Post-exertional symptoms distinguish Myalgic Encephalomyelitis/Chronic Fatigue Syndrome subjects from healthy controls, by  in Work, vol. 66, no. 2, pp. 265-275, 20 Jul 2020 [doi: 10.3233/WOR-203168]


Research abstract:


Post-exertional malaise (PEM) is an exacerbation of symptoms that leads to a reduction in functionality. Recognition of PEM is important for the diagnosis and treatment of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS).


Symptoms following cardiopulmonary exercise testing were compared between ME/CFS patients and healthy controls.


Open-ended questionnaires were provided to subjects following two maximal exercise tests, 24 hours apart. Subjects evaluated how they felt at five time points. Responses were classified into 19 symptom categories.


ME/CFS subjects (n = 49) reported an average of 14±7 symptoms compared to 4±3 by controls (n = 10). During the seven days afterwards, ME/CFS subjects reported 4±3 symptoms. None were reported by controls. Fatigue, cognitive dysfunction, and sleep problems were reported with the greatest frequency. ME/CFS patients reported more symptom categories at higher frequencies than controls. The largest differences were observed in cognitive dysfunction, decrease in function, and positive feelings.


A standardized exertional stimulus produced prolonged, diverse symptoms in ME/CFS subjects. This provides clues to the underlying pathophysiology of ME/CFS, leading to improved diagnosis and treatment.


5. Conclusion

The presence of symptoms during and after the two-day CPET and the extended recovery time in the ME/CFS group exemplify PEM. Two key symptoms, cognitive dysfunction and a decrease in function, can potentially indicate the occurrence of PEM. This is consistent with a 2019 survey of 1,534 ME/CFS subjects where the top selected PEM consequence was “reduced stamina and functional ability” (selected by 99.4%) followed by “physical fatigue” (98.9%), “cognitive exhaustion” (97.4%), and “problems thinking” (97.4%). Other complaints prominent in ME/CFS patients after activity are fatigue, muscle/joint pain, headaches and sleep disturbances. The disparity in the time to recover may serve as an additional marker. These symptoms and the rate of recovery contribute to the existing literature on PEM and assist health care professionals in recognizing PEM.

By discerning both the attributes of PEM and its manifestations in each patient, health care providers can identify patients with ME/CFS and devise patient-specific treatment plans to combat the onset and reduce the severity of symptoms. OTs are already familiar with the concepts of energy conservation and activity management but these concepts may need to be modified for ME/CFS patients. For example, more rest may be needed following activity compared to other medical conditions. Patients may reach a plateau of activity which is improved but not close to “normal” since the physiological underpinnings of ME/CFS are not yet fully understood. Early diagnosis and symptom management promote the maintenance of or even improvement in patient function.

This paper also sheds light on the possible risks of a 2-day CPET. It does not appear that patients or research subjects suffer permanent or protracted damage from CPET. Our data show that recovery is bimodal, with approximately half of subjects taking a week or less to recover. This information can be shared with patients or research subjects so that they might make a better informed decision. Exploration of this bimodal pattern may also help discover subgroups within or the pathophysiology underlying ME/CFS.

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