patients with sarcoidosis and IPF followed-up at a single hospital was undertaken. Questionnaire data included validated measures of fatigue, anxiety, depression, sleepiness and dyspnoea, plus measures of disease severity including spirometry data. Questionnaires were administered to 232 patients (82 healthy volunteers, 73 sarcoidosis patients and 77 IPF patients). Sarcoidosis patients had statistically higher sleepiness scores but no significant difference was seen between overall measures of fatigue, anxiety or depression. Stratification by severity revealed a non-statistically significant tendency towards more severe fatigue scores in sarcoidosis. Regression analysis failed to identify any significant predictor variables measured in the sarcoidosis cohort, though in the IPF group both dyspnoea and sleepiness scores were significant predictors of fatigue (R2=0.74). Both sarcoidosis and IPF patients suffer with fatigue, although sarcoidosis patients tended towards reporting more severe fatigue scores, suggesting a subgroup with severe fatigue. The fatigue experienced by the two groups appears to be different; sarcoidosis patients report greater frequency of mental fatigue whereas IPF patients appear to suffer exhaustion, potentially related to dyspnoea. Dyspnoea and sleepiness scores modeled the majority of fatigue in the IPF group, whereas no single factor was able to predict fatigue in sarcoidosis.

Monitoring and Managing Fatigue in Basketball

PubMed Central

Edwards, Toby; Spiteri, Tania; Piggott, Benjamin; Bonhotal, Joshua; Joyce, Christopher

2018-01-01

The sport of basketball exposes athletes to frequent high intensity movements including sprinting, jumping, accelerations, decelerations and changes of direction during training and competition which can lead to acute and accumulated chronic fatigue. Fatigue may affect the ability of the athlete to perform over the course of a lengthy season. The ability of practitioners to quantify the workload and subsequent fatigue in basketball athletes in order to monitor and manage fatigue levels may be beneficial in maintaining high levels of performance and preventing unfavorable physical and physiological training adaptations. There is currently limited research quantifying training or competition workload outside of time motion analysis in basketball. In addition, systematic research investigating methods to monitor and manage athlete fatigue in basketball throughout a season is scarce. To effectively optimize and maintain peak training and playing performance throughout a basketball season, potential workload and fatigue monitoring strategies need to be discussed. PMID:29910323

Translating Fatigue to Human Performance.

PubMed

Enoka, Roger M; Duchateau, Jacques

2016-11-01

Despite flourishing interest in the topic of fatigue-as indicated by the many presentations on fatigue at the 2015 Annual Meeting of the American College of Sports Medicine-surprisingly little is known about its effect on human performance. There are two main reasons for this dilemma: 1) the inability of current terminology to accommodate the scope of the conditions ascribed to fatigue, and 2) a paucity of validated experimental models. In contrast to current practice, a case is made for a unified definition of fatigue to facilitate its management in health and disease. On the basis of the classic two-domain concept of Mosso, fatigue is defined as a disabling symptom in which physical and cognitive function is limited by interactions between performance fatigability and perceived fatigability. As a symptom, fatigue can only be measured by self-report, quantified as either a trait characteristic or a state variable. One consequence of such a definition is that the word fatigue should not be preceded by an adjective (e.g., central, mental, muscle, peripheral, and supraspinal) to suggest the locus of the changes responsible for an observed level of fatigue. Rather, mechanistic studies should be performed with validated experimental models to identify the changes responsible for the reported fatigue. As indicated by three examples (walking endurance in old adults, time trials by endurance athletes, and fatigue in persons with multiple sclerosis) discussed in the review, however, it has proven challenging to develop valid experimental models of fatigue. The proposed framework provides a foundation to address the many gaps in knowledge of how laboratory measures of fatigue and fatigability affect real-world performance.

Exploring the relationship between work-related rumination, sleep quality, and work-related fatigue.

PubMed

Querstret, Dawn; Cropley, Mark

2012-07-01

This study examined the association among three conceptualizations of work-related rumination (affective rumination, problem-solving pondering, and detachment) with sleep quality and work-related fatigue. It was hypothesized that affective rumination and poor sleep quality would be associated with increased fatigue and that problem-solving pondering and detachment would be associated with decreased fatigue. The mediating effect of sleep quality on the relationship between work-related rumination and fatigue was also tested. An online questionnaire was completed by a heterogeneous sample of 719 adult workers in diverse occupations. The following variables were entered as predictors in a regression model: affective rumination, problem-solving pondering, detachment, and sleep quality. The dependent variables were chronic work-related fatigue (CF) and acute work-related fatigue (AF). Affective rumination was the strongest predictor of increased CF and AF. Problem-solving pondering was a significant predictor of decreased CF and AF. Poor sleep quality was predictive of increased CF and AF. Detachment was significantly negatively predictive for AF. Sleep quality partially mediated the relationship between affective rumination and fatigue and between problem-solving pondering and fatigue. Work-related affective rumination appears more detrimental to an individual's ability to recover from work than problem-solving pondering. In the context of identifying mechanisms by which demands at work are translated into ill-health, this appears to be a key finding and suggests that it is the type of work-related rumination, not rumination per se, that is important.

The Boeing 747 fatigue integrity program

NASA Technical Reports Server (NTRS)

Spencer, M. M.

1972-01-01

The fatigue integrity program which was established to insure economic operations and to provide foundation data for inspection and maintenance is discussed. Significant features of the 747 fatigue integrity program are: (1) fatigue analyses which are continually updated to reflect design changes, fatigue test results, and static and flight load survey measurements; (2) material selection and detail design by using initial fatigue analyses, service experience, and testing; and (3) fatigue testing to check detail design quality and to verify the analyses, culminated by the test of a structurally complete airframe. Fatigue stress analyses were performed with the aid of experimental as well as analytical procedures. Extensive application was made of the stress severity factor, developed at Boeing, for evaluating peak stresses in complex joints. A frame of reference was established by families of structural fatigue performance curves (S-N curves) encompassing the range of materials and fatigue qualities anticipated for the 747 airplane design.

Chronic fatigue syndrome: aetiology, diagnosis and treatment

PubMed Central

Avellaneda Fernández, Alfredo; Pérez Martín, Álvaro; Izquierdo Martínez, Maravillas; Arruti Bustillo, Mar; Barbado Hernández, Francisco Javier; de la Cruz Labrado, Javier; Díaz-Delgado Peñas, Rafael; Gutiérrez Rivas, Eduardo; Palacín Delgado, Cecilia; Rivera Redondo, Javier; Ramón Giménez, José Ramón

2009-01-01

Chronic fatigue syndrome is characterised by intense fatigue, with duration of over six months and associated to other related symptoms. The latter include asthenia and easily induced tiredness that is not recovered after a night's sleep. The fatigue becomes so severe that it forces a 50% reduction in daily activities. Given its unknown aetiology, different hypotheses have been considered to explain the origin of the condition (from immunological disorders to the presence of post-traumatic oxidative stress), although there are no conclusive diagnostic tests. Diagnosis is established through the exclusion of other diseases causing fatigue. This syndrome is rare in childhood and adolescence, although the fatigue symptom per se is quite common in paediatric patients. Currently, no curative treatment exists for patients with chronic fatigue syndrome. The therapeutic approach to this syndrome requires a combination of different therapeutic modalities. The specific characteristics of the symptomatology of patients with chronic fatigue require a rapid adaptation of the educational, healthcare and social systems to prevent the problems derived from current systems. Such patients require multidisciplinary management due to the multiple and different issues affecting them. This document was realized by one of the Interdisciplinary Work Groups from the Institute for Rare Diseases, and its aim is to point out the main social and care needs for people affected with Chronic Fatigue Syndrome. For this, it includes not only the view of representatives for different scientific societies, but also the patient associations view, because they know the true history of their social and sanitary needs. In an interdisciplinary approach, this work also reviews the principal scientific, medical, socio-sanitary and psychological aspects of Chronic Fatigue Syndrome. PMID:19857242

Development of a patient reported outcome scale for fatigue in multiple sclerosis: The Neurological Fatigue Index (NFI-MS)

PubMed Central

2010-01-01

Background Fatigue is a common and debilitating symptom in multiple sclerosis (MS). Best-practice guidelines suggest that health services should repeatedly assess fatigue in persons with MS. Several fatigue scales are available but concern has been expressed about their validity. The objective of this study was to examine the reliability and validity of a new scale for MS fatigue, the Neurological Fatigue Index (NFI-MS). Methods Qualitative analysis of 40 MS patient interviews had previously contributed to a coherent definition of fatigue, and a potential 52 item set representing the salient themes. A draft questionnaire was mailed out to 1223 people with MS, and the resulting data subjected to both factor and Rasch analysis. Results Data from 635 (51.9% response) respondents were split randomly into an 'evaluation' and 'validation' sample. Exploratory factor analysis identified four potential subscales: 'physical', 'cognitive', 'relief by diurnal sleep or rest' and 'abnormal nocturnal sleep and sleepiness'. Rasch analysis led to further item reduction and the generation of a Summary scale comprising items from the Physical and Cognitive subscales. The scales were shown to fit Rasch model expectations, across both the evaluation and validation samples. Conclusion A simple 10-item Summary scale, together with scales measuring the physical and cognitive components of fatigue, were validated for MS fatigue. PMID:20152031

Rapid Assessment of the Role of Microstructural Variability in the Fatigue Behavior of Structural Alloys using Ultrasonic Fatigue

DTIC Science & Technology

2007-06-23

6 %AI-2%Sn- 4 %Zr- 6 %Mo in the very high cycle regime. The microstructure is a two-phase structure with primary a grains (ap grains) in a transformed [3...aluminum [2], magnesium [3], nickel-based [ 4 ], and titanium [5,6] alloy systems. Fatigue crack initiation is known to consume the majority of fatigue...microstructural neighborhood affects this process. In fatigue studies of alpha + beta titanium alloys, [ 6 -9] cyclic deformation localization is first observed in

Features that exacerbate fatigue severity in joint hypermobility syndrome/Ehlers-Danlos syndrome - hypermobility type.

PubMed

Krahe, Anne Maree; Adams, Roger David; Nicholson, Leslie Lorenda

2018-08-01

To assess the prevalence, severity and impact of fatigue on individuals with joint hypermobility syndrome (JHS)/Ehlers-Danlos syndrome - hypermobility type (EDS-HT) and establish potential determinants of fatigue severity in this population. Questionnaires on symptoms and signs related to fatigue, quality of life, mental health, physical activity participation and sleep quality were completed by people with JHS/EDS-HT recruited through two social media sites. Multiple regression analysis was performed to identify predictors of fatigue in this population. Significant fatigue was reported by 79.5% of the 117 participants. Multiple regression analysis identified five predictors of fatigue severity, four being potentially modifiable, accounting for 52.3% of the variance in reported fatigue scores. Predictors of fatigue severity were: the self-perceived extent of joint hypermobility, orthostatic dizziness related to heat and exercise, levels of participation in personal relationships and community, current levels of physical activity and dissatisfaction with the diagnostic process and management options provided for their condition. Fatigue is a significant symptom associated with JHS/EDS-HT. Assessment of individuals with this condition should include measures of fatigue severity to enable targeted management of potentially modifiable factors associated with fatigue severity. Implications for rehabilitation Fatigue is a significant symptom reported by individuals affected by joint hypermobility syndrome/Ehlers-Danlos syndrome - hypermobility type. Potentially modifiable features that contribute to fatigue severity in this population have been identified. Targeted management of these features may decrease the severity and impact of fatigue in joint hypermobility syndrome/Ehlers-Danlos syndrome - hypermobility type.

Effects of local and widespread muscle fatigue on movement timing.

PubMed

Cowley, Jeffrey C; Dingwell, Jonathan B; Gates, Deanna H

2014-12-01

Repetitive movements can cause muscle fatigue, leading to motor reorganization, performance deficits, and/or possible injury. The effects of fatigue may depend on the type of fatigue task employed, however. The purpose of this study was to determine how local fatigue of a specific muscle group versus widespread fatigue of various muscle groups affected the control of movement timing. Twenty healthy subjects performed an upper extremity low-load work task similar to sawing for 5 continuous minutes both before and after completing a protocol that either fatigued all the muscles used in the task (widespread fatigue) or a protocol that selectively fatigued the primary muscles used to execute the pushing stroke of the sawing task (localized fatigue). Subjects were instructed to time their movements with a metronome. Timing error, movement distance, and speed were calculated for each movement. Data were then analyzed using a goal-equivalent manifold approach to quantify changes in goal-relevant and non-goal-relevant variability. We applied detrended fluctuation analysis to each time series to quantify changes in fluctuation dynamics that reflected changes in the control strategies used. After localized fatigue, subjects made shorter, slower movements and exerted greater control over non-goal-relevant variability. After widespread fatigue, subjects exerted less control over non-goal-relevant variability and did not change movement patterns. Thus, localized and widespread muscle fatigue affected movement differently. Local fatigue may reduce the available motor solutions and therefore cause greater movement reorganization than widespread muscle fatigue. Subjects altered their control strategies but continued to achieve the timing goal after both fatigue tasks.

Roughness Effects on Fretting Fatigue

NASA Astrophysics Data System (ADS)

Yue, Tongyan; Abdel Wahab, Magd

2017-05-01

Fretting is a small oscillatory relative motion between two normal loaded contact surfaces. It may cause fretting fatigue, fretting wear and/or fretting corrosion damage depending on various fretting couples and working conditions. Fretting fatigue usually occurs at partial slip condition, and results in catastrophic failure at the stress levels below the fatigue limit of the material. Many parameters may affect fretting behaviour, including the applied normal load and displacement, material properties, roughness of the contact surfaces, frequency, etc. Since fretting damage is undesirable due to contacting, the effect of rough contact surfaces on fretting damage has been studied by many researchers. Experimental method on this topic is usually focusing on rough surface effects by finishing treatment and random rough surface effects in order to increase fretting fatigue life. However, most of numerical models on roughness are based on random surface. This paper reviewed both experimental and numerical methodology on the rough surface effects on fretting fatigue.

Understanding and Counteracting Fatigue in Flight Crews

NASA Technical Reports Server (NTRS)

Mallis, Melissa; Neri, David; Rosekind, Mark; Gander, Philippa; Caldwell, John; Graeber, Curtis

2007-01-01

The materials included in the collection of documents describe the research of the NASA Ames Fatigue Countermeasures Group (FCG), which examines the extent to which fatigue, sleep loss, and circadian disruption affect flight-crew performance. The group was formed in 1980 in response to a Congressional request to examine a possible safety problem of uncertain magnitude due to transmeridian flying and a potential problem due to fatigue in association with various factors found in air-transport operations and was originally called the Fatigue/Jet Lag Program. The goals of the FCG are: (1) the development and evaluation of strategies for mitigating the effects of sleepiness and circadian disruption on pilot performance levels; (2) the identification and evaluation of objective approaches for the prediction of alertness changes in flight crews; and (3) the transfer and application of research results to the operational field via classes, workshops, and safety briefings. Some of the countermeasure approaches that have been identified to be scientifically valid and operationally relevant are brief naps (less than 40 min) in the cockpit seat and 7-min activity breaks, which include postural changes and ambulation. Although a video-based alertness monitor based on slow eyelid closure shows promise in other operational environments, research by the FCG has demonstrated that in its current form at the time of this reporting, it is not feasible to implement it in the cockpit. Efforts also focus on documenting the impact of untreated fatigue on various types of flight operations. For example, the FCG recently completed a major investigation into the effects of ultra-long-range flights (20 continuous hours in duration) on the alertness and performance of pilots in order to establish a baseline set of parameters against which the effectiveness of new ultra-long-range fatigue remedies can be judged.

Chemotherapy-Induced Fatigue Correlates With Higher Fatigue Scores Before Treatment.

PubMed

Araújo, José Klerton Luz; Giglio, Adriana Del; Munhoz, Bruna Antenusse; Fonseca, Fernando Luiz Affonso; Cruz, Felipe Melo; Giglio, Auro Del

2017-06-01

Cancer chemotherapy can induce fatigue in about 20% to 30% of patients. So far, there is very little information as to the predictors of chemotherapy-induced fatigue (CIF). We evaluated potential predictors of CIF in a sample of patients with cancer with several types of solid tumors scheduled to receive chemotherapy according to institutional protocols. Before their first and second chemotherapy cycles, patients answered to the Brief Fatigue Inventory (BFI), Chalder, Mini Nutritional Assessment (MNA), Stress thermometer, and HADS questionnaires as well as provided blood samples for inflammatory markers. We evaluated 52 patients, 37 (71%) were female and mean age was 53 years. The most common tumors were breast cancer 21 (40%) and gastrointestinal tumors 12 (23%). Although 14 (25.2%) patients had an increase in their fatigue BFI scores equal or above 3 points from baseline, we observed no significant overall differences between BFI scores before and after chemotherapy. The only 2 factors associated with an increase of 3 points in the BFI scores after chemotherapy were race and higher baseline BFI levels. By multivariate analysis, overall BFI and Chalder scores after chemotherapy also correlated significantly with their respective baseline scores before treatment. HADS scores before treatment correlated with overall BFI scores postchemotherapy, whereas MNA scores before chemotherapy and female sex correlated with higher Chalder scores after treatment. We conclude that fatigue induced by chemotherapy is common and consistently associated with higher fatigue scores before treatment. Screening for fatigue before chemotherapy may help to identify patients who are prone to develop CIF.

Elevated temperature biaxial fatigue

NASA Technical Reports Server (NTRS)

Jordan, E. H.

1983-01-01

Biaxial fatigue is often encountered in the complex thermo-mechanical loadings present in gas turbine engines. Engine strain histories can involve non-constant temperature, mean stress, creep, environmental effects, both isotropic and anisotropic materials and non-proportional loading. Life prediction for the general case involving all the above factors is not a practicable research project. The current research program is limited to isothermal fatigue at room temperature and 1200 F of Hastalloy-X for both proportional and non-proportional loading. An improved method for predicting the fatigue life and deformation response under biaxial cycle loading is sought.

Validation of the Modified Fatigue Impact Scale in Parkinson's disease.

PubMed

Schiehser, Dawn M; Ayers, Catherine R; Liu, Lin; Lessig, Stephanie; Song, David S; Filoteo, J Vincent

2013-03-01

Fatigue is a common symptom in Parkinson's disease (PD); however, a multidimensional scale that measures the impact of fatigue on functioning has yet to be validated in this population. The aim of this study was to examine the validity of the Modified Fatigue Impact Scale (MFIS), a self-report measure that assesses the effects of fatigue on physical, cognitive, and psychosocial functioning, in a sample of nondemented PD patients. PD patients (N = 100) completed the MFIS, the Positive and Negative Affect Schedule (PANAS-X), and several additional measures of psychosocial, cognitive, and motor functioning. A Principal Component Analysis (PCA) and item analysis using Cronbach's alpha were conducted to determine structural validity and internal consistency of the MFIS. Correlational analyses were performed between the MFIS and the PANAS-X fatigue subscale to evaluate convergent validity and between the MFIS and measures of depression, anxiety, apathy, and disease-related symptoms to determine divergent validity. The PCA identified two viable MFIS subscales: a cognitive subscale and a combination of the original scale's physical and psychosocial subscales as one factor. Item analysis revealed high internal consistency of all 21 items and the items within the two subscales. The MFIS had strong convergent validity with the PANAS-X fatigue subscale and adequate divergent validity with measures of disease stage, motor function, and cognition. Overall, this study demonstrates that the MFIS is a valid multidimensional measure that can be used to evaluate the impact of fatigue on cognitive and physical/social functioning in PD patients without dementia. Published by Elsevier Ltd.

The Effect of Fatigue and Fatigue Intensity on Exercise Tolerance in Moderate COPD.

PubMed

Al-Shair, Khaled; Kolsum, Umme; Singh, Dave; Vestbo, Jørgen

2016-12-01

Fatigue is one of the most disabling symptoms in COPD, but little is known about the impact of fatigue on functional disability. We explored the impact of fatigue and fatigue intensity on exercise tolerance after adjusting for other factors using multivariate analysis and compared it to that of dyspnoea. A total of 119 patients with mainly moderate-severe stable COPD (38 % women, mean age 66 years) were enrolled. We used the Medical Research Council dyspnoea scores (MRC), Manchester COPD fatigue scale (MCFS) and its three dimensions, Borg scales for fatigue and dyspnoea, six-minute walk distance (6MWD), St George's Respiratory Questionnaire, the BODE index, and the Centre for Epidemiological Study on Depression scale (CES-D), and we measured spirometry, blood gases, systemic inflammatory markers and fat-free mass index (FFMI). Fatigue measured using the MCFS was associated with 6MWD and explained 22 % of the variability in 6MWD (p < 0.001). Fatigue remained associated with 6MWD after adjusting for MRC dyspnoea, FFMI and FEV 1 , FVC, PaO 2 , PaCO 2 , CES-D, TNF-alpha, smoking status, age and gender. We found that 33, 50 and 23 % of patients reported an increase by 2 scores on Borg scales for fatigue, dyspnoea or both at the end of the 6MWT. Fatigue scores (both before and after the 6MWT) were negatively correlated with 6MWD after adjusting for FEV 1 , FFMI, CES-D score and age (p = 0.007 and 0.001, respectively). In moderate stable COPD, fatigue may be a central driver of functional disability, to the same extent as dyspnoea.

Investigating Driver Fatigue versus Alertness Using the Granger Causality Network.

PubMed

Kong, Wanzeng; Lin, Weicheng; Babiloni, Fabio; Hu, Sanqing; Borghini, Gianluca

2015-08-05

Driving fatigue has been identified as one of the main factors affecting drivers' safety. The aim of this study was to analyze drivers' different mental states, such as alertness and drowsiness, and find out a neurometric indicator able to detect drivers' fatigue level in terms of brain networks. Twelve young, healthy subjects were recruited to take part in a driver fatigue experiment under different simulated driving conditions. The Electroencephalogram (EEG) signals of the subjects were recorded during the whole experiment and analyzed by using Granger-Causality-based brain effective networks. It was that the topology of the brain networks and the brain's ability to integrate information changed when subjects shifted from the alert to the drowsy stage. In particular, there was a significant difference in terms of strength of Granger causality (GC) in the frequency domain and the properties of the brain effective network i.e., causal flow, global efficiency and characteristic path length between such conditions. Also, some changes were more significant over the frontal brain lobes for the alpha frequency band. These findings might be used to detect drivers' fatigue levels, and as reference work for future studies.

Investigating Driver Fatigue versus Alertness Using the Granger Causality Network

PubMed Central

Kong, Wanzeng; Lin, Weicheng; Babiloni, Fabio; Hu, Sanqing; Borghini, Gianluca

2015-01-01

Driving fatigue has been identified as one of the main factors affecting drivers’ safety. The aim of this study was to analyze drivers’ different mental states, such as alertness and drowsiness, and find out a neurometric indicator able to detect drivers’ fatigue level in terms of brain networks. Twelve young, healthy subjects were recruited to take part in a driver fatigue experiment under different simulated driving conditions. The Electroencephalogram (EEG) signals of the subjects were recorded during the whole experiment and analyzed by using Granger-Causality-based brain effective networks. It was that the topology of the brain networks and the brain’s ability to integrate information changed when subjects shifted from the alert to the drowsy stage. In particular, there was a significant difference in terms of strength of Granger causality (GC) in the frequency domain and the properties of the brain effective network i.e., causal flow, global efficiency and characteristic path length between such conditions. Also, some changes were more significant over the frontal brain lobes for the alpha frequency band. These findings might be used to detect drivers’ fatigue levels, and as reference work for future studies. PMID:26251909

Group cohesion and organizational commitment: protective factors for nurse residents' job satisfaction, compassion fatigue, compassion satisfaction, and burnout.

PubMed

Li, Angela; Early, Sean F; Mahrer, Nicole E; Klaristenfeld, Jessica L; Gold, Jeffrey I

2014-01-01

Stress can have detrimental effects on nurse residents' levels of job satisfaction, compassion, fatigue, and burnout. This can lead to high turnover rates and poor quality of care among novice nurses. Therefore, it is critical to identify protective factors to prevent the onset of negative nurse outcomes (compassion fatigue, burnout, and job dissatisfaction) and to promote positive nurse outcomes (job satisfaction, compassion satisfaction). This study aimed to determine whether factors such as group cohesion and organizational commitment would be protective and moderate the association between stress exposure and posttraumatic stress symptoms and other negative nurse outcomes, thus facilitating positive outcomes. Findings showed that group cohesion was effective in moderating the negative effects of current stress exposure and posttraumatic stress symptoms on negative nurse outcomes, specifically on increased compassion fatigue and burnout, and reduced compassion satisfaction. In addition, organizational commitment was determined to promote positive nurse outcomes such as job satisfaction and compassion satisfaction. The study findings are promising, as retention of quality nurses is a significant problem for hospitals. Nurse managers and hospital administrators should be aware of the benefits of group cohesion and organizational commitment and strive to make the promotion of these factors a priority. Copyright © 2014 Elsevier Inc. All rights reserved.

