Clinical neurophysiology of fatigue

The Palliative Care Needs of Patients with Multiple Sclerosis, Parkinson's Related Diseases, and Motor Neurone Disease: A Secondary Analysis of the OPTCARE Neuro Trial Data

Background: Long-term neurological conditions include multiple sclerosis, Parkinson's-related diseases, and motor neurone disease. National and international guidelines recommend a palliative approach for advancing neurological disease, but there is little research describing and comparing the palliative care needs of these patients side by side. Objective: The aim of this study was to describe and compare the symptom burden and psychological distress of patients with multiple sclerosis, Parkinson's-related diseases, and motor neurone disease. Design: A cross-sectional secondary analysis of the OPTCARE Neuro trial data was performed. Setting/Subjects: Recruitment was from seven sites across the United Kingdom. Patients aged 18 years or older, severely affected by advanced stages of multiple sclerosis or Parkinson's-related diseases or any stage of motor neurone disease, with an unresolved symptom, and one other issue despite usual care were eligible. Measurements: Baseline demographics, Integrated Palliative care Outcome Scale (IPOS) Neuro, and Hospital Anxiety and Depression Scale (HADS) results were analyzed. Results: Data from 348 participants were analyzed. The mean IPOS Neuro-S24 score was 27, with no statistical difference found between groups (p = 0.341). The most common symptoms were poor mobility (68.5%), problems using legs (63%), and fatigue (34.8%). The HADS revealed that a quarter of participants met the criteria for a diagnosis of anxiety and depression. Conclusions: Multiple sclerosis, Parkinson's-related disease, and motor neurone disease patients who were eligible for the OPTCARE Neuro trial have unmet needs in the form of distressing physical and psychological symptoms. It is unclear how to address these needs. The answer likely lies in a collaborative approach between neurology, palliative care, psychology, and specialized allied health professionals. Future work should focus on investigating this.

Potential mechanisms underlying the effect of walking exercise on cancer-related fatigue in cancer survivors

PURPOSE

Cancer-related fatigue (CRF) is a common and debilitating long-term side effect of cancer and its treatment. While exercise has been shown to effectively reduce CRF, the underlying mechanisms are not fully clear. Therefore, the aim of this study was to explore the effects of a 4-month walking exercise program on fatigue severity and to explore potential underlying physiological, behavioral, and psychological mechanisms of action.

METHODS

We included 27 cancer survivors (59 ± 15 years, 37% female) with variable cancer diagnoses who were at least moderately fatigued and finished treatment between 6 and 36 months ago. This study with a quasi-experimental interrupted time-series design compared a 4-month walking intervention period with a 4-month control period. Measurements of fatigue and physiological, behavioral, and psychological factors were performed, supplemented with participants' perceptions on how exercise influenced their fatigue.

RESULTS

A significant and clinically relevant decrease in fatigue severity was found over time (β =  - 8.1, 95% CI =  - 12.1; - 4.2), but could not be attributed directly to the walking exercise intervention. Increases in muscle strength (β =  - 0.07, 95% CI =  - 0.12; - 0.02), physical activity (β =  - 0.1, 95% CI =  - 0.2; - 0.04), and sleep quality (β = 1.1, 95% CI = 0.3; 1.9), as well as decreases in muscle relaxation times (β = 0.09, 95% CI = 0.02; 0.16) and psychological distress (β = 1.1, 95% CI = 0.8; 1.3) were associated with reductions in fatigue severity. Resilience and physical well-being were perceived as most important constructs explaining the walking exercise effects on fatigue.

CONCLUSION

Our findings reveal potential physiological, behavioral, and psychological mechanisms underlying the multidimensional effects of exercise on fatigue severity.

IMPLICATIONS FOR CANCER SURVIVORS

Incorporating resistance exercise and addressing resilience and physical well-being might improve the efficacy of exercise interventions for cancer survivors.

Analysis and applications of respiratory surface EMG: report of a round table meeting

Surface electromyography (sEMG) can be used to measure the electrical activity of the respiratory muscles. The possible applications of sEMG span from patients suffering from acute respiratory failure to patients receiving chronic home mechanical ventilation, to evaluate muscle function, titrate ventilatory support and guide treatment. However, sEMG is mainly used as a monitoring tool for research and its use in clinical practice is still limited-in part due to a lack of standardization and transparent reporting. During this round table meeting, recommendations on data acquisition, processing, interpretation, and potential clinical applications of respiratory sEMG were discussed. This paper informs the clinical researcher interested in respiratory muscle monitoring about the current state of the art on sEMG, knowledge gaps and potential future applications for patients with respiratory failure.

Transcranial direct current stimulation for fatigue in neurological conditions: A systematic scoping review

BACKGROUND AND PURPOSE

Fatigue following neurological conditions negatively impacts daily activities, reducing overall quality of life. Transcranial direct current stimulation (tDCS) for fatigue management is still underexplored. This scoping review explores its use in managing fatigue among various neurological conditions.

METHODS

A thorough literature search was carried out using PubMed, Scopus, CINAHL, Web of Science, Embase, ProQuest, and the Cochrane Library. Google Scholar and clinicaltrials.gov were manually searched for gray literature and ongoing trials, respectively. Regardless of the study design, all studies utilizing tDCS for the management of fatigue in various neurological conditions were considered. Two reviewers independently screened all the studies, following which the data were retrieved.

RESULTS

Studies employing tDCS for fatigue management across neurological conditions is as follows: Multiple sclerosis (MS) (n = 28, 66%), stroke (n = 5, 12%), Parkinson's disease (PD) (n = 4, 10%), post-polio syndrome (PPS) (n = 2, 5%), traumatic brain injury (TBI) (n = 2, 5%), and amyotrophic lateral sclerosis (n = 1, 2%). All the studies used anodal stimulation, with the common stimulation site being the left dorsolateral prefrontal cortex for MS, stroke, and PD. A stimulation intensity of 1.0-4.0 mA with a duration ranging from 15 to 30 min in 1 to 24 sessions were commonly reported. The Fatigue Severity Scale (n = 21) and Modified Fatigue Impact Scale (n = 17) were frequently implemented outcome measures. Regardless of the study design, 36/42 (85.7%) studies reported an improvement in fatigue scores in the tDCS group. The common adverse events noted were tingling (n = 8, 35%), headache (n = 6, 26%), and itching (n = 6, 26%).

DISCUSSION

Application of tDCS for fatigue was explored in individuals with stroke, PD, PPS, and TBI after MS. Even though a wide range of treatment parameters and outcome measures were adopted to assess and target fatigue, tDCS proves to have a promising role in alleviating this symptom.

Post-stroke fatigue: a review of development, prevalence, predisposing factors, measurements, and treatments

Background

Post-stroke fatigue (PSF) is a ubiquitous and overwhelming symptom for most stroke survivors. However, there are no effective management strategies for PSF, which is partly due to our limited understanding.

Objective

In this paper, we review the development, prevalence, predisposing factors, measurements, and treatments of PSF.

Results

PSF is an independent symptom after stroke, with a prevalence ranging from 42 to 53%, which depends on the selection of measurement tools and stroke characteristics. It is affected by biological, physical, and psychological factors, among which inflammation may play a key role.

Conclusion

Numerous but non-specific evaluation measurement tools limit the management of PSF. In clinical practice, it may be beneficial to identify PSF by combining scales and objective indexes, such as walking tests and electromyographic examinations. There are no evidence-based interventions to improve PSF. However, increasing evidence suggests that transcranial direct-current stimulation and mindfulness-based interventions may become promising treatments. Further studies are urgently needed to better understand the etiology of PSF, thereby providing the basis for developing new measurement tools and targeted treatments.

