Category: Exercise

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

Abstract:

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.

 

Source: Sacco P, Hope PA, Thickbroom GW, Byrnes ML, Mastaglia FL. Corticomotor excitability and perception of effort during sustained exercise in the chronic fatigue syndrome. Clin Neurophysiol. 1999 Nov;110(11):1883-91. http://www.ncbi.nlm.nih.gov/pubmed/10576483

 

Impaired oxygen delivery to muscle in chronic fatigue syndrome

Abstract:

The purpose of this study was to determine if chronic fatigue syndrome (CFS) is associated with reduced oxygen delivery to muscles. Patients with CFS according to CDC (Center for Disease Control) criteria (n=20) were compared with normal sedentary subjects (n=12).

Muscle oxygen delivery was measured as the rate of post-exercise and post-ischaemia oxygen-haem resaturation. Oxygen-haem resaturation was measured in the medial gastrocnemius muscle using continuous-wavelength near-IR spectroscopy. Phosphocreatine resynthesis was measured simultaneously using (31)P magnetic resonance spectroscopy.

The time constant of oxygen delivery was significantly reduced in CFS patients after exercise (46.5+/-16 s; mean+/-S.D.) compared with that in controls (29.4+/-6.9 s). The time constant of oxygen delivery was also reduced (20.0+/-12 s) compared with controls (12.0+/-2.8 s) after cuff ischaemia. Oxidative metabolism was also reduced by 20% in CFS patients, and a significant correlation was found between oxidative metabolism and recovery of oxygen delivery.

In conclusion, oxygen delivery was reduced in CFS patients compared with that in sedentary controls. This result is consistent with previous studies showing abnormal autonomic control of blood flow. Reduced oxidative delivery in CFS patients could be specifically related to CFS, or could be a non-specific effect of reduced activity levels in these patients. While these results suggest that reduced oxygen delivery could result in reduced oxidative metabolism and muscle fatigue, further studies will be needed to address this issue.

Comment in: Chronic fatigue syndrome: the physiology of people on the low end of the spectrum of physical activity? [Clin Sci (Lond). 1999]

 

Source: McCully KK, Natelson BH. Impaired oxygen delivery to muscle in chronic fatigue syndrome. Clin Sci (Lond). 1999 Nov;97(5):603-8; discussion 611-3. http://www.ncbi.nlm.nih.gov/pubmed/10545311

 

Prediction of peak oxygen uptake in chronic fatigue syndrome

Abstract:

OBJECTIVES: To establish a simple, valid, and acceptable method of predicting peak oxygen uptake (VO2peak) in patients with chronic fatigue syndrome (CFS), which could provide a basis for subsequent exercise prescription at an appropriate intensity as part of a clinical rehabilitation programme.

METHODS: A total of 130 patients who met UK research criteria for CFS were taken from consecutive referrals for chronic fatigue to the University Department of Medicine at Withington Hospital, Manchester. VO2peak was determined using an incremental graded exercise test to exhaustion. Respiratory gas exchange, work rate, and heart rate were monitored throughout.

RESULTS: In all patients, VO2peak was found to correlate strongly and significantly with peak work rate (WRpeak) during testing (r2 = 0.88, p<0.001). In patients who exercised for longer than two minutes (n = 119), regression analysis established the relation as Vo2peak = 13.1 x WRPpeak + 284, where VO2 is given in ml/min and WR in W. The mean error between the measured VO2peak and the predicted value was 10.7%. The relation between increase in work rate and oxygen uptake across the group was highly significant (r2 = 0.87, p<0.001), and given as VO2increase = 12.0 x WRincrease, this value being similar to that expected for healthy individuals. Almost all (97%) subjects reported no exacerbation of symptoms after maximal exercise testing.

CONCLUSIONS: Using a simple to administer maximal exercise test on a cycle ergometer, it is possible to predict accurately the VO2peak of a patient with CFS from peak work rate alone. This value can then be used as an aid to setting appropriate exercise intensity for a rehabilitation programme. The increase in VO2 per unit increase in workload was consistent with that expected in healthy individuals, suggesting that the physiological response of the patients measured here was not abnormal. Contrary to the belief of many patients, maximal exercise testing to the point of subjective exhaustion proved to be harmless, with no subjects suffering any lasting deterioration in their condition after assessment.

 

Source: Mullis R, Campbell IT, Wearden AJ, Morriss RK, Pearson DJ. Prediction of peak oxygen uptake in chronic fatigue syndrome. Br J Sports Med. 1999 Oct;33(5):352-6. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1756205/ (Full article)

 

Acute effects of thirty minutes of light-intensity, intermittent exercise on patients with chronic fatigue syndrome

Abstract:

BACKGROUND AND PURPOSE: Currently, there is no consensus on exercise prescription for patients with chronic fatigue syndrome (CFS). This investigation examined whether light-intensity, intermittent physical activity exacerbated symptoms in patients with CFS immediately following exercise to 7 days following exercise. Subjects. Subjects were 9 women (mean age=44.2 years, SD=8.4, range=29-56; mean weight=74.2 kg, SD=18.8, range=56.36-110.91; and mean height=1.63 m, SD=0.8, range=1.55-1.78) and 1 man (age=48 years, weight=97.1 kg, and height= 1.98 m) who met the Centers for Disease Control and Prevention’s criteria fi)r (FS.