Orthostatic intolerance and fatigue in the hypermobility type of Ehlers-Danlos Syndrome.

PubMed

De Wandele, Inge; Rombaut, Lies; De Backer, Tine; Peersman, Wim; Da Silva, Hellen; De Mits, Sophie; De Paepe, Anne; Calders, Patrick; Malfait, Fransiska

2016-08-01

To investigate whether orthostatic intolerance (OI) is a significant predictor for fatigue in Ehlers-Danlos Syndrome, hypermobility type (EDS-HT). Eighty patients with EDS-HT and 52 controls participated in the first part of the study, which consisted of questionnaires. Fatigue was evaluated using the Checklist Individual Strength (CIS). As possible fatigue determinants OI [Autonomic Symptom Profile (ASP)], habitual physical activity (Baecke), affective distress [Hospital Anxiety and Depression Scale (HADS)], pain (SF36), medication use and generalized hypermobility (5-point score of Grahame and Hakim regarding generalized joint hypermobility) were studied. Next, a 20 min head-up tilt (70°) was performed in a subsample of 39 patients and 35 controls, while beat-to-beat heart rate and blood pressure were monitored (Holter, Finometer Pro). Before and after tilt, fatigue severity was assessed using a numeric rating scale. Patients scored significantly higher on the CIS [total score: EDS: 98.2 (18.63) vs controls: 45.8 (16.62), P < 0.001] and on the OI domain of the ASP [EDS: 22.78 (7.16) vs controls: 6.5 (7.78)]. OI was prevalent in EDS-HT (EDS: 74.4%, controls: 34.3%, P = 0.001), and frequently expressed as postural orthostatic tachycardia (41.0% of the EDS group). Patients responded to tilt with a higher heart rate and lower total peripheral resistance (p < 0.001; p = 0.032). This altered response correlated with fatigue in daily life (CIS). In the EDS-HT group, tilt provoked significantly more fatigue [numeric rating scale increase: EDS: +3.1 (1.90), controls: +0.5 (1.24), P < 0.001]. Furthermore, the factors OI, pain, affective distress, decreased physical activity and sedative use explained 47.7% of the variance in fatigue severity. OI is an important determinant of fatigue in EDS-HT. © The Author 2016. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Fatigue Behavior of Inconel 718 TIG Welds

NASA Astrophysics Data System (ADS)

Alexopoulos, Nikolaos D.; Argyriou, Nikolaos; Stergiou, Vasillis; Kourkoulis, Stavros K.

2014-08-01

Mechanical behavior of reference and TIG-welded Inconel 718 specimens was examined in the present work. Tensile, constant amplitude fatigue, and fracture toughness tests were performed in ambient temperature for both, reference and welded specimens. Microstructure revealed the presence of coarse and fine-grained heat-affected zones. It has been shown that without any post-weld heat treatment, welded specimens maintained their tensile strength properties while their ductility decreased by more than 40%. It was found that the welded specimens had lower fatigue life and this decrease was a function of the applied fatigue maximum stress. A 30% fatigue life decrease was noticed in the high cycle fatigue regime for the welded specimens while this decrease exceeded 50% in the low cycle fatigue regime. Cyclic stress-strain curves showed that Inconel 718 experiences a short period of hardening followed by softening for all fatigue lives. Cyclic fatigue response of welded specimens' exhibited cyclically stable behavior. Finally, a marginal decrease was noticed in the Mode I fracture toughness of the welded specimens.

Chronic Fatigue Syndrome: How Vulnerable Are Athletes?

ERIC Educational Resources Information Center

Eichner, Edward R.

1989-01-01

Discusses chronic fatigue syndrome as it affects elite athletes, noting that overtraining may mimic it. In some cases, athletes who have it perform exceedingly well in the face of debilitating fatigue. Among athletes and nonathletes, the cause and the mind-body connection are areas of controversy and research. (Author/SM)

[Fatigue symptoms and workplace related factors of long-term care workers employed in facilities].

PubMed

Kawamura, Sachiyo; Yamada, Kazuko; Morioka, Ikuharu

2015-01-01

"Regular visiting/on-demand response type long-term care" has recently been established. This will lead to a decrease in the burden on the family, but an increase in the burden of the care personnel who provide this kind of long-term care. The objectives of this study were to clarify the fatigue symptoms of long-term care workers in facilities that provide this kind of long-term care, and examine the related factors in the workplace. An anonymous questionnaire survey was conducted with 96 workers engaged in long-term care in facilities. The questionnaire was composed of cumulative fatigue symptoms index, work situation, supports in the workplace, and the attributes. The subjects were divided into two groups: those who had night shift between PM 6 to AM 8 with or without day shift (night shift group), and those who had only day shift (day shift group). The relationships between the fatigue symptom levels and work situation etc. were compared between the two groups. The night shift group consisted of 47 workers, whose mean age was 42.3 years and whose mean working experience was 6.0 years. The median number of persons they had visited in the previous month was 9. The day shift group consisted of 49 workers, whose mean age was 44.6 years and whose mean working experience was 5.9 years. The median number of persons they visited in the previous month was 9.5. Age and sex distributions showed no difference between the two groups. There was no difference in the work situations and the supports in the workplace, except for working time and the details of care the subjects were providing. The fatigue symptom levels were high in both groups, but in the night shift group the level of physical disorders was higher than in the day shift group. Satisfaction with work, education and training for mental health and consideration for traffic safety when making home visits were negatively related to fatigue symptom levels in both groups. Learning care during the previous year, and

Factors affecting sign retroreflectivity

DOT National Transportation Integrated Search

2001-01-01

This study was undertaken to better understand the factors that may affect road sign retroreflectivity, specifically age and physical orientation. A better understanding of these factors could provide guidance to ODOT in managing its inventory of roa...

Accelerated fatigue durability of a high performance composite

NASA Technical Reports Server (NTRS)

Rotem, A.

1982-01-01

The fatigue behavior of multidirectional graphite-epoxy laminates was analyzed theoretically and experimentally in an effort to establish an accelerated testing methodology. Analysis of the failure mechanism in fatigue of the laminates led to the determination of the failure mode governing fracture. The nonlinear, cyclic-dependent shear modulus was used to calculate the changing stress field in the laminate during the fatigue loading. Fatigue tests were performed at three different temperatures: 25 C, 74 C, and 114 C. The prediction of the S-N curves was made based on the artificial static strength artificial static strength at a reference temperature and the fatigue functions associated with them. The prediction of an S-N curve at other temperatures was performed using shifting factors determined for the specific failure mode. For multidirectional laminates, different S-N curves at different temperatures could be predicted using these shifting factors. Different S-N curves at different temperatures occur only when the fatigue failure mode is matrix dominated. It was found that whenever the fatigue failure mode is fiber dominated, temperature, over the range investigated, had no influence on the fatigue life. These results permit the prediction of long-time, low temperature fatigue behavior from data obtained in short time, high temperature testing, for laminates governed by a matrix failure mode.

Compassion fatigue among pediatric healthcare providers.

PubMed

Branch, Carole; Klinkenberg, Dean

2015-01-01

Compassion fatigue is a term used to describe the unique stressors affecting people in caregiving professions. For nurses and other direct care providers, the impact of compassion fatigue may result in stress-related symptoms, job dissatisfaction, decreased productivity, decreased patient satisfaction scores, safety issues, and job turnover. Those who care for seriously ill children and their families are at increased risk for compassion fatigue. Constant exposure to children who are suffering, in combination with work place stressors and personal issues, may contribute to the development of compassion fatigue. The Professional Quality of Life Scale Version 5 was used to determine the risk for compassion fatigue among 296 direct care providers at St. Louis Children's Hospital. Compassion satisfaction, burnout, and secondary traumatic stress scores did not differ by age, work category, level of education, or work experience. There were, however, significant differences in scores as a function of nursing unit. Nurses who work in the pediatric intensive care unit reported lower compassion satisfaction scores, and higher burnout and secondary traumatic stress scores. Results demonstrated the risk for compassion fatigue and provided data necessary to support development of a compassion fatigue program for direct care providers.

Severe hypoxia affects exercise performance independently of afferent feedback and peripheral fatigue.

PubMed

Millet, Guillaume Y; Muthalib, Makii; Jubeau, Marc; Laursen, Paul B; Nosaka, Kazunori

2012-04-01

To test the hypothesis that hypoxia centrally affects performance independently of afferent feedback and peripheral fatigue, we conducted two experiments under complete vascular occlusion of the exercising muscle under different systemic O(2) environmental conditions. In experiment 1, 12 subjects performed repeated submaximal isometric contractions of the elbow flexor to exhaustion (RCTE) with inspired O(2) fraction fixed at 9% (severe hypoxia, SevHyp), 14% (moderate hypoxia, ModHyp), 21% (normoxia, Norm), or 30% (hyperoxia, Hyper). The number of contractions (performance), muscle (biceps brachii), and prefrontal near-infrared spectroscopy (NIRS) parameters and high-frequency paired-pulse (PS100) evoked responses to electrical muscle stimulation were monitored. In experiment 2, 10 subjects performed another RCTE in SevHyp and Norm conditions in which the number of contractions, biceps brachii electromyography responses to electrical nerve stimulation (M wave), and transcranial magnetic stimulation responses (motor-evoked potentials, MEP, and cortical silent period, CSP) were recorded. Performance during RCTE was significantly reduced by 10-15% in SevHyp (arterial O(2) saturation, SpO(2) = ∼75%) compared with ModHyp (SpO(2) = ∼90%) or Norm/Hyper (SpO(2) > 97%). Performance reduction in SevHyp occurred despite similar 1) metabolic (muscle NIRS parameters) and functional (changes in PS100 and M wave) muscle states and 2) MEP and CSP responses, suggesting comparable corticospinal excitability and spinal and cortical inhibition between SevHyp and Norm. It is concluded that, in SevHyp, performance and central drive can be altered independently of afferent feedback and peripheral fatigue. It is concluded that submaximal performance in SevHyp is partly reduced by a mechanism related directly to brain oxygenation.

Traffic accidents involving fatigue driving and their extent of casualties.

PubMed

Zhang, Guangnan; Yau, Kelvin K W; Zhang, Xun; Li, Yanyan

2016-02-01

The rapid progress of motorization has increased the number of traffic-related casualties. Although fatigue driving is a major cause of traffic accidents, the public remains not rather aware of its potential harmfulness. Fatigue driving has been termed as a "silent killer." Thus, a thorough study of traffic accidents and the risk factors associated with fatigue-related casualties is of utmost importance. In this study, we analyze traffic accident data for the period 2006-2010 in Guangdong Province, China. The study data were extracted from the traffic accident database of China's Public Security Department. A logistic regression model is used to assess the effect of driver characteristics, type of vehicles, road conditions, and environmental factors on fatigue-related traffic accident occurrence and severity. On the one hand, male drivers, trucks, driving during midnight to dawn, and morning rush hours are identified as risk factors of fatigue-related crashes but do not necessarily result in severe casualties. Driving at night without street-lights contributes to fatigue-related crashes and severe casualties. On the other hand, while factors such as less experienced drivers, unsafe vehicle status, slippery roads, driving at night with street-lights, and weekends do not have significant effect on fatigue-related crashes, yet accidents associated with these factors are likely to have severe casualties. The empirical results of the present study have important policy implications on the reduction of fatigue-related crashes as well as their severity. Copyright © 2015 Elsevier Ltd. All rights reserved.

Validity of the Multidimensional Fatigue Symptom Inventory-Short Form in an African American Community-Based Sample

PubMed Central

Asvat, Yasmin; Malcarne, Vanessa L.; Sadler, Georgia R.; Jacobsen, Paul B.

2014-01-01

Objectives This study examined the psychometric properties of the Multidimensional Fatigue Symptom Inventory-Short Form (MFSI-SF) in a community-based sample of African Americans. Design. A sample of 340 African Americans (116 men, 224 women) ranging in age from 18–81 years were recruited from the community (e.g., churches, health fairs, beauty salons). Participants completed a brief demographic survey, the MFSI-SF and the Positive and Negative Affect Schedule. Results The structural validity of the MFSI-SF for a community-based sample of African Americans was not supported. The five dimensions of fatigue (General, Emotional, Physical, Mental, Vigor) found for Whites in prior research were not found for African Americans in this study. Instead, fatigue, while multidimensional for African Americans, was best represented by a unique four-four profile in which general and emotional fatigue are collapsed into a single dimension and physical fatigue, mental fatigue, and vigor are relatively distinct. Hence, in the absence of modifications, the MFSI-SF cannot be considered to be structurally invariant across ethnic groups. A modified four-factor version of the MFSI-SF exhibited excellent internal consistency reliability and evidence supports its convergent validity. Using the modified four-factor version, gender and age were not meaningfully associated with MFSI-SF scores. Conclusion Future research should further examine whether modifications to the MFSI-SF would, as the findings suggest, improve its validity as a measure of multidimensional fatigue in African Americans. PMID:24527980

Comparison of Fatigue Properties and Fatigue Crack Growth Rates of Various Implantable Metals

PubMed Central

Okazaki, Yoshimitsu

2012-01-01

The fatigue strength, effects of a notch on the fatigue strength, and fatigue crack growth rate of Ti-15Zr-4Nb-4Ta alloy were compared with those of other implantable metals. Zr, Nb, and Ta are important alloying elements for Ti alloys for attaining superior long-term corrosion resistance and biocompatibility. The highly biocompatible Ti-15Zr-4Nb-4Ta alloy exhibited an excellent balance between strength and ductility. Its notched tensile strength was much higher than that of a smooth specimen. The strength of 20% cold-worked commercially pure (C.P.) grade 4 Ti was close to that of Ti alloy. The tension-to-tension fatigue strength of an annealed Ti-15Zr-4Nb-4Ta rod at 107 cycles was approximately 740 MPa. The fatigue strength of this alloy was much improved by aging treatment after solution treatment. The fatigue strengths of C.P. grade 4 Ti and stainless steel were markedly improved by 20% cold working. The fatigue strength of Co-Cr-Mo alloy was markedly increased by hot forging. The notch fatigue strengths of 20% cold-worked C.P. grade 4 Ti, and annealed and aged Ti-15Zr-4Nb-4Ta, and annealed Ti-6Al-4V alloys were less than those of the smooth specimens. The fatigue crack growth rate of Ti-15Zr-4Nb-4Ta was the same as that of Ti-6Al-4V. The fatigue crack growth rate in 0.9% NaCl was the same as that in air. Stainless steel and Co-Cr-Mo-Ni-Fe alloy had a larger stress-intensity factor range (ΔK) than Ti alloy.

Exercise-Induced Fatigue and Caffeine Supplementation Affect Psychomotor Performance but Not Covert Visuo-Spatial Attention

PubMed Central

Connell, Charlotte J. W.; Thompson, Benjamin; Kuhn, Gustav; Gant, Nicholas

2016-01-01

Fatigue resulting from strenuous exercise can impair cognition and oculomotor control. These impairments can be prevented by administering psychostimulants such as caffeine. This study used two experiments to explore the influence of caffeine administered at rest and during fatiguing physical exercise on spatial attention—a cognitive function that is crucial for task-based visually guided behavior. In independent placebo-controlled studies, cohorts of 12 healthy participants consumed caffeine and rested or completed 180 min of stationary cycling. Covert attentional orienting was measured in both experiments using a spatial cueing paradigm. We observed no alterations in attentional facilitation toward spatial cues suggesting that covert attentional orienting is not influenced by exercise fatigue or caffeine supplementation. Response times were increased (impaired) after exercise and this deterioration was prevented by caffeine supplementation. In the resting experiment, response times across all conditions and cues were decreased (improved) with caffeine. Covert spatial attention was not influenced by caffeine. Together, the results of these experiments suggest that covert attentional orienting is robust to the effects of fatiguing exercise and not influenced by caffeine. However, exercise fatigue impairs response times, which can be prevented by caffeine, suggesting that pre-motor planning and execution of the motor responses required for performance of the cueing task are sensitive to central nervous system fatigue. Caffeine improves response time in both fatigued and fresh conditions, most likely through action on networks controlling motor function. PMID:27768747

Exercise-Induced Fatigue and Caffeine Supplementation Affect Psychomotor Performance but Not Covert Visuo-Spatial Attention.

PubMed

Connell, Charlotte J W; Thompson, Benjamin; Kuhn, Gustav; Gant, Nicholas

2016-01-01

Fatigue resulting from strenuous exercise can impair cognition and oculomotor control. These impairments can be prevented by administering psychostimulants such as caffeine. This study used two experiments to explore the influence of caffeine administered at rest and during fatiguing physical exercise on spatial attention-a cognitive function that is crucial for task-based visually guided behavior. In independent placebo-controlled studies, cohorts of 12 healthy participants consumed caffeine and rested or completed 180 min of stationary cycling. Covert attentional orienting was measured in both experiments using a spatial cueing paradigm. We observed no alterations in attentional facilitation toward spatial cues suggesting that covert attentional orienting is not influenced by exercise fatigue or caffeine supplementation. Response times were increased (impaired) after exercise and this deterioration was prevented by caffeine supplementation. In the resting experiment, response times across all conditions and cues were decreased (improved) with caffeine. Covert spatial attention was not influenced by caffeine. Together, the results of these experiments suggest that covert attentional orienting is robust to the effects of fatiguing exercise and not influenced by caffeine. However, exercise fatigue impairs response times, which can be prevented by caffeine, suggesting that pre-motor planning and execution of the motor responses required for performance of the cueing task are sensitive to central nervous system fatigue. Caffeine improves response time in both fatigued and fresh conditions, most likely through action on networks controlling motor function.

A survey of the prevalence of fatigue, its precursors and individual coping mechanisms among U.S. manufacturing workers.

PubMed

Lu, Lin; Megahed, Fadel M; Sesek, Richard F; Cavuoto, Lora A

2017-11-01

Advanced manufacturing has resulted in significant changes on the shop-floor, influencing work demands and the working environment. The corresponding safety-related effects, including fatigue, have not been captured on an industry-wide scale. This paper presents results of a survey of U.S. manufacturing workers for the: prevalence of fatigue, its root causes and significant factors, and adopted individual fatigue coping methods. The responses from 451 manufacturing employees were analyzed using descriptive data analysis, bivariate analysis and Market Basket Analysis. 57.9% of respondents indicated that they were somewhat fatigued during the past week. They reported the ankles/feet, lower back and eyes were frequently affected body parts and a lack of sleep, work stress and shift schedule were top selected root causes for fatigue. In order to respond to fatigue when it is present, respondents reported coping by drinking caffeinated drinks, stretching/doing exercises and talking with coworkers. Frequent combinations of fatigue causes and individual coping methods were identified. These results may inform the design of fatigue monitoring and mitigation strategies and future research related to fatigue development. Copyright © 2017 Elsevier Ltd. All rights reserved.

Fatigue properties of dissimilar metal laser welded lap joints

NASA Astrophysics Data System (ADS)

Dinsley, Christopher Paul

This work involves laser welding austenitic and duplex stainless steel to zinc-coated mild steel, more specifically 1.2mm V1437, which is a Volvo Truck Coiporation rephosphorised mild steel. The work investigates both tensile and lap shear properties of similar and dissimilar metal laser welded butt and lap joints, with the majority of the investigation concentrating on the fatigue properties of dissimilar metal laser welded lap joints. The problems encountered when laser welding zinc-coated steel are addressed and overcome with regard to dissimilar metal lap joints with stainless steel. The result being the production of a set of guidelines for laser welding stainless steel to zinc-coated mild steel. The stages of laser welded lap joint fatigue life are defined and the factors affecting dissimilar metal laser welded lap joint fatigue properties are analysed and determined; the findings suggesting that dissimilar metal lap joint fatigue properties are primarily controlled by the local stress at the internal lap face and the early crack growth rate of the material at the internal lap face. The lap joint rotation, in turn, is controlled by sheet thickness, weld width and interfacial gap. Laser welded lap joint fatigue properties are found to be independent of base material properties, allowing dissimilar metal lap joints to be produced without fatigue failure occurring preferentially in the weaker parent material, irrespective of large base material property differences. The effects of Marangoni flow on the compositions of the laser weld beads are experimentally characterised. The results providing definite proof of the stirring mechanism within the weld pool through the use of speeds maps for chromium and nickel. Keywords: Laser welding, dissimilar metal, Zinc-coated mild steel, Austenitic stainless steel, Duplex stainless steel, Fatigue, Lap joint rotation, Automotive.

Stress management skills, neuroimmune processes and fatigue levels in persons with chronic fatigue syndrome

PubMed Central

Lattie, Emily G.; Antoni, Michael H.; Fletcher, Mary Ann; Penedo, Frank; Czaja, Sara; Lopez, Corina; Perdomo, Dolores; Sala, Andreina; Nair, Sankaran; Fu, Shih Hua; Klimas, Nancy

2012-01-01

Objectives Stressors and emotional distress responses impact chronic fatigue syndrome (CFS) symptoms, including fatigue. Having better stress management skills might mitigate fatigue by decreasing emotional distress. Because CFS patients comprise a heterogeneous population, we hypothesized that the role of stress management skills in decreasing fatigue may be most pronounced in the subgroup manifesting the greatest neuroimmune dysfunction. Methods In total, 117 individuals with CFS provided blood and saliva samples, and self-report measures of emotional distress, perceived stress management skills (PSMS), and fatigue. Plasma interleukin-1-beta (IL-1β, IL-2, IL-6, IL-10, and tumor necrosis factor-alpha (TNF-α), and diurnal salivary cortisol were analyzed. We examined relations among PSMS, emotional distress, and fatigue in CFS patients who did and did not evidence neuroimmune abnormalities. Results Having greater PSMS related to less fatigue (p = .019) and emotional distress (p < .001), greater diurnal cortisol slope (p = .023) and lower IL-2 levels (p = .043). PSMS and emotional distress related to fatigue levels most strongly in CFS patients in the top tercile of IL-6, and emotional distress mediated the relationship between PSMS and fatigue most strongly in patients with the greatest circulating levels of IL-6 and a greater inflammatory (IL-6):anti-inflammatory (IL-10) cytokine ratio. Discussion CFS patients having greater PSMS show less emotional distress and fatigue, and the influence of stress management skills on distress and fatigue appear greatest among patients who have elevated IL-6 levels. These findings support the need for research examining the impact of stress management interventions in subgroups of CFS patients showing neuroimmune dysfunction. PMID:22417946

Stress management skills, neuroimmune processes and fatigue levels in persons with chronic fatigue syndrome.

PubMed

Lattie, Emily G; Antoni, Michael H; Fletcher, Mary Ann; Penedo, Frank; Czaja, Sara; Lopez, Corina; Perdomo, Dolores; Sala, Andreina; Nair, Sankaran; Fu, Shih Hua; Klimas, Nancy

2012-08-01

Stressors and emotional distress responses impact chronic fatigue syndrome (CFS) symptoms, including fatigue. Having better stress management skills might mitigate fatigue by decreasing emotional distress. Because CFS patients comprise a heterogeneous population, we hypothesized that the role of stress management skills in decreasing fatigue may be most pronounced in the subgroup manifesting the greatest neuroimmune dysfunction. In total, 117 individuals with CFS provided blood and saliva samples, and self-report measures of emotional distress, perceived stress management skills (PSMS), and fatigue. Plasma interleukin-1-beta (IL-1β, IL-2, IL-6, IL-10, and tumor necrosis factor-alpha (TNF-α), and diurnal salivary cortisol were analyzed. We examined relations among PSMS, emotional distress, and fatigue in CFS patients who did and did not evidence neuroimmune abnormalities. Having greater PSMS related to less fatigue (p=.019) and emotional distress (p<.001), greater diurnal cortisol slope (p=.023) and lower IL-2 levels (p=.043). PSMS and emotional distress related to fatigue levels most strongly in CFS patients in the top tercile of IL-6, and emotional distress mediated the relationship between PSMS and fatigue most strongly in patients with the greatest circulating levels of IL-6 and a greater inflammatory (IL-6):anti-inflammatory (IL-10) cytokine ratio. CFS patients having greater PSMS show less emotional distress and fatigue, and the influence of stress management skills on distress and fatigue appear greatest among patients who have elevated IL-6 levels. These findings support the need for research examining the impact of stress management interventions in subgroups of CFS patients showing neuroimmune dysfunction. Copyright © 2012 Elsevier Inc. All rights reserved.

Cerebral mechanisms underlying the effects of music during a fatiguing isometric ankle-dorsiflexion task.

