On the relationship between subjective and objective measures of fatigue

Probing sustained attention and fatigue across the lifespan

Trait fatigues reflects tiredness that persists throughout a prolonged period, whereas state fatigue is a short-term reaction to intense or prolonged effort. We investigated the impact of sustained attention (using the SART) on both trait and state fatigue levels in the general population. An online version of the SART was undertaken by 115 participants, stratified across the whole adult lifespan. While pre-task trait fatigue was a strong indicator of the initial state fatigue levels, undergoing the task itself induced an increase in reported subjective state fatigue, and an accompanying reduction in subjective energy rating. Consistent with this finding, greater subjective state fatigue levels were associated with reduced accuracy. In addition, age was the best predictor of inter-participant accuracy (the older the participants, the greater the accuracy), and learning (i.e., task duration reducing reaction times). Moreover, a ceiling effect occurred where participants with higher trait fatigue did not experience greater state fatigue changes relative to those with low trait scores. In summary, we found improved accuracy in older adults, as well as a tight coupling between state fatigue and SART performance decline (in an online environment). The findings warrant further investigation into fatigue as a dynamic, task-dependent state and into SART performance as an objective measure and inducer of fatigue.

Assessment of Self-report, Palpation, and Surface Electromyography Dataset During Isometric Muscle Contraction

Measuring muscle fatigue involves assessing various components within the motor system. While subjective and sensor-based measures have been proposed, a comprehensive comparison of these assessment measures is currently lacking. This study aims to bridge this gap by utilizing three commonly used measures: participant self-reported perceived muscle fatigue scores, a sports physiotherapist's manual palpation-based muscle tightness scores, and surface electromyography sensors. Compensatory muscle fatigue occurs when one muscle group becomes fatigued, leading to the involvement and subsequent fatigue of other muscles as they compensate for the workload. The evaluation of compensatory muscle fatigue focuses on nine different upper body muscles selected by the sports physiotherapist. With a cohort of 30 male subjects, this study provides a valuable dataset for researchers and healthcare practitioners in sports science, rehabilitation, and human performance. It enables the exploration and comparison of diverse methods for evaluating different muscles in isometric contraction.

Relationship between subjective and objective fatigue and sleep characteristics in individuals with anxiety and mood disorders: An exploratory study

OBJECTIVE

Fatigue and sleep disturbances are important symptoms of anxiety and mood disorders (AMD). Studies about the relationship between these variables usually rely on self-report assessments. Therefore, the aim of our exploratory study was to investigate the independent correlations between subjective and objective fatigue and sleep characteristics in individuals with AMD.

METHODS

In sum, 233 individuals with AMD attending a stress-related disorders day care unit (78.5 % females, mean age 39.0 years old) participated in a cross-sectional study. Participants completed the Patient Health Questionnaire-9, Generalized Anxiety Disorder-7, Multidimensional Fatigue Inventory-20, and Pittsburgh Sleep Quality Index self-report questionnaires, as well as an exercise capacity workload test for assessing objective fatigue and polysomnography monitoring for evaluation of sleep structure.

RESULTS

In individuals with AMD, exercise capacity workload was associated with lower percent of stage 1 sleep (β = - 0.17, p = 0.006), REM latency (β = -0.13, p = 0.042), and wake after sleep onset (β = -0.12, p = 0.039). General fatigue was associated with a higher percent of body movements (β = 0.12, p = 0.047), as well as mental fatigue was associated with a higher percent of body movements (β = 0.13, p = 0.029), and a higher score on the PSQI (β = 0.21, p = 0.002).

CONCLUSIONS

Objective sleep characteristics were associated with objective assessment of fatigue, while subjective sleep quality was associated with subjectively assessed mental fatigue.

