Category: Exercise

Blood flow and muscle metabolism in chronic fatigue syndrome

Abstract:

The purpose of this study was to determine if chronic fatigue syndrome (CFS) is associated with reduced blood flow and oxidative delivery to skeletal muscle. Patients with CFS according to CDC (Center for Disease Control) criteria ( n =19) were compared with normal sedentary subjects ( n =11). Muscle blood flow was measured with Doppler ultrasound after cuff ischaemia and exercise. Muscle oxygen delivery was measured as the rate of post-exercise and post-ischaemic oxygen-haem resaturation. Oxygen-haem resaturation was measured in the medial gastrocnemius muscle using continuous wavelength near-IR spectroscopy. Muscle metabolism was measured using (31)P magnetic resonance spectroscopy. CFS patients and controls were not different in the peak blood flow after cuff ischaemia, the rate of recovery of phosphocreatine after submaximal exercise, and the rate of recovery of oxygen saturation after cuff ischaemia. In conclusion, CFS patients showed no deficit in blood flow or oxidative metabolism. This suggests that CFS symptoms do not require abnormal peripheral function.

 

Source: McCully KK, Smith S, Rajaei S, Leigh JS Jr, Natelson BH. Blood flow and muscle metabolism in chronic fatigue syndrome.  Clin Sci (Lond). 2003 Jun;104(6):641-7. http://www.ncbi.nlm.nih.gov/pubmed/12589704

 

Activity rhythm degrades after strenuous exercise in chronic fatigue syndrome

Abstract:

Post-exertional exacerbation of symptoms is one of the major characteristics of chronic fatigue syndrome (CFS). In this study, we evaluated the hypothesis that disturbances in circadian chronobiological regulation may play a role in generating this phenomenon.

We recorded physical activity for 6-day periods in 16 women (10 CFS and 6 sedentary healthy controls, CON) before and after performing a maximal treadmill test. We calculated activity rhythms by computing autocorrelation coefficients by cutting 1 day apart from the data as a template and sliding it sequentially through each of the other days; all of 6 days were used as the templates. The peak value of autocorrelation coefficient (R) and the time between peak R’s (circadian period, CP) were calculated. CFS patients had a lengthening (P < .05) of mean circadian period (MCP) that was longer than 24 h (P < .05), while MCP in CON remained unchanged. No difference was found in the standard error of each subject’s MCP (circadian period variability, CPV) before and after exercise for both groups.

We interpret this increase in circadian rest-activity period seen in CFS patients following exercise to indicate that exhaustive exercise interferes with normal entrainment to 24-h zeitgeber(s). This effect may be associated in part with the common patient complaint of symptom worsening following exertion.

Copyright 2002 Elsevier Science Inc.

 

Source: Ohashi K, Yamamoto Y, Natelson BH. Activity rhythm degrades after strenuous exercise in chronic fatigue syndrome. Physiol Behav. 2002 Sep;77(1):39-44. http://www.ncbi.nlm.nih.gov/pubmed/12213500

 

Physical performance and prediction of 2-5A synthetase/RNase L antiviral pathway activity in patients with chronic fatigue syndrome

Abstract:

The elevated RNase L enzyme activity observed in some Chronic Fatigue Syndrome (CFS) patients may be linked to the low exercise tolerance and functional impairment that typify this disease. The purpose of this investigation was to determine if specific indicators of physical performance can predict abnormal RNase L activity in CFS patients. Seventy-three CFS patients performed a graded exercise test to voluntary exhaustion. Forty-six patients had elevated RNase L levels. This measure was employed as the dependent variable in a discriminant function analysis, with peak V02, exercise duration and Karnofsky Performance Scores (KPS) serving as the independent variables. All three variables entered the single significant function (p < 0.001). The elevated RNase L group had a lower peak V02 and duration than the normal group, but a higher KPS. The results suggest that both exercise testing and the RNase L biomarker have potential to aid in the diagnosis of CFS.

 

Source: Snell CR, Vanness JM, Strayer DR, Stevens SR. Physical performance and prediction of 2-5A synthetase/RNase L antiviral pathway activity in patients with chronic fatigue syndrome. In Vivo. 2002 Mar-Apr;16(2):107-9. http://www.ncbi.nlm.nih.gov/pubmed/12073768

 

Maximal oxygen uptake and lactate metabolism are normal in chronic fatigue syndrome

Abstract:

PURPOSE: Previous studies in chronic fatigue syndrome (CFS) have reported reductions in maximal oxygen uptake (VO(2max)), yet often the testing procedures have not followed accepted guidelines, and gender data have been pooled. The present study was undertaken to reevaluate exercise capacity in CFS patients by using “gold standard” maximal exercise testing methodology and stratifying results on a gender basis.