PubMed

Bigliassi, Marcelo; Karageorghis, Costas I; Nowicky, Alexander V; Orgs, Guido; Wright, Michael J

2016-10-01

The brain mechanisms by which music-related interventions ameliorate fatigue-related symptoms during the execution of fatiguing motor tasks are hitherto under-researched. The objective of the present study was to investigate the effects of music on brain electrical activity and psychophysiological measures during the execution of an isometric fatiguing ankle-dorsiflexion task performed until the point of volitional exhaustion. Nineteen healthy participants performed two fatigue tests at 40% of maximal voluntary contraction while listening to music or in silence. Electrical activity in the brain was assessed by use of a 64-channel EEG. The results indicated that music downregulated theta waves in the frontal, central, and parietal regions of the brain during exercise. Music also induced a partial attentional switching from associative thoughts to task-unrelated factors (dissociative thoughts) during exercise, which led to improvements in task performance. Moreover, participants experienced a more positive affective state while performing the isometric task under the influence of music. © 2016 Society for Psychophysiological Research.

Cooking methods and depressive symptoms are joint risk factors for fatigue among migrant Indonesian women working domestically in Taiwan.

PubMed

Palupi, Khairizka Citra; Shih, Chun-Kuang; Chang, Jung-Su

2017-06-01

Fatigue is a critical occupational health risk among migrant workers. Globally, more than half of migrant workers are women. However, the prevalence rate and risk factors for fatigue in domestically employed migrant women are unknown. In total, 194 Indonesian women migrants aged 20-50 years who were working in Taipei were studied. Self-perceived acculturation, dietary acculturation, BMI and haemoglobin were evaluated. Fatigue and depressive symptoms were assessed using the Brief Fatigue Inventory and Beck Depression Inventory-II, respectively. The prevalence of fatigue was 27.8%. Depressive symptoms (p<0.0001), cooking methods (p=0.027), and self-perceived feelings of sadness and weakness (p=0.003) were associated with fatigue. After adjustment for covariates, the ORs for depressive symptoms (OR: 5.40; 95% CI: 2.32-12.6), deep frying/stir frying (OR: 5.23; 95% CI: 1.27-21.5), and self-perceived feelings of sadness and weakness (OR: 3.41; 95% CI: 1.26-9.25) remained significant. An interactive analysis revealed that women without depressive symptoms who used deep frying/stir frying as a cooking method had a 3.5-fold (1-12.3) higher risk of fatigue than did those who used non-deep frying and stir frying as cooking methods (which served as the reference) for cooking. By contrast, women with depressive symptoms who used non-deep frying and stir frying had a 6.5-fold (2.8-15.3) higher risk of fatigue, and the risk increased sharply to 12.6-fold (1.26-125.8) if they used deep frying and stir frying for cooking. The risk of fatigue among migrant women working domestically is increased when they exhibit depressive symptoms and their cooking technique is frying.

Acromiohumeral Distance and 3-Dimensional Scapular Position Change After Overhead Muscle Fatigue

PubMed Central

Maenhout, Annelies; Dhooge, Famke; Van Herzeele, Maarten; Palmans, Tanneke; Cools, Ann

2015-01-01

Context: Muscle fatigue due to repetitive and prolonged overhead sports activity is considered an important factor contributing to impingement-related rotator cuff pathologic conditions in overhead athletes. The evidence on scapular and glenohumeral kinematic changes after fatigue is contradicting and prohibits conclusions about how shoulder muscle fatigue affects acromiohumeral distance. Objective: To investigate the effect of a fatigue protocol resembling overhead sports activity on acromiohumeral distance and 3-dimensional scapular position in overhead athletes. Design: Cross-sectional study. Setting: Institutional laboratory. Patients or Other Participants: A total of 29 healthy recreational overhead athletes (14 men, 15 women; age = 22.23 ± 2.82 years, height = 178.3 ± 7.8 cm, mass = 71.6 ± 9.5 kg). Intervention(s) The athletes were tested before and after a shoulder muscle-fatiguing protocol. Main Outcome Measure(s) Acromiohumeral distance was measured using ultrasound, and scapular position was determined with an electromagnetic motion-tracking system. Both measurements were performed at 3 elevation positions (0°, 45°, and 60° of abduction). We used a 3-factor mixed model for data analysis. Results: After fatigue, the acromiohumeral distance increased when the upper extremity was actively positioned at 45° (Δ = 0.78 ± 0.24 mm, P = .002) or 60° (Δ = 0.58 ± 0.23 mm, P = .02) of abduction. Scapular position changed after fatigue to a more externally rotated position at 45° (Δ = 4.97° ± 1.13°, P < .001) and 60° (Δ = 4.61° ± 1.90°, P = .001) of abduction, a more upwardly rotated position at 45° (Δ = 6.10° ± 1.30°, P < .001) and 60° (Δ = 7.20° ± 1.65°, P < .001) of abduction, and a more posteriorly tilted position at 0°, 45°, and 60° of abduction (Δ = 1.98° ± 0.41°, P < .001). Conclusions: After a fatiguing protocol, we found changes in acromiohumeral distance and scapular position that corresponded with an impingement

The Piper Fatigue Scale-12 (PFS-12): psychometric findings and item reduction in a cohort of breast cancer survivors.

PubMed

Reeve, Bryce B; Stover, Angela M; Alfano, Catherine M; Smith, Ashley Wilder; Ballard-Barbash, Rachel; Bernstein, Leslie; McTiernan, Anne; Baumgartner, Kathy B; Piper, Barbara F

2012-11-01

Brief, valid measures of fatigue, a prevalent and distressing cancer symptom, are needed for use in research. This study's primary aim was to create a shortened version of the revised Piper Fatigue Scale (PFS-R) based on data from a diverse cohort of breast cancer survivors. A secondary aim was to determine whether the PFS captured multiple distinct aspects of fatigue (a multidimensional model) or a single overall fatigue factor (a unidimensional model). Breast cancer survivors (n = 799; stages in situ through IIIa; ages 29-86 years) were recruited through three SEER registries (New Mexico, Western Washington, and Los Angeles, CA) as part of the Health, Eating, Activity, and Lifestyle (HEAL) study. Fatigue was measured approximately 3 years post-diagnosis using the 22-item PFS-R that has four subscales (Behavior, Affect, Sensory, and Cognition). Confirmatory factor analysis was used to compare unidimensional and multidimensional models. Six criteria were used to make item selections to shorten the PFS-R: scale's content validity, items' relationship with fatigue, content redundancy, differential item functioning by race and/or education, scale reliability, and literacy demand. Factor analyses supported the original 4-factor structure. There was also evidence from the bi-factor model for a dominant underlying fatigue factor. Six items tested positive for differential item functioning between African-American and Caucasian survivors. Four additional items either showed poor association, local dependence, or content validity concerns. After removing these 10 items, the reliability of the PFS-12 subscales ranged from 0.87 to 0.89, compared to 0.90-0.94 prior to item removal. The newly developed PFS-12 can be used to assess fatigue in African-American and Caucasian breast cancer survivors and reduces response burden without compromising reliability or validity. This is the first study to determine PFS literacy demand and to compare PFS-R responses in African

The Piper Fatigue Scale-12 (PFS-12): Psychometric Findings and Item Reduction in a Cohort of Breast Cancer Survivors

PubMed Central

Reeve, Bryce B.; Stover, Angela M.; Alfano, Catherine M.; Smith, Ashley Wilder; Ballard-Barbash, Rachel; Bernstein, Leslie; McTiernan, Anne; Baumgartner, Kathy B.; Piper, Barbara F.

2013-01-01

Purpose Brief, valid measures of fatigue, a prevalent and distressing cancer symptom, are needed for use in research. This study’s primary aim was to create a shortened version of the revised Piper Fatigue Scale (PFS-R) based on data from a diverse cohort of breast cancer survivors. A secondary aim was to determine whether the PFS captured multiple distinct aspects of fatigue (a multidimensional model) or a single overall fatigue factor (a unidimensional model). Methods Breast cancer survivors (n=799; stages in situ through IIIa; ages 29–86 yrs) were recruited through 3 SEER registries (New Mexico, Western Washington, and Los Angeles, CA) as part of the Health, Eating, Activity, and Lifestyle (HEAL) study. Fatigue was measured approximately 3 years post-diagnosis using the 22-item PFS-R that has 4 subscales (Behavior, Affect, Sensory, and Cognition). Confirmatory factor analysis was used to compare unidimensional and multidimensional models. Six criteria were used to make item selections to shorten the PFS-R: scale’s content validity, items’ relationship with fatigue, content redundancy, differential item functioning by race and/or education, scale reliability, and literacy demand. Results Factor analyses supported the original 4-factor structure. There was also evidence from the bi-factor model for a dominant underlying fatigue factor. Six items tested positive for differential item functioning between African-American and Caucasian survivors. Four additional items either showed poor association, local dependence, or content validity concerns. After removing these 10 items, the reliability of the PFS-12 subscales ranged from 0.87–0.89, compared to 0.90–0.94 prior to item removal. Conclusion The newly developed PFS-12 can be used to assess fatigue in African-American and Caucasian breast cancer survivors and reduces response burden without compromising reliability or validity. This is the first study to determine PFS literacy demand and to compare PFS

Mechanisms of in vivo muscle fatigue in humans: investigating age‐related fatigue resistance with a computational model

PubMed Central

Callahan, Damien M.; Umberger, Brian R.

2016-01-01

Key points Muscle fatigue can be defined as the transient decrease in maximal force that occurs in response to muscle use. Fatigue develops because of a complex set of changes within the neuromuscular system that are difficult to evaluate simultaneously in humans.The skeletal muscle of older adults fatigues less than that of young adults during static contractions. The potential sources of this difference are multiple and intertwined.To evaluate the individual mechanisms of fatigue, we developed an integrative computational model based on neural, biochemical, morphological and physiological properties of human skeletal muscle.Our results indicate first that the model provides accurate predictions of fatigue and second that the age‐related resistance to fatigue is due largely to a lower reliance on glycolytic metabolism during contraction.This model should prove useful for generating hypotheses for future experimental studies into the mechanisms of muscle fatigue. Abstract During repeated or sustained muscle activation, force‐generating capacity becomes limited in a process referred to as fatigue. Multiple factors, including motor unit activation patterns, muscle fibre contractile properties and bioenergetic function, can impact force‐generating capacity and thus the potential to resist fatigue. Given that neuromuscular fatigue depends on interrelated factors, quantifying their independent effects on force‐generating capacity is not possible in vivo. Computational models can provide insight into complex systems in which multiple inputs determine discrete outputs. However, few computational models to date have investigated neuromuscular fatigue by incorporating the multiple levels of neuromuscular function known to impact human in vivo function. To address this limitation, we present a computational model that predicts neural activation, biomechanical forces, intracellular metabolic perturbations and, ultimately, fatigue during repeated isometric contractions

Characterizing Fatigue: The Effects of Ethnicity and Acculturation

PubMed Central

Cordero, Elizabeth D.; Loredo, Jose S.; Murray, Kate E.; Dimsdale, Joel E.

2012-01-01

It is unknown if fatigue measures like the Multidimensional Fatigue Symptom Inventory-Short Form (MFSI-SF; Stein, Jacobsen, Blanchard, & Thors, 2004) appropriately describe fatigue in Hispanics or if acculturation plays a role in fatigue. This study compared fatigue in community samples of Hispanics and Anglos. The MFSI-SF and pertinent questionnaires were administered to adults in San Diego County via telephone survey. Some differences in fatigue were observed in initial comparisons between Hispanics and Anglos, including when acculturation was considered. When age and education were controlled, Hispanics reported less general fatigue than Anglos, regardless of acculturation status, p = < .01. Exploratory factor analyses indicate that the MFSI-SF general-fatigue subscale was problematic for Hispanics. Implications, limitations, and future directions are discussed. PMID:22773899

Factors affecting the energy cost of level running at submaximal speed.

PubMed

Lacour, Jean-René; Bourdin, Muriel

2015-04-01

Metabolic measurement is still the criterion for investigation of the efficiency of mechanical work and for analysis of endurance performance in running. Metabolic demand may be expressed either as the energy spent per unit distance (energy cost of running, C r) or as energy demand at a given running speed (running economy). Systematic studies showed a range of costs of about 20 % between runners. Factors affecting C r include body dimensions: body mass and leg architecture, mostly calcaneal tuberosity length, responsible for 60-80 % of the variability. Children show a higher C r than adults. Higher resting metabolism and lower leg length/stature ratio are the main putative factors responsible for the difference. Elastic energy storage and reuse also contribute to the variability of C r. The increase in C r with increasing running speed due to increase in mechanical work is blunted till 6-7 m s(-1) by the increase in vertical stiffness and the decrease in ground contact time. Fatigue induced by prolonged or intense running is associated with up to 10 % increased C r; the contribution of metabolic and biomechanical factors remains unclear. Women show a C r similar to men of similar body mass, despite differences in gait pattern. The superiority of black African runners is presumably related to their leg architecture and better elastic energy storage and reuse.

The Nottingham Fatigue After Stroke (NotFAST) study: results from follow-up six months after stroke.

PubMed

Hawkins, Louise; Lincoln, Nadina B; Sprigg, Nikola; Ward, Nick S; Mistri, Amit; Tyrrell, Pippa; Worthington, Esme; Drummond, Avril

2017-12-01

Background Post-stroke fatigue is common and disabling. Objectives The aim of NotFAST was to examine factors associated with fatigue in stroke survivors without depression, six months after stroke. Methods Participants were recruited from four UK stroke units. Those with high levels of depressive symptoms (score ≥7 on Brief Assessment Schedule Depression Cards) or aphasia were excluded. Follow-up assessment was conducted at six months after stroke. They were assessed on the Fatigue Severity Scale, Rivermead Mobility Index, Nottingham Extended Activities of Daily Living scale, Barthel Index, Beck Anxiety Index, Brief Assessment Schedule Depression Cards, Impact of Event Scale-Revised, and Sleep Hygiene Index. Results Of the 371 participants recruited, 263 (71%) were contacted at six months after stroke and 213 (57%) returned questionnaires. Approximately half (n = 109, 51%) reported fatigue at six months. Of those reporting fatigue initially (n = 88), 61 (69%) continued to report fatigue. 'De novo' (new) fatigue was reported by 48 (38%) of those not fatigued initially. Lower Nottingham Extended Activities of Daily Living scores and higher Beck Anxiety Index scores were independently associated with fatigue at six months. Conclusions Half the stroke survivors reported fatigue at six months post-stroke. Reduced independence in activities of daily living and higher anxiety levels were associated with the level of fatigue. Persistent and delayed onset fatigue may affect independence and participation in rehabilitation, and these findings should be used to inform the development of appropriate interventions.

Fatigue management in the workplace

PubMed Central

Sadeghniiat-Haghighi, Khosro; Yazdi, Zohreh

2015-01-01

Workers’ fatigue is a significant problem in modern industry, largely because of high demand jobs, long duty periods, disruption of circadian rhythms, and accumulative sleep debt that are common in many industries. Fatigue is the end result of integration of multiple factors such as time awake, time of day, and workload. Then, the full understanding of circadian biologic clock, dynamics of transient and cumulative sleep loss, and recovery is required for effective management of workplace fatigue. It can be more investigated in a new field of sleep medicine called occupational sleep medicine. Occupational sleep medicine is concerned with maintaining best productivity and safety in the industrial settings. The fatigue risk management system (FRMS) is a comprehensive approach that is based on applying scientific evidence of sleep knowledge to manage workers fatigue. It is developing rapidly in the highly safety demand jobs; especially truck drivers, pilots, and power plant workers. The objective of this review is to explain about fatigue in the workplace with emphasis on its association work performance and errors/accidents. Also, we discussed about different methods of fatigue measurement and management. PMID:26257477

Persevering through postpartum fatigue.

PubMed

Runquist, Jennifer

2007-01-01

To construct a substantive theory of postpartum fatigue. Grounded theory. Participants were recruited in the hospital after delivery and interviewed in their homes. Thirteen primiparae (n=5) and multiparae (n=8) women between 2 and 5 weeks postpartum from diverse ethnic, age, obstetric, and financial contexts were theoretically sampled. Persevering was the central human process around which the grounded theory emerged. The process of persevering was explained through the relationships of influencing factors, postpartum fatigue, coping techniques, self-transcendence, and caregiving. Participants persevered in caregiving of infants and older children in spite of an overwhelming desire to rest and sleep using self-identified coping techniques in combination with the belief that their children brought purpose and meaning to their lives. The theory "Persevering Through Postpartum Fatigue" contributes a more complete understanding of the complex phenomenon of postpartum fatigue as it is expressed in the everyday lives of women during the postpartum period. The results may be used to develop and implement health-promoting nursing interventions to reduce postpartum fatigue and its health-related consequences.

How are compassion fatigue, burnout, and compassion satisfaction affected by quality of working life? Findings from a survey of mental health staff in Italy.

PubMed

Cetrano, Gaia; Tedeschi, Federico; Rabbi, Laura; Gosetti, Giorgio; Lora, Antonio; Lamonaca, Dario; Manthorpe, Jill; Amaddeo, Francesco

2017-11-21

Quality of working life includes elements such as autonomy, trust, ergonomics, participation, job complexity, and work-life balance. The overarching aim of this study was to investigate if and how quality of working life affects Compassion Fatigue, Burnout, and Compassion Satisfaction among mental health practitioners. Staff working in three Italian Mental Health Departments completed the Professional Quality of Life Scale, measuring Compassion Fatigue, Burnout, and Compassion Satisfaction, and the Quality of Working Life Questionnaire. The latter was used to collect socio-demographics, occupational characteristics and 13 indicators of quality of working life. Multiple regressions controlling for other variables were undertaken to predict Compassion Fatigue, Burnout, and Compassion Satisfaction. Four hundred questionnaires were completed. In bivariate analyses, experiencing more ergonomic problems, perceiving risks for the future, a higher impact of work on life, and lower levels of trust and of perceived quality of meetings were associated with poorer outcomes. Multivariate analysis showed that (a) ergonomic problems and impact of work on life predicted higher levels of both Compassion Fatigue and Burnout; (b) impact of life on work was associated with Compassion Fatigue and lower levels of trust and perceiving more risks for the future with Burnout only; (c) perceived quality of meetings, need of training, and perceiving no risks for the future predicted higher levels of Compassion Satisfaction. In order to provide adequate mental health services, service providers need to give their employees adequate ergonomic conditions, giving special attention to time pressures. Building trustful relationships with management and within the teams is also crucial. Training and meetings are other important targets for potential improvement. Additionally, insecurity about the future should be addressed as it can affect both Burnout and Compassion Satisfaction. Finally

Developing measures of fatigue using an alcohol comparison to validate the effects of fatigue on performance.

PubMed

Williamson, A M; Feyer, A M; Mattick, R P; Friswell, R; Finlay-Brown, S

2001-05-01

The effects of 28 h of sleep deprivation were compared with varying doses of alcohol up to 0.1% blood alcohol concentration (BAC) in the same subjects. The study was conducted in the laboratory. Twenty long-haul truck drivers and 19 people not employed as professional drivers acted as subjects. Tests were selected that were likely to be affected by fatigue, including simple reaction time, unstable tracking, dual task, Mackworth clock vigilance test, symbol digit coding, visual search, sequential spatial memory and logical reasoning. While performance effects were seen due to alcohol for all tests, sleep deprivation affected performance on most tests, but had no effect on performance on the visual search and logical reasoning tests. Some tests showed evidence of a circadian rhythm effect on performance, in particular, simple reaction time, dual task, Mackworth clock vigilance, and symbol digit coding, but only for response speed and not response accuracy. Drivers were slower but more accurate than controls on the symbol digit test, suggesting that they took a more conservative approach to performance of this test. This study demonstrated which tests are most sensitive to sleep deprivation and fatigue. The study therefore has established a set of tests that can be used in evaluations of fatigue and fatigue countermeasures.

Fatigue, Creep-Fatigue, and Thermomechanical Fatigue Life Testing of Alloys

NASA Technical Reports Server (NTRS)

Halford, Gary R.; Lerch, Bradley A.; McGaw, Michael A.

2000-01-01

The fatigue crack initiation resistance of an alloy is determined by conducting a series of tests over a range of values of stress amplitude or strain range. The observed number of cycles to failure is plotted against the stress amplitude or strain range to obtain a fatigue curve. The fatigue properties quoted for an alloy are typically the constants used in the equation(s) that describe the fatigue curve. Fatigue lives of interest may be as low as 10(exp 2) or higher than 10(exp 9) cycles. Because of the enormous scatter associated with fatigue, dozens of tests may be needed to confidently establish a fatigue curve, and the cost may run into several thousands of dollars. To further establish the effects on fatigue life of the test temperature, environment, alloy condition, mean stress effects, creep-fatigue effects, thermomechanical cycling, etc. requires an extraordinarily large and usually very costly test matrix. The total effort required to establish the fatigue resistance of an alloy should not be taken lightly. Fatigue crack initiation tests are conducted on relatively small and presumed to be initially crack-free, samples of an alloy that are intended to be representative of the alloy's metallurgical and physical condition. Generally, samples are smooth and have uniformly polished surfaces within the test section. Some may have intentionally machined notches of well-controlled geometry, but the surface at the root of the notch is usually not polished. The purpose of polishing is to attain a reproducible surface finish. This is to eliminate surface finish as an uncontrolled variable. Representative test specimen geometries will be discussed later. Test specimens are cyclically loaded until macroscopically observable cracks initiate and eventually grow to failure. Normally, the fatigue failure life of a specimen is defined as the number of cycles to separation of the specimen into two pieces. Alternative definitions are becoming more common, particularly for

From monoscale to multiscale modeling of fatigue crack growth: Stress and energy density factor

NASA Astrophysics Data System (ADS)

Sih, G. C.

2014-01-01

The formalism of the earlier fatigue crack growth models is retained to account for multiscaling of the fatigue process that involves the creation of macrocracks from the accumulation of micro damage. The effects of at least two scales, say micro to macro, must be accounted for. The same data can thus be reinterpreted by the invariancy of the transitional stress intensity factors such that the microcracking and macrocracking data would lie on a straight line. The threshold associated with the sigmoid curve disappears. Scale segmentation is shown to be a necessity for addressing multiscale energy dissipative processes such as fatigue and creep. Path independency and energy release rate are monoscale criteria that can lead to unphysical results, violating the first principles. Application of monoscale failure or fracture criteria to nanomaterials is taking toll at the expense of manufacturing super strength and light materials and structural components. This brief view is offered in the spirit of much needed additional research for the reinforcement of materials by creating nanoscale interfaces with sustainable time in service. The step by step consideraton at the different scales may offer a better understanding of the test data and their limitations with reference to space and time.

Quantifying the history dependency of muscle recovery from a fatiguing intermittent task.

PubMed

Rashedi, Ehsan; Nussbaum, Maury A

2017-01-25

Muscle fatigue and recovery are complex processes influencing muscle force generation capacity. While fatigue reduces this capacity, recovery acts to restore the unfatigued muscle state. Many factors can potentially affect muscle recovery, and among these may be a task dependency of recovery following an exercise. However, little has been reported regarding the history dependency of recovery after fatiguing contractions. We examined the dependency of muscle recovery subsequent to four different histories of fatiguing muscle contractions, imposed using two cycle times (30 and 60s) during low to moderate levels (15% and 25% of maximum voluntary contraction (MVC)) of intermittent static exertions involving index finger abduction. MVC and low-frequency electrical stimulation (LFES) measures (i.e., magnitude, rise and relaxation rates) of muscle capacity were used, all of which indicated a dependency of muscle recovery on the muscle capacity state existing immediately after fatiguing exercise. This dependency did not appear to be modified by either the cycle time or exertion level leading to that state. These results imply that the post-exercise rate of recovery is primarily influenced by the immediate post-exercise muscle contractile status (estimated by MVC and LFES measures). Such results may help improve existing models of muscle recovery, facilitating more accurate predictions of localized muscle fatigue development and thereby helping to enhance muscle performance and reduce the risk of injury. Copyright © 2016 Elsevier Ltd. All rights reserved.

Development and characterization of fatigue resistant Aramid reinforced aluminium laminates (ARALL) for fatigue Critical aircraft components

NASA Astrophysics Data System (ADS)

Qaiser, M. H.; Umar, S.; Nauman, S.

2014-06-01

The structural weight of an aircraft has always been a controlling parameter that governs its fuel efficiency and transport capacity. In pursuit of achieving light-weight aircraft structures, high design stress levels have to be adopted and materials with high specific strength such as Aluminum etc. are to be deployed. However, an extensive spectrum of fatigue load exists at the aircraft wings and other aerodynamic components that may cause initiation and propagation of fatigue cracks and concludes in a catastrophic rupture. Fatigue is therefore the limiting design parameter in such cases and materials with high fatigue resistance are then required. A major improvement in the fatigue behavior was observed by laminating Kevlar fibers with Aluminum using epoxy. ARALL (Aramid Reinforced ALuminum Laminates) is a fatigue resistant hybrid composite that consists of layers of thin high strength aluminum alloy sheets surface bonded with aramid fibers. The intact aramid fibers tie up the fatigue cracks, thus reducing the stress intensity factor at the crack tip as a result of which the fatigue properties of can be enhanced with orders of magnitude as compared to monolithic high strength Aluminum alloy sheets. Significant amount of weight savings can be achieved in fatigue critical components in comparison with the traditional materials used in aircraft.

