Muscle strength, endurance and recovery in the post-infection fatigue syndrome

Pre-Transplant Dual-Energy X-ray Absorptiometry (DXA)-Derived Body Composition Measures as Predictors of Treatment Outcomes and Early Post-Transplant Complications in Patients with Multiple Myeloma (MM) Treated with Autologous Hematopoietic Stem Cell Transplantation (AutoHSCT)

Background/Objectives: Changes in muscle mass and bone density are common in multiple myeloma (MM) patients. Dual-energy X-ray absorptiometry (DXA) offers precise, non-invasive insights into a patient's physical condition before autologous stem cell transplantation (autoHSCT). This study examines how pre-transplant body composition impacts treatment outcomes and early complications in MM patients undergoing autoHSCT. Methods: This study is a single-center, retrospective analysis of patients with MM who were treated with first or second autoHSCT and underwent DXA pre-transplant between 11 August 2019 and 12 June 2024. Results: We conducted a study of pre-transplant body composition in 127 patients with MM. Among them, 108 (85%) qualified for first autoHSCT, while 19 (15%) qualified for a second. The median age of the patients was 64 years (range 50-73). In the Cox proportional hazards regression conducted in the group of women, Total Body %Fat was a statistically significant predictor for progression-free survival (PFS) (HR = 0.07, 95% CI = 0.01,0.6, p = 0.0157). In the Mann-Whitney U test conducted on males, Lean Mass/Height2 and Appen. Lean Height2 were statistically significant predictors of early infections after autoHSCT (Z = 1.98, p = 0.0473 and Z = 2.32, p = 0.0204, respectively). In males, Fat Mass/Height2 was a significant predictor of non-infectious toxicity related to treatment (Z = -1.98, p = 0.0476). Conclusions: In women, higher levels of adipose tissue initially appear to exert a protective effect; however, this benefit diminishes over time, with greater fat mass eventually correlating with an increased risk of disease progression. In men, muscle mass has been identified as a significant predictor of early infection risk post-autoHSCT. Furthermore, our findings indicate that an increased amount of adipose tissue in men is statistically associated with a higher risk of non-infectious treatment-related toxicity. These conclusions highlight the critical need for further investigation into the role of body composition.

The Adaptive Force as a Potential Biomechanical Parameter in the Recovery Process of Patients with Long COVID

Long COVID patients show symptoms, such as fatigue, muscle weakness and pain. Adequate diagnostics are still lacking. Investigating muscle function might be a beneficial approach. The holding capacity (maximal isometric Adaptive Force; AFisomax) was previously suggested to be especially sensitive for impairments. This longitudinal, non-clinical study aimed to investigate the AF in long COVID patients and their recovery process. AF parameters of elbow and hip flexors were assessed in 17 patients at three time points (pre: long COVID state, post: immediately after first treatment, end: recovery) by an objectified manual muscle test. The tester applied an increasing force on the limb of the patient, who had to resist isometrically for as long as possible. The intensity of 13 common symptoms were queried. At pre, patients started to lengthen their muscles at ~50% of the maximal AF (AFmax), which was then reached during eccentric motion, indicating unstable adaptation. At post and end, AFisomax increased significantly to ~99% and 100% of AFmax, respectively, reflecting stable adaptation. AFmax was statistically similar for all three time points. Symptom intensity decreased significantly from pre to end. The findings revealed a substantially impaired maximal holding capacity in long COVID patients, which returned to normal function with substantial health improvement. AFisomax might be a suitable sensitive functional parameter to assess long COVID patients and to support therapy process.

Case report: Individualized pulsed electromagnetic field therapy in a Long COVID patient using the Adaptive Force as biomarker

The increasing prevalence of Long COVID is an imminent public health disaster, and established approaches have not provided adequate diagnostics or treatments. Recently, anesthetic blockade of the stellate ganglion was reported to improve Long COVID symptoms in a small case series, purportedly by "rebooting" the autonomic nervous system. Here, we present a novel diagnostic approach based on the Adaptive Force (AF), and report sustained positive outcome for one severely affected Long COVID patient using individualized pulsed electromagnetic field (PEMF) at the area C7/T1. AF reflects the capacity of the neuromuscular system to adapt adequately to external forces in an isometric holding manner. In case, maximal isometric AF (AFisomax) is exceeded, the muscle merges into eccentric muscle action. Thereby, the force usually increases further until maximal AF (AFmax) is reached. In case adaptation is optimal, AFisomax is ~99-100% of AFmax. This holding capacity (AFisomax) was found to be vulnerable to disruption by unpleasant stimulus and, hence, was regarded as functional parameter. AF was assessed by an objectified manual muscle test using a handheld device. Prior to treatment, AFisomax was considerably lower than AFmax for hip flexors (62 N = ~28% AFmax) and elbow flexors (71 N = ~44% AFmax); i.e., maximal holding capacity was significantly reduced, indicating dysfunctional motor control. We tested PEMF at C7/T1, identified a frequency that improved neuromuscular function, and applied it for ~15 min. Immediately post-treatment, AFisomax increased to ~210 N (~100% AFmax) at hip and 184 N (~100% AFmax) at elbow. Subjective Long COVID symptoms resolved the following day. At 4 weeks post-treatment, maximal holding capacity was still on a similarly high level as for immediately post-treatment (~100% AFmax) and patient was symptom-free. At 6 months the patient's Long COVID symptoms have not returned. This case report suggests (1) AF could be a promising diagnostic for post-infectious illness, (2) AF can be used to test effective treatments for post-infectious illness, and (3) individualized PEMF may resolve post-infectious symptoms.

Kidney Transplant Modifies the Architecture and Microenvironment of Basal Cell Carcinomas

BACKGROUND/AIMS

Basal cell carcinoma (BCC) is a frequent type of nonmelanoma skin cancer, which shows a greater prevalence in kidney-transplanted (KT) patients than in the general population. The study of this tumor in KT patients may allow us to understand the influence of the tumor inflammatory microenvironment on cancer behavior, and to design new image analysis methods to determine prognosis and apply personalized medicine. The major hypothesis of the present work is that antirejection drugs, by modifying the B-cell/T-cell balance, induce measurable differences in tumoral cell microarchitecture and in the inflammatory microenvironment in KT patients compared to nontransplanted controls.

