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PubMed2005

Increased daily physical activity and fatigue symptoms in chronic fatigue syndrome.

Individuals with chronic fatigue syndrome (CFS) have been shown to have reduced activity levels associated with heightened feelings of fatigue. Previous research has demonstrated that exercise training has beneficial effects on fatigue-related symptoms in individuals with CFS. PURPOSE: The aim of this study was to sustain an increase in daily physical activity in CFS patients for 4 weeks and assess the effects on fatigue, muscle pain and overall mood. METHODS: Six CFS and seven sedentary controls were studied. Daily activity was assessed by a CSA accelerometer. Following a two week baseline period, CFS subjects were asked to increase their daily physical activity by 30% over baseline by walking a prescribed amount each day for a period of four weeks. Fatigue, muscle pain and overall mood were reported daily using a 0 to 100 visual analog scale and weekly using the Profile of Mood States (Bipolar) questionnaire. RESULTS: CFS patients had significantly lower daily activity counts than controls (162.5 +/- 51.7 x 103 counts/day vs. 267.2 +/- 79.5 x 103 counts/day) during a 2-week baseline period. At baseline, the CFS patients reported significantly (P < 0.01) higher fatigue and muscle pain intensity compared to controls but the groups did not differ in overall mood. CFS subjects increased their daily activity by 28 +/- 19.7% over a 4 week period. Overall mood and muscle pain worsened in the CFS patients with increased activity. CONCLUSION: CFS patients were able to increase their daily physical activity for a period of four weeks. In contrast to previous studies fatigue, muscle pain, and overall mood did not improve with increased activity. Increased activity was not presented as a treatment which may account for the differential findings between this and previous studies. The results suggest that a daily "activity limit" may exist in this population. Future studies on the impact of physical activity on the symptoms of CFS patients are needed.

Journal Article↗
PubMed1998

Chronic fatigue and chronic fatigue syndrome: shifting boundaries and attributions.

The subjective symptom of "fatigue" is one of the most widespread in the general population and is a major source of healthcare utilization. Prolonged fatigue is often associated with neuropsychological and musculoskeletal symptoms that form the basis of several syndromal diagnoses including chronic fatigue syndrome, fibromyalgia, and neurasthenia, and is clearly not simply the result of a lack of force generation from the muscle. Current epidemiologic research in this area relies predominantly on self-report data to document the prevalence and associations of chronic fatigue. Of necessity, this subjective data source gives rise to uncertain diagnostic boundaries and consequent divergent epidemiologic, clinical, and pathophysiologic research findings. This review will highlight the impact of the case definition and ascertainment methods on the varying prevalence estimates of chronic fatigue syndrome and patterns of reported psychological comorbidty. It will also evaluate the evidence for a true postinfective fatigue syndrome.

Chronic Disease↗
PubMed2002

The effect of a polynutrient supplement on fatigue and physical activity of patients with chronic fatigue syndrome: a double-blind randomized controlled trial.

BACKGROUND: The efficacy of dietary supplements in chronic fatigue syndrome (CFS) is uncertain, with conflicting evidence. AIM: To assess the effect of a polynutrient supplement on fatigue and physical activity of patients with CFS. DESIGN: Prospective randomized placebo-controlled, double-blind trial. METHODS: Fifty-three patients (16 males, 37 females) fulfilling the CDC criteria of CFS. The entry criteria were a score on the Checklist Individual Strength subscale fatigue severity (CIS fatigue) >or=40 and a weighted sum score of >or=750 for the eight subscales of the Sickness Impact Profile (SIP8) and no use of nutritional supplements in the 4 weeks prior to entry. The exclusion criteria were pregnancy and lactose intolerance. The intervention-a polynutrient supplement containing several vitamins, minerals and (co)enzymes, or placebo, twice daily for 10 weeks-was preceded by 2 weeks of baseline measurements. Outcome measurements took place in week 9 and 10 of the intervention. Five participants dropped out (4 supplement, 1 placebo). The main outcome measures were CIS fatigue score, number of CDC symptoms and SIP8 score. Efficacy analyses were performed on an intention-to-treat basis. RESULTS: No significant differences were found between the placebo and the treated group on any of the outcome measures: CIS fatigue +2.16 (95%CI -4.3 to +4.39, p=0.984); CDC symptoms +0.42 (95%CI -0.61 to +1.46, p=0.417); SIP8 +182 (95%CI -165 to +529, p=0.297). No patient reported full recovery. DISCUSSION: The findings do not support the use of a broad-spectrum nutritional supplement in treating CFS-related symptoms.