Fatigue response of perforated titanium for application in laminar flow control

NASA Technical Reports Server (NTRS)

Johnson, W. Steven; Miller, Jennifer L.; Newman, Jr., James

1996-01-01

The room temperature tensile and fatigue response of non-perforated and perforated titanium for laminar flow control application was investigated both experimentally and analytically. Results showed that multiple perforations did not affect the tensile response, but did reduce the fatigue life. A two dimensional finite element stress analysis was used to determine that the stress fields from adjacent perforations did not influence one another. The stress fields around the holes did not overlap one another, allowing the materials to be modeled as a plate with a center hole. Fatigue life was predicted using an equivalent MW flow size approach to relate the experimental results to microstructural features of the titanium. Predictions using flaw sizes ranging from 1 to 15 microns correlated within a factor of 2 with the experimental results by using a flow stress of 260 MPa. By using two different flow stresses in the crack closure model and correcting for plasticity, the experimental results were bounded by the predictions for high applied stresses. Further analysis of the complex geometry of the perforations and the local material chemistry is needed to further understand the fatigue behavior of the perforated titanium.

The relation between pathological worrying and fatigue in a working population.

PubMed

Andrea, H; Beurskens, A J H M; Kant, Ij; Davey, G C L; Field, A P; van Schayck, C P

2004-10-01

This study aimed to explore cross-sectional and longitudinal associations between pathological worry and fatigue in a working population. In employees with very low or very high fatigue levels, psychometrics of the Penn State Worry Questionnaire (PSWQ; measuring pathological worry) and the Checklist Individual Strength (CIS; measuring fatigue) were examined and their cross-sectional and longitudinal associations were explored. Pathological worry and fatigue can be measured as different constructs. However, pathological worry and fatigue were also associated on a cross-sectional level. Pathological worry predicted fatigue level 10 months later, but this association disappeared after adjustment for the cross-sectional association between pathological worry and fatigue. Although they can be measured as different constructs, pathological worry and fatigue seem to be associated. When studying longitudinal relations between pathological worry and fatigue, their cross-sectional association should be taken into account. Pathological worry might not be a risk factor for fatigue per se, but might act more like a mediating factor.

On Generating Fatigue Crack Growth Thresholds

NASA Technical Reports Server (NTRS)

Forth, Scott C.; Newman, James, Jr.; Forman, Royce G.

2003-01-01

The fatigue crack growth threshold, defining crack growth as either very slow or nonexistent, has been traditionally determined with standardized load reduction methodologies. These experimental procedures can induce load history effects that result in crack closure. This history can affect the crack driving force, i.e. during the unloading process the crack will close first at some point along the wake or blunt at the crack tip, reducing the effective load at the crack tip. One way to reduce the effects of load history is to propagate a crack under constant amplitude loading. As a crack propagates under constant amplitude loading, the stress intensity factor range, Delta K, will increase, as will the crack growth rate. da/dN. A fatigue crack growth threshold test procedure is experimentally validated that does not produce load history effects and can be conducted at a specified stress ratio, R. The authors have chosen to study a ductile aluminum alloy where the plastic deformations generated during testing may be of the magnitude to impact the crack opening.

Effect of flooring on standing comfort and fatigue.

PubMed

Cham, R; Redfern, M S

2001-01-01

This study investigated the influence of flooring on subjective discomfort and fatigue during standing and on potentially related objective measures. Participants stood for 4 h on each of 7 flooring conditions while performing computer tasks. During the 3rd and 4th h, floor type had a significant effect on a number of subjective ratings, including lower-leg and lower-back discomfort/fatigue and 2 of 4 objective variables (center of pressure weight shift and lower-extremity skin temperature). In addition, lower-leg volumetric measurements showed tendencies toward greater lower-extremity swelling on uncomfortable floors. The hard floor and 1 floor mat condition consistently had the worst discomfort/fatigue and objective ratings. Significant relationships were noted between the affected subjective ratings and objective variables. In general, floor mats characterized by increased elasticity, decreased energy absorption, and increased stiffness resulted in less discomfort and fatigue. Thus flooring properties do affect low-back and lower-leg discomfort/fatigue, but the result may be detectable only after 3 h of standing. Potential applications of this research include the reduction of work-related health problems associated with long-term standing.

Chronic fatigue in developing countries: population based survey of women in India.

PubMed

Patel, Vikram; Kirkwood, Betty R; Weiss, Helen; Pednekar, Sulochana; Fernandes, Janice; Pereira, Bernadette; Upadhye, Medha; Mabey, David

2005-05-21

To describe the prevalence of and risk factors for chronic fatigue in a developing country; in particular, to determine the association of anaemia, mental health, and gender disadvantage factors with chronic fatigue. Community survey. Primary health centre catchment area in Goa, India. 3000 randomly sampled women aged 18 to 50 years. Data on the primary outcome (reporting of fatigue for at least six months) and psychosocial exposures elicited by structured interview; presence of anaemia determined from a blood sample. 2494 (83%) women consented to participate; 12.1% (95% confidence interval 10.8 to 13.4%) complained of chronic fatigue. In multivariate analyses, older women (P = 0.03) and those experiencing socioeconomic deprivation-less education (P < 0.001), families in debt (P = 0.09), or hunger in the past three months (P = 0.03)-were more likely to report chronic fatigue. After adjustment for these factors, factors indicating gender disadvantage (notably sexual violence by the husband; P < 0.001) and poor mental health (P < 0.001) were strongly associated with chronic fatigue. Although women with a high body mass index had a reduced risk, suggesting an influence of poor nutrition, no association was found between chronic fatigue and haemoglobin concentrations. Chronic fatigue was commonly reported by women in this community study from India. The strongest associations with chronic fatigue were for psychosocial factors indicative of poor mental health and gender disadvantage.

Selective effect of physical fatigue on motor imagery accuracy.

PubMed

Di Rienzo, Franck; Collet, Christian; Hoyek, Nady; Guillot, Aymeric

2012-01-01

While the use of motor imagery (the mental representation of an action without overt execution) during actual training sessions is usually recommended, experimental studies examining the effect of physical fatigue on subsequent motor imagery performance are sparse and yielded divergent findings. Here, we investigated whether physical fatigue occurring during an intense sport training session affected motor imagery ability. Twelve swimmers (nine males, mean age 15.5 years) conducted a 45 min physically-fatiguing protocol where they swam from 70% to 100% of their maximal aerobic speed. We tested motor imagery ability immediately before and after fatigue state. Participants randomly imagined performing a swim turn using internal and external visual imagery. Self-reports ratings, imagery times and electrodermal responses, an index of alertness from the autonomic nervous system, were the dependent variables. Self-reports ratings indicated that participants did not encounter difficulty when performing motor imagery after fatigue. However, motor imagery times were significantly shortened during posttest compared to both pretest and actual turn times, thus indicating reduced timing accuracy. Looking at the selective effect of physical fatigue on external visual imagery did not reveal any difference before and after fatigue, whereas significantly shorter imagined times and electrodermal responses (respectively 15% and 48% decrease, p<0.001) were observed during the posttest for internal visual imagery. A significant correlation (r=0.64; p<0.05) was observed between motor imagery vividness (estimated through imagery questionnaire) and autonomic responses during motor imagery after fatigue. These data support that unlike local muscle fatigue, physical fatigue occurring during intense sport training sessions is likely to affect motor imagery accuracy. These results might be explained by the updating of the internal representation of the motor sequence, due to temporary

Selective Effect of Physical Fatigue on Motor Imagery Accuracy

PubMed Central

Di Rienzo, Franck; Collet, Christian; Hoyek, Nady; Guillot, Aymeric

2012-01-01

While the use of motor imagery (the mental representation of an action without overt execution) during actual training sessions is usually recommended, experimental studies examining the effect of physical fatigue on subsequent motor imagery performance are sparse and yielded divergent findings. Here, we investigated whether physical fatigue occurring during an intense sport training session affected motor imagery ability. Twelve swimmers (nine males, mean age 15.5 years) conducted a 45 min physically-fatiguing protocol where they swam from 70% to 100% of their maximal aerobic speed. We tested motor imagery ability immediately before and after fatigue state. Participants randomly imagined performing a swim turn using internal and external visual imagery. Self-reports ratings, imagery times and electrodermal responses, an index of alertness from the autonomic nervous system, were the dependent variables. Self-reports ratings indicated that participants did not encounter difficulty when performing motor imagery after fatigue. However, motor imagery times were significantly shortened during posttest compared to both pretest and actual turn times, thus indicating reduced timing accuracy. Looking at the selective effect of physical fatigue on external visual imagery did not reveal any difference before and after fatigue, whereas significantly shorter imagined times and electrodermal responses (respectively 15% and 48% decrease, p<0.001) were observed during the posttest for internal visual imagery. A significant correlation (r = 0.64; p<0.05) was observed between motor imagery vividness (estimated through imagery questionnaire) and autonomic responses during motor imagery after fatigue. These data support that unlike local muscle fatigue, physical fatigue occurring during intense sport training sessions is likely to affect motor imagery accuracy. These results might be explained by the updating of the internal representation of the motor sequence, due to temporary

The effect of muscle fatigue on in vivo tibial strains.

PubMed

Milgrom, Charles; Radeva-Petrova, Denitsa R; Finestone, Aharon; Nyska, Meir; Mendelson, Stephen; Benjuya, Nisim; Simkin, Ariel; Burr, David

2007-01-01

Stress fracture is a common musculoskeletal problem affecting athletes and soldiers. Repetitive high bone strains and strain rates are considered to be its etiology. The strain level necessary to cause fatigue failure of bone ex vivo is higher than the strains recorded in humans during vigorous physical activity. We hypothesized that during fatiguing exercises, bone strains may increase and reach levels exceeding those measured in the non-fatigued state. To test this hypothesis, we measured in vivo tibial strains, the maximum gastrocnemius isokinetic torque and ground reaction forces in four subjects before and after two fatiguing levels of exercise: a 2km run and a 30km desert march. Strains were measured using strain-gauged staples inserted percutaneously in the medial aspect of their mid-tibial diaphysis. There was a decrease in the peak gastrocnemius isokinetic torque of all four subjects' post-march as compared to pre-run (p=0.0001), indicating the presence of gastrocnemius muscle fatigue. Tension strains increased 26% post-run (p=0.002, 95 % confidence interval (CI) and 29% post-march (p=0.0002, 95% CI) as compared to the pre-run phase. Tension strain rates increased 13% post-run (p=0.001, 95% CI) and 11% post-march (p=0.009, 95% CI) and the compression strain rates increased 9% post-run (p=0.0004, 95% CI) and 17% post-march (p=0.0001, 95% CI). The fatigue state increases bone strains well above those recorded in rested individuals and may be a major factor in the stress fracture etiology.

Cognitive and Physical Fatigue Tasks Enhance Pain, Cognitive Fatigue and Physical Fatigue in People with Fibromyalgia

PubMed Central

Dailey, Dana L; Keffala, Valerie J; Sluka, Kathleen A

2014-01-01

Objective Fibromyalgia is a condition characterized by chronic widespread muscle pain and fatigue. The primary objective of this study was to determine if pain, perceived cognitive fatigue, and perceived physical fatigue were enhanced in participants with fibromyalgia compared to healthy controls during a cognitive fatigue task, a physical fatigue task and a dual fatigue task. Methods Twenty four people with fibromyalgia and 33 healthy controls completed pain, fatigue and function measures. A cognitive fatigue task (Controlled Oral Word Association Test) and physical fatigue task (Valpar peg test) were done individually and combined for a dual fatigue task. Resting pain, perceived cognitive fatigue and perceived physical fatigue were assessed during each task using visual analogue scales. Function was assessed with shoulder range of motion and grip. Results People with fibromyalgia had significantly higher increases in pain, cognitive fatigue and physical fatigue when compared to healthy controls after completion of a cognitive fatigue task, a physical fatigue task, or a dual fatigue task (p<0.01). People with fibromyalgia performed equivalently on measures of physical performance and cognitive performance on the physical and cognitive fatigue tasks, respectively. Conclusions These data show that people with fibromyalgia show larger increases in pain, perceived cognitive fatigue and perceived physical fatigue to both cognitive and physical fatigue tasks compared to healthy controls. The increases in pain and fatigue during cognitive and physical fatigue tasks could influence subject participation in daily activities and rehabilitation. PMID:25074583

Exercise and fatigue.

PubMed

Ament, Wim; Verkerke, Gijsbertus J

2009-01-01

Physical exercise affects the equilibrium of the internal environment. During exercise the contracting muscles generate force or power and heat. So physical exercise is in fact a form of mechanical energy. This generated energy will deplete the energy stocks within the body. During exercise, metabolites and heat are generated, which affect the steady state of the internal environment. Depending on the form of exercise, sooner or later sensations of fatigue and exhaustion will occur. The physiological role of these sensations is protection of the exercising subject from the deleterious effects of exercise. Because of these sensations the subject will adapt his or her exercise strategy. The relationship between physical exercise and fatigue has been the scope of interest of many researchers for more than a century and is very complex. The exercise intensity, exercise endurance time and type of exercise are all variables that cause different effects within the body systems, which in turn create different types of sensation within the subject's mind during the exercise. Physical exercise affects the biochemical equilibrium within the exercising muscle cells. Among others, inorganic phosphate, protons, lactate and free Mg2+ accumulate within these cells. They directly affect the mechanical machinery of the muscle cell. Furthermore, they negatively affect the different muscle cell organelles that are involved in the transmission of neuronal signals. The muscle metabolites produced and the generated heat of muscle contraction are released into the internal environment, putting stress on its steady state. The tremendous increase in muscle metabolism compared with rest conditions induces an immense increase in muscle blood supply, causing an increase in the blood circulatory system and gas exchange. Nutrients have to be supplied to the exercising muscle, emptying the energy stocks elsewhere in body. Furthermore, the contracting muscle fibres release cytokines, which in

Fatigue associated with newly approved vascular endothelial growth factor receptor tyrosine kinase inhibitors in cancer patients: an up-to-date meta-analysis.

PubMed

Li, Jing; Gu, Jian

2017-10-01

The fatigue associated with five newly approved vascular endothelial growth factor receptor tyrosine kinase inhibitors (VEGFR-TKIs) (regorafenib, vandetanib, cabozantinib, lenvatinib, axitinib) is poorly understood. We conducted this systematic review to fully investigate the fatigue associated with these VEGFR-TKIs in cancer patients. Relevant studies of randomized controlled trials in cancer patients treated with the five VEGFR-TKIs were retrieved and a systematic evaluation was conducted. EMBASE, MEDLINE, and PubMed were searched for articles published until March 2017. Thirteen randomized controlled trials and 4395 patients were included. The current analysis suggested that the use of five newly approved VEGFR-TKIs increased the risk of all-grade fatigue (1.43; 95% CI 1.23-1.66; p < 0.00001) and high-grade (≥grade 3) fatigue (1.97; 95% CI1.44-2.70; p < 0.0001). On subgroup analysis, the risk ratio (RR) of all-grade fatigue varied significantly within drug type, but high-grade fatigue did not. The RR of all-grade and high-grade fatigue did not vary significantly according to cancer type, treatment line, and treatment duration. The risk of high-grade fatigue may vary with treatment duration, whereas all-grade fatigue may not. The available data suggest that the use of the five newly approved VEGFR-TKIs is associated with a significantly increased risk of fatigue in cancer patients. Physicians should be aware of this adverse effect and should monitor cancer patients receiving these drugs.

Inspiratory muscle fatigue affects latissimus dorsi but not pectoralis major activity during arms only front crawl sprinting.

PubMed

Lomax, Mitch; Tasker, Louise; Bostanci, Ozgur

2014-08-01

The purpose of this study was to determine whether inspiratory muscle fatigue (IMF) affects the muscle activity of the latissimus dorsi and pectoralis major during maximal arms only front crawl swimming. Eight collegiate swimmers were recruited to perform 2 maximal 20-second arms only front crawl sprints in a swimming flume. Both sprints were performed on the same day, and IMF was induced 30 minutes after the first (control) sprint. Maximal inspiratory and expiratory mouth pressures (PImax and PEmax, respectively) were measured before and after each sprint. The median frequency (MDF) of the electromyographic signal burst was recorded from the latissimus dorsi and pectoralis major during each 20-second sprint along with stroke rate and breathing frequency. Median frequency was assessed in absolute units (Hz) and then referenced to the start of the control sprint for normalization. After IMF inducement, stroke rate increased from 56 ± 4 to 59 ± 5 cycles per minute, and latissimus dorsi MDF fell from 67 ± 11 Hz at the start of the sprint to 61 ± 9 Hz at the end. No change was observed in the MDF of the latissimus dorsi during the control sprint. Conversely, the MDF of the pectoralis major shifted to lower frequencies during both sprints but was unaffected by IMF. As the latter induced fatigue in the latissimus dorsi, which was not otherwise apparent during maximal arms only control sprinting, the presence of IMF affects the activity of the latissimus dorsi during front crawl sprinting.

Fatigue mitigation effects of en-route napping on commercial airline pilots flying international routes

NASA Astrophysics Data System (ADS)

Baldwin, Jarret Taylor

The introduction of ultra-long range commercial aircraft and the evolution of the commercial airline industry has provided new opportunities for air carriers to fly longer range international route segments while deregulation, industry consolidation, and the constant drive to reduce costs wherever possible has pressured airline managements to seek more productivity from their pilots. At the same time, advancements in the understanding of human physiology have begun to make their way into flight and duty time regulations and airline scheduling practices. In this complex and ever changing operating environment, there remains an essential need to better understand how these developments, and other daily realities facing commercial airline pilots, are affecting their fatigue management strategies as they go about their rituals of getting to and from their homes to work and performing their flight assignments. Indeed, the need for commercial airline pilots to have access to better and more effective fatigue mitigation tools to combat fatigue and insure that they are well rested and at the top of their game when flying long-range international route segments has never been greater. This study examined to what extent the maximum fatigue states prior to napping, as self-accessed by commercial airline pilots flying international route segments, were affected by a number of other common flight assignment related factors. The study also examined to what extent the availability of scheduled en-route rest opportunities, in an onboard crew rest facility, affected the usage of en-route napping as a fatigue mitigation strategy, and to what extent the duration of such naps affected the perceived benefits of such naps as self-accessed by commercial airline pilots flying international route segments. The study utilized an online survey tool to collect data on crew position, prior flight segments flown in the same duty period, augmentation, commuting, pre-flight rest obtained in the

Shared responsibility for managing fatigue: Hearing the pilots

PubMed Central

O’Keeffe, Karyn M.; Signal, T. Leigh; Gander, Philippa H.

2018-01-01

In commercial aviation, fatigue is defined as a physiological state of reduced mental or physical performance capability resulting from sleep loss, extended wakefulness, circadian phase, and/or workload. The International Civil Aviation Organisation mandates that responsibility for fatigue risk management is shared between airline management, pilots, and support staff. However, to date, the majority of research relating to fatigue mitigations in long range operations has focused on the mitigations required or recommended by regulators and operators. Little research attention has been paid to the views or operational experience of the pilots who use these (or other) mitigations. This study focused on pilots’ views and experiences of in-flight sleep as the primary fatigue mitigation on long range flights. It also sought information about other fatigue mitigation strategies they use. Thematic analysis was used to explore written comments from diary and survey data collected during long range and ultra-long range trips (N = 291 pilots on three different aircraft types, 17 different out-and-back trips, and four airlines based on three continents). The findings indicate that the recommended fatigue mitigation strategies on long-haul flights (particularly in-flight sleep) are effective and well-utilised, consistent with quantitative findings from the same trips. Importantly however, the analyses also highlight areas that require further investigation, including flight preparation strategies in relation to the uncertainty of in-flight break allocation. There were two strategies for sleep prior to a flight: maximising sleep if pilots were expecting later breaks in the flight; or minimising sleep if they were expecting breaks earlier or at unfavourable times in the circadian cycle. They also provide a broader view of the factors that affect the amount and quality of pilots’ in-flight sleep, about which evidence has previously been largely anecdotal. The study underscores

The Effects of Fracture Origin Size on Fatigue Properties of Ductile Cast Iron with Small Chill Structures

NASA Astrophysics Data System (ADS)

Sameshima, Daigo; Nakamura, Takashi; Horikawa, Noritaka; Oguma, Hiroyuki; Endo, Takeshi

Reducing the weight of a machine structure is an increasingly important consideration both for the conservation of resources during production and for the energy saving during operation. With these objectives in mind, thin-walled ductile cast iron has recently been developed. Because rapid cooling could result in brittle microstructure of cementite (chill) in this cast iron, it is necessary to investigate the effect of cementite on the fatigue properties. Therefore, fatigue tests were carried out on a ductile cast iron of block castings which contained a relatively small amount of cementite. Fracture surface observation indicated that the fracture origins were located at graphite clusters and cast shrinkage porosity, not at cementite. It appears that when the size of the cementite is smaller than that of the graphite, the cementite does not affect the fatigue properties of ductile cast iron. Not surprisingly, the fatigue lives were found to increase with decrease in the size of the fatigue fracture origin. The threshold initial stress intensity factor range ΔKini,th for fatigue failure was found to be about 3-4MPa√m, independent of microstructure.

Fatigue Crack Growth Characteristics of Thin Sheet Titanium Alloy Ti 6-2-2-2-2

NASA Technical Reports Server (NTRS)

Smith, Stephen W.; Piascik, Robert S.

2001-01-01

Fatigue crack growth rates of Ti 6-2-2-2-2 as a function of stress ratio, temperature (24 or 177 C), tensile orientation and environment (laboratory air or ultrahigh vacuum) are presented. Fatigue crack growth rates of Ti 6-2-2-2-2 are also compared with two more widely used titanium alloys (Timetal 21S and Ti 6Al-4V). The fatigue crack growth rate (da/dN) of Ti 6-2-2-2-2 in laboratory air is dependent upon stress ratio (R), particularly in the near-threshold and lower-Paris regimes. For low R (less than approximately 0.5), da/dN is influenced by crack closure behavior. At higher R (> 0.5), a maximum stress-intensity factor (K(sub max)) dependence is observed. Fatigue crack growth behavior is affected by test temperature between 24 and 177 C. For moderate to high applied cyclic-stress-intensity factors (delta-K), the slope of the log da/dN versus log delta-K curve is lower in 177 C laboratory air than 24 C laboratory air. The difference in slope results in lower values of da/dN for exposure to 177 C laboratory air compared to room temperature laboratory air. The onset of this temperature effect is dependent upon the applied R. This temperature effect has not been observed in ultrahigh vacuum. Specimen orientation has been shown to affect the slope of the log da/dN versus log delta-K curve in the Paris regime.

Factors affecting construction performance: exploratory factor analysis

NASA Astrophysics Data System (ADS)

Soewin, E.; Chinda, T.

2018-04-01

The present work attempts to develop a multidimensional performance evaluation framework for a construction company by considering all relevant measures of performance. Based on the previous studies, this study hypothesizes nine key factors, with a total of 57 associated items. The hypothesized factors, with their associated items, are then used to develop questionnaire survey to gather data. The exploratory factor analysis (EFA) was applied to the collected data which gave rise 10 factors with 57 items affecting construction performance. The findings further reveal that the items constituting ten key performance factors (KPIs) namely; 1) Time, 2) Cost, 3) Quality, 4) Safety & Health, 5) Internal Stakeholder, 6) External Stakeholder, 7) Client Satisfaction, 8) Financial Performance, 9) Environment, and 10) Information, Technology & Innovation. The analysis helps to develop multi-dimensional performance evaluation framework for an effective measurement of the construction performance. The 10 key performance factors can be broadly categorized into economic aspect, social aspect, environmental aspect, and technology aspects. It is important to understand a multi-dimension performance evaluation framework by including all key factors affecting the construction performance of a company, so that the management level can effectively plan to implement an effective performance development plan to match with the mission and vision of the company.

Fatigue Risk Management: A Maritime Framework

PubMed Central

Grech, Michelle Rita

2016-01-01

It is evident that despite efforts directed at mitigating the risk of fatigue through the adoption of hours of work and rest regulations and development of codes and guidelines, fatigue still remains a concern in shipping. Lack of fatigue management has been identified as a contributory factor in a number of recent accidents. This is further substantiated through research reports with shortfalls highlighted in current fatigue management approaches. These approaches mainly focus on prescriptive hours of work and rest and include an individualistic approach to managing fatigue. The expectation is that seafarers are responsible to manage and tolerate fatigue as part of their working life at sea. This attitude is an accepted part of a seafarer’s role. Poor compliance is one manifest of this problem with shipboard demands making it hard for seafarers to follow hours of work and rest regulations, forcing them into this “poor compliance” trap. This makes current fatigue management approaches ineffective. This paper proposes a risk based approach and way forward for the implementation of a fatigue risk management framework for shipping, aiming to support the hours of work and rest requirements. This forms part of the work currently underway to review and update the International Maritime Organization, Guidelines on Fatigue. PMID:26840326

Fatigue Risk Management: A Maritime Framework.