Effect of Exergaming on Quality of Life, Fatigue, and Strength and Endurance Muscle in Cancer Patients: A Randomized Crossover Trial

Objective: To analyze the influence of exergaming (EXE) quality of life, cancer-related fatigue (CRF), electromyography, and strength and endurance muscle in a randomized crossover trial. Methods: We conducted a single-blinded, randomized, and crossover trial, which included 38 cancer volunteers undergoing chemotherapy (Age = 60.07 ± 12.10 years; body mass index = 26.79 ± 5.33 kg/m2). All volunteers were randomized into two intervention moments: EXE and without intervention (WI) and after 1-month washout period of crossing of the evaluated moments. The intervention was performed on an EXE protocol using Xbox 360 Kinect®, with the game "Your Shape Fitness Evolved 2012" two to three times per week for 20 sessions. All volunteers were assessed the CRF and quality-of-life levels through the Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F) questionnaire, the median frequency (MDF) by surface electromyography, maximal voluntary isometric contraction (MVIC), and the muscle endurance time at 80% MVIC of the dorsiflexors and plantar flexors using dynamometer. Results: In the comparison between EXE and WI moments, were observed increase in the scores for quality of life (P < 0.001), subscale fatigue (P < 0.001), in the MDF values of right lateral gastrocnemius muscles: P = 0.017, muscle endurance time (left dorsiflexion [LDF]: P < 0.001; right dorsiflexion [RDF]: P < 0.001; left plantar flexion [LPF]: P < 0.001; RPF: P = 0.039), and muscle strength (LDF: P < 0.001; RDF: P < 0.001; LPF: P = 0.002). Conclusion: The crossover study, the EXE protocol promoted improvement in cancer-related fatigue (CRF) and quality of life, increased MVIC, endurance time, and MDF values of the dorsiflexor and plantar flexor muscles of cancer volunteers undergoing chemotherapy.

Physical and mental health impairments experienced by operating surgeons and camera-holder assistants during laparoscopic surgery: a cross-sectional survey

Introduction

Surgeons may experience physical and mental health problems because of their jobs, which may lead to chronic muscle damage, burnout, or even withdrawal. However, these are often ignored in camera-holder assistants during laparoscopic surgery. We aimed to analyze the differences between operating surgeons and camera-holder assistants.

Methods

From January 1, 2022, to December 31, 2022, a cross-sectional survey was conducted to evaluate the muscle pain, fatigue, verbal scolding, and task load for operating surgeons and camera-holder assistants. The Nordic Musculoskeletal Questionnaire, the Space Administration Task Load Index, and the Surgical Task Load Index (SURG-TLX) were combined in the questionnaire.

Results

2,184 operations were performed by a total of 94 operating surgeons and 220 camera assistants. 81% of operating surgeons and 78% of camera-holder assistants reported muscle pain/discomfort during the procedure. The most affected anatomic region was the shoulders for operating surgeons, and the lower back for camera-holder assistants. Intraoperative fatigue was reported by 41.7% of operating surgeons and 51.7% of camera-holder assistants. 55.2% of camera-holder assistants reported verbal scolding from the operating surgeons, primarily attributed to lapses in laparoscope movement coordination. The SURG-TLX results showed that the distributions of mental, physical, and situational stress for operating surgeons and camera-holder assistants were comparable.

Conclusion

Like operating surgeons, camera-holder assistants also face similar physical and mental health impairments while performing laparoscopic surgery. Improvements to the working conditions of the camera-holder assistant should not be overlooked.

Judicialization and cancer: quality of life of patients and caregivers in the COVID-19 pandemic

BACKGROUND

In Brazil, cancer patients and caregivers of cancer patients seek judicial intervention for free access to medications from the public health system. Indeed, the COVID-19 pandemic potentially affected the health-related quality of life of cancer patients and caregivers of cancer patients. This study aimed to describe the sociodemographic profile and assess the health-related quality of life of patients and caregivers in the state of Goias, Brazil, in 2020.

METHODS

A cross-sectional study was conducted using the Medical Outcomes Study 36-Item Short Form Health Survey (SF-36) and a sociodemographic questionnaire.

RESULTS

A total of 88 (67,7%) patients and 42 (32,3%) caregivers participated in the study, mostly women (55,5%); aged from 18 to 60 (66%) years old; with up to nine years of education (73,1%) and monthly family income lower than the minimum wage (69,2%); married or in a stable union (92,3%); living with multiple people in the same household (73,8%). The quality of life domains with the best scores were mental health for patients and pain for caregivers. The most affected quality of life domain was physical limitation for patients and caregivers. Factors associated with better quality of life were female gender and age between 18 and 60 years in patients, more than 9 years of education, living with multiple people in the same house, and having a monthly family income higher than US$200 for caregivers.

CONCLUSION

The study found evidence of physical and emotional vulnerability during the pandemic, highlighting the need to strengthen public policies of assistance support to this population.

Prevalence of Chronic Fatigue in Post COVID-19 Patients in Twin Cities

COVID-19 is linked to clinically severe symptoms despite the initial infection has subsided. The acute symptoms and recovery from coronavirus disease 2019 (COVID-19) are mainly in the headlines. However, many people who have recovered deal with ongoing physical, mental, and psychological issues long beyond the acute stage. The most persistent and debilitating of these symptoms is fatigue. Objective: To determine the prevalence of chronic fatigue in post COVID-19 patients living in Twin cities (Rawalpindi and Islamabad). Methods: A descriptive cross-sectional survey was conducted and the data were collected from the population living in Islamabad and Rawalpindi using a non-probability convenient sampling technique. The study was completed within 6 months after the approval from the ethical committee. Data were collected through a self-structured questionnaire containing demographics and a fatigue severity scale was used to assess chronic fatigue. Results: There were 382 participants enrolled in total. Out of which 54.2% were females and 45.8% were males. According to the results of the fatigue severity scale 65.4% participants reported chronic fatigue. Out of the 207 female participants, 148 (71.5%) reported chronic Fatigue while 159 (28.5%) were non-fatigued. The results also showed that out of 175 males, 102 (58.3%) reported chronic fatigue and 59 (41.7%) were non-fatigued. Conclusions: The current study concluded that most of the population in the Twin cities (Rawalpindi and Islamabad) had a prevalence of chronic fatigue in post COVID-19 patients.

The predictive role of fatigue and neuropsychological components on functional outcomes in COVID-19 after a multidisciplinary rehabilitation program

OBJECTIVE

To verify the impact of altered cognitive functioning and higher levels of mental fatigue, both reported after coronavirus disease 2019 (COVID-19), on rehabilitation treatment outcomes.

METHODS

In this real-practice retrospective pre-post intervention cohort study, cognitive functioning, measured through standardized neuropsychological measures, and individual levels of fatigue, depression and anxiety symptoms, were evaluated at admission to a rehabilitation program in individuals who had been hospitalized for COVID-19. The rehabilitation program effectiveness was measured through the Functional Independence Measure.

RESULTS

Among the patient sample (n = 66), 87.88% reported experiencing high levels of fatigue at admission, while 16.67% reported depressive symptoms, and 22.73% reported anxiety symptoms. After rehabilitation, the sample displayed a significant decrease in the level of disability, in both the motor and cognitive subscales. Neuropsychological and psychological functioning did not play a predictive role. The 45 patients who received mechanical ventilation during intensive care, representing 68.18% of the sample, benefited more from rehabilitation treatment.

CONCLUSIONS

The results support the importance of an early rehabilitation program after COVID-19 infection, independent of the initial neuropsychological and psychological functioning. Respiratory assistance may represent a crucial factor for short-term neuropsychological disease after-effects. Future studies on the long-term neuropsychological effect of COVID-19 infection on individual levels of disability are necessary.

The use of non-linear tools to analyze the variability of force production as an index of fatigue: A systematic review

Background: Fatigue is a process that results in a decreased ability to produce force, and which could eventually affect performance and increase the risk of injury. Force variability analysis has been proposed to describe the level of fatigue with the purpose of detecting the development of fatigue. Variability is credited to play a functional and adaptive role through which the components of a system self-organize to solve a motor problem. Non-linear tools have been applied to analyze the variability of physiological signals, revealing that the structure of motor fluctuations provides relevant information about the functional role of variability. It has been suggested that the presence of lower complexity in the variability structure could reveal a less functional and adaptative state (e.g., ageing or illness). In the last years, an increased number of studies have applied these techniques to force variability analysis in relation to fatigue. Objective: To provide an overview of the current knowledge on the use of non-linear tools on force variability as a fatigue index. Methods: Following PRISMA guidelines, a systematic search of SPORTDiscus, Scopus, Web of Science and PubMed was carried out. Studies included were: a) original studies that analyzed the effect of fatigue on humans during an action focused on force production; b) published studies with their title and abstract in English; c) studies that applied non-linear tools on a signal directly related to force production. Results: Twenty-five studies were included in this review. The relationship between fatigue and the complexity of force variability, the type of action and relative intensity, the nature of the signal and the non-linear tools used, and the methods of data acquisition and processing were identified. Conclusion: The articles reviewed suggest that fatigue leads to a decrease in complexity mostly in isometric contractions, but this is not as clear in dynamic contractions. This fatigue-induced loss of complexity seems to be a result of changes in the nervous system at the central level, albeit triggered by peripheral mechanisms. It should be noted that non-linear tools are affected by the relative intensity of contraction, non-stationarity, and the acquisition and treatment of the signal.