METHODS: Sixteen male and 17 female CFS patients and their gender-, age-, and mass-matched sedentary controls performed incremental exercise to volitional exhaustion on a stationary cycle ergometer while selected cardiorespiratory and metabolic variables were measured.

RESULTS: VO(2max) in male CFS patients was not different from control values (CFS: 40.5 +/- 6.7; controls: 43.3 +/- 8.6; mL x kg(-1) x min(-1)) and was 96.3 +/- 17.9% of the age-predicted value, indicating no functional aerobic impairment (3.7 +/- 17.9%). In female CFS patients, VO(2max) was lower than control values (CFS: 30.0 +/- 4.7; controls: 34.2 +/- 5.6; mL x kg(-1) x min(-1), P = 0.002), but controls were higher than the age-predicted value (112.6 +/- 15.4%, P = 0.008) whereas the CFS patients were 101.2 +/- 20.4%, indicating no functional aerobic impairment (-1.2 +/- 20.4%). Maximal heart rate (HR(max)) in male CFS patients was lower than their matched controls (CFS: 184 +/- 10; controls: 192 +/- 12; beats x min(-1); P = 0.016) but was 99.1 +/- 5.5% of their age-predicted value. In female CFS patients, HR(max) was not different from controls (CFS: 183 +/- 11; controls: 186 +/- 10; beats x min(-1)) and was 98.9 +/- 5.1% of the age-predicted value. The VO(2) at the lactate threshold (LT) in each gender group, whether expressed in mL x kg(-1) x min(-1) or as a percentage of VO(2max), was not different between CFS patients and controls.

CONCLUSIONS: In contrast to most previous reports, the present study found that VO(2max), HR(max), and the LT in CFS patients of both genders were not different from the values expected in healthy sedentary individuals of a similar age.

Comment in:

Chronic fatigue syndrome, deconditioning, and graded exercise therapy. [Med Sci Sports Exerc. 2002]

VO2max and lactate production are not normal in all patients with chronic fatigue. [Med Sci Sports Exerc. 2002]

 

Source: Sargent C, Scroop GC, Nemeth PM, Burnet RB, Buckley JD. Maximal oxygen uptake and lactate metabolism are normal in chronic fatigue syndrome. Med Sci Sports Exerc. 2002 Jan;34(1):51-6. http://www.ncbi.nlm.nih.gov/pubmed/11782647

 

Blood volume and its relation to peak O(2) consumption and physical activity in patients with chronic fatigue

Abstract:

Individuals with chronic fatigue syndrome (CFS) experience a number of somatic complaints including severe, disabling fatigue, and exercise intolerance. We hypothesized that hypovolemia, through its interaction with central hemodynamics, would contribute to the exercise intolerance associated with this disorder. We examined blood volume, peak aerobic power, habitual physical activity, fatigue level, and their interrelations to understand the physiological basis of this disorder.

Seventeen patients who met the Centers for Disease Control criteria for CFS and 17 age-matched controls participated in the study. Blood volume was assessed using a single bolus injection of Evans blue dye. Peak oxygen consumption was measured during exercise on an upright cycle ergometer. Supine cardiac output and stroke volumes were measured using CO(2) rebreathing. Questionnaires were used to assess habitual physical activity and fatigue.

Patients displayed a trend for a 9% lower blood volume (58.3 +/- 2.1 vs. 64.2 +/- 2.5 ml/kg, P = 0.084) and had a 35% lower peak oxygen consumption (22.0 +/- 1.2 vs. 33.6 +/- 1.9 ml/kg, P < 0.001). These two variables were highly related within the patients (r = 0.835, P < 0.001) and the controls (r = 0.850, P < 0.001). Peak ventilation and habitual physical activity were significantly lower in the patients. Fatigue level was not related to any of the measured physiological parameters within the CFS group.

In conclusion, individuals with CFS have a significantly lower peak oxygen consumption and an insignificant trend toward lower blood volume compared with controls. These variables were highly related in both subject groups, indicating that blood volume is a strong physiological correlate of peak oxygen consumption in patients with CFS.