PubMed

Grech, Michelle Rita

2016-01-29

It is evident that despite efforts directed at mitigating the risk of fatigue through the adoption of hours of work and rest regulations and development of codes and guidelines, fatigue still remains a concern in shipping. Lack of fatigue management has been identified as a contributory factor in a number of recent accidents. This is further substantiated through research reports with shortfalls highlighted in current fatigue management approaches. These approaches mainly focus on prescriptive hours of work and rest and include an individualistic approach to managing fatigue. The expectation is that seafarers are responsible to manage and tolerate fatigue as part of their working life at sea. This attitude is an accepted part of a seafarer's role. Poor compliance is one manifest of this problem with shipboard demands making it hard for seafarers to follow hours of work and rest regulations, forcing them into this "poor compliance" trap. This makes current fatigue management approaches ineffective. This paper proposes a risk based approach and way forward for the implementation of a fatigue risk management framework for shipping, aiming to support the hours of work and rest requirements. This forms part of the work currently underway to review and update the International Maritime Organization, Guidelines on Fatigue.

A central factor in pure tone auditory fatigue.

DOT National Transportation Integrated Search

1963-09-01

A long accumulation of psychophysical and physiological evidence indicates that auditory fatigue has its locus of effect in the cochlea; transfer studies with negative or questionable results, and studies of cochlear chemistry and potentials with pos...

Interpolated twitches in fatiguing single mouse muscle fibres: implications for the assessment of central fatigue

PubMed Central

Place, Nicolas; Yamada, Takashi; Bruton, Joseph D; Westerblad, Håkan

2008-01-01

An electrically evoked twitch during a maximal voluntary contraction (twitch interpolation) is frequently used to assess central fatigue. In this study we used intact single muscle fibres to determine if intramuscular mechanisms could affect the force increase with the twitch interpolation technique. Intact single fibres from flexor digitorum brevis of NMRI mice were dissected and mounted in a chamber equipped with a force transducer. Free myoplasmic [Ca2+] ([Ca2+]i) was measured with the fluorescent Ca2+ indicator indo-1. Seven fibres were fatigued with repeated 70 Hz tetani until 40% initial force with an interpolated pulse evoked every fifth tetanus. Results showed that the force generated by the interpolated twitch increased throughout fatigue, being 9 ± 1% of tetanic force at the start and 19 ± 1% at the end (P < 0.001). This was not due to a larger increase in [Ca2+]i induced by the interpolated twitch during fatigue but rather to the fact that the force–[Ca2+]i relationship is sigmoidal and fibres entered a steeper part of the relationship during fatigue. In another set of experiments, we observed that repeated tetani evoked at 150 Hz resulted in more rapid fatigue development than at 70 Hz and there was a decrease in force (‘sag’) during contractions, which was not observed at 70 Hz. In conclusion, the extent of central fatigue is difficult to assess and it may be overestimated when using the twitch interpolation technique. PMID:18403421

Fatigue and associated performance decrements in air transport operations

NASA Technical Reports Server (NTRS)

Lyman, E. G.; Orlady, H. W.

1981-01-01

A study of safety reports was conducted to examine the hypothesis that fatigue and associated performance decrements occur in air transport operations, and that these are associated with some combination of factors: circadian desynchronosis, duty time; pre-duty activity; sleep; work scheduling; workload; and environmental deprivation. The findings are based on a selected sample of reported incidents in which the reporter associated fatigue with the occurrence. In comparing the fatigue reports with a control set, significant performance decrements were found to exist related to time-of-day, awareness and attention to duty, less significantly, final phases of flights. The majority of the fatigue incidents involved such unsafe events as altitude deviations, takeoffs and landing without clearance, and the like. Considerations of duty and sleep are the major factors in the reported fatigue conditions.

Recent Developments in Assessing Microstructure-Sensitive Early Stage Fatigue of Polycrystals (Postprint)

DTIC Science & Technology

2014-04-01

can strongly affect formation of fatigue cracks. El Bartali et al. [7] quantified plastic strain at the grain scale in a duplex stainless steel and mea... Fatigue Fract Eng Mater Struct 2013. [7] El Bartali A, Aubin V, Degallaix S. Fatigue damage analysis in a duplex stainless steel by digital image...S. Surface observation and measurement techniques to study the fatigue damage micromechanisms in a duplex stainless steel . Int J Fatigue 2009;31:2049

Experimental characterization of fatigue strength in butt welded joint considering the geometry and the effect of cooling rate of the weld

NASA Astrophysics Data System (ADS)

Arzola, Nelson; Hernández, Edgar

2017-05-01

In this work the experimental characterization of fatigue strength in butt welded joints considering the geometry and the post-weld cooling cycle was performed. ASTM A-36 structural steel was used as the base metal for the shielded metal arc welding process, with welding electrode E6013. Two experimental factors were established: weld bead geometry and the post-weld cooling rate. Two levels for each factor, the welding reinforcement (1 and 3 mm), and the rate of cooling, slow (quiet air) and fast (immersion in water) are evaluated respectively. For the uniaxial fatigue tests, 8 samples were selected for each treatment for a total of 32 specimens. The mechanical and fractomechanical properties of fusion zone, heat affected zone and base metal in relation to the analysis of failure mechanisms were analysed. The fatigue crack growth rates were estimated based on the counting of microstrations. Furthermore, experimental tests, such as uniaxial tension, microindentation hardness, Charpy impact and metallographic analysis, were made to know the influence of the experimental factors in the fatigue strength. On this research, about the 78.13% of the samples obtained a resistance higher than the recommended one by class FAT 100. The results showed that the geometry of the joint is the factor of greatest influence on fatigue strength for butt welded joints; the greater the weld reinforcement the lower the fatigue strength of the joint. Although it is also important to consider other geometric factors of less impact as it is the weld toe radius and the welding chord width.

Fatigue in Younger and Older Drivers: Effectiveness of an Alertness-Maintaining Task.

PubMed

Song, Woojin; Woon, Fu L; Doong, Alice; Persad, Carol; Tijerina, Louis; Pandit, Pooja; Cline, Carol; Giordani, Bruno

2017-09-01

The aim of this study was to examine the effects of an alertness-maintaining task (AMT) in older, fatigued drivers. Fatigue during driving increases crash risk, and previous research suggests that alertness and driving in younger adults may be improved using a secondary AMT during boring, fatigue-eliciting drives. However, the potential impact of an AMT on driving has not been investigated in older drivers whose ability to complete dual tasks has been shown to decline and therefore may be negatively affected with an AMT in driving. Younger ( n = 29) and older drivers ( n = 39) participated in a 50-minute simulated drive designed to induce fatigue, followed by four 10-minute sessions alternating between driving with and without an AMT. Younger drivers were significantly more affected by fatigue on driving performance than were older drivers but benefitted significantly from the AMT. Older drivers did not demonstrate increased driver errors with fatigue, and driving did not deteriorate significantly during participation in the AMT condition, although their speed was significantly more variable with the AMT. Consistent with earlier research, an AMT applied during fatiguing driving is effective in improving alertness and reducing driving errors in younger drivers. Importantly, older drivers were relatively unaffected by fatigue, and use of an AMT did not detrimentally affect their driving performance. These results support the potential use of an AMT as a new automotive technology to improve fatigue and promote driver safety, though the benefits of such technology may differ between different age groups.

Factors Affecting Medical Service Quality.

PubMed

Mosadeghrad, Ali Mohammad

2014-02-01

A better understanding of factors influencing quality of medical service can pinpoint better strategies for quality assurance in medical services. This study aimed to identify factors affecting the quality of medical services provided by Iranian physicians. Exploratory in-depth individual interviews were conducted with sixty-four physicians working in various medical institutions in Iran. Individual, organizational and environmental factors enhance or inhibit the quality of medical services. Quality of medical services depends on the personal factors of the physician and patient, and factors pertaining to the healthcare setting and the broader environment. Differences in internal and external factors such as availability of resources, patient cooperation and collaboration among providers affect the quality of medical services and patient outcomes. Supportive leadership, proper planning, education and training and effective management of resources and processes improve the quality of medical services. This article contributes to healthcare theory and practice by developing a conceptual framework for understanding factors that influence medical services quality.

Physiological signal analysis for fatigue level of experienced and inexperienced drivers.

PubMed

Li, Rui; Su, Wencheng; Lu, Zhangping

2017-02-17

We studied the changes in driving fatigue levels of experienced and inexperienced drivers at 3 periods of the day: 9:00 a.m.-12:00 p.m., 12:00 p.m.-2:00 p.m., and 4:00 p.m.-6:00 p.m. Thirty drivers were involved in 120-min real-car driving, and sleepiness ratings (Stanford Sleepiness Scale, SSS; Hoddes et al. 1973 ), electroencephalogram (EEG) signals, and heart rates (HRs) were recorded. Together with principal component analysis, the relationship between EEG signals and HR was explored and used to determine a comprehensive indicator of driving fatigue. Then the comprehensive indicator was assessed via paired t test. Experienced and inexperienced drivers behaved significantly differently in terms of subjective fatigue during preliminary trials. At the beginning of trials and after termination, subjective fatigue level was aggravated with prolonged continuous driving. Moreover, we discussed the changing rules of EEG signals and HR and found that with prolonged time, the ratios of δ and β waves significantly declined, whereas that of the θ wave significantly rose. The ratio of (α + θ)/β significantly rose both before trials and after termination, but HR dropped significantly. However, one-factor analysis of variance shows that driving experience significantly affects the θ wave, (α + θ)/β ratio, and HR. We found that in a monotonous road environment, fatigue symptoms occurred in inexperienced drivers and experienced drivers after about 60 and 80 min of continuous driving, respectively. Therefore, as for drivers with different experiences, restriction on continuous driving time would avoid fatigued driving and thereby eliminate traffic accidents. We find that the comprehensive indicator changes significantly with fatigue level. The integration of different indicators improves the recognition accuracy of different driving fatigue levels.

Cues of Fatigue: Effects of Sleep Deprivation on Facial Appearance

PubMed Central

Sundelin, Tina; Lekander, Mats; Kecklund, Göran; Van Someren, Eus J. W.; Olsson, Andreas; Axelsson, John

2013-01-01

Study Objective: To investigate the facial cues by which one recognizes that someone is sleep deprived versus not sleep deprived. Design: Experimental laboratory study. Setting: Karolinska Institutet, Stockholm, Sweden. Participants: Forty observers (20 women, mean age 25 ± 5 y) rated 20 facial photographs with respect to fatigue, 10 facial cues, and sadness. The stimulus material consisted of 10 individuals (five women) photographed at 14:30 after normal sleep and after 31 h of sleep deprivation following a night with 5 h of sleep. Measurements: Ratings of fatigue, fatigue-related cues, and sadness in facial photographs. Results: The faces of sleep deprived individuals were perceived as having more hanging eyelids, redder eyes, more swollen eyes, darker circles under the eyes, paler skin, more wrinkles/fine lines, and more droopy corners of the mouth (effects ranging from b = +3 ± 1 to b = +15 ± 1 mm on 100-mm visual analog scales, P < 0.01). The ratings of fatigue were related to glazed eyes and to all the cues affected by sleep deprivation (P < 0.01). Ratings of rash/eczema or tense lips were not significantly affected by sleep deprivation, nor associated with judgements of fatigue. In addition, sleep-deprived individuals looked sadder than after normal sleep, and sadness was related to looking fatigued (P < 0.01). Conclusions: The results show that sleep deprivation affects features relating to the eyes, mouth, and skin, and that these features function as cues of sleep loss to other people. Because these facial regions are important in the communication between humans, facial cues of sleep deprivation and fatigue may carry social consequences for the sleep deprived individual in everyday life. Citation: Sundelin T; Lekander M; Kecklund G; Van Someren EJW; Olsson A; Axelsson J. Cues of fatigue: effects of sleep deprivation on facial appearance. SLEEP 2013;36(9):1355-1360. PMID:23997369

Probabilistic fatigue methodology for six nines reliability

NASA Technical Reports Server (NTRS)

Everett, R. A., Jr.; Bartlett, F. D., Jr.; Elber, Wolf

1990-01-01

Fleet readiness and flight safety strongly depend on the degree of reliability that can be designed into rotorcraft flight critical components. The current U.S. Army fatigue life specification for new rotorcraft is the so-called six nines reliability, or a probability of failure of one in a million. The progress of a round robin which was established by the American Helicopter Society (AHS) Subcommittee for Fatigue and Damage Tolerance is reviewed to investigate reliability-based fatigue methodology. The participants in this cooperative effort are in the U.S. Army Aviation Systems Command (AVSCOM) and the rotorcraft industry. One phase of the joint activity examined fatigue reliability under uniquely defined conditions for which only one answer was correct. The other phases were set up to learn how the different industry methods in defining fatigue strength affected the mean fatigue life and reliability calculations. Hence, constant amplitude and spectrum fatigue test data were provided so that each participant could perform their standard fatigue life analysis. As a result of this round robin, the probabilistic logic which includes both fatigue strength and spectrum loading variability in developing a consistant reliability analysis was established. In this first study, the reliability analysis was limited to the linear cumulative damage approach. However, it is expected that superior fatigue life prediction methods will ultimately be developed through this open AHS forum. To that end, these preliminary results were useful in identifying some topics for additional study.

Breast cancer and fatigue: issues for the workplace.

PubMed

Mock, V

1998-09-01

1. Women with breast cancer are at high risk for fatigue as a side effect of treatment with surgery, radiation, and chemotherapy. The risk is compounded by the multiple roles of women who return to work during treatment. 2. The fatigue experience includes a physical component of decreased functional status, an affective component of emotional distress, and a cognitive component of difficulty concentrating. These characteristics of fatigue may present significant challenges for employees. 3. The Family Medical Leave Act provides 12 weeks of unpaid leave to receive medical treatment and/or recover from treatment for breast cancer. 4. The nurse in the workplace can assess and monitor the effects of fatigue and teach employees to manage fatigue through energy conservation, effective use of energy, and health promotion activities to restore energy levels.

Anomolous Fatigue Crack Growth Phenomena in High-Strength Steel

NASA Technical Reports Server (NTRS)

Forth, Scott C.; James, Mark A.; Johnston, William M., Jr.; Newman, James C., Jr.

2004-01-01

The growth of a fatigue crack through a material is the result of a complex interaction between the applied loading, component geometry, three-dimensional constraint, load history, environment, material microstructure and several other factors. Previous studies have developed experimental and computational methods to relate the fatigue crack growth rate to many of the above conditions, with the intent of discovering some fundamental material response, i.e. crack growth rate as a function of something. Currently, the technical community uses the stress intensity factor solution as a simplistic means to relate fatigue crack growth rate to loading, geometry and all other variables. The stress intensity factor solution is a very simple linear-elastic representation of the continuum mechanics portion of crack growth. In this paper, the authors present fatigue crack growth rate data for two different high strength steel alloys generated using standard methods. The steels exhibit behaviour that appears unexplainable, compared to an aluminium alloy presented as a baseline for comparison, using the stress intensity factor solution.

Fatigue life and crack growth prediction methodology

NASA Technical Reports Server (NTRS)

Newman, J. C., Jr.; Phillips, E. P.; Everett, R. A., Jr.

1993-01-01

The capabilities of a plasticity-induced crack-closure model and life-prediction code to predict fatigue crack growth and fatigue lives of metallic materials are reviewed. Crack-tip constraint factors, to account for three-dimensional effects, were selected to correlate large-crack growth rate data as a function of the effective-stress-intensity factor range (delta(K(sub eff))) under constant-amplitude loading. Some modifications to the delta(K(sub eff))-rate relations were needed in the near threshold regime to fit small-crack growth rate behavior and endurance limits. The model was then used to calculate small- and large-crack growth rates, and in some cases total fatigue lives, for several aluminum and titanium alloys under constant-amplitude, variable-amplitude, and spectrum loading. Fatigue lives were calculated using the crack growth relations and microstructural features like those that initiated cracks. Results from the tests and analyses agreed well.

Mental Fatigue and Physical and Cognitive Performance During a 2-Bout Exercise Test.

PubMed

Vrijkotte, Susan; Meeusen, Romain; Vandervaeren, Cloe; Buyse, Luk; Cutsem, Jeroen van; Pattyn, Nathalie; Roelands, Bart

2018-04-01

The 2-bout exercise protocol has been developed to diagnose nonfunctional overreaching and the "overtraining syndrome." It consists of 2 maximal exercise bouts separated by 4 hours. Mental fatigue negatively influences performance, but the effects of its occurrence during the 2-bout exercise protocol have never been investigated. The aim of this study was to examine whether mental fatigue (induced during the rest period) influences physical and cognitive performance during/after the second exercise bout of the 2-bout exercise protocol. Nine healthy, well-trained male cyclists participated in a single-blind, randomized, placebo-controlled crossover study. The intervention consisted of either 1.5-hour rest (control) or performing a computer-based Stroop task to induce mental fatigue. Cognitive (Eriksen Flanker task), physiological (lactate, maximum heart rate, and maximum wattage), and subjective data (mental fatigue-visual analog scale, Profile of Mood States, and rating of perceived exertion) were gathered. Ratings of fatigue, tension, and mental fatigue were affected in the mental fatigue condition (P < .05). Neither physiological nor cognitive differences were found between conditions. Ratings of mental fatigue were already affected after the first maximum exercise test (P < .05). Neither physical nor cognitive performance was affected by mental fatigue, but subjective ratings did reveal significant differences. It is recommended to exclude mentally challenging tasks during the 2-bout exercise protocol rest period to ascertain unaffected subjective test results. This study should be repeated in athletes diagnosed with nonfunctional overreaching/overtraining syndrome.

14 CFR 27.571 - Fatigue evaluation of flight structure.

Code of Federal Regulations, 2010 CFR

2010-01-01

... § 27.309, except that maneuvering load factors need not exceed the maximum values expected in operation... paragraph (a)(3) of this section. (b) Fatigue tolerance evaluation. It must be shown that the fatigue tolerance of the structure ensures that the probability of catastrophic fatigue failure is extremely remote...

Interactive processes link the multiple symptoms of fatigue in sport competition.

PubMed

Knicker, Axel J; Renshaw, Ian; Oldham, Anthony R H; Cairns, Simeon P

2011-04-01

Muscle physiologists often describe fatigue simply as a decline of muscle force and infer this causes an athlete to slow down. In contrast, exercise scientists describe fatigue during sport competition more holistically as an exercise-induced impairment of performance. The aim of this review is to reconcile the different views by evaluating the many performance symptoms/measures and mechanisms of fatigue. We describe how fatigue is assessed with muscle, exercise or competition performance measures. Muscle performance (single muscle test measures) declines due to peripheral fatigue (reduced muscle cell force) and/or central fatigue (reduced motor drive from the CNS). Peak muscle force seldom falls by >30% during sport but is often exacerbated during electrical stimulation and laboratory exercise tasks. Exercise performance (whole-body exercise test measures) reveals impaired physical/technical abilities and subjective fatigue sensations. Exercise intensity is initially sustained by recruitment of new motor units and help from synergistic muscles before it declines. Technique/motor skill execution deviates as exercise proceeds to maintain outcomes before they deteriorate, e.g. reduced accuracy or velocity. The sensation of fatigue incorporates an elevated rating of perceived exertion (RPE) during submaximal tasks, due to a combination of peripheral and higher CNS inputs. Competition performance (sport symptoms) is affected more by decision-making and psychological aspects, since there are opponents and a greater importance on the result. Laboratory based decision making is generally faster or unimpaired. Motivation, self-efficacy and anxiety can change during exercise to modify RPE and, hence, alter physical performance. Symptoms of fatigue during racing, team-game or racquet sports are largely anecdotal, but sometimes assessed with time-motion analysis. Fatigue during brief all-out racing is described biomechanically as a decline of peak velocity, along with altered

Fatigue in children with cancer at the end of life.

PubMed

Ullrich, Christina K; Dussel, Veronica; Hilden, Joanne M; Sheaffer, Jan W; Moore, Caron L; Berde, Charles B; Wolfe, Joanne

2010-10-01

Fatigue is a prevalent source of suffering in children with advanced cancer; yet, little is known about it. This study aimed to describe fatigue experienced by children with advanced cancer and to identify the factors associated with suffering from fatigue and its treatment. A retrospective cross-sectional study of 141 parents of children who died of cancer (response rate: 64%) was conducted in two tertiary-level U.S. pediatric hospitals. By parent report, 96% of children experienced fatigue in the last month of life. Nearly 50% experienced significant suffering from fatigue; this was associated with suffering from pain, dyspnea, anorexia, nausea/vomiting, diarrhea, anxiety, sadness, or fear (P<0.05), and with side effects from pain or dyspnea treatment (P<0.05). In multivariate analysis of symptom-related factors, suffering from nausea/vomiting (odds ratio [OR]=3.93, 95% confidence interval [CI]=1.23-12.61, P=0.02); anorexia (OR=7.52, 95% CI=1.87-30.25, P=0.005); and fear (OR=5.13, 95% CI=2.03-12.96, P ≤ 0.001) remained independently associated with fatigue. Children suffering from fatigue had primary oncologists with fewer years' experience than children who did not suffer from fatigue (mean=7.7 years, standard deviation [SD]=4.9 vs. mean of 9.9 years, SD=6.0, P=0.02). Among children with fatigue, 17 of 129 (13%) received fatigue-directed treatment, which was successful in 3 of 12 (25%). Children experiencing side effects from dyspnea or pain treatment were more likely to be treated for fatigue (relative risk=1.25, 95% CI=1.06-1.47, P=0.009). Fatigue is a common source of suffering in children with cancer at the end of life. Palliation of this symptom is rarely successful. Increased attention to factors associated with fatigue and effective interventions to ameliorate fatigue are needed. Copyright © 2010 U.S. Cancer Pain Relief Committee. Published by Elsevier Inc. All rights reserved.

Measurement of fatigue in industries.

PubMed

Saito, K

1999-04-01

Fatigue of workers is a complex phenomenon resulting from various factors in technically innovated modern industries, and it appears as a feeling of exhaustion, lowering of physiological functions, breakdown of autonomic nervous balance, and decrease in work efficiency. On the other hand industrial fatigue is caused by excessive workload, remarkable alteration in working posture and diurnal and nocturnal rhythms in daily life. Working modes in modern industries have changed from work with the whole body into that with the hands, arms, legs and/or eyes which are parts of the body, and from physical work to mental work. Visual display terminal (VDT) work is one of the most characteristic jobs in the various kinds of workplaces. A large number of fatigue tests have already been adopted, but it is still hard to draw a generalized conclusion as to the method of selecting the most appropriate test battery for a given work load. As apparatus for fatigue measurement of VDT work we have developed VRT (Visual Reaction Test) and the Portable Fatigue Meter. Furthermore, we have presented immune parameters of peripheral blood and splenic T cells for physical fatigue.

Influence of sleep disturbance, fatigue, vitality on oral health and academic performance in indian dental students

PubMed Central

ASAWA, KAILASH; SEN, NANDINI; BHAT, NAGESH; TAK, MRIDULA; SULTANE, PRATIBHA; MANDAL, ARITRA

2017-01-01

Background Oral health and academic performance are important contributing factors for a student’s professional life. Countless factors affect both, among which sleep, vitality and fatigue are less explored areas that also have a strong impact. Objective The objective of the study was to assess the association of sleep disturbances, fatigue and vitality with self reported oral health status, oral hygiene habits and academic performance of dental students of Udaipur. Methods A descriptive cross-sectional study was conducted among undergraduate and postgraduate dental students of Udaipur. Self-administered structured questionnaire was used to assess the psychological factors, vitality, sleep quality, fatigue, self reported oral health status, habits and academic performance. Analysis of variance and stepwise multiple linear regression were utilized for statistical analysis with 95% confidence level and 5% level of significance. Results Of the 230 participants, 180 (78.3%) were undergraduates and 50 (21.7%) were postgraduates. Among them, females showed higher scores in disturbed sleep index (2.69±2.14) as compared to males (2.45±1.91). Respondents who had “Poor” dental health, scored more in disturbed sleep index (3.15±1.64) and fatigue scale (20.00±4.88). Subjects who flossed “everyday”, were found to have good sleep and more energy (p=0.01) and those who assessed themselves as excellent students scored more in the Vitality Scale (p=0.01) and less in the Sleep index (p=0.01). Conclusion The present study confirms that disturbed sleep, aliveness and fatigue, all are interlinked with each other and are imperative factors having the potential to alter the oral health status, habits and academics of dental students. PMID:28781530

Determinants of seafarers' fatigue: a systematic review and quality assessment.

