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.     

Is the chronic fatigue syndrome an exercise phobia? A case control study

OBJECTIVE: The aim of this study was to test whether patients with chronic fatigue syndrome (CFS) have an exercise phobia, by measuring anxiety-related physiological and psychological reactions to ordinary activity and exercise. METHODS: Patients and healthy but sedentary controls were assessed over 8 h of an ordinary day, and before, during and after an incremental exercise test on a motorised treadmill. To avoid confounding effects, those with a comorbid psychiatric disorder were excluded. Heart rate, galvanic skin resistance (GSR) and the amount of activity undertaken were measured, along with state and trait measures of anxiety. RESULTS: Patients with CFS were more fatigued and sleep disturbed than were the controls and noted greater effort during the exercise test. No statistically significant differences were found in either heart rate or GSR both during a normal day and before, during and after the exercise test. Patients with CFS were more symptomatically anxious at all times, but this did not increase with exercise. CONCLUSION: The data suggest that CFS patients without a comorbid psychiatric disorder do not have an exercise phobia.     

Impact of a maximal exercise test on symptoms and activity in chronic fatigue syndrome

OBJECTIVE: This study examined the effects of exercise on symptoms and activity in chronic fatigue syndrome (CFS). METHODS: Twenty CFS patients and 20 neighborhood controls performed an incremental exercise test until exhaustion. Fatigue, muscle pain, minutes spent resting, and the level of physical activity were assessed with a self-observation list. Physical activity was assessed with an actometer as well. Data were obtained 3 days before the maximal exercise test (MET) up to 5 days thereafter. RESULTS: For CFS patients, daily observed fatigue was increased up to 2 days after the exercise test. For controls, self-observed fatigue returned to baseline after 2 h. Both CFS patients and controls spent more minutes resting on the day before and on the day after the MET. For CFS patients, self-observed minutes resting increased on the day of the exercise test. For neither group, a decrease of actometer recorded or self-observed physical activity after exercise was found. CONCLUSION: Fatigue in CFS patients increased after exercise, but the level of actual physical activity remained unchanged.     

Hormonal responses to exercise in chronic fatigue syndrome

Chronic fatigue syndrome (CFS) is a debilitating disease characterized by severe, unexplained fatigue and postexertional exacerbation of symptoms. We examined basal endocrine function in a group of CFS patients and a carefully matched group of sedentary controls. The subjects then completed a graded, maximal exercise test on a treadmill, and additional blood samples were drawn 4 min and a day after the end of exercise. There were no differences in basal hormone levels before exercise. Plasma adrenocorticotropin, epinephrine, prolactin and thyrotropin responses 4 min after exercise were lower in the CFS group, but the growth hormone response may have been exaggerated, and the plasma norepinephrine response was similar to that in controls. The next day, there were no differences in hormone levels between the groups, which suggests that long-term changes in endocrine function are unlikely to be a cause of the prolonged fatigue that occurs in CFS patients after a bout of exertion.     

Attributions and self-esteem in depression and chronic fatigue syndromes

There is considerable overlap in symptomatology between chronic fatigue syndrome (CFS) and affective disorder. We report a comparison of depressive phenomenology and attributional style between a group of CFS subjects seen in a specialized medical setting, which included a high proportion with depression diagnosed by Research Diagnostic Criteria (RDC) and depressed controls seen in a specialized psychiatric setting. Significant symptomatic differences between the depressed CFS group and depressed controls were observed for features such as self-esteem and guilt as well as attribution of illness. All the CFS groups tended to attribute their symptoms to external causes whereas the depressed controls experienced inward attribution. This may have resulted from differences in the severity of mood disorder between the samples, but it is also suggested that an outward style of attribution protects the depressed CFS patients from cognitive changes associated with low mood but at the expense of greater vulnerability towards somatic symptoms such as fatigue.     