Fatigue and Human Performance: An Updated Framework

Fatigue has been defined differently in the literature depending on the field of research. The inconsistent use of the term fatigue complicated scientific communication, thereby limiting progress towards a more in-depth understanding of the phenomenon. Therefore, Enoka and Duchateau (Med Sci Sports Exerc 48:2228-38, 2016, [3]) proposed a fatigue framework that distinguishes between trait fatigue (i.e., fatigue experienced by an individual over a longer period of time) and motor or cognitive task-induced state fatigue (i.e., self-reported disabling symptom derived from the two interdependent attributes performance fatigability and perceived fatigability). Thereby, performance fatigability describes a decrease in an objective performance measure, while perceived fatigability refers to the sensations that regulate the integrity of the performer. Although this framework served as a good starting point to unravel the psychophysiology of fatigue, several important aspects were not included and the interdependence of the mechanisms driving performance fatigability and perceived fatigability were not comprehensively discussed. Therefore, the present narrative review aimed to (1) update the fatigue framework suggested by Enoka and Duchateau (Med Sci Sports Exerc 48:2228-38, 2016, [3]) pertaining the taxonomy (i.e., cognitive performance fatigue and perceived cognitive fatigue were added) and important determinants that were not considered previously (e.g., effort perception, affective valence, self-regulation), (2) discuss the mechanisms underlying performance fatigue and perceived fatigue in response to motor and cognitive tasks as well as their interdependence, and (3) provide recommendations for future research on these interactions. We propose to define motor or cognitive task-induced state fatigue as a psychophysiological condition characterized by a decrease in motor or cognitive performance (i.e., motor or cognitive performance fatigue, respectively) and/or an increased perception of fatigue (i.e., perceived motor or cognitive fatigue). These dimensions are interdependent, hinge on different determinants, and depend on body homeostasis (e.g., wakefulness, core temperature) as well as several modulating factors (e.g., age, sex, diseases, characteristics of the motor or cognitive task). Consequently, there is no single factor primarily determining performance fatigue and perceived fatigue in response to motor or cognitive tasks. Instead, the relative weight of each determinant and their interaction are modulated by several factors.

Efficacy and safety of fermented Prunus mume vinegar on fatigue improvement in adults with unexplained fatigue: A randomized controlled trial

Background

The accumulation of fatigue leads to reduced physical, emotional, psychological, and social functions.

Objectives

Fermented Prunus mume vinegar (PV) improves fatigue in animals; however, studies in humans have not been conducted. We aimed to examine the effects and safety of consuming fermented PV for 8 weeks on fatigue indices in adults with unexplained fatigue while considering the placebo effect.

Methods

A randomized, double-blind, placebo-controlled trial was conducted in adults of >19 years, who were diagnosed with unexplained fatigue for at least 1 month. Eighty participants were randomly assigned to receive daily 70 mL of fermented PV (2.56 mg/g, chlorogenic acid, and 15.3 mg/g, citric acid) or a placebo for 8 weeks. At baseline and 4 and 8 weeks after treatment, the participants were visited for blood tests (liver enzyme, glucose, creatinine, lactate, malondialdehyde [MDA], and creatine kinase [CK]) and questionnaires (Fatigue Severity Scale [FSS], fatigue visual analog scale [VAS], Beck Depression Inventory [BDI], the Korean version of the Brief Encounter Psychosocial Instrument [BEPSI-K], EQ-5D-3L, and EQ-VAS]).

Results

Fermented PV supplementation for 8 weeks did not remarkably improve the fatigue indices when compared to placebo. Additionally, differences in fatigue VAS, BDI, BEPSI-K, EQ-5D-3L, EQ-VAS, lactate, CK, and MDA concentrations between the groups were not observed. However, FSS had positively correlated with fatigue VAS, BDI, and BEPSI-K, whereas it was negatively correlated with EQ-5D-3L and EQ-VAS at the baseline and 8 weeks. None of the participants reported adverse events.

Conclusion

The efficacy of fermented PV did not exceed the efficacy of placebo in adults with unexplained fatigue.

Clinical trial registration

[ClinicalTrials.gov], identifier [NCT04319692].

Exploring the concept inability to work fulltime in the context of work disability assessments: a qualitative study

Background

In many countries inability to work fulltime is recognized as an important concept in work disability assessments. However, consensus is lacking regarding the concept and how it should be assessed. This study seeks to conceptualize and operationalize the concept of inability to work fulltime, and includes perspectives of both patients and physicians. Research questions involve identifying: 1. key elements, 2. measurable indicators, and 3. valid methods for assessing indicators of inability to work fulltime.

Methods

We used a qualitative study with a thematic content analysis design to conceptualize inability to work fulltime, based on nineteen semi-structured interviews conducted among insurance and occupational health physicians, and representatives of patient organizations.