PubMed

Dohrmann, Solveig Boeggild; Leppin, Anja

2017-01-01

Fatigue jeopardizes seafarer's health and safety. Thus, knowledge on determinants of fatigue is of great importance to facilitate its prevention. However, a systematic analysis and quality assessment of all empirical evidence specifically for fatigue are still lacking. The aim of the present article was therefore to systematically detect, analyze and assess the quality of this evidence. Systematic searches in ten databases were performed. Searches considered articles published in scholarly journals from 1980 to April 15, 2016. Nineteen out of 98 eligible studies were included in the review. The main reason for exclusion was fatigue not being the outcome variable. Most evidence was available for work time-related factors suggesting that working nights was most fatiguing, that fatigue levels were higher toward the end of watch or shift, and that the 6-h on-6-h off watch system was the most fatiguing. Specific work demands and particularly the psychosocial work environment have received little attention, but preliminary evidence suggests that stress may be an important factor. A majority of 12 studies were evaluated as potentially having a high risk of bias. Realistic countermeasures ought to be established, e.g., in terms of shared or split night shifts. As internal as well as external validity of many study findings was limited, the range of factors investigated was insufficient and few studies investigated more complex interactions between different factors, knowledge derived from studies of high methodological quality investigating different factors, including psychosocial work environments, are needed to support future preventive programs.

Familiality and Heritability of Fatigue in an Australian Twin Sample.

PubMed

Corfield, Elizabeth C; Martin, Nicholas G; Nyholt, Dale R

2017-06-01

Familial factors have previously been implicated in the etiology of fatigue, of which a significant proportion is likely attributable to genetic influences. However, family studies have primarily focused on chronic fatigue syndrome, while univariate twin studies have investigated broader fatigue phenotypes. The results for similar fatigue phenotypes vary between studies, particularly with regard to sex-specific contributions to the heritability of the traits. Therefore, the current study aims to investigate the familiality and sex-specific effects of fatigue experienced over the past few weeks in an older Australian population of 660 monozygotic (MZ) twin pairs, 190 MZ singleton twins, 593 dizygotic (DZ) twin pairs, and 365 DZ singleton twins. Higher risks for fatigue were observed in MZ compared to DZ co-twins of probands with fatigue. Univariate heritability analyses indicated fatigue has a significant genetic component, with a heritability (h 2) estimate of 40%. Sex-specific effects did not significantly contribute to the heritability of fatigue, with similar estimates for males (h 2 = 41%, 95% CI [18, 62]) and females (h 2 = 40%, 95% CI [27, 52]). These results indicate that fatigue experienced over the past few weeks has a familial contribution, with additive genetic factors playing an important role in its etiology.

Development and Application of a Clinical Microsystem Simulation Methodology for Human Factors-Based Research of Alarm Fatigue.

PubMed

Kobayashi, Leo; Gosbee, John W; Merck, Derek L

2017-07-01

(1) To develop a clinical microsystem simulation methodology for alarm fatigue research with a human factors engineering (HFE) assessment framework and (2) to explore its application to the comparative examination of different approaches to patient monitoring and provider notification. Problems with the design, implementation, and real-world use of patient monitoring systems result in alarm fatigue. A multidisciplinary team is developing an open-source tool kit to promote bedside informatics research and mitigate alarm fatigue. Simulation, HFE, and computer science experts created a novel simulation methodology to study alarm fatigue. Featuring multiple interconnected simulated patient scenarios with scripted timeline, "distractor" patient care tasks, and triggered true and false alarms, the methodology incorporated objective metrics to assess provider and system performance. Developed materials were implemented during institutional review board-approved study sessions that assessed and compared an experimental multiparametric alerting system with a standard monitor telemetry system for subject response, use characteristics, and end-user feedback. A four-patient simulation setup featuring objective metrics for participant task-related performance and response to alarms was developed along with accompanying structured HFE assessment (questionnaire and interview) for monitor systems use testing. Two pilot and four study sessions with individual nurse subjects elicited true alarm and false alarm responses (including diversion from assigned tasks) as well as nonresponses to true alarms. In-simulation observation and subject questionnaires were used to test the experimental system's approach to suppressing false alarms and alerting providers. A novel investigative methodology applied simulation and HFE techniques to replicate and study alarm fatigue in controlled settings for systems assessment and experimental research purposes.

The effects of fatigue on performance in simulated nursing work.

PubMed

Barker, Linsey M; Nussbaum, Maury A

2011-09-01

Fatigue is associated with increased rates of medical errors and healthcare worker injuries, yet existing research in this sector has not considered multiple dimensions of fatigue simultaneously. This study evaluated hypothesised causal relationships between mental and physical fatigue and performance. High and low levels of mental and physical fatigue were induced in 16 participants during simulated nursing work tasks in a laboratory setting. Task-induced changes in fatigue dimensions were quantified using both subjective and objective measures, as were changes in performance on physical and mental tasks. Completing the simulated work tasks increased total fatigue, mental fatigue and physical fatigue in all experimental conditions. Higher physical fatigue adversely affected measures of physical and mental performance, whereas higher mental fatigue had a positive effect on one measure of mental performance. Overall, these results suggest causal effects between manipulated levels of mental and physical fatigue and task-induced changes in mental and physical performance. STATEMENT OF RELEVANCE: Nurse fatigue and performance has implications for patient and provider safety. Results from this study demonstrate the importance of a multidimensional view of fatigue in understanding the causal relationships between fatigue and performance. The findings can guide future work aimed at predicting fatigue-related performance decrements and designing interventions.

Vibration fatigue using modal decomposition

NASA Astrophysics Data System (ADS)

Mršnik, Matjaž; Slavič, Janko; Boltežar, Miha

2018-01-01

Vibration-fatigue analysis deals with the material fatigue of flexible structures operating close to natural frequencies. Based on the uniaxial stress response, calculated in the frequency domain, the high-cycle fatigue model using the S-N curve material data and the Palmgren-Miner hypothesis of damage accumulation is applied. The multiaxial criterion is used to obtain the equivalent uniaxial stress response followed by the spectral moment approach to the cycle-amplitude probability density estimation. The vibration-fatigue analysis relates the fatigue analysis in the frequency domain to the structural dynamics. However, once the stress response within a node is obtained, the physical model of the structure dictating that response is discarded and does not propagate through the fatigue-analysis procedure. The structural model can be used to evaluate how specific dynamic properties (e.g., damping, modal shapes) affect the damage intensity. A new approach based on modal decomposition is presented in this research that directly links the fatigue-damage intensity with the dynamic properties of the system. It thus offers a valuable insight into how different modes of vibration contribute to the total damage to the material. A numerical study was performed showing good agreement between results obtained using the newly presented approach with those obtained using the classical method, especially with regards to the distribution of damage intensity and critical point location. The presented approach also offers orders of magnitude faster calculation in comparison with the conventional procedure. Furthermore, it can be applied in a straightforward way to strain experimental modal analysis results, taking advantage of experimentally measured strains.

Generating Fatigue Crack Growth Thresholds with Constant Amplitude Loads

NASA Technical Reports Server (NTRS)

Forth, Scott C.; Newman, James C., J.; Forman, Royce G.

2002-01-01

The fatigue crack growth threshold, defining crack growth as either very slow or nonexistent, has been traditionally determined with standardized load reduction methodologies. Some experimental procedures tend to induce load history effects that result in remote crack closure from plasticity. This history can affect the crack driving force, i.e. during the unloading process the crack will close first at some point along the wake, reducing the effective load at the crack tip. One way to reduce the effects of load history is to propagate a crack under constant amplitude loading. As a crack propagates under constant amplitude loading, the stress intensity factor, K, will increase, as will the crack growth rate, da/dN. A fatigue crack growth threshold test procedure is developed and experimentally validated that does not produce load history effects and can be conducted at a specified stress ratio, R.

An assessment of fatigue in patients with postural orthostatic tachycardia syndrome.

PubMed

Wise, Shelby; Ross, Amanda; Brown, Abigail; Evans, Meredyth; Jason, Leonard

2017-05-01

Individuals with postural orthostatic tachycardia syndrome share many symptoms with those who have chronic fatigue syndrome; one of which is severe fatigue. Previous literature found that those with chronic fatigue syndrome experience many forms of fatigue. The goal of this study was to investigate whether individuals with postural orthostatic tachycardia syndrome also experience multidimensional fatigue and whether these individuals can be clustered into subgroups based on the types of fatigue they endorse. A convenience sample of 138 participants (aged 14-29) with postural orthostatic tachycardia syndrome completed questionnaires that assessed fatigue, brain fog symptom severity, activities that improve brain fog, and brain fog-related disability. An exploratory factor analysis was conducted on the Fatigue Types Questionnaire, and a three-factor solution was produced. Factor scores were then used to cluster the patients into groups using a TwoStep cluster analysis. This resulted in two clusters, a high severity group and a low severity group. The clusters were then compared on a number of items related to symptom expression. Individuals within the more severe cluster had significantly more brain fog at the beginning and end of the survey when compared to cluster two. Those in the more severe cluster also described more activity impairment as well as more frequent, more severe, and more debilitation from postural orthostatic tachycardia syndrome and brain fog. The findings of the factor analysis suggest that patients with postural orthostatic tachycardia syndrome experience fatigue as a multidimensional construct and they also can be subgrouped based on symptom severity.

Cues of fatigue: effects of sleep deprivation on facial appearance.

PubMed

Sundelin, Tina; Lekander, Mats; Kecklund, Göran; Van Someren, Eus J W; Olsson, Andreas; Axelsson, John

2013-09-01

To investigate the facial cues by which one recognizes that someone is sleep deprived versus not sleep deprived. Experimental laboratory study. Karolinska Institutet, Stockholm, Sweden. Forty observers (20 women, mean age 25 ± 5 y) rated 20 facial photographs with respect to fatigue, 10 facial cues, and sadness. The stimulus material consisted of 10 individuals (five women) photographed at 14:30 after normal sleep and after 31 h of sleep deprivation following a night with 5 h of sleep. Ratings of fatigue, fatigue-related cues, and sadness in facial photographs. The faces of sleep deprived individuals were perceived as having more hanging eyelids, redder eyes, more swollen eyes, darker circles under the eyes, paler skin, more wrinkles/fine lines, and more droopy corners of the mouth (effects ranging from b = +3 ± 1 to b = +15 ± 1 mm on 100-mm visual analog scales, P < 0.01). The ratings of fatigue were related to glazed eyes and to all the cues affected by sleep deprivation (P < 0.01). Ratings of rash/eczema or tense lips were not significantly affected by sleep deprivation, nor associated with judgements of fatigue. In addition, sleep-deprived individuals looked sadder than after normal sleep, and sadness was related to looking fatigued (P < 0.01). The results show that sleep deprivation affects features relating to the eyes, mouth, and skin, and that these features function as cues of sleep loss to other people. Because these facial regions are important in the communication between humans, facial cues of sleep deprivation and fatigue may carry social consequences for the sleep deprived individual in everyday life.

Fatigue and durability of Nitinol stents.

PubMed

Pelton, A R; Schroeder, V; Mitchell, M R; Gong, Xiao-Yan; Barney, M; Robertson, S W

2008-04-01

Nitinol self-expanding stents are effective in treating peripheral artery disease, including the superficial femoral, carotid, and renal arteries. However, fracture occurrences of up to 50% have been reported in some stents after one year. These stent fractures are likely due to in vivo cyclic displacements. As such, the cyclic fatigue and durability properties of Nitinol-based endovascular stents are discussed in terms of an engineering-based experimental testing program. In this paper, the combined effects of cardiac pulsatile fatigue and stent-vessel oversizing are evaluated for application to both stents and stent subcomponents. In particular, displacement-controlled fatigue tests were performed on stent-like specimens processed from Nitinol microtubing. Fatigue data were collected with combinations of simulated oversizing conditions and pulsatile cycles that were identified by computer modeling of the stent that mimic in vivo deformation conditions. These data are analyzed with non-linear finite element computations and are illustrated with strain-life and strain-based constant-life diagrams. The utility of this approach is demonstrated in conjunction with 10 million cycle pulsatile fatigue tests of Cordis SMART Control((R)) Nitinol self-expanding stents to calculate fatigue safety factors and thereby predict in vivo fatigue resistance. These results demonstrate the non-linear constant fatigue-life response of Nitinol stents, whereby, contrary to conventional engineering materials, the fatigue life of Nitinol is observed to increase with increasing mean strain.

Fatigue reduction during aggregated and distributed sequential stimulation.

PubMed

Bergquist, Austin J; Babbar, Vishvek; Ali, Saima; Popovic, Milos R; Masani, Kei

2017-08-01

Transcutaneous neuromuscular electrical stimulation (NMES) can generate muscle contractions for rehabilitation and exercise. However, NMES-evoked contractions are limited by fatigue when they are delivered "conventionally" (CONV) using a single active electrode. Researchers have developed "sequential" (SEQ) stimulation, involving rotation of pulses between multiple "aggregated" (AGGR-SEQ) or "distributed" (DISTR-SEQ) active electrodes, to reduce fatigue (torque-decline) by reducing motor unit discharge rates. The primary objective was to compare fatigue-related outcomes, "potentiation," "variability," and "efficiency" between CONV, AGGR-SEQ, and DISTR-SEQ stimulation of knee extensors in healthy participants. Torque and current were recorded during testing with fatiguing trains using each NMES type under isometric and isokinetic (180°/s) conditions. Compared with CONV stimulation, SEQ techniques reduced fatigue-related outcomes, increased potentiation, did not affect variability, and reduced efficiency. SEQ techniques hold promise for reducing fatigue during NMES-based rehabilitation and exercise; however, optimization is required to improve efficiency. Muscle Nerve 56: 271-281, 2017. © 2016 Wiley Periodicals, Inc.

Predictors of fatigue and work ability in cancer survivors.

PubMed

van Muijen, P; Duijts, S F A; Bonefaas-Groenewoud, K; van der Beek, A J; Anema, J R

2017-12-30

Workers diagnosed with cancer are at risk for job loss or work disability. To determine predictors of fatigue and work ability at 36 months after diagnosis in a population of cancer survivors. Individuals diagnosed with cancer and who applied for work disability benefit at 24 months of sick leave were surveyed at the time of application and again 12 months later. Fatigue was measured using the Functional Assessment of Chronic Illness-Fatigue scale questionnaire and work ability was measured using the work ability index. Linear regression analyses were applied to identify predictors. There were 336 participants. Participants who were divorced or widowed had more physical limitations, more depressive symptoms and were more fatigued at baseline, and who worked in health care demonstrated higher levels of fatigue. Lower fatigue was predicted by having received chemotherapy. A higher level of work ability was predicted by having received chemotherapy, better global health and better work ability at baseline. Lower work ability was predicted by being principal wage earner, insecurity about being free of disease, having more physical limitations and having greater wage loss. Socio-demographic, health- and work-related factors were associated with fatigue and work ability in cancer survivors on long-term sick leave. As fatigue and poor work ability are important risk factors for work disability, addressing the identified predictive factors may assist in mitigation of work disability in cancer survivors. © The Author 2017. Published by Oxford University Press on behalf of the Society of Occupational Medicine. All rights reserved. For Permissions, please email: journals.permissions@oup.com

Effect of lubricant composition on the fatigue properties of ultra-high molecular weight polyethylene for total knee replacement.

PubMed

Aurora, A; DesJardins, J D; Joseph, P F; LaBerge, M

2006-05-01

Ultrahigh molecular weight polyethylene (UHMWPE) fatigue is a critical factor affecting the longevity of total knee replacement (TKR) bearings. With the increased need for laboratory studies to mimic near in vivo conditions for accurate characterization of material performance, the present study investigated the role of hyaluronic acid (HA) in testing lubricant on the crack growth response of UHMWPE. It was hypothesized that the change in lubricant viscosity as a result of HA would affect the fatigue life of the polymer. A fracture mechanics approach as per ASTM E 647 was adopted for this study. Surface micrograph and surface chemistry analyses were employed to study the micromechanisms of fatigue failure and protein adsorption of the specimen surfaces. Rheological analysis indicated that the addition of HA to diluted bovine serum increased testing lubricant viscosity. HA concentrations of 2.22, 0.55, and 1.5 g/l closely matched the viscosity ranges reported for osteoarthritis, rheumatoid arthritic diseased joint fluid, and periprosthetic fluids respectively. Results showed that the addition of HA to standard diluted bovine serum lubricants, in concentrations similar to that of periprosthetic fluid, delayed crack initiation and crack growth during fatigue testing.

Hope and fatigue in chronic illness: The role of perceived stress.

PubMed

Hirsch, Jameson K; Sirois, Fuschia M

2016-04-01

Fatigue is a debilitating symptom of chronic illness that is deleteriously affected by perceived stress, a process particularly relevant to inflammatory disease. Hopefulness, a goal-based motivational construct, may beneficially influence stress and fatigue, yet little research has examined these associations. We assessed the relation between hope and fatigue, and the mediating effect of stress, in individuals with fibromyalgia, arthritis, and inflammatory bowel disease. Covarying age, sex, and pain, stress partially mediated the association between hope and fatigue; those with greater hope reported less stress and consequent fatigue. Therapeutically, bolstering hope may allow proactive management of stressors, resulting in less fatigue. © The Author(s) 2014.

49 CFR Appendix D to Part 228 - Guidance on Fatigue Management Plans

Code of Federal Regulations, 2012 CFR

2012-10-01

... treatment of any medical condition that may affect alertness or fatigue, including sleep disorders; (3... employee fatigue and cumulative sleep loss; (5) Methods to minimize accidents and incidents that occur as a... drowsiness and fatigue while an employee is on duty; (7) Opportunities to obtain restful sleep at lodging...

49 CFR Appendix D to Part 228 - Guidance on Fatigue Management Plans

Code of Federal Regulations, 2013 CFR

2013-10-01

... treatment of any medical condition that may affect alertness or fatigue, including sleep disorders; (3... employee fatigue and cumulative sleep loss; (5) Methods to minimize accidents and incidents that occur as a... drowsiness and fatigue while an employee is on duty; (7) Opportunities to obtain restful sleep at lodging...

49 CFR Appendix D to Part 228 - Guidance on Fatigue Management Plans

Code of Federal Regulations, 2014 CFR

2014-10-01

... treatment of any medical condition that may affect alertness or fatigue, including sleep disorders; (3... employee fatigue and cumulative sleep loss; (5) Methods to minimize accidents and incidents that occur as a... drowsiness and fatigue while an employee is on duty; (7) Opportunities to obtain restful sleep at lodging...

Cognitive behavioral therapy positively affects fatigue in patients with multiple sclerosis: Results of a randomized controlled trial.

PubMed

van den Akker, Lizanne E; Beckerman, Heleen; Collette, Emma H; Twisk, Jos Wr; Bleijenberg, Gijs; Dekker, Joost; Knoop, Hans; de Groot, Vincent

2017-10-01

Fatigue is a common symptom in multiple sclerosis (MS) and often restricts societal participation. Cognitive behavioral therapy (CBT) may alleviate MS-related fatigue, but evidence in literature is inconclusive. To evaluate the effectiveness of CBT to improve MS-related fatigue and participation. In a multi-center, assessor-masked, randomized controlled trial, participants with severe MS-related fatigue were assigned to CBT or control treatment. CBT consisted of 12 individual sessions with a psychologist trained in CBT, the control treatment consisted of three consultations with a MS nurse, both delivered over 16 weeks. Assessments were at baseline, 8, 16 (i.e. post-intervention), 26, and 52 weeks post-baseline. Primary outcomes were the Checklist Individual Strength-fatigue subscale (CIS20r fatigue) and the Impact on Participation and Autonomy questionnaire (IPA). Data were analyzed according to the intention-to-treat principle, using mixed-model analysis. Between 2011 and 2014, 91 patients were randomized (CBT: n = 44; control: n = 47). Between-group analysis showed a positive post-intervention effect for CBT on CIS20r fatigue (T16: -6.7 (95% confidence interval (CI) = -10.7; -2.7) points) that diminished during follow-up (T52: 0.5 (95% CI = -3.6; 4.4)). No clinically relevant effects were found on societal participation. Severe MS-related fatigue can be reduced effectively with CBT in the short term. More research is needed on how to maintain this effect over the long term.

Trajectories of Evening Fatigue in Oncology Outpatients Receiving Chemotherapy

PubMed Central

Wright, Fay; Melkus, Gail D’Eramo; Hammer, Marilyn; Schmidt, Brian L.; Knobf, M. Tish; Paul, Steven M.; Cartwright, Frances; Mastick, Judy; Cooper, Bruce A.; Chen, Lee-May; Melisko, Michelle; Levine, Jon D.; Kober, Kord; Aouizerat, Bradley E.; Miaskowski, Christine

2015-01-01

Context Fatigue is a distressing, persistent sense of physical tiredness that is not proportional to a person’s recent activity. Fatigue impacts patients’ treatment decisions and can limit their self-care activities. While significant interindividual variability in fatigue severity has been noted, little is known about predictors of interindividual variability in initial levels and trajectories of evening fatigue severity in oncology patients receiving chemotherapy (CTX). Objectives To determine whether demographic, clinical, and symptom characteristics were associated with initial levels as well as the trajectories of evening fatigue. Methods A sample of outpatients with breast, gastrointestinal, gynecological, and lung cancer (N=586) completed demographic and symptom questionnaires a total of six times over two cycles of CTX. Fatigue severity was evaluated using the Lee Fatigue Scale. Hierarchical linear modeling (HLM) was used to answer the study objectives. Results A large amount of interindividual variability was found in the evening fatigue trajectories. A piecewise model fit the data best. Patients who were White, diagnosed with breast, gynecological, or lung cancer, and who had more years of education, child care responsibilities, lower functional status, and higher levels of sleep disturbance and depression reported higher levels of evening fatigue at enrollment. Conclusion This study identified both non-modifiable (e.g., ethnicity) and modifiable (e.g., child care responsibilities, depressive symptoms, sleep disturbance) risk factors for more severe evening fatigue. Using this information, clinicians can identify patients at higher risk for more severe evening fatigue, provide individualized patient education, and tailor interventions to address the modifiable risk factors. PMID:25828560

Fatigue failure of materials under broad band random vibrations

NASA Technical Reports Server (NTRS)

Huang, T. C.; Lanz, R. W.

1971-01-01

The fatigue life of material under multifactor influence of broad band random excitations has been investigated. Parameters which affect the fatigue life are postulated to be peak stress, variance of stress and the natural frequency of the system. Experimental data were processed by the hybrid computer. Based on the experimental results and regression analysis a best predicting model has been found. All values of the experimental fatigue lives are within the 95% confidence intervals of the predicting equation.

S-N Fatigue and Fatigue Crack Propagation Behaviors of X80 Steel at Room and Low Temperatures

NASA Astrophysics Data System (ADS)

Jung, Dae-Ho; Kwon, Jae-Ki; Woo, Nam-Sub; Kim, Young-Ju; Goto, Masahiro; Kim, Sangshik

2014-02-01

In the present study, the S-N fatigue and the fatigue crack propagation (FCP) behaviors of American Petroleum Institute X80 steel were examined in the different locations of the base metal (BM), weld metal (WM), and heat-affected zone (HAZ) at 298 K, 223 K, and 193 K (25 °C, -50 °C, and -80 °C). The resistance to S-N fatigue of X80 BM specimen increased greatly with decreasing temperature from 298 K to 193 K (25 °C to -80 °C) and showed a strong dependency on the flow strength (½(yield strength + tensile strength)). The FCP rates of X80 BM specimen were substantially reduced with decreasing temperature from 298 K to 223 K (25 °C to -50 °C) over the entire ∆ K regime, while further reduction in FCP rates was not significant with temperature from 223 K to 193 K (-50 °C to -80 °C). The FCP rates of the X80 BM and the WM specimens were comparable with each other, while the HAZ specimen showed slightly better FCP resistance than the BM and the WM specimens over the entire ∆K regime at 298 K (25 °C). Despite the varying microstructural characteristics of each weld location, the residual stress appeared to be a controlling factor to determine the FCP behavior. The FCP behaviors of high strength X80 steel were discussed based on the microstructural and the fractographic observations.

Factors affecting mobility in community-dwelling older Koreans with chronic illnesses.

PubMed

Yeom, Hye-A; Baldwin, Carol M; Lee, Myung-Ah; Kim, Su-Jeong

2015-03-01

This descriptive study aims to describe the levels of mobility in community-dwelling older Koreans with chronic illnesses, and to examine the associations of their mobility with sleep patterns, physical activity and physical symptoms including fatigue and pain. The participants were a total of 384 community-dwelling older adults recruited from three senior centers in Seoul, Korea. Measures included mobility assessed using 6-minute walk test (6MWT), physical activity behavior, sleep profiles, fatigue and pain. Data were collected from July to December 2012. The mean 6MWT distance was 212.68 meters. Over 90% of the study participants (n = 373) were classified as having impaired mobility using 400 meters as the cutoff point diagnostic criteria of normal mobility in 6MWT. The 6MWT distance was 246.68 meters for participants in their 60s, 212.32 meters for those in their 70s, and 175.54 meters for those in their 80s. Significant predictors of mobility included younger age, taking mediation, regular physical activity, female gender, higher income, higher fatigue and better perception on sleep duration, which explained 18% of the total variance of mobility. A high-risk group for mobility limitation includes low income, sedentary older men who are at risk for increased fatigue and sleep deficit. Further research should incorporate other psychological and lifestyle factors such as depression, smoking, drinking behavior, and/or obesity into the prediction model of mobility to generate specific intervention strategies for mobility enhancement recommendations for older adults. Copyright © 2015. Published by Elsevier B.V.