METHODS

In this retrospective study in an Italian cohort including 15 KT patients and 15 control subjects from the general population who developed BCC, we analyzed tissue microarchitecture and inflammatory infiltrates of BCC using state-of-the-art nonlinear image analysis techniques such as fractal dimension and sample entropy of internuclear distances.

RESULTS

KT patients showed a nonsignificant trend to a greater number of nuclei in the basal cell layer compared to non-KT controls and subtle changes in the intact skin compared to controls. Similarly, the number of mitoses per unit length was almost doubled in the patients with KT compared to controls. However, when the number of mitotic cells was normalized by the total number of cells in the basal layer (mitotic index), these differences were not significant, although a clear trend was still present. Finally, KT patients showed a nonsignificant trend to an increased -density of inflammatory cells close to the tumoral cell layer. When considering the intact skin, this difference was significant, with a 70% increase in the density of inflammatory cells.

CONCLUSION

Data comparing the microarchitecture of BCC in normal subjects and KT patients are scanty, and the present study is the first to use nonlinear image analysis techniques to this aim. The observed differences underscore the relevance of T-cell suppression in cancer behavior. These data suggest that BCC develops in treated patients with specific biological characteristics which should be further analyzed in terms of therapeutic response.

Chronic fatigue syndrome

“Chronic fatigue syndrome” (Sharpeet al, 1991) is an operational definition for conditions of disabling physical fatigue, of over six months duration, unexplained by primary physical or psychiatric causes. It encompasses nomenclature such as “myalgic encephalomyelitis” (Acheson, 1959), “post-viral fatigue syndrome” (Behanet al, 1985) and “chronic mononucleosis syndrome” (Straus, 1988).

Association between cognitive performance, physical fitness, and physical activity level in women with chronic fatigue syndrome

Limited scientific evidence suggests that physical activity is directly related to cognitive performance in patients with chronic fatigue syndrome (CFS). To date, no other study has examined the direct relationship between cognitive performance and physical fitness in these patients. This study examined whether cognitive performance and physical fitness are associated in female patients with CFS and investigated the association between cognitive performance and physical activity level (PAL) in the same study sample. We hypothesized that patients who performed better on cognitive tasks would show increased PALs and better performance on physical tests. The study included 31 women with CFS and 13 healthy inactive women. Participants first completed three cognitive tests. Afterward, they undertook a test to determine their maximal handgrip strength, performed a bicycle ergometer test, and were provided with an activity monitor. In patients with CFS, lower peak oxygen uptake and peak heart rate were associated with slower psychomotor speed (p < 0.05). Maximal handgrip strength was correlated with working memory performance (p < 0.05). Both choice and simple reaction time were lower in patients with CFS relative to healthy controls (p < 0.05 and p < 0.001, respectively). In conclusion, physical fitness, but not PAL, is associated with cognitive performance in female patients with CFS.

Characterization of fatigue states in medicine and psychiatry by structured interview

CONTEXT

Unexplained fatigue states are prevalent, with uncertain diagnostic boundaries.

OBJECTIVE

Patients with fatigue-related illnesses were investigated by questionnaire and a novel semistructured interview to identify discriminatory features.

METHODS

Cross-sectional samples of women from specialist practices with chronic fatigue syndrome (n = 20), postcancer fatigue (PCF; n = 20), or major depression (n = 16) were recruited. Additionally, two longitudinal samples were studied: women with fatigue associated with acute infection who subsequently developed postinfective fatigue syndrome (n = 20) or recovered uneventfully (n = 21), and women undergoing adjuvant therapy for breast cancer experiencing treatment-related fatigue who subsequently developed PCF (n = 16) or recovered uneventfully (n = 16). Patients completed self-report questionnaires, and trained interviewers applied the Semi-structured Clinical Interview for Neurasthenia. The receiver operating characteristics curves of the interview were measured against clinician-designated diagnoses. Cluster analyses were performed to empirically partition participants by symptom characteristics.

RESULTS

The interview had good internal consistency (Cronbach alpha "fatigue" = .83), and diagnostic sensitivity and specificity for chronic fatigue syndrome (100% and 83%) and major depression (100% and 72%), with reasonable parameters for PCF (72% and 58%). Empirical clustering by "fatigue" or "neurocognitive difficulties" items allocated most patients to one group, whereas "mood disturbance" items correctly classified patients with depression only.

CONCLUSIONS

The Semi-structured Clinical Interview for Neurasthenia offers reliable diagnostic use in assessing fatigue-related conditions. The symptom domains of fatigue and neurocognitive difficulties are shared across medical and psychiatric boundaries, whereas symptoms of depression such as anhedonia are distinguishing.

Recovery of upper limb muscle function in chronic fatigue syndrome with and without fibromyalgia

BACKGROUND

Chronic fatigue syndrome (CFS) patients frequently complain of muscle fatigue and abnormally slow recovery, especially of the upper limb muscles during and after activities of daily living. Furthermore, disease heterogeneity has not yet been studied in relation to recovery of muscle function in CFS. Here, we examine recovery of upper limb muscle function from a fatiguing exercise in CFS patients with (CFS+FM) and without (CFS-only) comorbid fibromyalgia and compare their results with a matched inactive control group.

DESIGN

In this case-control study, 18 CFS-only patients, 30 CFS+FM patients and 30 healthy inactive controls performed a fatiguing upper limb exercise test with subsequent recovery measures.

RESULTS

There was no significant difference among the three groups for maximal handgrip strength of the non-dominant hand. A significant worse recovery of upper limb muscle function was found in the CFS+FM, but not in de CFS-only group compared with the controls (P < 0·05).

CONCLUSIONS

This study reveals, for the first time, delayed recovery of upper limb muscle function in CFS+FM, but not in CFS-only patients. The results underline that CFS is a heterogeneous disorder suggesting that reducing the heterogeneity of the disorder in future research is important to make progress towards a better understanding and uncovering of mechanisms regarding the nature of divers impairments in these patients.