Benefits of interval-training on fatigue and functional capacities in Charcot-Marie-Tooth disease

Exercise intolerance and undue fatigue are common complaints in patients with Charcot-Marie-Tooth (CMT) disease. Reduced physical ability is due directly to the disease, but it is also due to physical deconditioning. The aim of this study was to test whether 24 weeks of interval-training exercise (ITE) cycling can significantly improve physiological, neuromuscular, and functional capacities and alleviate fatigue in CMT patients. Eight CMT patients (4 CMT1A and 4 CMT2) participated in ITE for 3 nonconsecutive days per week. Cardiovascular fitness, muscle strength, fatigue resistance, and functional capacities were measured before and after 12 weeks of supervised hospital training and again after another 12 weeks of unsupervised home training. Training was well tolerated. There were significant improvements in cardiorespiratory capacities, isokinetic concentric strength, and functional ability measurements. All patients experienced an improvement in their self-reported visual analogic scale for fatigue and pain during training. However, there was no significant change in their isometric force production and indices of fatigue resistance after training. Although the improvement in exercise tolerance may be due in part to reversal of the deconditioning effect of their related sedentary lifestyle, this clinical trial suggests that ITE can benefit CMT patients especially in their functional performance and subjective perception of pain and fatigue. Moreover, the improvement observed at the end of the first supervised period ITE was maintained after the second unsupervised home period, although there was no further improvement in performance and tolerance.     

The relation of sleep difficulties to fatigue, mood and disability in chronic fatigue syndrome

The relationship of sleep complaints to mood, fatigue, disability, and lifestyle was examined in 69 chronic fatigue syndrome (CFS) patients without psychiatric disorder, 58 CFS patients with psychiatric disorder, 38 psychiatric out-patients with chronic depressive disorders, and 45 healthy controls. The groups were matched for age and gender. There were few differences between the prevalence or nature of sleep complaints of CFS patients with or without current DSM-IIIR depression, anxiety or somatization disorder. CFS patients reported significantly more naps and waking by pain, a similar prevalence of difficulties in maintaining sleep, and significantly less difficulty getting off to sleep compared to depressed patients. Sleep continuity complaints preceded fatigue in only 20% of CFS patients, but there was a strong association between relapse and sleep disturbance. Certain types of sleep disorder were associated with increased disability or fatigue in CFS patients. Disrupted sleep appears to complicate the course of CFS. For the most part, sleep complaints are either attributable to the lifestyle of CFS patients or seem inherent to the underlying condition of CFS. They are generally unrelated to depression or anxiety in CFS.     

Fatigue syndromes: a comparison of chronic "postviral" fatigue with neuromuscular and affective disorders.

Patients (n = 47) presenting to a neurological centre with unexplained chronic "postviral" fatigue (CFS) were studied prospectively. Controls were patients with peripheral fatiguing neuromuscular diseases and inpatients with major depression in a psychiatric hospital. Seventy-two percent of the CFS patients were cases of psychiatric disorder, using criteria that excluded fatigue as a symptom, compared with 36% of the neuromuscular group. There was no difference in subjective complaints of physical fatigue between all groups. Mental fatigue and fatigability was equally common in CFS and affective patients, but only occurred in those neuromuscular patients who were also cases of psychiatric disorder. Overall, the CFS patients more closely resembled the affective than the neuromuscular patients. Attribution of symptoms to physical rather than psychological causes was the principal difference between matched CFS and psychiatric controls. The symptoms of "postviral" fatigue had little ability to discriminate between CFS and affective disorder. The fatigue in CFS appeared central in origin, suggesting it is not primarily a neuromuscular illness. The implications for research and treatment of chronic fatigue are discussed.     

EFFECT OF ACUTE SUBMAXIMAL EXERCISE ON INTRAOCULAR PRESSURE IN ATHLETES AND SEDENTARY SUBJECTS

The existing literature is controversial regarding the relationship between physical fitness and intraocular pressure (IOP). Therefore, the effects of acute submaximal exercise on IOP were compared in athletes and sedentary subjects. Acute exercise increased IOP in male athletes, but had no effect in sedentary men. Also, it decreased IOP in sedentary women, but had no effect in female athletes. Sex and physical fitness both were significant factors influencing the changes in IOP due to exercise. These results suggest that acute dynamic exercise is useful to decrease IOP in sedentary women, but not in male athletes. These results may help glaucoma screeners.     