 

Source: Farquhar WB, Hunt BE, Taylor JA, Darling SE, Freeman R. Blood volume and its relation to peak O(2) consumption and physical activity in patients with chronic fatigue. Am J Physiol Heart Circ Physiol. 2002 Jan;282(1):H66-71. http://ajpheart.physiology.org/content/282/1/H66.long (Full article)

 

Cardiovascular responses of women with chronic fatigue syndrome to stressful cognitive testing before and after strenuous exercise

Abstract:

OBJECTIVE: The purpose of this study was to compare the cardiovascular responses of patients with chronic fatigue syndrome (CFS) to healthy control subjects when performing stressful cognitive tasks before and after strenuous exercise.

METHOD: Beat-by-beat blood pressure and electrocardiogram were recorded on 19 women with CFS and 20 healthy nonexercising (ie, sedentary) women while they performed cognitive tests before, immediately after, and 24 hours after incremental exercise to exhaustion.

RESULTS: Diminished heart rate (p <.01) and systolic (p <.01) and diastolic (p <.01) blood pressure responses to stressful cognitive testing were seen in patients with CFS when compared with healthy, sedentary controls. This diminished stress response was seen consistently in patients with CFS across three separate cognitive testing sessions. Also, significant negative correlations between self-ratings of CFS symptom severity and cardiovascular responses were seen (r = -0.62, p <.01).

CONCLUSIONS: Women with CFS have a diminished cardiovascular response to cognitive stress; however, exercise did not magnify this effect. Also, the data showed that the patients with the lowest cardiovascular reactivity had the highest ratings of CFS symptom severity, which suggests that the individual response of the patient with CFS to stress plays a role in the common complaint of symptoms worsening after stress.

 

Source: LaManca JJ, Peckerman A, Sisto SA, DeLuca J, Cook S, Natelson BH. Cardiovascular responses of women with chronic fatigue syndrome to stressful cognitive testing before and after strenuous exercise. Psychosom Med. 2001 Sep-Oct;63(5):756-64. http://www.ncbi.nlm.nih.gov/pubmed/11573024

 

Physiological responses to incremental exercise in patients with chronic fatigue syndrome

Abstract:

PURPOSE: The purpose of this investigation was to characterize the physiological response profiles of patients with chronic fatigue syndrome (CFS), to an incremental exercise test, performed to the limit of tolerance.

METHODS: Fifteen patients (12 women and three men) who fulfilled the case definition for chronic fatigue syndrome, and 15 healthy, sedentary, age- and sex-matched controls, performed an incremental progressive all-out treadmill test (cardiopulmonary exercise test).

RESULTS: As a group, the CFS patients demonstrated significantly lower cardiovascular as well as ventilatory values at peak exercise, compared with the control group. At similar relative submaximal exercise levels (% peak VO(2)), the CFS patients portrayed response patterns (trending phenomenon) characterized, in most parameters, by similar intercepts, but either lower (VCO(2), HR, O(2pulse), V(E), V(T), PETCO(2)) or higher (B(f), V(E)/VCO(2)) trending kinetics in the CFS compared with the control group. It was found that the primary exercise-related physiological difference between the CFS and the control group was their significantly lower heart rate at any equal relative and at maximal work level. Assuming maximal effort by all (indicated by RER, PETCO(2), and subjective exhaustion), these results could indicate either cardiac or peripheral insufficiency embedded in the pathology of CFS patients.

CONCLUSION: We conclude that indexes from cardiopulmonary exercise testing may be used as objective discriminatory indicators for evaluation of patients complaining of chronic fatigue syndrome.

 

Source: Inbar O, Dlin R, Rotstein A, Whipp BJ. Physiological responses to incremental exercise in patients with chronic fatigue syndrome. Med Sci Sports Exerc. 2001 Sep;33(9):1463-70. http://www.ncbi.nlm.nih.gov/pubmed/11528333

 

The use of a symptom “self-report” inventory to evaluate the acceptability and efficacy of a walking program for patients suffering with chronic fatigue syndrome

Abstract:

OBJECTIVES: The purpose of this research was to evaluate the effectiveness of the modality of walking as a management strategy for patients suffering with chronic fatigue syndrome (CFS).

METHODS: Six males and fourteen females with medically diagnosed CFS (CDC, 1994), completed a 12-week walking program. Prior to starting the program subjects underwent an incremental walking exercise test to predetermine their walking intensity. The SCL-90-R symptom “self-report” questionnaire was administered prior to, and at the completion of, the walking program.