Results

Inability to work fulltime is conceptualized as a complex concept which is strongly individually determined and variable due to time and underlying disease. Key dimensions of inability to work fulltime included besides the disease itself, also personal factors like psychological and lifestyle factors, as well as environmental factors related to the work situation and social context. Fatigue, cognitive impairments, and restrictions in functioning in- and outside work were reported as important measurable indicators. A combined use of self-assessment, assessment interviews, and testing, and assessment in the actual (work) setting was identified for assessing these indicators.

Conclusion

Taking into account the complex and variable nature of inability to work fulltime, we found it advisable to use multiple methods and multiple time points for the assessment. Results of this study provide starting points for further research on the operationalization of inability to work fulltime in a work disability context.

Measurement of fatigue in clinicians within hospital settings: a systematic review protocol of measurement properties

OBJECTIVE

The objective of this review is to evaluate measurement properties of instruments used to measure fatigue in clinicians within hospital settings.

INTRODUCTION

Research has shown that clinician fatigue leads to accidents and mistakes, and puts patient safety at risk. The problem of managing fatigue in clinicians may need a more complex approach than only restricting work hours. It may be helpful to include a measure of fatigue in the workplace so that fatigue may be quantified, predicted, and correlated to performance.

INCLUSION CRITERIA

Articles will include clinicians working in hospitals, and will evaluate and present measurement properties of the instruments used to measure fatigue. The studies of interest include validation studies, quantitative research, and instrument development reports.

METHODS

Databases to be searched include PubMed, Scopus, Web of Science, Cochrane Library, Embase, PsycINFO, CINAHL, EThOS (Electronic Thesis Online Service), ProQuest Dissertations and Theses: Global, and will be limited to publications in English. There will be no date limits. Articles will be screened and those meeting the inclusion criteria will be retained and assessed for methodological quality by two independent appraisers. Data will be presented using a narrative synthesis and tables presenting the measurement properties of each instrument and ancillary data.

SYSTEMATIC REVIEW REGISTRATION NUMBER

PROSPERO CRD42020186226.

An observational study of the association between sleep disturbance, fatigue and cognition in the post-acute period after mild traumatic brain injury in prospectively studied premorbidly healthy adults

The literature examining the relationship between sleep disturbance, fatigue, and cognition in premorbidly healthy civilian adults after mTBI is very limited. The current study aimed to investigate the relationships of sleep disturbance and fatigue with cognition while controlling for psychological distress and age. Using a prospective observational design, we assessed 60 premorbidly healthy individuals approximately 8 weeks after mTBI. Participants were assessed with the Pittsburgh Sleep Quality Index and the Multidimensional Fatigue Inventory as well as measures of speed of information processing, attention, memory, and executive function; depression and anxiety were also assessed. Findings revealed associations between sleep disturbance and cognition (r²= .586, p < .001) as well as between fatigue and cognition (r²= .390, p < .01), independent of the impact of psychological status and age. Associations were evident in the domains of processing speed, attention, and memory, but were most consistently apparent on measures of executive function. Greater sleep disturbance was most consistently associated with poorer cognitive function. Unexpectedly, higher levels of fatigue were associated with better cognitive function, which may be explained by the coping hypothesis. Given sleep interventions have been shown to improve sleep disturbance, these findings suggest that sleep intervention may also result in improved cognition after mTBI.

Incorporating methods and findings from neuroscience to better understand placebo and nocebo effects in sport

Placebo and nocebo effects are a factor in sports performance. However, the majority of published studies in sport science are descriptive and speculative regarding mechanisms. It is therefore not unreasonable for the sceptic to argue that placebo and nocebo effects in sport are illusory, and might be better explained by variations in phenomena such as motivation. It is likely that, in sport at least, placebo and nocebo effects will remain in this empirical grey area until researchers provide stronger mechanistic evidence. Recent research in neuroscience has identified a number of consistent, discrete and interacting neurobiological and physiological pathways associated with placebo and nocebo effects, with many studies reporting data of potential interest to sport scientists, for example relating to pain, fatigue and motor control. Findings suggest that placebos and nocebos result in activity of the opioid, endocannabinoid and dopamine neurotransmitter systems, brain regions including the motor cortex and striatum, and measureable effects on the autonomic nervous system. Many studies have demonstrated that placebo and nocebo effects associated with a treatment, for example an inert treatment presented as an analgesic or stimulant, exhibit mechanisms similar or identical to the verum or true treatment. Such findings suggest the possibility of a wide range of distinct placebo and nocebo mechanisms that might influence sports performance. In the present paper, we present some of the findings from neuroscience. Focussing on fatigue as an outcome and caffeine as vehicle, we propose three approaches that researchers in sport might incorporate in their studies in order to better elucidate mechanisms of placebo/nocebo effects on performance.