Chronic fatigue syndrome

Chronic fatigue syndrome (CFS) is an illness characterized by disabling fatigue of at least 6 months. The aetiology of the condition has been hotly debated. In this chapter the evidence for CFS as a post viral condition and/or a neurological condition is reviewed. Although there is evidence that CFS is triggered by certain viruses in some patients and that neurobiological changes such as hypocortisolism are associated with the syndrome, neither mechanism is sufficient to explain the extent of the symptoms or disability experienced by patients. It is unlikely that CFS can be understood through one aetiological mechanisms. Rather it is a complex illness which is best explained in terms of a multifactorial cognitive behavioural model. This model proposes that CFS is precipitated by life events and/or viral illness in vulnerable individuals, such as those who are genetically predisposed, prone to distress, high achievement, and over or under activity. A self perpetuating cycle where physiological changes, illness beliefs, reduced and inconsistent activity, sleep disturbance, medical uncertainty and lack of guidance interact to maintain symptoms. Treatments based on this model including cognitive behavioural therapy and graded exercise therapy are effective at significantly reducing fatigue and disability in CFS. This chapter provides a description of these approaches and details of the trials conducted in the area.

Loss of capacity to recover from acidosis on repeat exercise in chronic fatigue syndrome: a case-control study

BACKGROUND

Chronic fatigue syndrome (CFS) patients frequently describe difficulties with repeat exercise. Here, we explore muscle bioenergetic function in response to three bouts of exercise.

METHODS

A total of 18 CFS (CDC 1994) patients and 12 sedentary controls underwent assessment of maximal voluntary contraction (MVC), repeat exercise with magnetic resonance spectroscopy and cardio-respiratory fitness test to determine anaerobic threshold.

RESULT

Chronic fatigue syndrome patients undertaking MVC fell into two distinct groups: 8 (45%) showed normal PCr depletion in response to exercise at 35% of MVC (PCr depletion >33%; lower 95% CI for controls); 10 CFS patients had low PCr depletion (generating abnormally low MVC values). The CFS whole group exhibited significantly reduced anaerobic threshold, heart rate, VO(2) , VO(2) peak and peak work compared to controls. Resting muscle pH was similar in controls and both CFS patient groups. However, the CFS group achieving normal PCr depletion values showed increased intramuscular acidosis compared to controls after similar work after each of the three exercise periods with no apparent reduction in acidosis with repeat exercise of the type reported in normal subjects. This CFS group also exhibited significant prolongation (almost 4-fold) of the time taken for pH to recover to baseline.

CONCLUSION

When exercising to comparable levels to normal controls, CFS patients exhibit profound abnormality in bioenergetic function and response to it. Although exercise intervention is the logical treatment for patients showing acidosis, any trial must exclude subjects who do not initiate exercise as they will not benefit. This potentially explains previous mixed results in CFS exercise trials.

An evaluation of exclusionary medical/psychiatric conditions in the definition of chronic fatigue syndrome

BACKGROUND

The diagnosis of chronic fatigue syndrome (CFS) in research studies requires the exclusion of subjects with medical and psychiatric conditions that could confound the analysis and interpretation of results. This study compares illness parameters between individuals with CFS who have and those who do not have exclusionary conditions.

METHODS

We used a population-based telephone survey of randomly selected individuals, followed by a clinical evaluation in the study metropolitan, urban, and rural counties of Georgia, USA. The medical and psychiatric histories of the subjects were examined and they underwent physical and psychiatric examinations and laboratory screening. We also employed the multidimensional fatigue inventory (MFI), the medical outcomes survey short form-36 (SF-36) and the US Centres for Disease Control and Prevention symptom inventory (SI).

RESULTS

Twenty-nine percent (1,609) of the 5623 subjects who completed the detailed telephone interview reported exclusionary diagnoses and we diagnosed an exclusionary condition in 36% of 781 clinically evaluated subjects. Both medical and psychiatric exclusionary conditions were more common in women, blacks and participants from rural areas. Subjects with and without exclusions had similar levels of fatigue and impairment as measured by the MFI and SF-36; those with CFS-like illness (not meeting the formal CFS definition) were more likely to have an exclusionary diagnosis. After adjusting for demographics, body mass index, fatigue subscales, SF-36 subscales and CFS symptoms, CFS-like illness did not remain significantly associated with having an exclusionary diagnosis.

CONCLUSION

Medical and psychiatric illnesses associated with fatigue are common among the unwell. Those who fulfill CFS-like criteria need to be evaluated for potentially treatable conditions. Those with exclusionary conditions are equally impaired as those without exclusions.

In-Patient Treatment of Chronic Fatigue Syndrome

A cognitive behavioural model for the development of chronic fatigue syndrome (CFS) is outlined. Six patients with CFS are described who were treated as in-patients using cognitive behaviour therapy. Treatment consisted of graded consistent exposure to activity and cognitive restructuring. Substantial improvements were made in all but one patient up to three months after discharge.

Muscle histopathology and physiology in chronic fatigue syndrome

Chronic fatigue syndrome (CFS) is characterized by fatigue at rest which is made worse by exercise. Previous biopsy studies on small numbers of CFS patients have shown a range of morphological changes to which have been attributed fatigue and myalgia. We have now studied 108 patients with CFS or muscle pain and 22 normal volunteers by light and electron microscopy. There was no consistent correlation between symptoms and changes in fibre type prevalence, fibre size, degenerative or regenerative features, glycogen depletion, or mitochondrial abnormalities. Physiological contractile properties of quadriceps (maximal isometric force generation, frequency: force characteristics and relaxation rate) were also examined before and for up to 48 hours after a symptom-limited incremental cycle ergometer exercise test in 12 CFS patients and 12 normal volunteers. Voluntary and stimulated force characteristics were normal at rest and during recovery. Exercise duration was similar in the two groups although CFS patients had higher perceived exertion scores in relation to heart rate during exercise, indicating a reduced effort sensation threshold. On physiological and pathological grounds it is clear that CFS is not a myopathy. Psychological/psychiatric factors appear to be of greater importance in this condition.