RESULTS: At the completion of the 12 weeks of walking, changes in four of the nine SCL-90-R dimensions were significant (somatisation, paranoid ideation, phobic anxiety, and psychoticism). Also significant were the changes in the combination indices, the Global Indices of Distress (GID) and the Positive Symptom Total (PST).

CONCLUSION: This group of CFS subjects, by way of “self-report”, indicated the possibility of an exercise-induced decrease in psychological stress. The walking intervention may have evoked positive changes in their well-being and, furthermore, provided no evidence of any exacerbation in their symptoms.

 

Source: Coutts R, Weatherby R, Davie A. The use of a symptom “self-report” inventory to evaluate the acceptability and efficacy of a walking program for patients suffering with chronic fatigue syndrome. J Psychosom Res. 2001 Aug;51(2):425-9. http://www.ncbi.nlm.nih.gov/pubmed/11516764

 

Patient education to encourage graded exercise in chronic fatigue syndrome. Trial has too many shortcomings

Comment on: Randomised controlled trial of patient education to encourage graded exercise in chronic fatigue syndrome. [BMJ. 2001]

 

Editor—Powell et al’s controlled trial of graded physical exercise in chronic fatigue syndrome has several shortcomings.1

Firstly, the only tool that was used to assess the level of physical activity was entirely subjective. This was a single item (the third item) of the 11 item standardised SF-36 health survey questionnaire. Use of this single item alone as a valid measure of physical fitness is hardly acceptable in the absence of objective data.

Secondly, in a randomised study one can only compare like with like. In this case, all patients in the intervention arms had a minimum of three telephone contacts during the first three months. Patients in the control group were abandoned to primary care after the randomisation. Why did the investigators not maintain the same number of telephone contacts with the control group? They could have discussed anything but chronic fatigue.

Thirdly, frequent early contacts with patients in the three intervention groups (and not the control group) might have confounded the outcome measures by positively influencing the results. This view is supported by the maximum difference emerging as early as three months among patients who had had the illness for an average of over four years, with little change thereafter. By speaking to the patients Powell et al might have provided them with a coping strategy that the control group could not access. Furthermore, did the authors ask the patients to keep an activity diary to record the intensity (mild/moderate) and duration (minutes/hours a day) of physical exercise so that they could note any difference across the intervention groups?

Because no objective measures of physical activity (for example, exercise endurance) were included before and after the interventions for assessing outcome in this study, the reported beneficial effects of graded physical exercise are based on weak evidence. Moreover, the authors did not use the current diagnostic criteria to select patients with chronic fatigue syndrome. Why are we reading this in the BMJ?

You can read the full comment here: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1120585/

 

Source: Chaudhuri A. Patient education to encourage graded exercise in chronic fatigue syndrome. Trial has too many shortcomings. BMJ. 2001 Jun 23;322(7301):1545-6. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1120585/ (Full comment)

 

Cognitive compromise following exercise in monozygotic twins discordant for chronic fatigue syndrome: fact or artifact?

Abstract:

This study examined the effects of exhaustive exercise on cognitive functioning among 21 monozygotic twin pairs discordant for chronic fatigue syndrome (CFS). The co-twin control design adjusts for genetic and family environmental factors not generally accounted for in more traditional research designs of neuropsychological function.

Participants pedaled a cycle ergometer to exhaustion; maximum oxygen output capacity (VO2max) as well as perceived exertion were recorded. Neuropsychological tests of brief attention and concentration, speed of visual motor information processing, verbal learning and recognition memory, and word and category fluency were administered with alternate forms to participants pre- and postexercise.

The preexercise neuropsychological test performance of CFS twins tended to be slightly below that of the healthy twin controls on all measures. However, twins with CFS did not demonstrate differential decrements in neuropsychological functioning after exercise relative to their healthy co-twins. Because exercise does not appear to diminish cognitive function, rehabilitative treatment approaches incorporating exercise are not contraindicated in CFS.

 

Source: Claypoole K, Mahurin R, Fischer ME, Goldberg J, Schmaling KB, Schoene RB, Ashton S, Buchwald D. Cognitive compromise following exercise in monozygotic twins discordant for chronic fatigue syndrome: fact or artifact? Appl Neuropsychol. 2001;8(1):31-40. http://www.ncbi.nlm.nih.gov/pubmed/11388121