The Association of Body Mass Index and Body Composition with Pain, Disease Activity, Fatigue, Sleep and Anxiety in Women with Fibromyalgia

The link between fibromyalgia syndrome (FMS) and obesity has not been thoroughly investigated. The purpose of this study was to examine the relationships among body mass index (BMI) and body composition parameters, including fat mass, fat mass percentage, and visceral fat, as well as FMS features, such as tender point count (TPC), pain, disease activity, fatigue, sleep quality, and anxiety, in a population of FMS women and healthy controls. A total of seventy-three women with FMS and seventy-three healthy controls, matched on weight, were included in this cross-sectional study. We used a body composition analyzer to measure fat mass, fat mass percentage, and visceral fat. Tender point count (TPC) was measured by algometry pressure. The disease severity was measured with the Fibromyalgia Impact Questionnaire (FIQ-R) and self-reported global pain was evaluated with the visual analog scale (VAS). To measure the quality of sleep, fatigue, and anxiety we used the Pittsburgh Sleep Quality Questionnaire (PSQI), the Spanish version of the multidimensional fatigue inventory (MFI), and the Beck Anxiety Inventory (BAI), respectively. Of the women in this study, 38.4% and 31.5% were overweight and obese, respectively. Significant differences in FIQ-R.1 (16.82 ± 6.86 vs. 20.66 ± 4.71, p = 0.030), FIQ-R.3 (35.20 ± 89.02 vs. 40.33 ± 5.60, p = 0.033), and FIQ-R total score (63.87 ± 19.12 vs. 75.94 ± 12.25, p = 0.017) among normal-weight and overweight FMS were observed. Linear analysis regression revealed significant associations between FIQ-R.2 (β(95% CI)= 0.336, (0.027, 0.645), p = 0.034), FIQ-R.3 (β(95% CI)= 0.235, (0.017, 0.453), p = 0.035), and FIQ-R total score (β(95% CI)= 0.110, (0.010, 0.209), p = 0.032) and BMI in FMS women after adjusting for age and menopause status. Associations between sleep latency and fat mass percentage in FMS women (β(95% CI)= 1.910, (0.078, 3.742), p = 0.041) and sleep quality and visceral fat in healthy women (β(95% CI)= 2.614, (2.192, 3.036), p = 0.008) adjusted for covariates were also reported. The higher BMI values are associated with poor FIQ-R scores and overweight and obese women with FMS have higher symptom severity. The promotion of an optimal BMI might contribute to ameliorate some of the FMS symptoms.

Functional work breaks in a high-demanding work environment: an experimental field study

Work breaks are known to have positive effects on employees' health, performance and safety. Using a sample of twelve employees working in a stressful and cognitively demanding working environment, this experimental field study examined how different types of work breaks (boxing, deep relaxation and usual breaks) affect participants' mood, cognitive performance and neurophysiological state compared to a control condition without any break. In a repeated measures experimental design, cognitive performance was assessed using an auditory oddball test and a Movement Detection Test. Brain cortical activity was recorded using electroencephalography. Individual's mood was analysed using a profile of mood state. Although neurophysiological data showed improved relaxation of cortical state after boxing (vs. 'no break' and 'deep relaxation'), neither performance nor mood assessment showed similar results. It remains questionable whether there is a universal work break type that has beneficial effects for all individuals. Practitioner Summary: Research on work breaks and their positive effects on employees' health and performance often disregards break activities. This experimental field study in a stressful working environment investigated the effect of different work break activities. A universal work break type that is beneficial for this workplace could not be identified.