Sense of Effort During a Fatiguing Exercise Protocol in Chronic Fatigue Syndrome

The purpose of this study was to determine whether chronic fatigue syndrome (CFS) subjects would produce greater force production in their matching limb during a fatiguing contralateral limb-matching task of the elbow flexors, compared with healthy, matched controls. Eight CFS subjects and 8 healthy, matched control subjects participated in a fatiguing task that consisted of intermittent submaximal contractions (30% maximal voluntary contraction) of the nondominant arm performed over a 45 min duration. Each minute, the subject attempted to match the force of the nondominant arm with their dominant arm (without visual feedback for the dominant arm). Results showed that average matching force and ratings of perceived effort values were significantly higher in the CFS group during the fatiguing task (P = 0.04, P = 0.02, respectively). This study demonstrated objectively that CFS subjects experienced a greater sense of effort in the elbow flexors while performing a fatiguing task.

Evaluation of maximal exercise performance, fatigue, and depression in athletes with acquired chronic training intolerance

OBJECTIVE

This study compared differences in maximal strength and aerobic capacity and symptoms of fatigue and depression in athletes with acquired training intolerance (ATI) and control athletes (CON) matched for age and current training volume who did not have symptoms of excessive or chronic fatigue associated with their sporting activity.

SETTING

University of Cape Town, Sports Science Institute of South Africa.

PARTICIPANTS

Twenty ATI and 10 CON athletes participated in the trial. Although the ATI athletes reported symptoms of excessive fatigue during exercise, or symptoms of fatigue that occurred at rest and during activities of daily living, they did not fulfill the criteria for a diagnosis of chronic fatigue syndrome.

MAIN OUTCOME MEASURES

A training and comprehensive medical history was recorded from all subjects. The Beck Depression Inventory Short Form (BDI-SF) was used to assess levels of depression in both ATI and control subjects. Maximal force output during a 5-second isometric voluntary knee extensor muscle contraction, and maximal aerobic capacity (VO2max), maximal heart rate (HRmax), and maximal blood lactate concentrations during a treadmill running test were measured in all subjects.

RESULTS

There were no differences in maximal isometric force output, peak treadmill running speed, VO2max, HRmax, or blood lactate concentration at rest or after maximal exercise testing between the ATI and CON athletes. However, the BDI-SF scores were higher in the ATI (7.7 +/- 6.6 arbitrary units) than in the CON athletes (1.7 +/- 1.5 arbitrary units; (P = 0.0052).

CONCLUSIONS

These findings suggest that the symptoms of excessive fatigue and acquired training intolerance described by these ATI athletes do not affect their maximal isometric and maximal aerobic capacity, and may be associated with psychologic depression in these athletes.

Diminished central activation during maximal voluntary contraction in chronic fatigue syndrome

OBJECTIVE

We have investigated whether central activation failure (CAF) is increased during local muscle fatigue in chronic fatigue syndrome (CFS).

METHODS

Fourteen female CFS patients and 14 age-matched healthy female controls made a 2 min sustained maximal voluntary contraction (MVC) of the biceps brachii muscle. Before, during, and after sustained MVC, electrical endplate stimulation was applied. Force and 5 channel surface EMG (sEMG) were registered.

RESULTS

Although force responses upon stimulation during rest did not differ between patients and controls, MVC was significantly lower in patients. Already at the beginning of sustained MVC, CFS patients showed significantly larger CAF than controls (36.5+/-17.0% and 12.9+/-13.3%, respectively). For all individual patients mean CAF over the first 45 s was higher than 30%, while it was below 30% for all controls. Less peripheral fatigue in patients was demonstrated by the changes in muscle fibre conduction velocity and the differences between force responses before and after contraction.

CONCLUSIONS

Central activation is diminished in CFS patients. Possible causes include changed perception, impaired concentration, reduced effort and physiologically defined changes, e.g. in the corticospinal excitability or the concentration of neurotransmitters. As a consequence, demands on the muscle are lower, resulting in less peripheral fatigue.

SIGNIFICANCE

CFS patients show reduced central activation during MVC. The underlying pathophysiological processes remain still to be determined.

Infectious mononucleosis: return to play

Infectious mononucleosis most commonly affects adolescents and young adults with a febrile illness accompanied by pharyngitis,lymph node enlargement, and transient fatigue. The diagnosis is usually confirmed with demonstration of heterophile antibodies. Typical signs and symptoms are reviewed, along with pitfalls in diagnosis and management. The rare complication of splenic rupture serves to focus recommendations for returning athletes to strenuous physical activities. Because careful prospective studies of infectious mononucleosis in athletes are lacking, review of available literature suggests that clinicians may recommend a return to all sports in those without spleen enlargement 4 weeks after the onset of illness.

Coping and illness cognitions: chronic fatigue syndrome

The chronic fatigue syndrome (CFS) is described, and research on coping with this illness reviewed and analysed. CFS is a severely disabling illness of unknown etiology, which has occurred in epidemic forms all over the world. However, the number of sufferers has dramatically increased over previous years. The heterogeneous symptomatology of CFS was reviewed, and diagnostic criteria were discussed. The difficulty in establishing causality was emphasized. An interaction of factors appears most likely to be associated with illness onset and maintenance. As the mediating factor could be sufferers' coping behavior, the existing coping literature was reviewed. There might be an association between coping and physical and psychological well-being. Finally, recommendations are made for longitudinal research on coping and coping effectiveness, and for the development of therapeutic interventions.

Chronic fatigue syndrome: new insights and old ignorance

Chronic fatigue syndrome (CFS) is a condition characterized by impairment of neurocognitive functions and quality of sleep and of somatic symptoms such as recurrent sore throat, muscle aches, arthralgias, headache, and postexertional malaise. A majority of patients describe an infectious onset but the link between infections and CFS remains uncertain. Findings show an activation of the immune system, abberations in several hypothalamic-pituitary axes and involvement of other parts of the central nervous system. The origin is bound to be complex and it may well be that the solution will come together with a more generally altered view about mind-body dualism, and the concept of illness and disease.