Dimensionality, psychometric properties, and population-based norms of the Turkish version of the Chalder Fatigue Scale among adults

BACKGROUND

Fatigue is emerging as a major public health problem that is highly associated with poor health-related quality of life and disability. Among adults, fatigue has become increasingly common because of workload or lifestyle changes. This study aimed to cross-culturally adapt the Chalder Fatigue Scale (CFS) into Turkish, to investigate its psychometric properties, and to establish normative data in healthy adults by age and gender.

METHODS

The validity of the CFS was tested with a total sample of 476 healthy adults aged 20-40 years (264 males and 212 females) and test-retest/measurement error analyses were performed with 161 participants (94 males and 67 females). The test-retest reliability was examined using the intraclass correlation coefficient (ICC), and internal consistency was determined using Cronbach's α-coefficient. Predictive validity was assessed using the Receiver Operating Characteristic to validate the cut-off value of the CFS for non-fatigued and fatigued participants. Factor analyses and hypothesis testing were conducted to assess construct validity. Hypothesis testing examined convergent and known-group validity by testing 14 predefined hypotheses.

RESULTS

The mean (SD) and median (25-75%) CFS scores were 10.7 (4.9) and 11 (7-14) for the total sample (n = 476). The cut-off point for CFS was set at ≥ 12 with a sensitivity of 65.8% and a specificity of 85.9%. The CFS provided evidence of excellent fit of the two-factor structure (CFI = 0.963, RMSEA = 0.06, SRMR = 0.02). There was evidence of strong internal consistency demonstrated by Cronbach's α = 0.863 and good test-retest reliability by ICC = 0.76. Thirteen out of 14 hypotheses (92.9%) were confirmed and the scale showed low to moderate correlation with other measurement instruments (r = 0.31-0.51).

CONCLUSIONS

The CFS has been shown to be a reliable and valid instrument that can be used in various populations for the assessment of fatigue.

LEVEL OF EVIDENCE

Level II.

Falls in people post-Guillain-Barré syndrome in the United Kingdom: A national cross-sectional survey of community based adults

Guillain-Barré syndrome (GBS) has several enduring effects that can lead to further harm and/or lower quality of life. These effects include falling and body pain, neither of which have been fully explored. This study aims to examine the risk factors associated with falling and potential causes of body pain in a post-GBS population. A cross-sectional survey of 216 participants was conducted using an electronic questionnaire that included. Self-report measures for: overall health, balance, anxiety and depression levels, body pain and demographics related to GBS experience and falls. A large proportion of individuals post-GBS experience ongoing problems beyond those expected with ageing. Comparative tests indicated that people reporting falls in the previous 12 months had: poorer levels of mobility, poorer F-scores, higher levels of body pain, poorer balance, poorer anxiety and depression scores and higher levels of fatigue. Gender did not appear to contribute to falls. Injuries following falls were associated with a lack of physiotherapy postdischarge and time since GBS. In a regression analysis of the identified and expected key variables, age and body pain statistically predicted falls. In over a quarter of cases reported here, respondents did not receive community physiotherapy following hospital discharge. In the midst and aftermath of COVID-19, provision of rehabilitation needs to be recalibrated, not just for COVID patients, but the wider community with ongoing needs. Issues around well-being and quality of life in the post-GBS community also need further consideration.

Recent Trends and Practices Toward Assessment and Rehabilitation of Neurodegenerative Disorders: Insights From Human Gait

The study of human movement and biomechanics forms an integral part of various clinical assessments and provides valuable information toward diagnosing neurodegenerative disorders where the motor symptoms predominate. Conventional gait and postural balance analysis techniques like force platforms, motion cameras, etc., are complex, expensive equipment requiring specialist operators, thereby posing a significant challenge toward translation to the clinics. The current manuscript presents an overview and relevant literature summarizing the umbrella of factors associated with neurodegenerative disorder management: from the pathogenesis and motor symptoms of commonly occurring disorders to current alternate practices toward its quantification and mitigation. This article reviews recent advances in technologies and methodologies for managing important neurodegenerative gait and balance disorders, emphasizing assessment and rehabilitation/assistance. The review predominantly focuses on the application of inertial sensors toward various facets of gait analysis, including event detection, spatiotemporal gait parameter measurement, estimation of joint kinematics, and postural balance analysis. In addition, the use of other sensing principles such as foot-force interaction measurement, electromyography techniques, electrogoniometers, force-myography, ultrasonic, piezoelectric, and microphone sensors has also been explored. The review also examined the commercially available wearable gait analysis systems. Additionally, a summary of recent progress in therapeutic approaches, viz., wearables, virtual reality (VR), and phytochemical compounds, has also been presented, explicitly targeting the neuro-motor and functional impairments associated with these disorders. Efforts toward therapeutic and functional rehabilitation through VR, wearables, and different phytochemical compounds are presented using recent examples of research across the commonly occurring neurodegenerative conditions [viz., Parkinson's disease (PD), Alzheimer's disease (AD), multiple sclerosis, Huntington's disease (HD), and amyotrophic lateral sclerosis (ALS)]. Studies exploring the potential role of Phyto compounds in mitigating commonly associated neurodegenerative pathologies such as mitochondrial dysfunction, α-synuclein accumulation, imbalance of free radicals, etc., are also discussed in breadth. Parameters such as joint angles, plantar pressure, and muscle force can be measured using portable and wearable sensors like accelerometers, gyroscopes, footswitches, force sensors, etc. Kinetic foot insoles and inertial measurement tools are widely explored for studying kinematic and kinetic parameters associated with gait. With advanced correlation algorithms and extensive RCTs, such measurement techniques can be an effective clinical and home-based monitoring and rehabilitation tool for neuro-impaired gait. As evident from the present literature, although the vast majority of works reported are not clinically and extensively validated to derive a firm conclusion about the effectiveness of such techniques, wearable sensors present a promising impact toward dealing with neurodegenerative motor disorders.

Experienced fatigue in people with rare disorders: a scoping review on characteristics of existing research

BACKGROUND

Experienced fatigue is an under-recognized and under-researched feature in persons with many different rare diseases. A better overview of the characteristics of existing research on experienced fatigue in children and adults with rare diseases is needed. The purpose of this review was to map and describe characteristics of existing research on experienced fatigue in a selection of rare diseases in rare developmental defects or anomalies during embryogenesis and rare genetic diseases. Furthermore, to identify research gaps and point to research agendas.

METHODS

We applied a scoping review methodology, and performed a systematic search in March 2020 in bibliographic databases. References were sorted and evaluated for inclusion using EndNote and Rayyan. Data were extracted on the main research questions concerning characteristics of research on experienced fatigue (definition and focus on fatigue, study populations, research questions investigated and methods used).

RESULTS

This review included 215 articles on ten different rare developmental defects/anomalies during embryogenesis and 35 rare genetic diseases. Of the 215 articles, 82 had investigation of experienced fatigue as primary aim or outcome. Included were 9 secondary research articles (reviews) and 206 primary research articles. A minority of articles included children. There were large differences in the number of studies in different diseases. Only 29 of 215 articles gave a description of how they defined the concept of experienced fatigue. The most common research-question reported on was prevalence and/ -or associations to fatigue. The least common was diagnostics (development or validation of fatigue assessment methods for a specific patient group). A large variety of methods were used to investigate experienced fatigue, impeding comparisons both within and across diagnoses.

CONCLUSION

This scoping review on the characteristics of fatigue research in rare diseases found a large variety of research on experienced fatigue. However, the minority of studies had investigation of experienced fatigue as a primary aim. There was large variation in how experienced fatigue was defined and also in how it was measured, both within and across diagnoses. More research on experienced fatigue is needed, both in children and adults with rare diseases. This review offers a basis for further research.

