Tag: higher perceived exertion scores

Elevated Perceived Exertion in People With Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and Fibromyalgia: A Meta-analysis

Abstract:

Purpose: Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) and Fibromyalgia (FM) are two debilitating illnesses primarily characterized by chronic symptoms of fatigue and musculoskeletal pain, respectively. Some investigators have observed an elevated sense of effort in these patient groups, however, this effect has not been substantiated via quantitative review. As such, we conducted a meta-analysis of perceived exertion (RPE) responses to aerobic exercise in ME/CFS and FM compared to healthy adults.

Methods: Case-control studies involving adults with ME/CFS or FM that measured RPE and heart rate responses to acute aerobic exercise were included. Data sources included: PubMed, Scopus/Embase, CINAHL, CENTRAL, and Google Scholar. Risk of bias was assessed by evaluating each study’s description of participant characteristics, matching procedures, and administration of RPE scales. Hedges’ d effect sizes for RPE were calculated and aggregated using random effects models and potential moderators were explored with meta-regression analysis.

Results: Forty-one effects were extracted from 37 studies involving 1016 patients and 686 healthy controls. We observed a large (Hedges’ d=0.85; 95% CI: 0.62, 1.08) effect indicating higher RPE in patients than controls. The mean effect size was significantly moderated (p<0.001; R=0.38) by whether RPE data were analyzed at a peak or submaximal intensity (b=0.60, z=4.6, p<0.001) and the type of patient group that was studied (b = 0.25, z = 2.08, p=0.04).

Conclusions: People with ME/CFS and FM perceive aerobic exercise as more effortful than healthy adults, but the exact causes are unclear. The large magnitude of this effect merits further exploration of underlying mechanisms which could provide insight into the pathophysiology of ME/CFS and FM or the broader debate about the nature of central and/or peripheral signals that influence RPE.

Source: Barhorst EE, Andrae WE, Rayne TJ, Falvo MJ, Cook DB, Lindheimer JB. Elevated Perceived Exertion in People with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and Fibromyalgia: A Meta-analysis [published online ahead of print, 2020 Jun 15]. Med Sci Sports Exerc. 2020;10.1249/MSS.0000000000002421. doi:10.1249/MSS.0000000000002421 https://pubmed.ncbi.nlm.nih.gov/32555018/

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

 

Muscle histopathology and physiology in chronic fatigue syndrome

Abstract:

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.

 

Source: Edwards RH1, Gibson H, Clague JE, Helliwell T. Muscle histopathology and physiology in chronic fatigue syndrome. Ciba Found Symp. 1993;173:102-17; discussion 117-31. http://www.ncbi.nlm.nih.gov/pubmed/8491096