Corticomotor excitability and perception of effort during sustained exercise in the chronic fatigue syndrome

OBJECTIVE

We have investigated the possibility of a central basis for the complaints of fatigue and poor exercise tolerance in subjects with chronic fatigue syndrome (CFS).

METHODS

Transcranial magnetic stimulation of the motor cortex was used to measure sequential changes in motor evoked potential (MEP) amplitude, post-excitatory silent period (SP) duration and twitch force of the biceps brachii muscle during a 20% maximum isometric elbow flexor contraction maintained to the point of exhaustion. Ten patients with post-infectious CFS and 10 age- and sex-matched control subjects were studied. Results were analysed using non-parametric repeated measures analysis of variance (Friedman's test) and Mann-Whitney U-tests for intra- and inter-group comparisons respectively.

RESULTS

Mean endurance time for the CFS group was lower (13.1+/-3.2 min, mean +/- SEM) than controls (18.6+/-2.6 min, P < 0.05) and CFS subjects reported higher ratings of perceived exertion. During the exercise period MEP amplitude and SP duration increased in both groups but to a lesser extent in CFS subjects. Interpolated twitch force amplitude also increased during exercise, being more pronounced in CFS subjects.

CONCLUSION

The findings are in keeping with an exercise-related diminution in central motor drive in association with an increased perception of effort in CFS.

Demonstration of delayed recovery from fatiguing exercise in chronic fatigue syndrome

Patients with the chronic fatigue syndrome (CFS) complain consistently of delay in recovery of peripheral muscle function after exercise. The purpose of this study was to try to confirm this observation. A fatiguing exercise test was carried out on the quadriceps muscle group of ten patients and ten control subjects. The test consisted of 18 maximum voluntary contractions (MVCs) with a 50% duty cycle (10 s contraction, 10 s rest), and the force generated by each contraction was recorded using a KinCom dynamometer. This was followed by a recovery phase lasting 200 min in which quadriceps strength was evaluated at increasing intervals, and a follow-up session at 24 h post-exercise involving three 10 s MVCs. Throughout the exercise period, the MVCs obtained from the control group were significantly higher than those of the patient group (P = 0.006), but both groups showed a parallel decline in force over the 18 contractions, in keeping with a similar endurance capacity. Recovery was prolonged in the patient group, however, with a significant difference compared to initial MVCs being evident during the recovery phase after exercise (P = 0.001) and also at 24 h (P < 0.001). In contrast, the control group achieved MVCs which were not significantly different from initial values during the recovery phase, and maintained these at 24 h. These findings support the clinical complaint of delayed recovery after exercise in patients with CFS.

Correlation between symptom fatigue and muscular fatigue in multiple sclerosis

The symptom of fatigue is a frequent complaint in multiple sclerosis (MS) patients. Signs of fatigability have been documented in these patients as well. However, correlation with signs of objective fatigue had not been clarified in MS. The aim of this study was to ascertain the existence of muscular fatigue in multiple sclerosis patients, and to find out if there is a correlation between the subjective symptom of fatigue and muscular fatigue. Fifty MS patients and 50 age and sex matched volunteers were studied using isometric and isotonic tests using the dominant hand. Strength was studied in the baseline condition and also after recovery of either an isotonic (experiment A) or isometric effort (experiment B). Maximum strength, strength in relationship to weight, slope of fatigability in 11 consecutive contractions, and strength and duration of a maximum effort were calculated. Fatigue as a symptom was measured using the Fatigue Severity Scale (FSS) and the Fatigue Descriptive Scale (FDS). Non-parametric techniques were used for the statistical analysis. Patients with MS had less isometric and isotonic strength, but the recovery was the same as recovery in the control group. There was a negative linear correlation between the symptom of fatigue and the baseline strength. In conclusion, this study supports the existence of signs of muscular fatigue in MS patients. However, the recovery after exercise is normal. The correlation between the baseline scores in strength and the symptom of fatigue suggest that the same cause (probably pyramidal deficits) may be involved in both of them. Copyright 1998 Lippincott Williams & Wilkins

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.

Immune system activation and fatigue during treadmill running: role of interferon

Extreme fatigue often accompanies infection and other diseases, but the causal mechanisms are unknown. Recent research has focused on various cytokines as potential immune system mediators of fatigue during illness. Interferon-alpha/beta (IFN-alpha/beta) has attracted the most interest in this regard.

PURPOSE

The purpose of this research was to study the effect of IFN-alpha/beta on fatigue during treadmill running in mice.

METHODS

Mice (male CD-1) were acclimated to treadmill running for 4 d before experimental sessions. In experiment 1 (EXP 1), mice were injected with either polyI:C (pI:C) (5 mg.kg-1 body weight) or saline (CON) 12 or 24 h before the exercise session. These sessions consisted of treadmill running to fatigue (approximately 3 h, 19-24 m.min-1, 5% grade, no shock). In experiment 2 (EXP 2), mice were injected 24 h before exercise with normal rabbit serum (CON), pI:C, or pI:C + anti-IFN-alpha/beta antibody (pI:C + Ab).

RESULTS

The results of EXP 1 showed that the plasma IFN-alpha/beta titer was much higher at 24 h than at 12 h after pI:C injection (P < 0.001) and that run time to fatigue was significantly reduced only when the exercise occurred 24 h after injection (P < 0.05). In EXP 2, administration of the anti-IFN-alpha/beta antibody attenuated both the pI:C-induced increase in plasma IFN-alpha/beta (P < 0.001) and the decrease in run time to fatigue (r = -0.81, P < 0.001).

CONCLUSIONS

These results suggest that immune system activation by pI:C was associated with early fatigue during prolonged treadmill exercise and that this effect may, at least partially, result from increased IFN-alpha/beta.

