Characterization of post–exertional malaise in patients with Myalgic Encephalomyelitis/ Chronic Fatigue Syndrome, by Barbara Stussman, Ashley Williams, Joseph Snow, Angelique Gavin, Remle Scott, Avindra Nath and Brian Walitt in Front. Neurol., 18 September 2020 []


Research abstract:


Myalgic encephalomyelitis/chronic fatigue syndrome is characterized by persistent and disabling fatigue, exercise intolerance, cognitive difficulty, and musculoskeletal/joint pain. Post–exertional malaise is a worsening of these symptoms after a physical or mental exertion and is considered a central feature of the illness. Scant observations in the available literature provide qualitative assessments of post–exertional malaise in patients with myalgic encephalomyelitis/ chronic fatigue syndrome. To enhance our understanding, a series of outpatient focus groups were convened.


Nine focus groups totaling 43 patients who reported being diagnosed with myalgic encephalomyelitis/ chronic fatigue syndrome were held between November 2016 and August 2019. Focus groups queried post–exertional malaise in daily life and participants’ retrospective memory of post–exertional malaise that followed an exercise provocation with a cardiopulmonary exercise test. Data analysis followed the grounded theory method to systematically code and categorize the data to find meaningful patterns. A qualitative software package was used to move text into categories during data coding.


A wide range of symptoms were attributed to exertion both in daily lives and following cardiopulmonary exercise testing. While three core symptoms emerged (exhaustion, cognitive difficulties, and neuromuscular complaints), participants’ descriptions were notable for their unique individual variations. Of 18 participants who responded to questions centered around symptoms following a cardiopulmonary exercise test, 17 reported that symptoms started within 24 h and peaked in severity within 72 h following the cardiopulmonary exercise test. Patients described post–exertional malaise as interfering with their ability to lead a “normal” life.


The experience of post–exertional malaise in myalgic encephalomyelitis/chronic fatigue syndrome varies greatly between individuals and leads to a diminished quality of life. myalgic encephalomyelitis/ chronic fatigue syndrome patients describe post–exertional malaise as all-encompassing with symptoms affecting every part of the body, difficult to predict or manage, and requiring complete bedrest to fully or partially recover. Given the extensive variability in patients, further research identifying subtypes of post–exertional malaise could lead to better targeted therapeutic options.

Excerpts from Results

Theme 1. PEM Was Triggered by Three Broad Categories of Events
We asked focus group participants to give examples of activities that caused them to have PEM. Notably, there were three broad categories of activities: physical activity, cognitive effort, and emotion precipitated, although there was overlap across the three groups. These categories included triggers such as household chores, social activities, errands outside of the home, physical exercise, cognitive activities, and emotional moments (Figure 1).

Theme 2. Effects of PEM Were Impacted by Baseline Pre-exertional Symptoms
When focus group participants were asked to describe PEM following exertion, many expressed the importance of understanding their “starting point” or “baseline.” Participants described the pliable nature of symptoms and how successive exertion can compound symptoms.

Theme 3. PEM Had a Wide Symptom Range With Few Differences Between Daily PEM and Following CPET, With Three Core Symptoms (Exhaustion, Cognitive Difficulties, and Neuromuscular Complaints)…

Theme 3a. Exhaustion
Participants explained that the exhaustion from PEM is different than what they experienced before having ME/CFS…

Theme 3b. Cognitive Difficulties
Cognitive difficulties were described as both difficulty thinking clearly/paying attention and difficulty speaking or finding words…

Theme 3c. Neuromuscular Complaints
Patients often complained of neuromuscular symptoms, which included muscle pain/aches and muscle weakness…

Theme 4. PEM Following CPET Was More Immediate and of Longer Duration Than PEM in Daily Life

Theme 5. The Manner of Onset of PEM Symptoms Varied
Separate from when PEM began (as shown in Figures 4, 5), we also determined whether participants perceived the onset of symptoms as sudden or gradual…

Theme 6. Complete Rest Was Necessary to Gain Any Relief in PEM Symptoms
When asked what could alleviate PEM symptoms, virtually every participant agreed that while in an episode of PEM, complete rest was absolutely necessary to reduce symptoms…

Theme 7. Planning and Moderation of Energy Expenditure Was Essential to Avoiding PEM
An interesting theme that emerged during focus group discussions centered around the steps taken by participants to manage activity levels in their daily lives to minimize the effects of PEM…

Theme 8. The Uncertainty and Debility of PEM Created Despair
…Participants talked at length about living with the unpredictability of PEM and having to adjust their lives to try to avoid severe PEM…

ME/CFS patients describe PEM as all-encompassing with symptoms affecting every part of the body, difficult to predict or manage, and requiring complete bedrest to fully or partially recover. Through in-depth focus group discussions, ME/CFS patients describe PEM as disruptive to living a self-described “normal” life, sometimes leading to hopelessness or despair. Given the extensive variability in PEM symptoms and timeframes for onset, peak, and recovery, further research identifying subtypes of PEM could lead to better targeted therapeutic options…


MECFSSkeptic blog post,  by Michiel Tack: Summary of the NIH’s exploration of post-exertional malaise

Press release: NIH study details self-reported experiences with post-exertional malaise in ME/CFS

Medical newsResearchers explore clinical and biological aspects of myalgic encephalomyelitis/ chronic fatigue syndrome

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