Effect of acute submaximal exercise on intraocular pressure in athletes and sedentary subjects

The existing literature is controversial regarding the relationship between physical fitness and intraocular pressure (IOP). Therefore, the effects of acute submaximal exercise on IOP were compared in athletes and sedentary subjects. Acute exercise increased IOP in male athletes, but had no effect in sedentary men. Also, it decreased IOP in sedentary women, but had no effect in female athletes. Sex and physical fitness both were significant factors influencing the changes in IOP due to exercise. These results suggest that acute dynamic exercise is useful to decrease IOP in sedentary women, but not in male athletes. These results may help glaucoma screeners.     

Objective assessment of personality disorder in chronic fatigue syndrome

OBJECTIVES: This study aims to objectively assess the prevalence and nature of personality disorders in depressed and nondepressed chronic fatigue syndrome (CFS) patients and compare this to depressed and healthy control groups. METHODS: Sixty-one patients attending a tertiary referral clinic with chronic fatigue syndrome, 40 psychiatric inpatients with depressive disorder and 45 healthy medical students completed the Structured Clinical Interview for DSM-III-R Diagnoses (SCID-II) in addition to providing routine clinical and demographic information. RESULTS: Thirty-nine percent of the CFS group, 73% of the depressed group and 4% of the healthy group were diagnosed with personality disorders. Cluster C disorders were the most common in both the CFS and depressed group. The depressed CFS patients had more Cluster B personality disorders than nondepressed CFS patients. Overall for CFS patients there was no association between mood state and personality disorder. CONCLUSIONS: High levels of personality disorder are found on objective assessment of CFS patients attending a teaching hospital clinic. This cannot be accounted for by comorbid depression.     

Cardiovascular health and fitness after stroke

Stroke patients have profound cardiovascular and muscular deconditioning, with metabolic fitness levels that are about half those found in age-matched sedentary controls. Physical deconditioning, along with elevated energy demands of hemiparetic gait, define a detrimental combination termed diminished physiological fitness reserve that can greatly limit that can greatly limit performance of activities of daily living. The physiological features that underlie worsening metabolic fitness in the chronic phase of stroke include gross muscular atrophy, altered muscle molecular phenotype, increased intramuscular area fat, elevated tissue inflammatory markers, and diminished peripheral blood flow dynamics. Epidemiological evidence further suggests that the reduced cardiovascular fitness and secondary biological changes in muscle may propagate components of the metabolic syndrome, conferring added morbidity and mortality risk. This article reviews some of the consequences of poor fitness in chronic stroke and the potential biological underpinnings that support a rationale for more aggressive approaches to exercise therapy in this population.     

Physical capacity,respiratory quotient and energy expenditure during exercise in male patients with schizophrenia compared with healthy controls

BackgroundDespite massive research on weight gain and metabolic complications in schizophrenia there are few studies on energy expenditure and no current data on physical capacity.AimTo determine oxygen uptake capacity, respiratory quotient (RQ) and energy expenditure during a submaximal exercise test in patients with schizophrenia and healthy controls.MethodTen male patients and 10 controls were included. RQ and energy expenditure were investigated with indirect calorimetry during a cycle ergometer test. The submaximal work level was defined by heart rate and perceived exhaustion. Physical capacity was determined from predicted maximal oxygen uptake capacity (VO_2-max).ResultsThe patients exhibited significantly higher RQ on submaximal workloads and lower physical capacity. A significant lower calculated VO_2-max remained after correction for body weight and fat free mass (FFM). Energy expenditure did not differ on fixed workloads.ConclusionRQ was rapidly increasing in the patients during exercise indicating a faster transition to carbohydrate oxidation and anaerobic metabolism that also implies a performance closer to maximal oxygen uptake even at submaximal loads. This may restrict the capacity for everyday activity and exercise and thus contribute to the risk for weight gain. Physical capacity was consequently significantly lower in the patients.     