Fatigability and the Role of Neuromuscular Impairments in Chronic Kidney Disease

BACKGROUND

The combination of neuromuscular impairments plus psychosocial aspects of chronic kidney disease (CKD) may predispose these patients to greater risk for experiencing increased levels of fatigability. There has been extensive clinical and scientific interest in the problem of fatigue in CKD and end-stage kidney disease (ESKD) patients, whereas less attention has been directed to understanding fatigability. Accordingly, the primary purposes of this review are to (1) discuss fatigue and fatigability and their potential interactions in patients with CKD and ESKD, (2) provide evidence for increased fatigability in CKD and ESKD patients, (3) examine how commonly experienced neuromuscular impairments in CKD and ESKD patients may contribute to the severity of performance fatigability, and (4) highlight preliminary evidence on the effects of exercise as a potential clinical treatment for targeting fatigability in this population.

SUMMARY

Fatigue is broadly defined as a multidimensional construct encompassing a subjective lack of physical and/or mental energy that is perceived by the individual to interfere with usual or desired activities. In contrast, fatigability is conceptualized within the context of physical activity and is quantified as the interactions between reductions in objective measures of performance (i.e., performance fatigability) and perceptual adjustments regulating activity performance (i.e., perceived fatigability). We propose herein a conceptual model to extend current understandings of fatigability by considering the interactions among fatigue, perceived fatigability, and performance fatigability. Neuromuscular impairments reported in patients with CKD and ESKD, including reductions in force capacity, skeletal muscle atrophy, mitochondrial dysfunction, abnormal skeletal muscle excitability, and neurological complications, may each contribute to the greater performance fatigability observed in these patients.

KEY MESSAGES

Considering the interactions among fatigue, perceived fatigability, and performance fatigability provides a novel conceptual framework to advance the understanding of fatigability in CKD and ESKD patients. Measures of fatigability may provide valuable clinical insights into the overall health status of CKD and ESKD patients. Existing data suggest that CKD and ESKD patients are at greater risk of experiencing increased fatigability, partly due to neuromuscular impairments associated with reduced kidney function. Further investigations are warranted to determine the potential clinical role fatigability measures can play in monitoring the health of CKD and ESKD patients, and in identifying potential treatments targeting fatigability in this patient population.

Neurosteroid Activation of GABA-A Receptors: A Potential Treatment Target for Symptoms in Primary Biliary Cholangitis?

Background and Aims

A third of patients with primary biliary cholangitis (PBC) experience poorly understood cognitive symptoms, with a significant impact on quality of life (QOL), and no effective medical treatment. Allopregnanolone, a neurosteroid, is a positive allosteric modulator of gamma-aminobutyricacid-A (GABA-A) receptors, associated with disordered mood, cognition, and memory. This study explored associations between allopregnanolone and a disease-specific QOL scoring system (PBC-40) in PBC patients.

Method

Serum allopregnanolone levels were measured in 120 phenotyped PBC patients and 40 age and gender-matched healthy controls. PBC subjects completed the PBC-40 at recruitment. Serum allopregnanolone levels were compared across PBC-40 domains for those with none/mild symptoms versus severe symptoms.

Results

There were no overall differences in allopregnanolone levels between healthy controls (median = 0.03 ng/ml (IQR = 0.025)) and PBC patients (0.031 (0.42), p = 0.42). Within the PBC cohort, higher allopregnanolone levels were observed in younger patients (r (120) = -0.53, p < 0.001) but not healthy controls (r (39) = -0.21, p = 0.21). Allopregnanolone levels were elevated in the PBC-40 domains, cognition (u = 1034, p = 0.02), emotional (u = 1374, p = 0.004), and itch (u = 795, p = 0.03). Severe cognitive symptoms associated with a younger age: severe (50 (12)) vs. none (60 (13); u = 423 p = 0.001).

Conclusion

Elevated serum allopregnanolone is associated with severe cognitive, emotional, and itch symptoms in PBC, in keeping with its known action on GABA-A receptors. Existing novel compounds targeting allopregnanolone could offer new therapies in severely symptomatic PBC, satisfying a significant unmet need.

Is fatigue a muscular phenomenon in Parkinson's disease? Implications for rehabilitation

BACKGROUND

Fatigue in Parkinson's Disease (PD) compromises patients' physical activity and poses questions on how to plan correct rehabilitation training. In addition, the relationship between subjective perceived fatigue and fatigue in motor performance is not yet entirely understood. As a consequence, a conclusive interpretation of muscular mechanisms of fatigue in PD has not yet been achieved. Among the various instrumental evaluations for fatigue, multichannel surface electromyography (sEMG) is a recognized tool that permits the study of myoelectric manifestations of fatigue.

AIM

To assess if muscles in PD show a different myoelectric fatigue pattern compared to the muscles of healthy age-matched subjects.

DESIGN

Observational controlled study.

POPULATION

Idiopathic Parkinson's Disease, Hohen &Yahr II and III stage, Parkinsonian Fatigue Scale average score ≥ 2.95, no therapy modification in the 4 weeks preceding the study; exclusion criteria: Mini Mental State Examination ≤ 24, upper limb disease/symptoms that might interfere with sEMG analysis, presence of other fatiguerelated conditions. Twenty patients were selected according to these criteria. Twenty untrained healthy subjects were matched.

METHODS

All subjects underwent a muscle fatigue protocol and a sEMG analysis of the right biceps brachii muscle during electrically stimulated and voluntary contractions in order to obtain a myoelectric fatigue muscular pattern. The myoelectric pattern is characterized by the modifications of the following sEMG variables: reduction of mean frequency and muscle fibre conduction velocity, increase of average rectified value.

RESULTS

No statistical differences where observed between groups for sEMG variables and muscular electric behaviour in all contraction conditions (all p> .05).

CONCLUSIONS

Our results show that parkinsonian muscles does not differ from the muscles of healthy age-matched subjects in developing peripheral myoelectric fatigue. Nevertheless, the role of fatigue perception at rest and particularly during physical activity must be clearly understood in order to further target the rehabilitative approach for fatigued parkinsonian patients and to reduce hypomobility.

CLINICAL REHABILITATION IMPACT

In rehabilitative terms, these findings allow us to highlight the possibility of performing sustained training with isometric contractions in PD subjects; therefore, fatigue "per se" does not constitute a barrier for the execution of muscular exercises, likewise intensive.

Using a System-Based Monitoring Paradigm to Assess Fatigue during Submaximal Static Exercise of the Elbow Extensor Muscles

Current methods for evaluating fatigue separately assess intramuscular changes in individual muscles from corresponding alterations in movement output. The purpose of this study is to investigate if a system-based monitoring paradigm, which quantifies how the dynamic relationship between the activity from multiple muscles and force changes over time, produces a viable metric for assessing fatigue. Improvements made to the paradigm to facilitate online fatigue assessment are also discussed. Eight participants performed a static elbow extension task until exhaustion, while surface electromyography (sEMG) and force data were recorded. A dynamic time-series model mapped instantaneous features extracted from sEMG signals of multiple synergistic muscles to extension force. A metric, called the Freshness Similarity Index (FSI), was calculated using statistical analysis of modeling errors to reveal time-dependent changes in the dynamic model indicative of performance degradation. The FSI revealed strong, significant within-individual associations with two well-accepted measures of fatigue, maximum voluntary contraction (MVC) force (rrm=-0.86) and ratings of perceived exertion (RPE) (rrm=0.87), substantiating the viability of a system-based monitoring paradigm for assessing fatigue. These findings provide the first direct and quantitative link between a system-based performance degradation metric and traditional measures of fatigue.

Effects of fatigue induced by repetitive movements and isometric tasks on reaction time

PURPOSE

The understanding of fatigue of the human motor system is important in the fields of ergonomics, sport, rehabilitation and neurology. In order to understand the interactions between fatigue and reaction time, we evaluated the effects of two different fatiguing tasks on reaction time.

METHODS

83 healthy subjects were included in a case-control study with three arms where single and double choice reaction time tasks were performed before and after 2 min fatiguing task (an isometric task, a finger tapping task and at rest).

RESULTS

After an isometric task, the right-fatigued hand was slower in the choice component of a double choice reaction time task (calculated as the individual difference between single and double choice reaction times); also, the subjects that felt more fatigued had slower choice reaction time respect to the baseline assessment. Moreover, in relationship to the performance decay after two minutes, finger tapping task produces more intense fatigability perception.

CONCLUSIONS

We confirmed that two minutes of isometric or repetitive tasks are enough to produce fatigue. The fatigue perception is more intense for finger tapping tasks in relation to the performance decay. We therefore confirmed that the two fatiguing tasks produced two different kind of fatigue demonstrating that with a very simple protocol it is possible to test subjects or patients to quantify different form of fatigue.