Adult↗
PubMed1996

Fatigue in multiple sclerosis compared with chronic fatigue syndrome: A quantitative assessment.

Fatigue, a common complaint among patients with multiple sclerosis (MS), is poorly characterized. We developed a computerized method that quantitatively measures fatigue, and defined a fatigue index (FI), which is the ratio between the integral of muscle strength decay over time and maximal voluntary contraction. Thirty patients (mean age, 37.4 +/- 10.3 years) were examined - 20 patients with pyramidal tract involvement and 10 patients with involvement of other neurological systems. We evaluated 10 patients during relapse and 3 months afterwards, and compared their results with those of four patients with chronic fatigue syndrome (CFS) and 13 age-matched health subjects. The FI was significantly higher in the MS patients as compared with the CFS patients and normal controls: 34.2 +/- 6.4% versus 27.5 +/- 1.0% and 23.6 +/- 6.8%, p < 0.05. Within the MS group, the FI correlated with the presence of pyramidal signs- 43.5% compared with 33% in patients without pyramidal signs, p < 0.01. In MS patients, fatigue worsened during a relapse affecting the pyramidal tract, but not during a relapse in other systems. These results demonstrate that fatigue can be quantitatively measured in MS patients, and that pyramidal dysfunction leads to increased fatigability.

Adolescent↗
PubMed2005

Prevalence of chronic fatigue and chronic fatigue syndrome in Korea: community-based primary care study.

There have been many epidemiological and clinical researches on chronic fatigue (CF) and chronic fatigue syndrome (CFS) since the 1990s, but such studies have been quite limited in Korea. The aim of this study was to investigate the point prevalence of CF and CFS in patients who visited community-based eight primary care clinics in Korea. The study subjects were 1,648 patients aged 18 yr and over who visited one of eight primary care clinics in Korea between the 7th and 17th of May 2001. The physicians determined the status of the subjects through fatigue-related questionnaires, medical history, physical examination, and laboratory tests. The subjects were categorized into no fatigue, prolonged fatigue, CF and then CF were further classified to medically explained CF (Physical CF and Psychological CF) and medically unexplained CF (CFS and idiopathic chronic fatigue). The point prevalence of CF and CFS were 8.4% (95% CI 7.1-9.7%) and 0.6% (95% CI 0.2-1.0%). Medically explained CF was 80.5% of CF, of which 57.1% had psychological causes. The clinical characteristics of CFS were distinguished from explained CF. CF was common but CFS was rare in community-based primary care settings in Korea.

Adolescent↗
PubMed2005

Short-interval cortical inhibition and corticomotor excitability with fatiguing hand exercise: a central adaptation to fatigue?

The central processes occurring during fatiguing exercise are not well understood, however transcranial magnetic stimulation (TMS) studies have reported increases both in corticomotor excitability, as measured by the motor-evoked potential (MEP) amplitude, and in long-interval intracortical inhibition, as measured by the duration of the post-MEP silent period. To determine whether short-interval cortical inhibition (SICI) is modulated by fatiguing exercise, we used single and paired-pulse TMS to measure MEP amplitude and SICI for the first dorsal interosseous (FDI) and abductor digiti minimi (ADM) muscles of the hand during, and for 20 min after, a 10-min intermittent maximal voluntary abduction of the index finger designed to fatigue the FDI muscle. For the FDI, the index of SICI increased at the onset of exercise (from 0.25+/-0.05 to 0.55+/-0.11, P < 0.05) and then decreased progressively as force declined. At the beginning of recovery, SICI again increased (0.57+/-0.11, P < 0.05) and remained elevated for the 20-min recovery period. In contrast, SICI for ADM did not change during or after exercise. MEP amplitude for both the FDI and ADM increased above baseline during exercise and then decreased below baseline during the recovery period. These results demonstrate that there are significant changes in SICI during and after a fatiguing exercise protocol that are isolated to the representation of the fatigued muscle. The inter-relationship between the changes in excitation and inhibition suggests the presence of a measured and adaptive process of modulation in central excitation and inhibition acting to increase corticomotor drive to the exercising muscle as fatigue is developing.