Chronic fatigue syndrome: a literature review from a physiatric perspective

To examine the literature on chronic fatigue syndrome (CFS), especially as it relates to cognitive deficits and exercise, more than 200 articles related to CFS were selected from computer-based research as well as pertinent articles noted in the references of individual articles. All were relevant articles on CFS, although articles in a foreign language were excluded. CFS is a controversial diagnosis of exclusion, but certain subgroups do appear to exist. It may represent multiple diseases or multiple stages of the same disease. Although cognitive deficits are commonly reported, the measured impairments are relatively subtle and are in the area of complex information processing speed, or efficiency. Magnetic resonance imaging, single-photon emission computer tomography, and neuroendocrine studies present preliminary evidence suggestive of the cerebral involvement primarily in the white matter. The weakness and fatigue may be the result of alterations in the central nervous system, not in the peripheral muscles. However, it is hard to separate the documented weakness and endurance deficits from deconditioning. Autonomic symptoms such as orthostatic intolerance and a predisposition to neurally mediated syncope may be explained by cardiovascular deconditioning, a postviral idiopathic autonomic neuropathy, or both. The review points out the need for more carefully designed studies of CFS that focus on the relationship between neuropathology, psychopathology and neuropsychologic functioning. The role of exercise as a stimulus for exacerbation or in treatment needs to be further studied using clear diagnostic criteria as well as control groups that carefully match the activity level.

Alteration of spatial-temporal parameters of gait in Chronic Fatigue Syndrome patients

Chronic Fatigue Syndrome (CFS) has been widely studied and a lot of information is available in the literature regarding the immunological, virological, neuroendocrinal and psychiatric aspects of the disease, but its aetiology is still poorly understood. Great attention has also been paid to the alteration of the muscular function caused by CFS. The aim of the present work was to study CFS patients' gait in order to find out objective measures which can better characterize the pathology. Spatial and temporal parameters of gait were collected from a group of 12 CFS informed volunteers by using the typical instrumentation of movement analysis, and raw data were statistically elaborated. Comparisons with reference data from a population of healthy subjects revealed significant abnormalities in the symmetry indices of the bilateral parameters and in the linear relationships among parameters, and between these parameters and the physical characteristics of the patients. Interestingly, the abnormalities were present as from the beginning of the gait, which indicates that they are unlikely to be caused by the rapid increasing fatigue. This strengthens the hypothesis of a direct involvement of the central nervous system (CNS) in the onset of the disease.

Possible mechanisms of central nervous system fatigue during exercise

Fatigue of voluntary muscular effort is a complex phenomenon. To date, relatively little attention has been placed on the role of the central nervous system (CNS) in fatigue during exercise despite the fact that the unwillingness to generate and maintain adequate CNS drive to the working muscle is the most likely explanation of fatigue for most people during normal activities. Several biological mechanisms have been proposed to explain CNS fatigue. Hypotheses have been developed for several neurotransmitters including serotonin (5-HT; 5-hydroxytryptamine), dopamine, and acetylcholine. The most prominent one involves an increase in 5-HT activity in various brain regions. Good evidence suggests that increases and decreases in brain 5-HT activity during prolonged exercise hasten and delay fatigue, respectively, and nutritional manipulations designed to attenuate brain 5-HT synthesis during prolonged exercise improve endurance performance. Other neuromodulators that may influence fatigue during exercise include cytokines and ammonia. Increases in several cytokines have been associated with reduced exercise tolerance associated with acute viral or bacterial infection. Accumulation of ammonia in the blood and brain during exercise could also negatively effect the CNS function and fatigue. Clearly fatigue during prolonged exercise is influenced by multiple CNS and peripheral factors. Further elucidation of how CNS influences affect fatigue is relevant for achieving optimal muscular performance in athletics as well as everyday life.

Fatigue in the chronic fatigue syndrome: a cognitive phenomenon?

What is the source of the perception of excessive fatigue in the chronic fatigue syndrome (CFS)? Studies of physiological response to aerobic activity, of muscle pathology and muscle function in CFS, are reviewed, and suggest that the subjective report of fatigue is not due to any peripheral impairment. In addition, current technological methods such as electroencephalography have failed to uncover the nature of any abnormality in the central motor unit. A physiological model which proposes that patients with CFS possess a reduced threshold for sensory fatigue signals is rejected, because it fails to account for recent findings. Instead, it is suggested that the perception of fatigue in CFS is enhanced by idiosyncrasies in cognitive processing. The implications of this view to our understanding of the perpetuation of CFS as a whole are explored.

Cognitive functioning in patients with chronic fatigue syndrome

A comprehensive battery of neuropsychological tests was administered to 35 outpatients suffering from Chronic Fatigue Syndrome (CFS). They were compared to 33 normal controls matched for age, gender, intelligence, and education. The patients displayed psychomotor slowing and impaired attention. The learning rate of verbal and visual material for patients with CFS was slower, and delayed recall of verbal and visual information was impaired. Because there was a high variability in cognitive impairment within the CFS group, it would be inappropriate to generalize results to the entire CFS population. Two neuropsychological variables indicating aspects of psychomotor performance and verbal memory were found to discriminate best between patients and controls.

Cognitive idiosyncrasies among children with the chronic fatigue syndrome: anomalies in self-reported activity levels

The possibility that children with the chronic fatigue syndrome (CFS) and their parents tend to display idiosyncratic cognitive processing concerning levels of activity was examined by means of subjective and objective measures of current activity, together with subjective and objective measures of desired and expected future activity. The degree to which subjective reports of current activity level reflect objectively measured activity level was examined in a group of children with CFS and a healthy control group. All subjects were assessed over a 3-day period by means of ambulatory activity monitoring, and self-reports and parent-reports of current activity level were collected by means of visual analog scales. Analysis of variance revealed a significant interaction between the method of measurement (objective versus subjective) and the participant group (CFS versus Healthy) with the CFS children and their parents underestimating actual level of activity relative to the healthy group. Desired and expected levels of future activity were also assessed by means of subjective report. Child and parent expected levels of future activity were compared with their desired levels. Although expected levels of future activity were similar in the two groups, the divergence between expected levels and corresponding desired levels was significantly greater in the CFS group. These results are discussed in terms of idiosyncratic cognitive processes, which are hypothesized to be associated with CFS and which may play a role in the maintenance of the disorder.