Peripheral nerve electrophysiology studies in relation to fatigue in patients with chronic inflammatory demyelinating polyneuropathy

OBJECTIVE

To explore the relationship between fatigue, standard electrophysiological parameters and number and size of functioning motor units in patients with chronic inflammatory demyelinating polyneuropathy (CIDP).

METHODS

Experienced fatigue was assessed using the linearly-weighted, modified Rasch-built fatigue severity scale (R-FSS) and the multidimensional Checklist of Individual Strength (CIS). Averaged electrophysiology values were calculated from multiple nerves. Motor Unit Number Index (MUNIX) technique was utilised to assess motor unit function. Assessments were repeated in 15 patients receiving regular intravenous immunoglobulin therapy, with changes in parameters calculated.

RESULTS

R-FSS and CIS scores did not correlate MUNIX or MUSIX sum scores from 3 different muscles. Inverse correlation was observed only between distal CMAP area and R-FSS but not CIS scores. However, changes in distal CMAP area and R-FSS scores on repeat assessment were not correlated.

CONCLUSIONS

Experienced fatigue does not appear to correlate with loss of functioning motor units in patients with CIDP. Changes in experienced fatigue on repeat assessment did not correlate with changes in any of the electrophysiological parameters, suggesting fatigue experienced in CIDP is not strongly correlated with peripheral nerve dysfunction.

SIGNIFICANCE

Nerve conduction studies and MUNIX values do not appear to be useful surrogate markers for fatigue in CIDP.

Liver cirrhosis turns life into an unpredictable roller coaster: A qualitative interview study

Aim

To explore how persons living with liver cirrhosis experience day‐to‐day life.

Background

Liver cirrhosis is the sixth most common cause of death among adults in Western countries. Persons with advanced liver cirrhosis report poor quality of life, in comparison with other chronic diseases. However, knowledge regarding day‐to‐day life during earlier stages of the disease is lacking. In other chronic diseases, the suffering process is well explored, while in liver cirrhosis, suffering is insufficiently investigated.

Design

An exploratory study, with a qualitative inductive interview approach.

Methods

A purposive maximum variation sample of 20 informants with liver cirrhosis aged 25–71, from two gastroenterology outpatient clinics in mid‐Sweden, were interviewed from September 2016 to October 2017. Interview data were analysed inductively with qualitative content analysis. Reporting followed the COREQ guidelines.

Results

The experiences of day‐to‐day life living with liver cirrhosis comprised four sub‐themes. Living with liver cirrhosis implied varying levels of deterioration, the most apparent being exhaustion or tiredness. The informants had to find ways of adapting to a new life situation. The insecurity of future health evoked existential reflections such as feeling emotionally and existentially distressed. Shame and guilt were reasons for feeling stigmatised. These sub‐themes emerged into one overarching theme of meaning: life turns into an unpredictable roller coaster. This is based on experiences of liver cirrhosis as an unpredictable disease with fluctuating symptoms, worries and disease progression.

Conclusion

Living with cirrhosis implies an unpredictable condition with a progressive, stigmatising disease. The fluctuating symptoms and deep concerns about future life pose an increased personal suffering.

Relevance to clinical practice

Within health care, knowledge of the person's experience is vital to enable and fulfil the person's healthcare needs. Clinical registered nurses need a person‐centred approach to strengthen their patients to cope with their new life situation.

Surface EMG in Clinical Assessment and Neurorehabilitation: Barriers Limiting Its Use

This article addresses the potential clinical value of techniques based on surface electromyography (sEMG) in rehabilitation medicine with specific focus on neurorehabilitation. Applications in exercise and sport pathophysiology, in movement analysis, in ergonomics and occupational medicine, and in a number of related fields are also considered. The contrast between the extensive scientific literature in these fields and the limited clinical applications is discussed. The "barriers" between research findings and their application are very broad, and are longstanding, cultural, educational, and technical. Cultural barriers relate to the general acceptance and use of the concept of objective measurement in a clinical setting and its role in promoting Evidence Based Medicine. Wide differences between countries exist in appropriate training in the use of such quantitative measurements in general, and in electrical measurements in particular. These differences are manifest in training programs, in degrees granted, and in academic/research career opportunities. Educational barriers are related to the background in mathematics and physics for rehabilitation clinicians, leading to insufficient basic concepts of signal interpretation, as well as to the lack of a common language with rehabilitation engineers. Technical barriers are being overcome progressively, but progress is still impacted by the lack of user-friendly equipment, insufficient market demand, gadget-like devices, relatively high equipment price and a pervasive lack of interest by manufacturers. Despite the recommendations provided by the 20-year old EU project on "Surface EMG for Non-Invasive Assessment of Muscles (SENIAM)," real international standards are still missing and there is minimal international pressure for developing and applying such standards. The need for change in training and teaching is increasingly felt in the academic world, but is much less perceived in the health delivery system and clinical environments. The rapid technological progress in the fields of sensor and measurement technology (including sEMG), assistive devices, and robotic rehabilitation, has not been driven by clinical demands. Our assertion is that the most important and urgent interventions concern enhanced education, more effective technology transfer, and increased academic opportunities for physiotherapists, occupational therapists, and kinesiologists.

Muscle contractile properties of cancer patients receiving chemotherapy: Assessment of feasibility and exercise effects

Background

This pilot trial explores the feasibility of measuring muscle contractile properties in patients with cancer, effects of exercise during chemotherapy on muscle contractile properties and the association between changes in contractile muscle properties and perceived fatigue.

Method

Patients who received (neo)adjuvant chemotherapy for breast or colon cancer were randomized to a 9‐12 week exercise intervention or a waitlist‐control group. At baseline and follow‐up, we measured knee extensor strength using maximal voluntary contraction (MVC), contractile muscle properties of the quadriceps muscle using electrical stimulation, and perceived fatigue using the Multidimensional Fatigue Inventory. Feasibility was assessed by the proportion of patients who successfully completed measurements of contractile muscle properties. Exercise effects on muscle contractile properties were explored using linear regression analyses. Between‐group differences >10% were considered potentially relevant. Pearson correlation (r_p) of changes in contractile muscle properties and changes in perceived fatigue was calculated.

Results

Twenty two of 30 patients completed baseline and follow‐up assessments. Measurements of contractile properties were feasible except for muscle fatigability. We found a potentially relevant between‐group difference in the rate of force development favoring the intervention group (1192 N/s, 95% CI = −335; 2739). Change in rate of force development was negatively correlated with change in perceived general (r_p = −0.54, P = .04) and physical (r_p = −0.59, P = .02) fatigue.

Conclusion

Chemotherapy induces a decrease in the rate of force development, which may reflect a larger loss in type II muscle fibers. This may be attenuated with (resistance) exercise. The increase in the rate of force development was related to a decrease in perceived fatigue.

Effect of Exergaming on Muscle Strength, Pain, and Functionality of Shoulders in Cancer Patients

Objective: To compare the strength of the middle deltoid muscle by means of dynamometry and the Shoulder Pain and Disability Index (SPADI) in participants in treatment for cancer after the practice of an exergaming protocol. Materials and Methods: We conducted a randomized controlled clinical trial. Thirty-eight voluntary participants were divided into two groups: cancer group (n = 19; age = 61.46 ± 8.79 years; body mass index [BMI] = 28.36 ± 4.94 kg/m3) and control group (n = 19; age = 57.62 ± 7.57 years; BMI = 28.06 ± 3.74 kg/m3), and they participated in the study. All participants performed an exergame protocol by using Xbox 360 Kinect® (Microsoft, Redmond) with the game Your Shape Fitness Evolved 2012 two to three times per week for 20 sessions. They were evaluated through the isometric dynamometer in the middle deltoid muscle and the SPADI at three moments: preintervention (EV1), after 10 sessions (EV2), and after 20 sessions (EV3). Results: The cancer group scored higher on both the disability index, in all three evaluations, and the pain index, in EV2 and EV3, when compared with the control group. There was a significant reduction in the disability score in EV2 and EV3 when compared with EV1 in the cancer group, whereas pain was lower in EV2 and EV3 when compared with EV1 in the control group. There were no significant interevaluation or intergroup differences in the maximal isometric voluntary contraction of the deltoid muscle of both upper limbs. Conclusion: At the end of the exergaming, protocol reduced the disability of the shoulder joint of the cancer group and decreased the differences between the groups for disability and pain scores, without changing isometric force.