Adaptation, Physiological↗
PubMed2005

Intramuscular pressure, tissue oxygenation and EMG fatigue measured during isometric fatigue-inducing contraction of the multifidus muscle.

Simultaneous measurement of intramuscular pressure (IMP), tissue oxygen partial pressure (pO(2)) and EMG fatigue parameters in the multifidus muscle during a fatigue-inducing sustained muscular contraction. The study investigated the following hypotheses: (1) Increases in IMP result in tissue hypoxia; (2) Tissue hypoxia is responsible for loss of function in the musculature. The nutrient supply to muscle during muscle contraction is still not fully understood. It is assumed that muscle contraction causes increased tissue pressure resulting in compromised perfusion and tissue hypoxia. This tissue hypoxia, in turn, leads to muscle fatigue and therefore to loss of function. To the authors' knowledge, no study has addressed IMP, pO(2) and EMG fatigue parameters in the same muscle to gain a deeper sight into muscle perfusion during contraction. As back muscles need to have a constant muscular tension to maintain trunk stability during stance and locomotion, muscle fatigue due to prolonged contraction-induced hypoxia could be an explanation for low back pain. Sixteen healthy subjects performed an isometric muscular contraction exercise at 60% of maximum force until the point of localized muscular fatigue. During this exercise, the individual changes of IMP, pO(2) and the median frequency (MF) of the surface EMG signal of the multifidus muscle were recorded simultaneously. In 12 subjects with a documented increase in intramuscular pressure, only five showed a decrease in tissue oxygen partial pressure, while this parameter remained unchanged in six other subjects and even increased in one. A fall in tissue pO(2) was associated with a drop in MF in only five subjects, while there was no correlation between these parameters in the other 11 subjects. To summarize, an increase in IMP correlated with a decrease in pO(2) and a drop in MF in only five out of 16 subjects. High intramuscular pressure values are not always associated with a hypoxia in muscle tissue. Tissue hypoxia is not automatically associated with a median frequency shift in the EMG signal's power spectrum.

Adult↗
PubMed2006

Comparison between fatigue, sleep disturbance, and circadian rhythm in cancer inpatients and healthy volunteers: evaluation of diagnostic criteria for cancer-related fatigue.

The aim of this study was to evaluate whether diagnostic criteria for cancer-related fatigue syndrome (CRFS) could be rigorously applied to cancer inpatients, and to explore the relationship between subjective fatigue and objective measures of physical activity, sleep, and circadian rhythm. Female cancer patients (n=25) and a comparison group of subjects without cancer (n=25) were studied. Study participants completed a structured interview for CRFS and questionnaires relating to fatigue, psychological symptoms, and quality of life (QoL). Wrist actigraphs worn for 72 hours were used as an objective measure of activity, sleep, and circadian rhythm. Compared to controls, cancer patients were more fatigued, had worse sleep quality, more disrupted circadian rhythms, lower daytime activity levels, and worse QoL. After exclusion of subjects with "probable" mood disorders, the prevalence of CRFS was 56%. Fatigue severity among the cancer patients was significantly correlated with low QoL, depression, constipation, and decreased self-reported physical functioning. It can be concluded that the diagnostic criteria for CRFS can be applied to cancer inpatients but strict application requires a rigorous assessment of psychiatric comorbidity. Despite cancer inpatients having greater impairments of sleep and circadian rhythm, it was found that fatigue severity did not appear to be related to these impairments.

Aged↗
PubMed1997

Fatigue-induced changes in group IV muscle afferent activity: differences between high- and low-frequency electrically induced fatigues.