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 (V_max) in the calf muscles using ³¹P magnetic resonance spectroscopy. V_max 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 V_max 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. © 1996 John Wiley & Sons, Inc.     

A longitudinal study of physical activity and body mass index among persons with unexplained chronic fatigue

OBJECTIVE AND METHODS: A cohort of 100 patients with unexplained chronic fatigue (CF) was assessed longitudinally for 1.5 years to determine if physical activity (kcal expended), exercise capacity (VO(2)max), perceived exertion, and body mass index (BMI) changed over time and were associated with changes in CF-related clinical status. RESULTS: BMI increased significantly over time but did not predict changes in clinical status. Increasing energy expenditure was associated with increasing vitality and decreasing CF symptom severity over time, and decreasing perceived exertion was associated with increasing physical functioning. However, increasing perceived exertion was also associated with increasing CF symptoms. CONCLUSIONS: These data do not support models that posit associations between CF and deconditioning.     

Possible relationship between chronic fatigue and postural tachycardia syndromes

Postural tachycardia syndrome refers to the development of symptoms such as light-headedness, visual blurring, palpitations and weakness on assuming an upright posture; these symptoms are relieved by resuming a supine posture. This syndrome is occasionally associated with idiopathic hypovolemia, impaired vasomotor tone, deconditioning and autonomic neuropathy, but has not been reported in association with chronic fatigue syndrome (CFS). We describe five patients who satisfied the CFS criteria of the Centres for Disease Control and Prevention. Upright tilt-table testing induced significant hypotension and increased heart rate in all five patients, consistent with clinical and auronomic manifestation of postural tachycardia syndrome.     

Possible use of repeated cold stress for reducing fatigue in Chronic Fatigue Syndrome: a hypothesis

Background  

Physiological fatigue can be defined as a reduction in the force output and/or energy-generating capacity of skeletal muscle after exertion, which may manifest itself as an inability to continue exercise or usual activities at the same intensity. A typical example of a fatigue-related disorder is chronic fatigue syndrome (CFS), a disabling condition of unknown etiology and with uncertain therapeutic options. Recent advances in elucidating pathophysiology of this disorder revealed hypofunction of the hypothalamic-pituitary-adrenal axis and that fatigue in CFS patients appears to be associated with reduced motor neurotransmission in the central nervous system (CNS) and to a smaller extent with increased fatigability of skeletal muscle. There is also some limited evidence that CFS patients may have excessive serotonergic activity in the brain and low opioid tone.     

Associations between neuroendocrine responses to the Insulin Tolerance Test and patient characteristics in chronic fatigue syndrome

OBJECTIVE: Subtle dysregulations of the hypothalamic-pituitary-adrenal (HPA) axis have been proposed as an underlying pathophysiological mechanism in chronic fatigue syndrome (CFS). This study attempted to assess the relationship between patient characteristics and HPA axis functioning using a neuroendocrine challenge test. METHOD: A test battery designed to assess different dimensions of CFS was given to 18 CFS patients and 17 controls. To evaluate the integrity of the HPA axis, the Insulin Tolerance Test (ITT), a centrally acting neuroendocrine challenge test, was performed on patients and controls. ACTH, salivary free cortisol and total plasma cortisol levels were assessed as a measure of the HPA axis stress response. Correlations of patient characteristics were calculated with integrated responses for all endocrine parameters. RESULTS: CFS patients had a significantly reduced area under the ACTH response curve (AUC) in the ITT. The AUC was significantly associated with the duration of CFS symptoms (r = -.592, P = .005) and the severity of fatigue symptomatology (r = -.41, P = .045). In addition, duration of CFS was correlated with the severity of fatigue symptoms (r = .38, P = .045). Similar associations were not observed for cortisol parameters. CONCLUSION: It has been postulated that neuroendocrine dysregulations observed in CFS are of an acquired nature. The results of a strong association between the integrated ACTH response and the duration of CFS emphasizes the need to consider factors known to be risk factors for the chronicity of CFS symptoms, such as profound inactivity, deconditioning and sleep abnormalities, as possible candidates for secondary causes of neuroendocrine dysregulations 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.