A Method to Differentiate Fatiguing Conditions in Surface Electromyography Signals using Instantaneous Spectral Centroid

The nonstationarity measure of surface Electromyography (sEMG) signals provide an index for muscle fatigue conditions. In this paper, a new framework has been proposed for the analysis of sEMG signal using Instantaneous Spectral Centroid (ISC). The novelty of the proposed work is use of topological signal processing method to quantify the nonstationarity of sEMG signal. For this, the signals are recorded from the biceps brachii muscles of 25 healthy subjects in isometric contraction. The analytical signals corresponding to nonfatigue and fatigue segments are computed using Hilbert Transform. Further, topological features such as center of gravity (CoG), triangular area function (TAF) and ISC are calculated from the geometrical representation of a transformed signal. The result indicates the increase of TAF in fatigue condition and the significant right shift of CoG in x-axis for 80% of subjects. Importantly, the ISC estimate is decreased by 17% upon fatiguing for 84% of subjects. The obtained results show statistical significance with p < 0.05. It is observed that the shape parameters are varied in accordance with the changes observed in global characteristics of sEMG signals during muscle fatigue. The preliminary results show that the topological features are able to quantify the nonstationarity in sEMG signal. Therefore, the proposed method can be used as a fatigue index for diagnosing various neuromuscular disorders.Clinical Relevance-This method can be used to establish metrics of muscle fatigue for the benefit of physicians especially in the field of fitness, sports, pre and post-surgery surveillance and rehabilitation.

The Potential Role of Neurophysiology in the Management of Multiple Sclerosis-Related Fatigue

Fatigue is a very common symptom among people with multiple sclerosis (MS), but its management in clinical practice is limited by the lack of clear evidence about the pathogenic mechanisms, objective tools for diagnosis, and effective pharmacological treatments. In this scenario, neurophysiology could play a decisive role, thanks to its ability to provide objective measures and to explore the peripheral and the central structures of the nervous system. We hereby review and discuss current evidence about the potential role of neurophysiology in the management of MS-related fatigue. In the first part, we describe the use of neurophysiological techniques for exploring the pathogenic mechanisms of fatigue. In the second part, we review the potential application of neurophysiology for monitoring the response to pharmacological therapies. Finally, we show data about the therapeutic implications of neurophysiological techniques based on non-invasive brain stimulation.

Characterization of surface electromyography signals of biceps brachii muscle in fatigue using symbolic motif features

Exercise-induced muscle damage is a condition which results in the loss of muscle function due to overexertion. Muscle fatigue is a precursor of this phenomenon. The characterization of muscle fatigue plays a crucial role in preventing muscle damage. In this work, an attempt is made to develop signal processing methods to understand the dynamics of the muscle’s electrical properties. Surface electromyography signals are recorded from 50 healthy adult volunteers under dynamic curl exercise. The signals are preprocessed, and the first difference signal is computed. Furthermore, ascending and descending slopes are used to generate a binary sequence. The binary sequence of various motif lengths is analyzed using features such as the average symbolic occurrence, modified Shannon entropy, chi-square value, time irreversibility, maximum probability of pattern and forbidden pattern ratio. The progression of muscle fatigue is assessed using trend analysis techniques. The motif length is optimized to maximize the rho value of features. In addition, the first and the last zones of the signal are compared with standard statistical tests. The results indicate that the recorded signals differ in both frequency and amplitude in both inter- and intra-subjects along the period of the experiment. The binary sequence generated has information related to the complexity of the signal. The presence of more repetitive patterns across the motif lengths in the case of fatigue indicates that the signal has lower complexity. In most cases, larger motif length resulted in better rho values. In a comparison of the first and the last zones, most of the extracted features are statistically significant with p < 0.05. It is observed that at the motif length of 13 all the extracted features are significant. This analysis method can be extended to diagnose other neuromuscular conditions.

Inertial Sensors Embedded in Smartphones as a Tool for Fatigue Assessment Based on Acceleration in Survivors of Breast Cancer

BACKGROUND

Cancer-related fatigue is a symptom commonly reported in survivors of breast cancer and is the most variable symptom. Besides questionnaires like PIPER to assess cancer-related fatigue, there is a need to objectively measure fatigue.

OBJECTIVE

The aim of this study was to assess the physiological dimension of fatigue based on acceleration during a 30-second maximal sit-to-stand test.

DESIGN

This was a cross-sectional study.

METHODS

Linear acceleration from a smartphone placed on the sternum was recorded in 70 survivors of breast cancer. Fourth-degree polynomial adjustment from the acceleration signal to the vertical and anterior-posterior axis was calculated. The fatigue temporal cut-off point was detected as a change in the curve slope of the first maximum point of acceleration.

RESULTS

Women were aged 51.8 (8.9) years with a body mass index of 25.4 (5.1) Kg/m2. They performed 23.6 (6.57) number of repetitions. The mean fatigue cut-off point from the total sample was 10.2 (3.1) seconds.

LIMITATIONS

Further research should employ time-prolonged tests to study acceleration behavior beyond 30 seconds as well as include a physiological criterion that justifies the nonlinear saturation of the acceleration-based criterion.

CONCLUSIONS

This study assessed fatigue through a low-cost and easy-to-use methodology during a functional and widely used test such as 30-second maximal sit-to-stand. This would allow clinicians to assess fatigue in a short-effort exercise to individualize exercise prescription dose, measure changes during intervention, and track fatigue objectively throughout survivorship.

Fatigue Evaluation through Machine Learning and a Global Fatigue Descriptor

Research in physiology and sports science has shown that fatigue, a complex psychophysiological phenomenon, has a relevant impact in performance and in the correct functioning of our motricity system, potentially being a cause of damage to the human organism. Fatigue can be seen as a subjective or objective phenomenon. Subjective fatigue corresponds to a mental and cognitive event, while fatigue referred as objective is a physical phenomenon. Despite the fact that subjective fatigue is often undervalued, only a physically and mentally healthy athlete is able to achieve top performance in a discipline. Therefore, we argue that physical training programs should address the preventive assessment of both subjective and objective fatigue mechanisms in order to minimize the risk of injuries. In this context, our paper presents a machine-learning system capable of extracting individual fatigue descriptors (IFDs) from electromyographic (EMG) and heart rate variability (HRV) measurements. Our novel approach, using two types of biosignals so that a global (mental and physical) fatigue assessment is taken into account, reflects the onset of fatigue by implementing a combination of a dimensionless (0-1) global fatigue descriptor (GFD) and a support vector machine (SVM) classifier. The system, based on 9 main combined features, achieves fatigue regime classification performances of 0.82 ± 0.24, ensuring a successful preventive assessment when dangerous fatigue levels are reached. Training data were acquired in a constant work rate test (executed by 14 subjects using a cycloergometry device), where the variable under study (fatigue) gradually increased until the volunteer reached an objective exhaustion state.

Neuromuscular Junction Abnormalities in Mitochondrial Disease: An Observational Cohort Study

Objective

To determine the prevalence of neuromuscular junction (NMJ) abnormalities in patients with mitochondrial disease.

Methods

Eighty patients with genetically proven mitochondrial disease were recruited from a national center for mitochondrial disease in the United Kingdom. Participants underwent detailed clinical and neurophysiologic testing including single-fiber electromyography.

Results

The overall prevalence of neuromuscular transmission defects was 25.6%. The highest prevalence was in patients with pathogenic dominant RRM2B variants (50%), but abnormalities were found in a wide range of mitochondrial genotypes. The presence of NMJ abnormalities was strongly associated with coexistent myopathy, but not with neuropathy. Furthermore, 15% of patients with NMJ abnormality had no evidence of either myopathy or neuropathy.

Conclusions

NMJ transmission defects are common in mitochondrial disease. In some patients, NMJ dysfunction occurs in the absence of obvious pre- or post-synaptic pathology, suggesting that the NMJ may be specifically affected.