Recordings of group IV afferent activity of tibialis anterior muscle were performed in paralysed rabbits during runs of electrically induced fatigue produced by direct muscle stimulation at a high (100 Hz, high-frequency fatigue HFF) or a low rate (10 Hz, low-frequency fatigue LFF). In addition to analysis of afferent nerve action potentials, muscle force and compound muscle action potentials (M waves) elicited by direct muscle stimulation with single shocks were recorded. Changes in M wave configuration were used as an index of the altered propagation of membrane potentials and the associated efflux of potassium from muscle fibers. The data show that increased group IV afferent activity occurred during LFF as well as HFF trials and developed parallel with force failure. Enhanced afferent activity was significantly higher during LFF (maximal delta f(impulses) = 249 +/- 35%) than HFF (147 +/- 45%). No correlation was obtained between the responses of group IV afferents to LFF or to pressure exerted on tibialis anterior muscle. On the other hand, decreased M wave amplitude was minimal with LFF while it was pronounced with HFF. Close correlations were found between fatigue-induced activation of group IV afferents and decreases in force or M wave amplitude, but their strength was significantly higher with LFF compared to HFF. Thus, electrically induced fatigue activates group IV muscle afferents with a prominent effect of low-frequency stimulation. The mechanism of muscle afferent stimulation does not seem to be due to the sole increase in extracellular potassium concentration, but also by the efflux of muscle metabolites, present during fatiguing contractions at low rate of stimulation.

Action Potentials↗
PubMedDate not supplied

Physical activity in chronic fatigue syndrome: assessment and its role in fatigue.

This paper describes the assessment of physical activity in chronic fatigue syndrome (CFS) and investigated the following questions: Do patients with CFS have low levels of physical activity; is there a relationship between actual level of physical activity and fatigue; can self-report measures adequately assess actual level of physical activity; what is the role of cognitions with respect to physical activity; and are results with respect to physical activity specific to CFS? Three different types of activity measures were used: self-report questionnaires, a 12-day self-observation list, and a motion-sensing device (Actometer) which was used as a reference for actual activity level. Fifty-one patients with CFS, 50 fatigued patients with multiple sclerosis (MS), and 53 healthy subjects participated in this study. Although none of the self-report questionnaires showed high correlations with the Actometer, questionnaires that require simple ratings of specified activities were related to the Actometer and can be used as acceptable substitutes, in contrast to instruments that require general subjective interpretations of activity that had low or non-significant correlations with the Actometer. Actometer results showed that CFS patients and MS patients had similar activity levels and both groups were significantly less active than healthy subjects. Compared to MS patients, CFS patients were more likely to indicate that they had been less active than other persons they knew. Activities which patients expected to result in higher fatigue levels were less frequently performed. Patients with CFS had significantly higher scores on this measure than MS patients and healthy subjects. Low levels of physical activity were related to severe fatigue in CFS but not in MS. In conclusion, although CFS patients have similar low activity levels than MS patients, there are also important differences between both groups: in CFS cognitive factors are more prominently involved in producing the low activity levels than in MS and in CFS patients activity level is related to fatigue but not in MS.

Adult↗
PubMed2003

Psychometric qualities of a brief self-rated fatigue measure: The Fatigue Assessment Scale.

OBJECTIVE: The main aim of this study was to examine the dimensionality and psychometric qualities of a new 10-item fatigue measure, the Fatigue Assessment Scale (FAS). METHODS: As part of a longitudinal study, the respondents, all workers with at least 20 working hours per week, completed the FAS, four related fatigue measures, a depression questionnaire, and an emotional stability scale. RESULTS: The FAS had a high internal consistency. The pattern of correlations and factor analysis showed good convergent and divergent validity. The FAS correlated strongly with the other fatigue scales. In a factor analysis of the five fatigue questionnaires, the FAS had the highest factor loading on a clear one-factor solution. Moreover, factor analyses revealed that fatigue, on the one hand, and depression and emotional stability, on the other hand, are separate constructs. Finally, it was shown that 8 out of the 10 FAS items were unbiased concerning gender; two had a uniform bias. CONCLUSIONS: The FAS represents a potentially valuable assessment instrument with promising internal consistency reliability and validity. Gender bias in the FAS does not have consequences for use of the FAS.

Adult↗
PubMed2004

Factor analysis of symptoms among subjects with unexplained chronic fatigue: what can we learn about chronic fatigue syndrome?