METHODS: Subjects performed 10 discontinuous 3-minute exercise bouts (separated by 3 minutes of recovery) at a self-selected, comfortable walking pace on a treadmill. Oxygen consumption, minute ventilation, respiratory exchange ratio, and heart rate were measured every minute during the exercise session. To assess degree of disability, general health status, activity level, symptoms, and mood, subjects completed various questionnaires before and after exercise.

RESULTS: Results indicated that degree of disability, general health status, symptoms, and mood did not change immediately and up to 7 days following exercise.

CONCLUSION AND DISCUSSION: Thirty minutes of intermittent walking did not exacerbate symptoms in subjects with CFS. The physiological data did not show any abnormal response to exercise. Although this study did not determine whether 30 minutes of continuous versus intermittent exercise would exacerbate symptoms, all 10 subjects felt that they could not exercise continuously for 30 minutes without experiencing symptom exacerbation. Despite this limitation, the results indicate that some individuals with CFS may be able to use low-level, intermittent exercise without exacerbating their symptoms.

Comment in: Benefits of exercise therapy. [Phys Ther. 2000]

 

Source: Clapp LL, Richardson MT, Smith JF, Wang M, Clapp AJ, Pieroni RE. Acute effects of thirty minutes of light-intensity, intermittent exercise on patients with chronic fatigue syndrome. Phys Ther. 1999 Aug;79(8):749-56. http://ptjournal.apta.org/content/79/8/749.long (Full article)

 

Immunological response in chronic fatigue syndrome following a graded exercise test to exhaustion

Abstract:

This study was conducted to evaluate the immunological response to an exhaustive treadmill exercise test in 20 female chronic fatigue syndrome patients compared to 14 matched sedentary controls. Venipuncture was performed at baseline and 4 min, 1 hr, and 24 hr postexercise.

White blood cells were labeled for monoclonal antibody combinations and were quantified by FACsan. Cytokines were assayed utilizing quantitative RT/PCR. No group difference was seen in VO2peak (28.6 +/- 1.6 vs 30.9 +/- 1.2 ml.kg-1.min-1; P > 0.05). However, 24 hr after exercise the patients’ fatigue levels were significantly increased (P < 0.05).

The counts of WBC, CD3+ CD8+ cells, CD3+ CD4+ cells, T cells, B cells, natural killer cells, and IFN-gamma changed across time (P’s < 0.01). No group differences were seen for any of the immune variables at baseline or after exercise (P’s > 0.05). The immune response of chronic fatigue syndrome patients to exhaustive exercise is not significantly different from that of healthy nonphysically active controls.

 

Source: LaManca JJ, Sisto SA, Zhou XD, Ottenweller JE, Cook S, Peckerman A, Zhang Q, Denny TN, Gause WC, Natelson BH. Immunological response in chronic fatigue syndrome following a graded exercise test to exhaustion. J Clin Immunol. 1999 Mar;19(2):135-42. http://www.ncbi.nlm.nih.gov/pubmed/10226888

 

Demonstration of delayed recovery from fatiguing exercise in chronic fatigue syndrome

Abstract:

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.

Copyright 1999 Lippincott Williams & Wilkins

 

Source: Paul L, Wood L, Behan WM, Maclaren WM. Demonstration of delayed recovery from fatiguing exercise in chronic fatigue syndrome. Eur J Neurol. 1999 Jan;6(1):63-9. http://www.ncbi.nlm.nih.gov/pubmed/10209352

 

Increased production of interleukin-6 by adherent and non-adherent mononuclear cells during ‘natural fatigue’ but not following ‘experimental fatigue’ in patients with chronic fatigue syndrome

Abstract:

In an investigator-blinded study, adherent (monocytes) and non-adherent cells (lymphocytes) from patients with chronic fatigue syndrome (CFS) were examined on two separate occasions (when feeling ‘fatigued’ and when feeling ‘rested’) for in vitro spontaneous, phytohemagglutinin- (PHA, for lymphocytes), and lipopolysaccharide- (LPS, for monocytes) induced production of IL-6 by ELISA assay.

A group of CFS patients and controls were also subjected to exercise-induced fatigue (‘experimental fatigue’) and IL-6 production was compared, in a double-blinded manner, prior to and following induction of fatigue.

A significant increase in spontaneous, PHA- and LPS-induced IL-6 secretion by both lymphocytes and monocytes was observed in CFS patients during ‘natural fatigue’ as compared to during state. However, no such changes in IL-6 production were observed during ‘experimental fatigue’.

These data suggest a role of IL-6 in natural symptomatology and perhaps in the pathogenesis of CFS. In addition, the data demonstrate that laboratory-induced fatigue (experimental fatigue) may not be a good model to study immunological changes in CFS; immunological parameters should be studied in a longitudinal manner during the natural course of the disease.