Fatigue in complete spinal cord injury and implications on total delay

The use of neuromuscular electrical stimulation (NMES) to artificially restore movement in people with complete spinal cord injury (SCI) induces an accelerated process of muscle fatigue. Fatigue increases the time between the beginning of NMES and the onset of muscle force (Delay_TOT ). Understanding how much muscle fatigue affects the Delay_TOT in people with SCI could help in the design of closed-loop neuroprostheses that compensate for this delay, thus making the control system more stable. The aim of this study was to evaluate the impact of the extent of fatigue on Delay_TOT and peak force of the lower limbs in people with complete SCI. Fifteen men-young adults with complete SCI (paraplegia and tetraplegia) and stable health-participated in the experiment. Delay_TOT was defined as the time interval between the beginning of NMES application until the onset of muscle force. The electrical intensity of NMES applied was adjusted individually and consisted of the amplitude required to obtain a full extension of the knee (0°), considering the maximum electrically stimulated extension (MESE). Subsequently, 70% of the MESE was applied during the fatigue induction protocol. Significant differences were identified between the moments before and after the fatigue protocol, both for peak force (P ≤ .026) and Delay_TOT (P ≤ .001). The medians and interquartile range of the Delay_TOT were higher in postfatigue (199.0 ms) when compared to the moment before fatigue (146.5 ms). The medians and interquartile range of the peak force were higher in unfatigued lower limbs (0.43 kgf) when compared to the moment postfatigue (0.27 kgf). The results support the hypothesis that muscle fatigue influences the increase in Delay_TOT and decrease in force production in people with SCI. For future applications, the combined evaluation of the delay and force in SCI patients provides valuable feedback for NMES paradigms. The study will provide potentially critical muscle mechanical evidence for the investigation of the evolution of atrophy.

An observational study of trait and state fatigue, and their relation to cognitive fatigability and saccade performance

Aim:

Different fatigue measurements and their relation to saccadic functions were investigated in 15 patients with a mild traumatic brain injury (mTBI) and 15 orthopedic controls.

Materials & methods:

State fatigue was measured with the Fatigue Severity Scale and trait fatigue with the question on fatigue in the Rivermead Post Concussion Questionnaire and fatigability as decreased performance over time on a neuropsychological measure.

Results:

Patients with an mTBI scored significantly higher in state fatigue and showed more fatigability compared with the orthopedic controls. Among patients with mTBI, state fatigue correlated with prosaccade latency and cognitive fatigability, while trait fatigue correlated with anxiety and antisaccade latency and variability.

Conclusion:

This pilot study indicates that saccade measurements might, in the future, be useful in the understanding of fatigue and in the search for prognostic factors after mTBI.

Fatigue Detection during Sit-To-Stand Test Based on Surface Electromyography and Acceleration: A Case Study

The latest studies of the 30-second sit-to-stand (30-STS) test aim to describe it by employing kinematic variables, muscular activity, or fatigue through electromyography (EMG) instead of a number of repetitions. The aim of the present study was to develop a detection system based on acceleration measured using a smartphone to analyze fatigue during the 30-STS test with surface electromyography as the criterion. This case study was carried out on one woman, who performed eight trials. EMG data from the lower limbs and trunk muscles, as well as trunk acceleration were recorded. Both signals from eight trials were preprocessed, being averaged and temporarily aligned. The EMG signal was processed, calculating the spectral centroid (SC) by Discrete Fourier Transform, while the acceleration signal was processed by Discrete Wavelet Transform to calculate its energy percentage. Regarding EMG, fatigue in the vastus medialis of the quadriceps appeared as a decrease in SC, with a descending slope of 12% at second 12, indicating fatigue. However, acceleration analysis showed an increase in the percentage of relative energy, acting like fatigue firing at second 19. This assessed fatigue according to two variables of a different nature. The results will help clinicians to obtain information about fatigue using an accessible and inexpensive device, i.e., as a smartphone.

Analysis of Dynamic Contractions from Biceps Brachii Muscle using Surface Electromyography signals and Multiscale Visibility Graph Features

In this work, an attempt is made to characterize the variation in the complexity of the surface electromyography (sEMG) signals in fatigue. For this, sEMG signals from 58 healthy volunteers are recorded from the biceps brachii muscle under well-defined dynamic contraction protocol. The contractions are segmented, and the initial and final curls are extracted. These are considered as nonfatigue and fatigue respectively. Further, visibility graphs are constructed at multiple scales, and median degree centrality (MSMC) is calculated in them. To quantify the variations in the MSMC, two features namely, the average and standard deviation are calculated. The results reveal that the recorded signals are non-stationary. The constructed networks form distinct clusters in space. The MSMC feature shows a decreasing trend with scale in both nonfatigue and fatigue conditions. Additionally, the extracted features have higher values in fatigue. This may be due to the motor unit synchronization, which causes an increase in connectivity between nodes. All the extracted features showed statistical significance with p<; 0.005. This approach of analysis can be extended to characterize muscle in other neuromuscular conditions.

Fatigue Due to Multiple Sclerosis: A Comparison Between Persian Medicine and Conventional Medicine

Fatigue is one of the most debilitating symptoms of multiple sclerosis (MS), and its definite pathophysiology is unclear. Studies have suggested some correlates for it including dysfunction or atrophy in different parts of the brain. This narrative review study compares the viewpoint of conventional medicine and Persian medicine (PM) about fatigue due to MS and introduces the treatments used for this complaint in PM with an evidence-based approach. PM scholars have used the term I’ya equal to fatigue and stated that I’ya might be due to exertion or not, while the latter (spontaneous I’ya) can be prodromal of a disease. This pathologic fatigue can be seen in a wide variety of neurologic diseases, though it is the most common in MS patients. Fatigue in MS can be considered one of the equivalents of spontaneous I’ya. According to PM texts, neurotonic herbs like Ferula, Citrus medica, Asarum europaeum, Ficus carica, and Juglans regia may be beneficial in alleviating fatigue by brain reinforcement. Different pharmacological mechanisms have been introduced for these plants including antioxidant and/or anti-inflammatory activities. The medicinal plants can be assumed as a valuable source for discovering new medicines for fatigue in MS. Designing preclinical and clinical studies evaluating the effects of mentioned medicinal herbs in fatigue is proposed for obtaining more conclusive results.

Cancer-related fatigue stratification system based on patient-reported outcomes and objective outcomes: A cancer-related fatigue ambulatory index

Although breast cancer mortality is decreasing, morbidity following treatment remains a significant issue, as patients face symptoms such as cancer-related fatigue (CRF). The aim of the present study is to develop a classification system that monitors fatigue via integration of an objective clinical assessment with patient self-report. Forty-three women participated in this research. Participants were post-treatment breast cancer survivors who had been surgically treated for their primary tumour with no evidence of neoplastic disease at the time of recruitment. Self-perceived fatigue was assessed with the Spanish version of the Piper Fatigue Scale-Revised (R-PFS). Objective fatigue was assessed by the 30 second Sit-to-Stand (30-STS) test. Confirmatory factor analysis was done with Maximum Likelihood Extraction (MLE). Internal consistency was obtained by Cronbach's α coefficients. Bivariate correlation showed that 30-STS performance was negatively-inversely associated with R-PFS. The MANOVA model explained 54.3% of 30-STS performance variance. Using normalized scores from the MLE, a classification system was developed based on the quartiles. This study integrated objective and subjective measures of fatigue to better allow classification of patient CRF experience. Results allowed development of a classification index to classify CRF severity in breast cancer survivors using the relationship between 30-STS and R-PFS scores. Future research must consider the patient-perceived and clinically measurable components of CRF to better understand this multidimensional issue.

Nanobubbles Water Curcumin Extract Reduces Injury Risks on Drop Jumps in Women: A Pilot Study

Purpose

To verify the beneficial effects of Nanobubbles water curcumin extract (NCE) supplementation on health promotion and to demonstrate the application of NCE in reducing the risk of musculoskeletal injury.

Methods

In the current study, 12 females were randomly assigned to NCE (15g/day) and maltodextrin groups. Performance and related body composition were evaluated at 2 time points—presupplementation (pre-) and after 4 weeks of postsupplementation (post-). The posttest consists of a set of biochemical parameters for antifatigue activity and injury status evaluation.

Results

NCE group exhibited significantly lower levels of alanine aminotransferase (ALT), alkaline phosphatase (ALP), triglycerides (TG), and higher high-density lipoprotein (HDL) after a 4-week supplementation, compared with the placebo group. After a 15-minute session on the spinning bike, serum lactate and ammonia levels were decreased and glucose was economized in the NEC group. 4-week-NCE supplementation was also able to reduce the peak vertical ground reaction force (PVGRF) during drop jump. Therefore, the risk of musculoskeletal system in lower extremity could be reduced.

Conclusion

We demonstrate that 4-week-NCE supplementation can also be used in explosiveness exercise for better physiological adaptation. Thus, NCE has potential for use with nutrient supplements toward a variety of benefits for athletics.