Do physical leisure time activities prevent fatigue? A 15 month prospective study of nurses' aides.

PubMed

Eriksen, W; Bruusgaard, D

2004-06-01

To test the hypothesis that physical leisure time activities reduce the risk of developing persistent fatigue. The hypothesis was tested in a sample that was homogeneous with respect to sex and occupation, with a prospective cohort design. Of 6234 vocationally active, female, Norwegian nurses' aides, not on leave because of illness or pregnancy when they completed a mailed questionnaire in 1999, 5341 (85.7%) completed a second questionnaire 15 months later. The main outcome measure was the prevalence of persistent fatigue-that is, always or usually feeling fatigued in the daytime during the preceding 14 days. In participants without persistent fatigue at baseline, reported engagement in physical leisure time activities for 20 minutes or more at least once a week during the three months before baseline was associated with a reduced risk of persistent fatigue at the follow up (odds ratio = 0.70; 95% confidence interval 0.55 to 0.89), after adjustments for age, affective symptoms, sleeping problems, musculoskeletal pain, long term health problems of any kind, smoking, marital status, tasks of a caring nature during leisure time, and work factors at baseline. The study supports the hypothesis that physical leisure time activities reduce the risk of developing persistent fatigue.

The revised HSE fatigue guidance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stacey, A.; Sharp, J.V.

1995-12-31

Fatigue cracking has been a principal cause of damage to North Sea structures and consequently considerable attention has been given to the development of guidance for the prediction of fatigue performance. The fatigue guidance of the Offshore Safety Division of the Health and Safety Executive (HSE) was recently revised and published, following a significant offshore industry review in the period 1987 to 1990, and is based on the results of a considerable amount of research and development work on the fatigue behavior of welded tubular and plated joints. As a result of this review, the revised fatigue guidance incorporates severalmore » new clauses and recommendations. The revised recommendations apply to joint classification, basic design S-N curves for welded joints and cast or forged steel components, the thickness effect, the effects of environment and the treatment of low and high stress ranges. Additionally, a new appendix on the derivation of stress concentration factors is included. The new clauses cover high strength steels, bolts and threaded connectors, moorings, repaired joints and the use of fracture mechanics analysis. This paper presents an overview of the revisions to the fatigue guidance, the associated background technical information and aspects of the fatigue behavior of offshore structures which are considered to require further investigation. 67 refs., 7 figs., 8 tabs.« less

Fatigue in patients with Juvenile Idiopathic Arthritis: relationship to perceived health, physical health, self-efficacy, and participation.

PubMed

Armbrust, Wineke; Lelieveld, Otto H T M; Tuinstra, Jolanda; Wulffraat, Nico M; Bos, G J F Joyce; Cappon, Jeannette; van Rossum, Marion A J; Sauer, Pieter J J; Hagedoorn, Mariët

2016-12-06

Fatigue is common in patients with JIA and affects daily life negatively. We assessed the presence and severity of fatigue in patients with JIA, including factors presumed associated with fatigue (e.g., disease activity, disability, pain, physical activity, exercise capacity, and self-efficacy), and whether fatigue is related to participation in physical education classes, school attendance, and sports frequency. The current study used baseline data of 80 patients with JIA (age 8-13) who participated in an intervention aimed at promoting physical activity. Primary outcome measurements were fatigue, assessed using the Pediatric-Quality-of-Life-Inventory (PedsQl)-Fatigue-scale and energy level assessed using a VAS scale. Other outcome measurements were disease activity (VAS Physician Global Assessment Scale), disability (Childhood Health Assessment Questionnaire), physical activity (accelerometer), exercise capacity (Bruce treadmill test), self-efficacy (Childhood Arthritis Self-Efficacy Scale), and participation (self-report). Sixty percent of patients with JIA suffered from daily low-energy levels; 27% suffered from very low-energy levels more than half the week. Low energy levels were best predicted by disability and low physical activity. Fatigue measured with the PEDsQL was higher compared to the control-population. Disability and low self-efficacy were main predictors of fatigue. Self-efficacy was a predictor of fatigue but did not act as moderator. Fatigue was a predictor for sports frequency but not for school attendance. Fatigue is a significant problem for JIA patients. Interventions aimed at reducing perceived disability, stimulating physical activity, and enhancing self-efficacy might reduce fatigue and thereby enhance participation. Trial number ISRCTN92733069.

A comparison of patients with Q fever fatigue syndrome and patients with chronic fatigue syndrome with a focus on inflammatory markers and possible fatigue perpetuating cognitions and behaviour.

PubMed

Keijmel, Stephan P; Saxe, Johanna; van der Meer, Jos W M; Nikolaus, Stephanie; Netea, Mihai G; Bleijenberg, Gijs; Bleeker-Rovers, Chantal P; Knoop, Hans

2015-10-01

Comparison of Q fever fatigue syndrome (QFS) and chronic fatigue syndrome (CFS) patients, with a focus on markers of inflammation and fatigue-related cognitive-behavioural variables. Data from two independent prospective studies on QFS (n=117) and CFS (n=173), respectively, were pooled and analyzed. QFS patients were less often female, had a higher BMI, and had less often received treatment for depression before the onset of symptoms. After controlling for symptom duration and correcting for differences in diagnostic criteria for QFS and CFS with respect to the level of impairment and the presence of additional symptoms, differences in the proportion of females and BMI remained significant. After correction, QFS patients were also significantly older. In all analyses QFS patients were as fatigued and distressed as CFS patients, but reported less additional symptoms. QFS patients had stronger somatic attributions, and higher levels of physical activity. No differences were found with regard to inflammatory markers and in other fatigue-related cognitive-behavioural variables. The relationship between cognitive-behavioural variables and fatigue, previously established in CFS, could not be confirmed in QFS patients with the exception of the negative relationship between physical activity and fatigue. Differences and similarities between QFS and CFS patients were found. Although the relationship between perpetuating factors and fatigue previously established in CFS could not be confirmed in QFS patients, the considerable overlap in fatigue-related cognitive-behavioural variables and the relationship found between physical activity and fatigue may suggest that behavioural interventions could reduce fatigue severity in QFS patients. Copyright © 2015 Elsevier Inc. All rights reserved.

Development of an algorithm for an EEG-based driver fatigue countermeasure.

PubMed

Lal, Saroj K L; Craig, Ashley; Boord, Peter; Kirkup, Les; Nguyen, Hung

2003-01-01

Fatigue affects a driver's ability to proceed safely. Driver-related fatigue and/or sleepiness are a significant cause of traffic accidents, which makes this an area of great socioeconomic concern. Monitoring physiological signals while driving provides the possibility of detecting and warning of fatigue. The aim of this paper is to describe an EEG-based fatigue countermeasure algorithm and to report its reliability. Changes in all major EEG bands during fatigue were used to develop the algorithm for detecting different levels of fatigue. The software was shown to be capable of detecting fatigue accurately in 10 subjects tested. The percentage of time the subjects were detected to be in a fatigue state was significantly different than the alert phase (P<.01). This is the first countermeasure software described that has shown to detect fatigue based on EEG changes in all frequency bands. Field research is required to evaluate the fatigue software in order to produce a robust and reliable fatigue countermeasure system. The development of the fatigue countermeasure algorithm forms the basis of a future fatigue countermeasure device. Implementation of electronic devices for fatigue detection is crucial for reducing fatigue-related road accidents and their associated costs.

The role of cytokines in cancer-related fatigue.

PubMed

Kurzrock, R

2001-09-15

Fatigue is prominent in cancer patients and probably multifactorial in origin. Factors contributing to fatigue include anemia, weight loss, fever, pain, medication, and infection. In cancer patients, many of these factors are influenced by a frequently disrupted balance between endogenous cytokine levels and their natural antagonists. Indeed, cancer cells and the immune system appear to overexpress a range of cytokines in patients with malignancies. Some of these cytokines act as autocrine or paracrine growth factors for the neoplastic tissue while simultaneously causing secondary symptoms related to fatigue. For instance, cancer-associated anemia may be due to a blunted erythropoietin response and/or cytokines (interleukin-1 [IL-1], IL-6, tumor necrosis factor-alpha [TNF-alpha]), which suppress erythropoiesis. Cancerous cachexia, a wasting syndrome and a hallmark of cancer, can be attributed to loss of appetite or enhanced energy expenditure. Several different interleukins, as well as TNF, interferon-gamma, and leukemia inhibitory factor, act as cachectins in animal models. Similarly, fever and night sweats are influenced by pyrogenic cytokines. Recently, molecules that function as cytokine antagonists have been identified. These molecules may be exploitable in combating the components of cancer-related fatigue, and may inhibit tumor growth as well. Copyright 2001 American Cancer Society.

Transformation fatigue and stress relaxation of shape memory alloy wires

NASA Astrophysics Data System (ADS)

Pappas, P.; Bollas, D.; Parthenios, J.; Dracopoulos, V.; Galiotis, C.

2007-12-01

The present work deals with the stress generation capability of nickel-titanium shape memory alloys (SMAs) under constrained conditions for two well-defined loading modes: recurrent crystalline transformation (transformation fatigue) and a one-step continuous activation (generated stress relaxation). The data acquired will be very useful during the design process of an SMA Ni-Ti element as a functional part of an assembly. Differential scanning calorimetry (DSC) was employed in order to investigate the transformation characteristics of the alloy before and after the tests. Transformation fatigue tests revealed that the parameter that affects more the rate of the functional degradation is the number of crystalline transitions the wire undergoes. Thus, the service life limit of this material as a stress generator can be reduced to a few thousand working cycles. For stress relaxation, the main factor that affects the ability for stress generation is the working temperature: the higher the temperature above the austenite finish (TAf) limit the higher the relaxation effect. Thermomechanical treatment of the alloy during the tests reveals the 'hidden' transformation from the cubic structure (B2) of austenite to the rhombohedral structure of the R-phase. It is believed that the gradual loss of the stress generation capability of the material under constrained conditions must be associated to a gradual slipping relaxation mechanism. Scanning electron microscopy (SEM) observations on as-received, re-trained, fatigued and stress-relaxed specimens in the martensitic state provide further support for this hypothesis.

Satisfaction with life in adults with Marfan syndrome (MFS): associations with health-related consequences of MFS, pain, fatigue, and demographic factors.

PubMed

Velvin, Gry; Bathen, Trine; Rand-Hendriksen, Svend; Geirdal, Amy Østertun

2016-07-01

The objective with this study was to explore satisfaction with life (SWL) among adults with Marfan syndrome (MFS) compared to the general Norwegian population and other patient groups and further to examine the associations between SWL and demographic factors, contact with social and health services, MFS-related health problems, chronic pain, and fatigue. This is a cross-sectional study with postal questionnaire, including the Satisfaction with Life Scale (SWLS), questions on demographic factors, health-related aspects of MFS, and validated instruments measuring chronic pain (Standardized Nordic Questionnaire) and fatigue (Fatigue Severity Scale). One hundred and seventeen adults with MFS were invited to participate, and 73 (62 %) participated. The SWLS mean score in adults with MFS was significantly lower than that reported for the general Norwegian population, but similar to or higher than that reported for other patient groups. Only fatigue, aortic dissection, and having regular contact with psychologist showed significant unique contribution to the SWLS score in the hierarchical multiple linear analyses. The total variance explained by the model was 45.2 % p ≤ 0.000, confirming that the combination of independent variables significantly predicted SWLS. The results reflect that MFS influences people's SWL and that particularly severe fatigue, aortic dissection, and psychological aspects are associated with lower SWL. This is important to take into account in the clinical work with people with MFS. Further investigation is needed, especially on larger sample groups. Studies with combination of qualitative and quantitative approaches are recommended to obtain more comprehensive and accurate knowledge about the consequences of MFS on satisfaction with life.

The fatigue strength of riveted joints and lugs

NASA Technical Reports Server (NTRS)

Schijve, J

1956-01-01

This report deals with a number of tests on riveted joints and lugs for the primary purpose of comparing the several types of riveted joints and to study the effect of various factors on the fatigue strength of lugs. A check was made to ascertain whether or not an estimate of the fatigue life at a certain loading could be made from the dimensions of the joint and the fatigue data of the unnotched materials. Recommendations are made on the proportioning of joints to obtain better fatigue behavior.

Psychometric properties of the multidimensional fatigue inventory in Brazilian Hodgkin's lymphoma survivors.

PubMed

Baptista, Renata Lyrio R; Biasoli, Irene; Scheliga, Adriana; Soares, Andrea; Brabo, Eloa; Morais, José Carlos; Werneck, Guilherme Loureiro; Spector, Nelson

2012-12-01

Fatigue is the most common symptom among Hodgkin's lymphoma survivors. To evaluate the psychometric properties of the Brazilian version of the Multidimensional Fatigue Inventory (MFI). The MFI was translated into Brazilian Portuguese using established forward-backward translation procedures, and the psychometric properties were evaluated in a sample of 200 Hodgkin's lymphoma survivors. The psychometric properties evaluated included internal consistency and construct validity. The MFI was administered along with the informed consent form. The overall Cronbach's alpha coefficient for the 20 items was 0.84, ranging from 0.59 to 0.81 for each of the five scales. Correlations between items and scales ranged from 0.32 to 0.72. The factor analysis yielded a five-factor solution that explained 65% of the variance. The first factor merged the original "general fatigue" and "physical fatigue" scales, as has been previously reported. The second factor identified the original "mental fatigue" scale and the fifth factor identified the original "reduced activity" scale. Questions from the original "reduced motivation" scale were represented in both factors three and four. The Brazilian version of the MFI showed satisfactory psychometric properties and can be considered a valid research tool for assessing cancer-related fatigue. Copyright © 2012 U.S. Cancer Pain Relief Committee. Published by Elsevier Inc. All rights reserved.

Extended cyclic fatigue life of F2 ProTaper instruments used in reciprocating movement.

PubMed

De-Deus, G; Moreira, E J L; Lopes, H P; Elias, C N

2010-12-01

To evaluate the cyclic fatigue fracture resistance of engine-driven F2 ProTaper instruments under reciprocating movement. A sample of 30 NiTi ProTaper F2 instruments was used. An artificial canal was made from a stainless steel tube, allowing the instruments to rotate freely. During mechanical testing, different movement kinematics and speeds were used, which resulted in three experimental groups (n = 10). The instruments from the first group (G1) were rotated at a nominal speed of 250 rpm until fracture, whilst the instruments from the second group (G2) were rotated at 400 rpm. In the third instrument group (G3), the files were driven under reciprocating movement. The time of fracture for each instrument was measured, and statistical analysis was performed using parametric methods. Reciprocating movement resulted in a significantly longer cyclic fatigue life (P < 0.05). Moreover, operating rpm was a significant factor affecting cyclic fatigue life (P < 0.05); instruments used at a rotational speed of 400 rpm (approximately 95 s) failed more rapidly than those used at 250 rpm (approximately 25 s). Movement kinematics is amongst the factors determining the resistance of rotary NiTi instruments to cyclic fracture. Moreover, the reciprocating movement promoted an extended cyclic fatigue life of the F2 ProTaper instrument in comparison with conventional rotation.

Daily cytokine fluctuations, driven by leptin, are associated with fatigue severity in chronic fatigue syndrome: evidence of inflammatory pathology.

PubMed

Stringer, Elizabeth Ann; Baker, Katharine Susanne; Carroll, Ian R; Montoya, Jose G; Chu, Lily; Maecker, Holden T; Younger, Jarred W

2013-04-09

Chronic fatigue syndrome (CFS) is a debilitating disorder characterized by persistent fatigue that is not alleviated by rest. The lack of a clearly identified underlying mechanism has hindered the development of effective treatments. Studies have demonstrated elevated levels of inflammatory factors in patients with CFS, but findings are contradictory across studies and no biomarkers have been consistently supported. Single time-point approaches potentially overlook important features of CFS, such as fluctuations in fatigue severity. We have observed that individuals with CFS demonstrate significant day-to-day variability in their fatigue severity. Therefore, to complement previous studies, we implemented a novel longitudinal study design to investigate the role of cytokines in CFS pathophysiology. Ten women meeting the Fukuda diagnostic criteria for CFS and ten healthy age- and body mass index (BMI)-matched women underwent 25 consecutive days of blood draws and self-reporting of symptom severity. A 51-plex cytokine panel via Luminex was performed for each of the 500 serum samples collected. Our primary hypothesis was that daily fatigue severity would be significantly correlated with the inflammatory adipokine leptin, in the women with CFS and not in the healthy control women. As a post-hoc analysis, a machine learning algorithm using all 51 cytokines was implemented to determine whether immune factors could distinguish high from low fatigue days. Self-reported fatigue severity was significantly correlated with leptin levels in six of the participants with CFS and one healthy control, supporting our primary hypothesis. The machine learning algorithm distinguished high from low fatigue days in the CFS group with 78.3% accuracy. Our results support the role of cytokines in the pathophysiology of CFS.

Crew fatigue safety performance indicators for fatigue risk management systems.

PubMed

Gander, Philippa H; Mangie, Jim; Van Den Berg, Margo J; Smith, A Alexander T; Mulrine, Hannah M; Signal, T Leigh

2014-02-01

Implementation of Fatigue Risk Management Systems (FRMS) is gaining momentum; however, agreed safety performance indicators (SPIs) are lacking. This paper proposes an initial set of SPIs based on measures of crewmember sleep, performance, and subjective fatigue and sleepiness, together with methods for interpreting them. Data were included from 133 landing crewmembers on 2 long-range and 3 ultra-long-range trips (4-person crews, 3 airlines, 220 flights). Studies had airline, labor, and regulatory support, and underwent independent ethical review. SPIs evaluated preflight and at top of descent (TOD) were: total sleep in the prior 24 h and time awake at duty start and at TOD (actigraphy); subjective sleepiness (Karolinska Sleepiness Scale) and fatigue (Samn-Perelli scale); and psychomotor vigilance task (PVT) performance. Kruskal-Wallis nonparametric ANOVA with post hoc tests was used to identify significant differences between flights for each SPI. Visual and preliminary quantitative comparisons of SPIs between flights were made using box plots and bar graphs. Statistical analyses identified significant differences between flights across a range of SPls. In an FRMS, crew fatigue SPIs are envisaged as a decision aid alongside operational SPIs, which need to reflect the relevant causes of fatigue in different operations. We advocate comparing multiple SPIs between flights rather than defining safe/unsafe thresholds on individual SPIs. More comprehensive data sets are needed to identify the operational and biological factors contributing to the differences between flights reported here. Global sharing of an agreed core set of SPIs would greatly facilitate implementation and improvement of FRMS.

Enhancement of the fatigue performance of Ti-6Al-4V implant products

NASA Astrophysics Data System (ADS)

Wimalasiri, Dematapaksha H. R. J.

Implants surgery, in particular hip implants, is fast becoming a routine, popular approach for curing diseases such as, osteoarthritis and rheumatic arthritis. However one potential problem with the insertion of a metal implant is that of the risk of fatigue failure. Numerous factors affect the propensity of a metal to fatigue, none more so than the physical and stress state of the surface. This research is focused on an assessment of the role of manufacturing processes on the fatigue performance of hip implants made from a Ti-6Al-4V alloy. The role of surface defects, surface residual stresses and material microstructural properties which influence fatigue performance were examined. Characterization of the implant material and of the processes involved in actual hip implant manufacturing were conducted. Rotating bend fatigue testing using hour glass shaped specimens was conducted to evaluate the fatigue performance at selected manufacturing stages. The surface roughness/defects and residual stresses were measured prior to conducting fatigue tests. A variation of fatigue limit, attributed to variations of surface roughness and surface residual stress was observed. The influence of parameters such as, stress ratio and mean stress effect, variation of fracture mechanics parameters (e.g. DeltaK[th]) and the limiting threshold conditions for different stages of cracks were investigated in the context of Kitagawa-Takahashi (K-T) type diagrams. Experimental data was used to develop models which were used to calculate, (i). fatigue life at respective stress amplitude and, (ii). the fatigue limit of components with known surface roughness/defect size and residual stress. To evaluate material crack growth properties a surface replication method was used. The output from both models showed good correlation with experimental data. Comprehensive fractography was conducted using optical, secondary electron, and infinite focus microscopy to support the results obtained from

Stereoscopic visual fatigue assessment and modeling

NASA Astrophysics Data System (ADS)

Wang, Danli; Wang, Tingting; Gong, Yue

2014-03-01

Evaluation of stereoscopic visual fatigue is one of the focuses in the user experience research. It is measured in either subjective or objective methods. Objective measures are more preferred for their capability to quantify the degree of human visual fatigue without being affected by individual variation. However, little research has been conducted on the integration of objective indicators, or the sensibility of each objective indicator in reflecting subjective fatigue. The paper proposes a simply effective method to evaluate visual fatigue more objectively. The stereoscopic viewing process is divided into series of sessions, after each of which viewers rate their visual fatigue with subjective scores (SS) according to a five-grading scale, followed by tests of the punctum maximum accommodation (PMA) and visual reaction time (VRT). Throughout the entire viewing process, their eye movements are recorded by an infrared camera. The pupil size (PS) and percentage of eyelid closure over the pupil over time (PERCLOS) are extracted from the videos processed by the algorithm. Based on the method, an experiment with 14 subjects was conducted to assess visual fatigue induced by 3D images on polarized 3D display. The experiment consisted of 10 sessions (5min per session), each containing the same 75 images displayed randomly. The results show that PMA, VRT and PERCLOS are the most efficient indicators of subjective visual fatigue and finally a predictive model is derived from the stepwise multiple regressions.

Real-Time Assessment of Fatigue in Patients With Multiple Sclerosis: How Does It Relate to Commonly Used Self-Report Fatigue Questionnaires?

PubMed

Heine, Martin; van den Akker, Lizanne Eva; Blikman, Lyan; Hoekstra, Trynke; van Munster, Erik; Verschuren, Olaf; Visser-Meily, Anne; Kwakkel, Gert

2016-11-01

(1) To assess real-time patterns of fatigue; (2) to assess the association between a real-time fatigue score and 3 commonly used questionnaires (Checklist Individual Strength [CIS] fatigue subscale, Modified Fatigue Impact Scale (MFIS), and Fatigue Severity Scale [FSS]); and (3) to establish factors that confound the association between the real-time fatigue score and the conventional fatigue questionnaires in patients with multiple sclerosis (MS). Cross-sectional study. MS-specialized outpatient facility. Ambulant patients with MS (N=165) experiencing severe self-reported fatigue. Not applicable. A real-time fatigue score was assessed by sending participants 4 text messages on a particular day (How fatigued do you feel at this moment?; score range, 0-10). Latent class growth mixed modeling was used to determine diurnal patterns of fatigue. Regression analyses were used to assess the association between the mean real-time fatigue score and the CIS fatigue subscale, MFIS, and FSS. Significant associations were tested for candidate confounders (eg, disease severity, work status, sleepiness). Four significantly different fatigue profiles were identified by the real-time fatigue score, namely a stable high (n=79), increasing (n=57), stable low (n=16), and decreasing (n=13). The conventional questionnaires correlated poorly (r<.300) with the real-time fatigue score. The Epworth Sleepiness Scale significantly reduced the regression coefficient between the real-time fatigue score and conventional questionnaires, ranging from 15.4% to 35%. Perceived fatigue showed 4 different diurnal patterns in patients with MS. Severity of sleepiness is an important confounder to take into account in the assessment of fatigue. Copyright © 2016 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Prevalence and Correlates of Fatigue in CKD and ESRD: Are Sleep Disorders a Key to Understanding Fatigue?