Reduced oxidative muscle metabolism in chronic fatigue syndrome

The purpose of this study was to determine if chronic fatigue syndrome (CSF) is characterized by abnormalities in oxidative muscle metabolism. Patients with CFS according to Centers for Disease Control (CDC) criteria (n = 22) were compared to normal sedentary subjects (n = 15). CFS patients were also tested before and 2 days after a maximal treadmill test. Muscle oxidative capacity was measured as the maximal rate of postexercise phosphocreatine (PCr) resynthesis using the ADP model (Vmax) in the calf muscles using 31P magnetic resonance spectroscopy. Vmax was significantly reduced in CFS patients (39.6 +/- 2.8 mmol/L/min, mean +/- SE) compared to controls (53.8 +/- 2.8 mmol/L/min). Two days postexercise there was no change in resting inorganic phosphate (Pi)/PCr or Vmax in the CFS patients (n = 14). In conclusion, oxidative metabolism is reduced in CFS patients compared to sedentary controls. In addition, a single bout of strenuous exercise did not cause a further reduction in oxidative metabolism, or alter resting Pi/PCr ratios.

Use of exercise for treatment of chronic fatigue syndrome

Chronic fatigue syndrome (CFS) is a condition that results in moderate to severe disability, the primary feature of which is fatigue of unknown origin. There is a lot of interest in classifying, characterising and treating patients with CFS. Currently, the two major theories of a medical cause of CFS are viral infection and immune dysregulation. Patients report critical reductions in levels of physical activity, and many experience 'relapses' of severe symptoms following even moderate levels of exertion. Despite this, most studies report CFS patients to have normal muscle strength and either normal or slightly reduced muscle endurance. Histological and metabolic studies report mixed results: CFS patients have either no impairment or mild impairment of mitochondria and oxidative metabolism compared with sedentary controls. Current treatments for CFS are symptom-based, with psychological, pharmacological and rehabilitation treatments providing some relief but no cure. Immunological and nutritional treatments have been tried but have not provided reproducible benefits. Exercise training programmes are thought to be beneficial (if 'relapses' can be avoided), although few controlled studies have been performed. CFS is a long-lasting disorder that can slowly improve with time, but often does not. Further studies are needed to better understand the multiple factors that can cause chronic fatigue illness, as well as the effect that exercise training has on the symptoms of CFS.

Chronic fatigue syndrome: current perspectives on evaluation and management

OBJECTIVE

To describe clinical and laboratory guidelines for assessment and management of patients presenting with chronic fatigue syndrome (CFS).

DATA SOURCES

Relevant international consensus diagnostic criteria and research literature on the epidemiology, pathophysiology, concurrent medical and psychological disturbance and clinical management of CFS.

CONCLUSIONS

Medical and psychiatric morbidity should be carefully assessed and actively treated, while unnecessary laboratory investigations and extravagant treatment regimens should be avoided. No single infective agent has been demonstrated as the cause of CFS, and immunopathological hypotheses remain speculative. The aetiological role of psychological factors is debated, but they do predict prolonged illness. The rate of spontaneous recovery appears to be high. Effective clinical management requires a multidisciplinary approach, with consideration of the medical, psychological and social factors influencing recovery.

Gait abnormalities in chronic fatigue syndrome

To evaluate our clinical impression that patients with the chronic fatigue syndrome (CFS) did not walk normally, we assessed gait kinematics at slow walking speeds (i.e., 0.45, 0.89 and 1.34 m/sec) and 30 m run time speeds on CFS patients and on a comparison group of sedentary controls. Run time was significantly slower for CFS than control subjects (p < 0.001). There was a significant interaction (p < 0.01) between group and speed for maximum hip angle during stance and swing phase with hip angle being significantly larger at 1.34 m/sec for CFS than controls subjects for both cases (p < 0.05). Knee flexion during stance and swing phases was significantly larger for controls than CFS subjects at 0.45 m/sec (p < 0.01). Ratio of stride length divided by leg length was significantly larger for the control subjects than for the CFS subjects with differences occurring at 0.45 and 0.89 m/sec (p < 0.01) but not 1.34 m/sec. The data indicate that CFS patients have gait abnormalities when compared to sedentary controls. These could be due to balance problems, muscle weakness, or central nervous system dysfunction; deciding which will require further research. Evaluation of gait may be a useful tool to measure outcome following therapeutic interventions.

Fatigue brought on by malfunction of the central and peripheral nervous systems

Increased fatigability necessarily occurs in every patient with muscle weakness, regardless of whether the latter is due to a central or peripheral neurological disorder. The tendency for disuse to increase fatigability, as a secondary phenomenon, must also be considered; disuse affects both motoneuron recruitment and the biochemical and physiological properties of the muscle fibers. In recent studies impaired recruitment has been observed in postpolio patients, while patients with multiple sclerosis or spinal cord injury have shown, in addition, altered neuromuscular function. Findings are also presented in ALS and the chronic fatigue syndrome. In general, the most dramatic increases in fatigability take place in disorders of the peripheral nervous system and almost any cell component can be incriminated. There is a need to study fatigability systematically in neurology and rehabilitation.

Chronic fatigue syndrome. 1: Etiology and pathogenesis

Chronic fatigue syndrome (CFS) is a disorder of unknown etiology characterized by debilitating fatigue and other somatic and neuropsychiatric symptoms. A range of heterogeneous clinical and laboratory findings have been reported in patients with CFS. Various theories have been proposed to explain the underlying pathophysiologic processes but none has been proved. Research findings of immunologic dysfunction and neuroendocrine changes suggest the possible dysregulation of interactions between the nervous system and the immune system. Without a clear understanding of its etiopathogenesis, CFS has no definitive treatment. Management approaches have been necessarily speculative, and they have evolved separately in a number of medical and nonmedical disciplines. The results of several controlled treatment studies have been inconclusive. An accurate case definition identifying homogeneous subtypes of CFS is needed. The integration of medical and psychologic treatment modalities and the use of both biologic and psychologic markers to evaluate treatment response will enhance future treatment strategies.