Disability and Contextual Factors in Patients with Amyotrophic Lateral Sclerosis - A Three-Year Observational Study

Background:

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by muscle weakness and wasting. Observational natural history studies can give information on body function/structure impairments, activity limitations and participation restrictions, i.e. disability. Information needed to plan and develop care and support.

Objective:

To describe and explore disease severity and impairments, activity limitations, participation restrictions and contextual factors over time. In specific, to explore concurrent presence of cognitive impairment, fatigue, anxiety, depression and pain, and whether these impairments were related to disease severity.

Methods:

In this three-year observational study, 60 patients with ALS were included at baseline. Follow-ups were performed every 6 months unless participants had deceased or declined participation. Data was collected from medical records, and by study-specific and standardized questionnaires administrated during home visits.

Results:

Regardless of disease severity; fatigue, anxiety, depression and pain were present in patients with ALS at each data collection. Approximately one-third experienced two or more of these impairments concurrently, i.e. at the same time point. Cognitive impairment could not be assessed in many patients due to their physical impairments. Disease severity was not associated with fatigue, anxiety, depression or pain.

Conclusions:

Patients with ALS need, throughout the course of the disease, to be regularly screened for commonly present impairments, activity limitations and participation restrictions so that person-centered interventions can be applied at the right time.

Muscle fatigue assessment during robot-mediated movements

BACKGROUND

Several neuromuscular disorders present muscle fatigue as a typical symptom. Therefore, a reliable method of fatigue assessment may be crucial for understanding how specific disease features evolve over time and for developing effective rehabilitation strategies. Unfortunately, despite its importance, a standardized, reliable and objective method for fatigue measurement is lacking in clinical practice and this work investigates a practical solution.

METHODS

40 healthy young adults performed a haptic reaching task, while holding a robotic manipulandum. Subjects were required to perform wrist flexion and extension movements in a resistive visco-elastic force field, as many times as possible, until the measured muscles (mainly flexor and extensor carpi radialis) exhibited signs of fatigue. In order to analyze the behavior and the characteristics of the two muscles, subjects were divided into two groups: in the first group, the resistive force was applied by the robot only during flexion movements, whereas, in the second group, the force was applied only during extension movements. Surface electromyographic signals (sEMG) of both flexor and extensor carpi radialis were acquired. A novel indicator to define the Onset of Fatigue (OF) was proposed and evaluated from the Mean Frequency of the sEMG signal. Furthermore, as measure of the subjects' effort throughout the task, the energy consumption was estimated.

RESULTS

From the beginning to the end of the task, as expected, all the subjects showed a decrement in Mean Frequency of the muscle involved in movements resisting the force. For the OF indicator, subjects were consistent in terms of timing of fatigue; moreover, extensor and flexor muscles presented similar OF times. The metabolic analysis showed a very low level of energy consumption and, from the behavioral point of view, the test was well tolerated by the subjects.

CONCLUSION

The robot-aided assessment test proposed in this study, proved to be an easy to administer, fast and reliable method for objectively measuring muscular fatigue in a healthy population. This work developed a framework for an evaluation that can be deployed in a clinical practice with patients presenting neuromuscular disorders. Considering the low metabolic demand, the requested effort would likely be well tolerated by clinical populations.

Collaborative Framework to Advance Symptom Science: An Intramural Perspective

PURPOSE

To describe the collaborative framework used by National Institute of Nursing Research (NINR) investigators to advance symptom science and to provide a research exemplar.

MODEL

The National Institutes of Health (NIH) Symptom Science Model (SSM) was developed to guide symptom science researchers to understand the molecular underpinnings of symptoms using innovative "omics" approaches. The process begins with a review of the literature to understand the state of the science of the symptoms of interest and is followed by cross-sectional, case-controlled, or longitudinal studies to identify potential biological correlates of these symptoms. The final steps include validation of these potential symptom biomarkers using multidisciplinary, collaborative, preclinical experiments, and proof-of-concept clinical trials.

RESEARCH EXEMPLAR

Using the NIH SSM as a guide, the identification of biologic correlates of symptoms using omics and bioinformatic strategies depends on determining the distinct phenotype of the symptoms of interest. The identified biologic correlates of these symptoms are then validated for their functional relevance using in vitro and ex vivo experiments, or through proof-of-concept clinical trials. NINR investigators observed that activation of specific receptors in neural networks can trigger inflammation-related fatigue development and predispose patients to develop chronicity of symptoms. Specifically targeting these neural receptors can reduce symptom intensity.

CONCLUSIONS

Through using the NIH SSM as a guide, NINR investigators quickly generate data and discoveries that significantly advance symptom science by simultaneously collaborating with multiple experts and core laboratories to identify more correlates and validate their functional relevance in order to further understand the biological underpinnings of the symptoms of interest.

CLINICAL RELEVANCE

The collaborative framework used by NINR investigators as guided by the NIH SSM identifies functionally relevant clinical markers that can explain the biological underpinnings of symptoms and can be targeted to optimize symptom management.

Muscle Extremely Low Frequency Magnetic Stimulation Eliminates the Effect of Fatigue on EEG-EMG Coherence during the Lateral Raise Task: A Pilot Quantitative Investigation

The aim of this study was to quantitatively investigate the effects of force load, muscle fatigue, and extremely low frequency (ELF) magnetic stimulation on electroencephalography- (EEG-) electromyography (EMG) coherence during right arm lateral raise task. Eighteen healthy male subjects were recruited. EEG and EMG signals were simultaneously recorded from each subject while three different loads (0, 1, and 3kg) were added on the forearm. ELF magnetic stimulation was applied to the subject's deltoid muscle between tasks during the resting period. Univariate ANOVA showed that all EEG-EMG coherence areas of C3, C4, CP5, and CP6 were not significantly affected by the force load (all p>0.05) and that muscle fatigue led to statistically significant reductions on the coherence area of gamma band in C3 (p=0.014) and CP5 (p=0.019). More interestingly, these statistically significant reductions disappeared with the application of muscle ELF magnetic stimulation, indicating its potential application to eliminate the effect of fatigue.

Analysis of Sequential Visibility Motifs in Isometric Surface Electromyography Signals in Fatiguing Condition

Muscle fatigue is the inability to exert the required force. Surface Electromyography (sEMG) is a technique used to study the muscle's electrical property. These generated signals are complex and nonstationary in nature. In this work, an attempt is made to utilize graph signal processing methods such as Sequential Visibility motif for the analysis of muscle fatigue condition. The sEMG signals of 41 healthy adult volunteers are acquired from the biceps brachii muscle during isometric contraction with a 6 Kg load. The subjects are asked to perform the exercise until they are unable to continue. The signals are preprocessed, and the first and last 500 ms of the signal are considered for analysis. The segmented signals are subjected to sequential visibility graph algorithm. Further, the number of motifs for a subgraph of four is calculated. The results show that the signals are unique for each subject. The frequency of higher degree motif is more in the case of fatigue. The frequency of each unique motif is capable of differentiating nonfatigue and fatigue conditions. Nonparametric statistical test result indicates all features are significant with p<0.05. This method of analysis can be extended to other varied neuromuscular conditions.

Effects of a Finger Tapping Fatiguing Task on M1-Intracortical Inhibition and Central Drive to the Muscle

The central drive to the muscle reduces when muscle force wanes during sustained MVC, and this is generally considered the neurophysiological footprint of central fatigue. The question is if force loss and the failure of central drive to the muscle are responsible mechanisms of fatigue induced by un-resisted repetitive movements. In various experimental blocks, we validated a 3D-printed hand-fixation system permitting the execution of finger-tapping and maximal voluntary contractions (MVC). Subsequently, we checked the suitability of the system to test the level of central drive to the muscle and developed an algorithm to test it at the MVC force plateau. Our main results show that the maximum rate of finger-tapping dropped at 30 s, while the excitability of inhibitory M1-intracortical circuits and corticospinal excitability increased (all by approximately 15%). Furthermore, values obtained immediately after finger-tapping showed that MVC force and the level of central drive to the muscle remained unchanged. Our data suggest that force and central drive to the muscle are not determinants of fatigue induced by short-lasting un-resisted repetitive finger movements, even in the presence of increased inhibition of the motor cortex. According to literature, this profile might be different in longer-lasting, more complex and/or resisted repetitive movements.