PubMed Central

Jhamb, Manisha; Liang, Kelly; Yabes, Jonathan; Steel, Jennifer L; Dew, Mary Amanda; Shah, Nirav; Unruh, Mark

2014-01-01

Background Fatigue is an important symptom to patients with advanced CKD. The aim of this study is to examine the prevalence and severity of fatigue among non-dialysis dependent CKD and ESRD patients; examine association of fatigue with subjective and objective sleep quality; identify other modifiable factors associated with fatigue. Methods Cross-sectional survey of 87 non-dialysis dependent CKD (eGFR ≤45 ml/min/1.73 m2) and 86 ESRD patients was done using Functional Assessment of Chronic Illness Therapy – Fatigue (FACIT-F) and SF-36 vitality scale. Higher FACIT-F score denoted less fatigue. Objective sleep was assessed using in-home polysomnography. Predictors of fatigue were determined using linear regression model. Results Mean FACIT-F score among all participants was 34.5±11.0. Mean scores were similar among CKD and ESRD groups (34.25±11.28 versus 34.73±10.86; p=0.73). On univariate analyses, patients with higher levels of fatigue were more likely to have cardiovascular disease, benzodiazepine use, depressive symptoms, slightly lower hemoglobin and serum albumin levels. There was no significant association between severity of sleep apnea and level of fatigue (Apnea Hypopnea Index 20.1±27.6 versus 20.3±22.0; p=0.69). Presence of cardiovascular disease, low serum albumin, depressive symptoms, poor subjective sleep quality, excessive daytime sleepiness and restless legs syndrome (RLS) were independently associated with greater fatigue in multivariable regression models. The FACIT-F score correlated closely with the SF-36 vitality score (r =0.81, p<0.0001). Conclusions Patients with advanced CKD and ESRD experience profound fatigue. Depressive symptoms, RLS, excessive daytime sleepiness, and low albumin levels may provide targets for interventions to improve fatigue in patients with advanced CKD. PMID:24335380

Effect of alloy composition on high-temperature bending fatigue strength of ferritic stainless steels

NASA Astrophysics Data System (ADS)

Ahn, Yong-Sik; Song, Jeon-Young

2011-12-01

Exhaust manifolds are subjected to an environment in which heating and cooling cycles occur due to the running pattern of automotive engines. This temperature profile results in the repeated bending stress of exhaust pipes. Therefore, among high-temperature characteristics, the bending fatigue strength is an important factor that affects the lifespan of exhaust manifolds. Here, we report on the effect of the alloy composition, namely the weight fraction of the elements Cr, Mo, Nb, and Ti, on the high-temperature bending fatigue strength of the ferritic stainless steel used in exhaust manifolds. Little difference in the tensile strength and bending fatigue strength of the different composition steels was observed below 600 °C, with the exception of the low-Cr steel. However, steels with high Cr, Mo, or Nb fractions showed considerably larger bending fatigue strength at temperatures of 800 °C. After heating, the precipitates from the specimens were extracted electrolytically and analyzed using scanning electron microscopy energy dispersive spectrometry and transmission electron microscopy. Alloying with Cr and Mo was found to increase the bending fatigue strength due to the substitutional solid solution effect, while alloying with Nb enhanced the strength by forming fine intermetallic compounds, including NbC and Fe2Nb.

Fatigue

MedlinePlus

... to help you find out what's causing your fatigue and recommend ways to relieve it. Fatigue itself is not a disease. Medical problems, treatments, and personal habits can add to fatigue. These include Taking certain medicines, such as antidepressants, ...

Persistent Fatigue in Hematopoietic Stem Cell Transplantation Survivors.

PubMed

Hacker, Eileen Danaher; Fink, Anne M; Peters, Tara; Park, Chang; Fantuzzi, Giamila; Rondelli, Damiano

Fatigue is highly prevalent after hematopoietic stem cell transplantation (HCT). It has been described as intense and may last for years following treatment. The aim of this study is to compare fatigue, physical activity, sleep, emotional distress, cognitive function, and biological measures in HCT survivors with persistent fatigue (n = 25) with age- and gender-matched healthy controls with occasional tiredness (n = 25). Data were collected using (a) objective, real-time assessments of physical activity and sleep over 7 days; (b) patient-reported fatigue assessments; (c) computerized objective testing of cognitive functioning; and (d) biological measures. Differences between groups were examined using multivariate analysis of variance. Survivors of HCT reported increased physical (P < .001), mental (P < .001), and overall (P < .001) fatigue as well as increased anxiety (P < .05) and depression (P < .01) compared with healthy controls. Red blood cell (RBC) levels were significantly lower in HCT survivors (P < .001). Levels of RBC for both groups, however, were in the normal range. Tumor necrosis factor-α (P < .001) and interleukin-6 (P < .05) levels were significantly higher in HCT survivors. Persistent fatigue in HCT survivors compared with healthy controls with occasional tiredness is accompanied by increased anxiety and depression along with decreased RBC counts. Elevated tumor necrosis factor-α and interleukin-6 levels may be important biomarkers. This study provides preliminary support for the conceptualization of fatigue as existing on a continuum, with tiredness anchoring one end and exhaustion the other. Persistent fatigue experienced by HCT survivors is more severe than the occasional tiredness of everyday life.

Behavior of Fatigue Crack Tip Opening in Air and Corrosive Atmosphere

NASA Astrophysics Data System (ADS)

Hayashi, Morihito; Toeda, Kazunori

In the study, a formula for predicting fatigue crack tip opening displacement is deduced firstly. And then, due to comparing actual crack growth rate with the deduced formula, the crack tip configuration factor is defined to figure out the crack tip opening configuration that is useful to clarify the behavior of fatigue crack tip formation apparently. Applying the concept, the crack growth of 7/3 brass and 6/4 brass is predicted from the formula, by replacing material properties such as plastic flow resistance, Young modulus, the Poisson ratio, and fatigue toughness, and fatigue test conditions such as the stress intensity factor range, the load ratio, and cycle frequency. Furthermore, the theoretically expected results are verified with the fatigue tests which were carried out on CT specimens under different load conditions of load ratio, cycle frequency, and cyclic peak load, in different environments of air or corrosive ammonia atmosphere, for various brasses. And by comparing and discussing the calculated crack growth rate with attained experimental results, the apparent configuration factor at the crack tip is determined. And through the attained factor which changes along with crack growth, the behaviors of fatigue crack tip formation under different test conditions have been found out.

Positive Affect and Inflammatory Activity in Breast Cancer Survivors: Examining the Role of Affective Arousal

PubMed Central

Moreno, Patricia I.; Moskowitz, Andrew L.; Ganz, Patricia A.; Bower, Julienne E.

2016-01-01

Objective Given the importance of positive affect and inflammation for well-being in cancer survivors, the current study examined the relationship between high and low arousal positive affect and inflammation in 186 women who completed treatment for early-stage breast cancer. Methods Measures of high and low arousal positive affect were completed within three months after treatment completion (baseline). Plasma markers of inflammation, including sTNF-RII, CRP, and IL-1ra, were assessed at baseline and 6 and 12 month follow-up assessments. Results Multilevel modeling analyses showed that high arousal positive affect was associated with lower levels of sTNF-RII, a marker of TNF activity, at treatment completion and prospectively predicted maintenance of these differences through the 6 and 12 month follow-ups controlling for biobehavioral confounds (b = −.055, t(156) = −2.40, p = .018). However, this association was no longer significant when controlling for fatigue. Exploratory analyses showed that low arousal positive affect was associated with lower levels of CRP at treatment completion and through the 6 and 12 month follow-ups; this association remained significant controlling for fatigue and other confounds (b = −.217, t(152) = −2.04, p = .043). Conclusion The relationship of high arousal positive affect (e.g., “active”) with sTNF-RII appears to be driven by the overlap of high arousal positive affect with fatigue while the relationship of low arousal positive affect (e.g., “calm”) with CRP was independent of fatigue. Future research should consider affective arousal when examining the association of positive affect with inflammation as this facet of positive affect may have important implications for interpretation of results. PMID:26867077

Evidence-Based Guidelines for Fatigue Risk Management in Emergency Medical Services

DOT National Transportation Integrated Search

2018-01-11

Background: Administrators of Emergency Medical Services (EMS) operations lack guidance on how to mitigate workplace fatigue, which affects greater than half of all EMS personnel. The primary objective of the Fatigue in EMS Project was to create an e...

Fatigue Exacerbation by Interval or Continuous Exercise in Chronic Fatigue Syndrome.

PubMed

Sandler, Carolina X; Lloyd, Andrew R; Barry, Benjamin K

2016-10-01

The objective of this study is to determine whether the typical exacerbation of symptoms in patients with chronic fatigue syndrome (CFS) after a bout of exercise differs between high-intensity interval training (HIIT) or continuous (CONT) aerobic exercise of the same duration and mechanical work. Participants with specialist-diagnosed CFS performed two 20-min bouts of cycling in a randomized crossover study. The bouts were either moderate-intensity continuous (70% age-predicted HR maximum) or high-intensity interval exercise, separated by at least 2 wk. Self-report questionnaires capturing fatigue, the related symptoms, and actigraphy were collected across 2 d before and 4 d after the exercise. Comparisons between exercise bouts were made using paired sample t-tests. Fourteen moderately affected participants who were unable to work, but not bed bound, completed the study (nine female, 32 ± 10 yr, 67 ± 11 kg). Mechanical work was matched successfully between the exercise bouts (HIIT, 83,037, vs CONT, 83,348 J, P = 0.84). Mean HR (HIIT, 76% ± 5%, vs CONT, 73% ± 6% age-predicted HR maximum, P < 0.05) and RPE (6-20) in the legs (HIIT, 15.4 ± 1.4, vs CONT, 13.2 ± 1.2, P < 0.001) were higher for the interval compared with continuous exercise. Mean fatigue scores (0-10) were similar before each exercise challenge (HIIT, 4.5 ± 1.8, vs CONT, 4.1 ± 1.7, P = 0.43). Participants reported an increase in fatigue scores after both challenges (mean difference: HIIT, 1.0 ± 1.3, P < 0.01; CONT, 1.5 ± 0.7, P < 0.001), but these exacerbations in fatigue were not statistically or clinically different (P = 0.20). High-intensity interval exercise did not exacerbate fatigue any more than continuous exercise of comparable workload. This finding supports evaluation of HIIT in graded exercise therapy interventions for patients with CFS.

Changes in interhemispheric motor connectivity after muscle fatigue

NASA Astrophysics Data System (ADS)

Peltier, Scott; LaConte, Stephen M.; Niyazov, Dmitriy; Liu, Jing; Sahgal, Vinod; Yue, Guang; Hu, Xiaoping

2005-04-01

Synchronized oscillations in resting state timecourses have been detected in recent fMRI studies. These oscillations are low frequency in nature (< 0.08 Hz), and seem to be a property of symmetric cortices. These fluctuations are important as a potential signal of interest, which could indicate connectivity between functionally related areas of the brain. It has also been shown that the synchronized oscillations decrease in some spontaneous pathological states. Thus, detection of these functional connectivity patterns may help to serve as a gauge of normal brain activity. The cognitive effects of muscle fatigue are not well characterized. Sustained fatigue has the potential to dynamically alter activity in brain networks. In this work, we examined the interhemispheric correlations in the left and right primary motor cortices and how they change with muscle fatigue. Resting-state functional MRI imaging was done before and after a repetitive unilateral fatigue task. We find that the number of significant correlations in the bilateral motor network decreases with fatigue. These results suggest that resting-state interhemispheric motor cortex functional connectivity is affected by muscle fatigue.

Microstructure-Sensitive Extreme Value Probabilities for High Cycle Fatigue of Ni-Base Superalloy IN100 (Preprint)

DTIC Science & Technology

2009-03-01

transition fatigue regimes; however, microplasticity (i.e., heterogeneous plasticity at the scale of microstructure) is relevant to understanding fatigue...and Socie [57] considered the affect of microplastic 14 Microstructure-Sensitive Extreme Value Probabilities for High Cycle Fatigue of Ni-Base...considers the local stress state as affected by intergranular interactions and microplasticity . For the calculations given below, the volumes over which

Influence of fatigue, depression, and demographic, socioeconomic, and clinical variables on quality of life of patients with epilepsy.

PubMed

Senol, Vesile; Soyuer, Ferhan; Arman, Fehim; Oztürk, Ahmet

2007-02-01

The purpose of this study was to define the influence of fatigue, depression, and clinical, demographic, and socioeconomic factors on the quality of life of patients with epilepsy. The study was performed on 103 adult patients who visited Erciyes University Epilepsy Outpatient Clinic between 2004 and 2005. Patients were evaluated with the Form of Negotiation, Quality of Life in Epilepsy Inventory (QOLIE-89), Beck Depression Inventory, and Fatigue Severity Scale. Mean age of the patients was 34.3+/-12.6, and mean duration of disease was 12.6+/-9.3 years. Among these patients, 52.4% were men, 49.5% were married, 15.5% had a university education, 53.4% had low incomes, 45.6% had generalized seizures, and 35.0% had experienced one or more seizures per month during the preceding year. The most significant variables in the domain of Overall quality of life were seizure frequency (P<0.001), depression (P<0.001), and fatigue (P<0.001); the variables in the domain of Mental Health were seizure frequency (P<0.001) and fatigue (P<0.001); the variable in the Cognitive domain was fatigue (P<0.001); the variables in the domain of Physical Health were social insurance coverage (P<0.01), fatigue (P<0.01), and age (P<0.01); the variables in the Epilepsy Targeted domain were depression (P<0.001), seizure frequency (P<0.001), and fatigue (P<0.01). Although quality of life has multiple determinants, seizure frequency, fatigue, and depression are the most important factors affecting quality of life in patients with epilepsy. One or more seizures per month, severe fatigue, and depression are associated with lower quality of life in some but not all domains. Partial correlations demonstrated that fatigue was a significant independent predictor of quality of life. The present study confirms that fatigue can be a powerful predictor of quality of life.

Subacromial impingement syndrome: An electromyographic study of shoulder girdle muscle fatigue.

PubMed

Alizadehkhaiyat, Omid; Roebuck, Margaret M; Makki, Ahmed T; Frostick, Simon P

2018-02-01

Muscle fatigue affecting glenohumeral and/or scapular muscles is suggested as one of the contributing factors to the development of subacromial impingement syndrome (SAIS). Nonetheless, the fatigability of shoulder girdle muscles in association with the pathomechanics of SAIS has not been reported. This study aimed to measure and compare fatigue progression within the shoulder girdle musculature of patients and healthy controls. 75 participants including 39 patients (20 females; 19 males) and 36 healthy controls (15 females; 21 males) participated in the study. Study evaluated the progression of muscle fatigue in 15 shoulder girdle muscles by means of surface and fine-wire EMG during submaximal contraction of four distinct movements (abduction, flexion, internal and external rotation). Shoulder strength, subjective pain experience (McGill Pain Questionnaire), and psychological status (Hospital Anxiety and Depression Scale) were also assessed. The results were compared between patient and control groups according to the gender. Despite marked fatigue observed in the majority of muscles particularly during flexion and abduction at 90°, overall results indicated a lower tendency of fatigue progression in the impingement group across the tests (p < 0.05 - p < 0.001). Shoulder Strength, pain experience, and psychological status were significantly different between the two groups (P < .05). Lower tendency to fatigue progression in the impingement group can be attributed to the presence of fear avoidance and pain-related muscle inhibition, which in turn lead to adaptations in motor programme to reduce muscle recruitment and activation. The significantly higher levels of pain experience and anxiety/depression in the impingement group further support this proposition. Copyright © 2017 Elsevier Ltd. All rights reserved.

Parental fatigue and parenting practices during early childhood: an Australian community survey.

PubMed

Cooklin, A R; Giallo, R; Rose, N

2012-09-01

Parenting behaviours are influenced by a range of factors, including parental functioning. Although common, the influence of parental fatigue on parenting practices is not known. The first aim of this study was to investigate the relationship between fatigue and parenting practices. The second aim was to identify parental psychosocial factors significantly associated with fatigue. A sample of 1276 Australian parents, of at least one child aged 0-5 years, completed a survey. Demographic, psychosocial (social support, coping responses) and parental sleep and self-care information was collected. Hierarchical regression was performed to assess the contribution of fatigue (modified Fatigue Assessment Scale) to parental practices (warmth, irritability and involvement), and parenting experiences (Parenting Stress Index, Parenting Sense of Competence Scale). Hierarchical multiple regression assessed the contribution of a range of parental sleep, psychosocial (social support, coping responses) and self-care variables to fatigue when demographic characteristics were held constant. Higher fatigue was significantly associated with lower parental competence (β=-0.17, P < 0.005), greater parenting stress (β= 0.21, P < 0.005) and more irritability in parent-child interactions (β= 0.11, P < 0.005). Several psychosocial characteristics were associated with higher parental fatigue, including inadequate social support, poorer diet, poorer sleep quality and ineffective coping styles including self-blame and behaviour disengagement. Fatigue is common, and results suggest that fatigue contributes to adverse parental practices and experiences. However, possible risk factors for higher fatigue were identified in this study, indicating opportunities for intervention, management and support for parents. © 2011 Blackwell Publishing Ltd.

Fatigue associated with prolonged graded running.

PubMed

Giandolini, Marlene; Vernillo, Gianluca; Samozino, Pierre; Horvais, Nicolas; Edwards, W Brent; Morin, Jean-Benoît; Millet, Guillaume Y

2016-10-01

Scientific experiments on running mainly consider level running. However, the magnitude and etiology of fatigue depend on the exercise under consideration, particularly the predominant type of contraction, which differs between level, uphill, and downhill running. The purpose of this review is to comprehensively summarize the neurophysiological and biomechanical changes due to fatigue in graded running. When comparing prolonged hilly running (i.e., a combination of uphill and downhill running) to level running, it is found that (1) the general shape of the neuromuscular fatigue-exercise duration curve as well as the etiology of fatigue in knee extensor and plantar flexor muscles are similar and (2) the biomechanical consequences are also relatively comparable, suggesting that duration rather than elevation changes affects neuromuscular function and running patterns. However, 'pure' uphill or downhill running has several fatigue-related intrinsic features compared with the level running. Downhill running induces severe lower limb tissue damage, indirectly evidenced by massive increases in plasma creatine kinase/myoglobin concentration or inflammatory markers. In addition, low-frequency fatigue (i.e., excitation-contraction coupling failure) is systematically observed after downhill running, although it has also been found in high-intensity uphill running for different reasons. Indeed, low-frequency fatigue in downhill running is attributed to mechanical stress at the interface sarcoplasmic reticulum/T-tubule, while the inorganic phosphate accumulation probably plays a central role in intense uphill running. Other fatigue-related specificities of graded running such as strategies to minimize the deleterious effects of downhill running on muscle function, the difference of energy cost versus heat storage or muscle activity changes in downhill, level, and uphill running are also discussed.

The Effect of Shoulder Muscle Fatigue on Acromiohumeral Distance and Scapular Dyskinesis in Women With Generalized Joint Hypermobility.

PubMed

Alibazi, Razie J; Moghadam, Afsun Nodehi; Cools, Ann M; Bakhshi, Enayatollah; Ahari, Alireza Aziz

2017-12-01

Muscle fatigue is considered to be one cause of shoulder pain, and subjects with generalized joint hypermobility (GJH) are affected more by shoulder pain. The purpose of this study was to examine the effects of muscle fatigue on acromiohumeral distance (AHD) and scapular dyskinesis in women with GJH. Thirty-six asymptomatic participants were assigned to either a GJH (n = 20) or control group (n = 16) using the Beighton scale. Before and after elevation fatigue trials, AHD was measured with ultrasonography at rest and when the arm was in 90° active elevation. A scapular dyskinesis test was used to visually observe alterations in scapular movement. Our results showed that in both groups, the fatigue reduced AHD in the 90° elevation position and increased the presence of scapular dyskinesis; however, no differences were found between the two groups. Although GJH has been identified as a factor for developing musculoskeletal disorders, generalized joint hypermobility did not result in changes to scapular dyskinesis or AHD, even after an elevation fatigue task. More studies are needed to evaluate the effects of muscle fatigue in subjects with GJH and a history of shoulder instability.

High validity and reliability of the PedsQL™ Multidimensional Fatigue Scale for Brazilian children with cancer.

PubMed

Nascimento, Lucila Castanheira; Nunes, Michelle Darezzo Rodrigues; Rocha, Ester Leonardo; Bomfim, Emiliana Omena; Floria-Santos, Milena; Dos Santos, Claudia Benedita; Dos Santos, Danielle Maria de Souza Serio; de Lima, Regina Aparecida Garcia

2015-01-01

Among the main factors that affect patients' quality of life, fatigue is a significant symptom experienced by children during treatment. Despite the high incidence, there has been no validated scale to evaluate fatigue in children with cancer in Brazil. The purpose of this study was to examine the psychometric properties of the PedsQL™ Multidimensional Fatigue Scale, using self-reports of Brazilian children, 8 to 18 years of age, and proxy reports. A cross-sectional method was used to collect data from 216 subjects over an 18-month period. Reliability ranged from .70 to .90 except for sleep/rest fatigue, self-report (α = .55). No floor or ceiling effects were found in any dimension. Convergent validity was higher than .40 and divergent validity had 100% adjustment. The root mean square error of approximation was acceptable. The comparative fit index was lower than expected. The agreement between self and proxy responses was weak and moderate. The results demonstrate the reliability and validity of the Brazilian version in children with cancer. This is the first validated scale that assesses fatigue in Brazilian children and adolescents with cancer. © 2014 by Association of Pediatric Hematology/Oncology Nurses.

[Attention, repetitive works, fatigue and stress].

PubMed

Tomei, G; Cinti, M E; Cerratti, D; Fioravanti, M

2006-01-01

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

The Experience and Self-Management of Fatigue in Hemodialysis Patients

PubMed Central

Horigan, Ann E.; Schneider, Susan M.; Docherty, Sharron; Barroso, Julie

2013-01-01

Fatigue is a common and debilitating symptom for adult patients with end stage renal disease on hemodialysis and has been associated with decreased survival and quality of life. Patients on hemodialysis must find ways to manage their fatigue and mitigate its effects on their lives. Currently, there is no description of the experience of fatigue for patients on hemodialysis living in the U.S., nor is there any description of the ways in which they manage their fatigue. The purpose of this qualitative descriptive work was to describe the experience and self-management of fatigue. Several themes were identified which included: the nature of fatigue, management of fatigue, consequences of fatigue, and factors associated with fatigue. This information will be valuable to nephrology nurses as they continue to care for and educate patients on hemodialysis. PMID:23767335

Driving fatigue in professional drivers: a survey of truck and taxi drivers.

PubMed

Meng, Fanxing; Li, Shuling; Cao, Lingzhi; Li, Musen; Peng, Qijia; Wang, Chunhui; Zhang, Wei

2015-01-01

Fatigue among truck drivers has been studied extensively; however, less is known regarding the fatigue experience of taxi drivers in heavily populated metropolitan areas. This study aimed to compare the differences and similarities between truck and taxi driver fatigue to provide implications for the fatigue management and education of professional drivers. A sample of 274 truck drivers and 286 taxi drivers in Beijing was surveyed via a questionnaire, which included items regarding work characteristics, fatigue experience, accident information, attitude toward fatigue, and methods of counteracting fatigue. Driver fatigue was prevalent among professional drivers, and it was even more serious for taxi drivers. Taxi drivers reported more frequent fatigue experiences and were involved in more accidents. Among the contributing factors to fatigue, prolonged driving time was the most important factor identified by both driver groups. Importantly, the reason for the engagement in prolonged driving was neither due to the lack of awareness concerning the serious outcome of fatigue driving nor because of their poor detection of fatigue. The most probable reason was the optimism bias, as a result of which these professional drivers thought that fatigue was more serious for other drivers than for themselves, and they thought that they were effective in counteracting the effect of fatigue on their driving performance. Moreover, truck drivers tended to employ methods that require stopping to counteract fatigue, whereas taxi drivers preferred methods that were simultaneous with driving. Although both driver groups considered taking a nap as one of the most effective means to address fatigue, this method was not commonly used. Interestingly, these drivers were aware that the methods they frequently used were not the most effective means to counteract fatigue. This study provides knowledge on truck and taxi drivers' characteristics in fatigue experience, fatigue attitude, and

The assessment of fatigue: Psychometric qualities and norms for the Checklist individual strength.

PubMed

Worm-Smeitink, M; Gielissen, M; Bloot, L; van Laarhoven, H W M; van Engelen, B G M; van Riel, P; Bleijenberg, G; Nikolaus, S; Knoop, H

2017-07-01

The Checklist Individual Strength (CIS) measures four dimensions of fatigue: Fatigue severity, concentration problems, reduced motivation and activity. On the fatigue severity subscale, a cut-off score of 35 is used. This study 1) investigated the psychometric qualities of the CIS; 2) validated the cut-off score for severe fatigue and 3) provided norms. Representatives of the Dutch general population (n=2288) completed the CIS. The factor structure was investigated using an exploratory factor analysis. Internal consistency and test-retest reliability were determined. Concurrent validity was assessed in two additional samples by correlating the CIS with other fatigue scales (Chalder Fatigue Questionnaire, MOS Short form-36 Vitality subscale, EORTC QLQ-C30 fatigue subscale). To validate the fatigue severity cut-off score, a Receiver Operating Characteristics analysis was performed with patients referred to a chronic fatigue treatment centre (n=5243) and a healthy group (n=1906). Norm scores for CIS subscales were calculated for the general population, patients with chronic fatigue syndrome (CFS; n=1407) and eight groups with other medical conditions (n=1411). The original four-factor structure of the CIS was replicated. Internal consistency (α=0.84-0.95) and test-retest reliability (r=0.74-0.86) of the subscales were high. Correlations with other fatigue scales were moderate to high. The 35 points cut-off score for severe fatigue is appropriate, but, given the 17% false positive rate, should be adjusted to 40 for research in CFS. The CIS is a valid and reliable tool for the assessment of fatigue, with a validated cut-off score for severe fatigue that can be used in clinical practice. Copyright © 2017. Published by Elsevier Inc.