OBJECTIVE: Chronic fatigue syndrome (CFS) case definitions agree that fatigue must be unexplained, debilitating and present for at least 6 months, but they differ over accompanying symptoms. Our objective was to compare the 1994 CFS case-defining symptoms with those identified by factor analysis. METHODS: We surveyed the Wichita population and measured the occurrence of 21 symptoms in 1391 chronically fatigued subjects who did not report fatigue-associated medical or psychiatric conditions. We used factor analyses to identify symptom dimensions of fatigue and cluster analysis to assign subjects to subgroups. RESULTS: Forty-three subjects had CFS. We confirmed three factors: musculoskeletal, infection and cognition-mood-sleep, essentially defined by CFS symptoms. Although factor scores were higher among CFS subjects, CFS and non-CFS distributions overlapped substantially. Three clusters also showed overlap between CFS and non-CFS subjects. CONCLUSION: CFS symptomatology is a multidimensional phenomenon overlapping with other unexplained fatiguing syndromes and this must be considered in CFS research.

Cluster Analysis↗
PubMed1999

Chronic fatigue syndrome, chronic fatigue, and psychiatric disorders: predictors of functional status in a national nursing sample.

Members of 2 nurses' associations (N = 71) were assessed using 2 mail questionnaires, a telephone questionnaire, the Diagnostic Interview Schedule, and medical records. Physicians reviewed participants to determine whether they met current criteria for chronic fatigue syndrome (CFS). Stepwise multivariate regression analyses were conducted to identify predictors of functional status scores. Impairments in physical, role, and social functioning increased as fatigue severity increased. Bodily pain increased as fatigue severity increased, and ratings of overall health increased as severity of fatigue decreased. Nurses with a current psychiatric diagnosis reported more impairments in emotional functioning than nurses with a lifetime diagnosis or no psychiatric diagnosis. Quality of life decreased as fatigue severity increased. Nurses with fatigue not meeting CFS criteria reported better quality of life than those with CFS or medical exclusions.

Adult↗
PubMed2004

Fatigue after brain injury: initial reliability study of the BNI Fatigue Scale.

OBJECTIVE: Fatigue is a common problem of many neurological disorders. Yet, few measures have been developed to adequately assess fatigue, particularly during the early stages following a brain injury. The purpose of this study was to document the psychometric properties of the BNI Fatigue Scale for use on an acute, inpatient neurorehabilitation unit. RESEARCH DESIGN: A prospective cohort of patients seen for inpatient rehabilitation following brain injury. PROCEDURES: The BNI Fatigue Scale was administered to an heterogeneous sample of 84 neurologic patients upon admission to the Neurorehabilitation unit within 20 days of their injury. RESULTS: Principle components factor analysis yielded a one-factor solution. Acceptable internal consistency was calculated for the scale items. Overall index of fatigue correlated significantly with the total scale score. CONCLUSIONS: This initial study on the BNI Fatigue Scale supports its reliability and clinical utility for use with acute neurological patients. Information obtained by this scale may help to guide the rehabilitation process and provide direction for intervention and treatment.

Brain Injuries↗
PubMed1998

Reliability and validity of the Multidimensional Fatigue Inventory (MFI-20) and the Rhoten Fatigue Scale among rural cancer outpatients.

Cancer patients typically experience fatigue while undergoing treatment for their disease. This study was an effort to identify a reliable and economical measure of fatigue. In particular, scores on the five subscales of the Multidimensional Fatigue Inventory (MFI-20) were analyzed for internal consistency and then correlated with scores on the Rhoten Fatigue Inventory to establish a measure of validity. Moderate-to-high Cronbach alphas coefficients were established for the General Fatigue subscale of the MFI-20 using a sample of 97 rural oncology outpatients (1). Partial associations with the Rhoten Fatigue Scale lend evidence to the validity of the MFI-20 measures.

Adult↗
PubMedDate not supplied

Chronic fatigue syndrome, fibromyalgia, and multiple chemical sensitivities in a community-based sample of persons with chronic fatigue syndrome-like symptoms.