 

Source: Gupta S, Aggarwal S, Starr A. Increased production of interleukin-6 by adherent and non-adherent mononuclear cells during ‘natural fatigue’ but not following ‘experimental fatigue’ in patients with chronic fatigue syndrome. Int J Mol Med. 1999 Feb;3(2):209-13. http://www.ncbi.nlm.nih.gov/pubmed/9917531

 

Chronic fatigue syndrome: physical and cardiovascular deconditioning

Abstract:

We investigated whether chronic fatigue syndrome (CFS) patients have physical and/or cardiovascular de-conditioning, in 273 CFS patients and 72 healthy controls.

We used laboratory tests to assess haematological, biochemical, endocrinological and immunological systems. The cardiovascular system was assessed by echocardiography and carotid echography. Body composition was determined by dual energy X-ray absorptiometry (DEXA).

CFS patients had smaller left ventricular end systolic (p < 0.001) and diastolic (p = 0.008) dimensions but thinner posterior walls (p = 0.02) than corresponding values in healthy controls. Left ventricular mass was also reduced in CFS patients (p = 0.006). Both maximum (p < 0.001) and minimum (p < 0.008) diameter of the carotid artery were smaller in CFS patients. The laboratory screening tests showed significant differences in serum albumin (p = 0.05), phosphate (p = 0.02), HDL-cholesterol (p = 0.03), HDL:total cholesterol ratio (p = 0.01), triglycerides (p = 0.02), neutrophils (p = 0.01) and thyroid-stimulating hormone (p = 0.04) between CFS patients and controls. Male CFS patients had an increased percentage of fat mass compared with healthy male subjects (p = 0.02).

This large group of CFS patients had evidence of physical and cardiovascular de-conditioning, suggesting that in these patients a graded exercise programme could lead to physical reconditioning and could increase their ability to perform physical activities.

 

Source: De Lorenzo F, Xiao H, Mukherjee M, Harcup J, Suleiman S, Kadziola Z, Kakkar VV. Chronic fatigue syndrome: physical and cardiovascular deconditioning. QJM. 1998 Jul;91(7):475-81. http://qjmed.oxfordjournals.org/content/91/7/475.long (Full article)

 

Physical activity before and after exercise in women with chronic fatigue syndrome

Abstract:

We measured physical activity after strenuous exercise in 20 women with chronic fatigue syndrome (CFS), compared to 20 sedentary healthy volunteers who exercised no more than once per week.

Activity was measured for 2 weeks using a portable waist-worn vertical accelerometer. After the first week of activity monitoring, all participants returned for a maximal treadmill test, followed by continued activity monitoring for the second week. Five activity measures were derived from the data: (i) average activity; (ii) total activity; (iii) duration of waking day; (iv) duration; and (v) number of daily rests. A repeated measures ANCOVA was used to determine post-treadmill group differences accounting for pre-treadmill differences.

There was a significant reduction in overall average activity after the treadmill test, with the greatest decrease on days 12 through 14. This reduction was accompanied by a significant increase in the duration of the waking day and number of daily rests. Thus, marked exertion does produce changes in activity, but later than self-report would suggest, and are apparently not so severe that CFS patients cannot compensate.

 

Source: Sisto SA, Tapp WN, LaManca JJ, Ling W, Korn LR, Nelson AJ, Natelson BH. Physical activity before and after exercise in women with chronic fatigue syndrome. QJM. 1998 Jul;91(7):465-73. http://qjmed.oxfordjournals.org/content/91/7/465.long (Full article)

 

Influence of exhaustive treadmill exercise on cognitive functioning in chronic fatigue syndrome

Abstract:

The purpose of this study was to determine the effect of exhaustive exercise on cognitive performance of patients with chronic fatigue syndrome(CFS) and sedentary healthy controls (CON).

Subjects were 19 women with CFS and 20 CON. A test battery consisting of 4 cognitive tests (CTB) was given pre-, immediately post-, and 24 hours post-treadmill exercise to exhaustion. No differences were seen on the CTB pre-exercise.

CFS patients improved at a slower rate than CON on the Symbol Digit Modalities Test (SDMT), Stroop Word Test (SWT), and Stroop Color Test (SCT). When compared with CON, a lower number of correct responses was seen for the CFS immediately postexercise on the SDMT (61 +/- 3 vs 66 +/- 2), SWT (137 +/- 6 vs 146 +/- 6), and SCT (99 +/- 4 vs 107 +/- 3), and 24 hours postexercise on the SDMT (64 +/- 3 vs 69 +/- 2), SWT (134 +/- 7 vs 148 +/- 5), and SCT (101 +/- 4 vs 106 +/- 3).

We conclude that after physically demanding exercise, CFS subjects demonstrated impaired cognitive processing compared with healthy individuals.

 

Source: LaManca JJ, Sisto SA, DeLuca J, Johnson SK, Lange G, Pareja J, Cook S, Natelson BH. Influence of exhaustive treadmill exercise on cognitive functioning in chronic fatigue syndrome. Am J Med. 1998 Sep 28;105(3A):59S-65S. http://www.ncbi.nlm.nih.gov/pubmed/9790484