The treatment of chronic fatigue syndrome: science and speculation

The chronic fatigue syndrome (CFS) is a heterogeneous disorder characterized by fatigue, neuropsychiatric symptoms, and various other somatic complaints. Treatment studies to date reflect both the diversity of medical disciplines involved in the management of patients with CFS and the multiple pathophysiologic mechanisms proposed. There have been few attempts to study integrated treatment programs, and although several controlled studies have been reported, no treatment has been shown clearly to result in long-term benefit in the majority of patients. Good clinical care integrating medical and psychologic concepts, together with symptomatic management, may prevent significant secondary impairment in the majority of patients. Future treatment studies should examine differential response rates for possible subtypes of the disorder (eg, documented viral onset, concurrent clinical depression), evaluate the extent of any synergistic effects between therapies (ie, medical and psychologic), and employ a wide range of biologic and psychologic parameters as markers of treatment response.

Single fibre EMG studies in chronic fatigue syndrome: a reappraisal

Single fibre EMG studies were carried out on the right extensor digitorum communis muscle in 30 subjects with chronic fatigue syndrome and in 30 age and sex matched controls. Abnormal jitter was seen in five patients with chronic fatigue syndrome. Slight but significant differences between the mean consecutive differences in the remainder of the chronic fatigue subjects and the control subjects were recorded. Overall the differences were so minor that it seems unlikely that a disturbance of neuromuscular function as reflected by jitter measurement has a pathogenetic role. It is suggested that the increased jitter seen may be explained by the effects of the variability of motor unit firing rates on the myogenic component of the jitter.

Treatment of the chronic fatigue syndrome. A review and practical guide

The chronic fatigue syndrome (CFS) was formally defined in 1988 to describe a syndrome of severe and disabling fatigue of uncertain aetiology associated with a variable number of somatic and/or psychological symptoms. CFS has been reported in most industrialised countries and is most prevalent in women aged between 20 and 50 years. Despite occasional claims to the contrary, the aetiology of CFS remains elusive. Although abnormalities in tests of immune function and cerebral imaging have been described in variable numbers of CFS patients, such findings have been inconsistent and cannot be relied upon, either to establish or exclude the diagnosis. Thus, diagnosis rests on fulfillment of the Centers for Disease Control case definition which was revised in 1992. This case definition remains somewhat controversial, largely due to its subjectiveness. The mainstay of treatment is establishing the diagnosis and educating the patient about the illness. An empathetic clinician can stop further consultations elsewhere ('doctor shopping') and subsequent excessive investigations, which frequently occur in such patients. Most patients should undertake a trial of antidepressant therapy, even if major depression is not present. The choice of antidepressant drug should tailor the tolerability profile to relief of particular CFS symptoms, such as insomnia or hypersomnia. Failure to improve within 12 weeks warrants an alternative antidepressant agent of another class. Many other drugs have been reported anecdotally to be beneficial, but no therapy has been demonstrated to be reproducibly useful in double-blind, placebo-controlled clinical trials with an adequate duration of follow-up.

Exercise performance and fatiguability in patients with chronic fatigue syndrome

To examine the role of delay in recovery of peripheral muscle function following exercise in the fatigue experienced by patients with the chronic fatigue syndrome (CFS) and to examine the influence of effort perception in limiting exercise performance in these patients, a study was carried out on a group of twelve patients with chronic fatigue syndrome and 12 sex and age-matched sedentary control subjects. Symptom limited incremental cycle exercise tests including measurements of perceived exertion were performed followed by examination of the contractile properties of the quadriceps muscle group for up to 48 hours. Muscle function was assessed by percutaneous electrical stimulation and maximum voluntary contractions. Muscle function at rest and during recovery was normal in CFS patients as assessed by maximum isometric voluntary contraction, 20:50 Hz tetanic force ratio and maximum relaxation rate. Exercise duration and the relationship between heart rate and work rate during exercise were similar in both groups. CFS patients had higher perceived exertion scores in relation to heart rate during exercise representing a reduced effort sensation threshold of 3.2 units on an unmodified Borg scale in CFS patients. Patients with chronic fatigue syndrome show normal muscle physiology before and after exercise. Raised perceived exertion scores during exercise suggest that central factors are limiting exercise capacity in these patients.

Biochemical and muscle studies in patients with acute onset post-viral fatigue syndrome

AIMS

To investigate in detail various biochemical and pathophysiological indices of muscle pathology in acute onset post-viral fatigue syndrome (PVFS).

METHODS

Twenty three patients with PVFS (of mean duration 4.6 years) were subjected to needle biopsy for histomorphometry and total RNA contents. Plasma analysis included serology and creatine kinase activities. Indices of whole body mass were also measured--namely, whole body potassium content and plasma carnosinase activities.

RESULTS

About 80% of the patients had serology indicative of persistent enteroviral infection as determined by VP1 antigen assay. Only about 10% of that same group of patients had serological indications of current enterovirus infection by IgM assay; a separate subset of 10% showed antibody changes suggestive of reactivation of Epstein-Barr virus. Quantitative morphometric analysis of skeletal muscle fibres indicated that the quadriceps muscle was normal or displayed only minor abnormalities in 22 patients. The Quetelet's Index (body mass index) and whole-body potassium values (index of lean body mass) were not affected in PVFS. The mean plasma carnosinase and creatinine kinase activities were also generally normal in these patients. The mean muscle RNA composition--mg RNA/mg DNA: was significantly reduced in acute onset PVFS by about 15%. The protein:DNA ratio was not significantly affected.

CONCLUSIONS

Patients with acute onset PVFS, therefore, lose muscle protein synthetic potential, but not muscle bulk. Histopathology is consistent with these observations. These perturbations may contribute to the apparent feature of perceived muscle weakness associated with the persistent viral infection in the muscle themselves.