OBJECTIVE: The aim of this study was to determine illness comorbidity rates for individuals with chronic fatigue syndrome (CFS), fibromyalgia (FM), and multiple chemical sensitivities (MCS). An additional objective was to identify characteristics related to the severity of fatigue, disability, and psychiatric comorbidity in each of these illness groups. METHODS: A random sample of 18,675 residents in Chicago, Illinois, was first interviewed by telephone. A control group and a group of individuals with chronic fatigue accompanied by at least four minor symptoms associated with CFS received medical and psychiatric examinations. RESULTS: Of the 32 individuals with CFS, 40.6% met criteria for MCS and 15.6% met criteria for FM. Individuals with MCS or more than one diagnosis reported more physical fatigue than those with no diagnosis. Individuals with more than one diagnosis also reported greater mental fatigue and were less likely to be working than those with no diagnosis. Individuals with CFS, MCS, FM, or more than one diagnosis reported greater disability than those with no diagnosis. CONCLUSIONS: Rates of coexisting disorders were lower than those reported in prior studies. Discrepancies may be in part attributable to differences in sampling procedures. People with CFS, MCS, or FM endure significant disability in terms of physical, occupational, and social functioning, and those with more than one of these diagnoses also report greater severity of physical and mental fatigue. The findings illustrate differences among the illness groups in the range of functional impairment experienced.

Adolescent↗
PubMed2006

Influence of melatonin on fatigue severity in patients with chronic fatigue syndrome and late melatonin secretion.

The effect of melatonin, a chronobiotic drug, was explored in 29 patients with chronic fatigue syndrome (CFS) and Dim Light Melatonin onset (DLMO) later than 21.30 hours, reflective of delayed circadian rhythmicity. The patients took 5 mg of melatonin orally, 5 h before DLMO during 3 months. Their responses to the checklist individual strength (CIS), a reliable questionnaire measuring the severity of personally experienced fatigue, were assessed twice with a 6-week interval immediately before the treatment and once after 3 months treatment. In the pre-treatment period the fatigue sub-score improved significantly. After treatment, the total CIS score and the sub-scores for fatigue, concentration, motivation and activity improved significantly. The sub-score fatigue normalized in two of the 29 patients in the pre-treatment period and in eight of 27 patients during treatment. This change was significant. In the patients with DLMO later than 22.00 hours (n=21) the total CIS score and the sub-scores for fatigue, concentration and activity improved significantly more than in the patients (n=8) with DLMO earlier than 22.00 hours. Melatonin may be an effective treatment for patients with CFS and late DLMO, especially in those with DLMO later than 22.00 hours.

Circadian Rhythm↗
PubMed1989

Age-related effects of fatigue and recovery from fatigue in rat medial gastrocnemius muscle.

Force-velocity, power-velocity and unloaded shortening data were obtained from in situ medial gastrocnemius muscle-tendon complexes (stimulated at 60 Hz) with intact circulation of mature male rats (approximately 125 days old). Measurements were carried out at the end of a long (15 s) contraction (fatigued muscles) or with a short (1 s) contraction either in the fresh state (fresh muscles) or in muscles which had recovered for 15 min after a long contraction. Compared to the fresh state fatigue reduced isometric force by 57%, maximal shortening velocity by approximately 40% and maximal power output by 81%. These reductions were similar to data previously obtained with younger rats (40 days old). However, the velocity data of the muscles which had recovered for 15 min after a long contraction showed a greater reduction in the mature rats. This difference between the two age groups together with a difference in the changes in the initial parts of the isometric force time curves suggest an age-dependent response of the fast-fatigable fibre population of these mixed muscles. In a separate series of experiments the underlying mechanism of the recovery from fatigue was studied in a group of young rats. Fatigue was induced with five long (15 s) contractions (each at 5 min intervals). The recovery of isometric force and power output was monitored with short contractions which indicated a plateau of recovery but the absolute values were still reduced after 60 min (85 and 71% of prefatigue values, respectively). Phosphocreatine concentration recovered rapidly, whereas the ATP concentration was still markedly reduced after 1 h of recovery. The time courses of recovery of inosine-5'-monophosphate (IMP) and lactate concentrations resembled those of force and power output. Thus it is possible that age-dependent differences in IMP and/or lactate production may play a role in fatigue and recovery from fatigue.

Adenosine Monophosphate↗