Post-exertional malaise

Post-exertional malaise (PEM) is a worsening of many ME/CFS symptoms as a result of physical or mental exertion. Patients, ME/CFS organizations, clinicians and researchers that work in the ME/CFS field often referred to it as "the marker," i.e., the main symptom that differentiates Myalgic encephalomyelitis (ME) and Chronic fatigue syndrome (CFS) from other fatiguing illnesses. PEM can last for days to weeks after the exertion.

Worsening symptoms include chronic fatigue, flu-like symptoms, brain fog (cognitive dysfunction), unrefreshing sleep, chronic pain, orthostatic intolerance, neurally mediated hypotension, POTS and more. "As with the severity, the exertion needed to trigger PEM theories case-by-case. For some, it might kick in after a little bit of exercise on top of a day's regular activities. For others, is incredible as it may seem, it can just take a trip to the mailbox, a shower, or sitting upright for an hour." Onset of PEM can be delayed 24-72 hours.

A 2016 DePaul University study focused on deciphering if post-exertional malaise was a generalized, full-body fatigue and/or a muscle-specific fatigue. The results suggested that PEM is composed of two empirically different experiences, one for generalized fatigue and one for muscle-specific fatigue.

2015 Institute of Medicine report


This landmark report published in 2015 by the United States Institute of Medicine report, which assessed all the evidence available, concluded:

"'There is sufficient evidence that PEM is a primary feature that helps distinguish ME/CFS from other conditions'"

Pages 84-86 of the report describe the evidence for post-exertional malaise in ME/CFS patients.

Required

 * In the International Consensus Criteria, (ICC) postexertional neuroimmune exhaustion is required for a diagnosis of ME.
 * In diagnosing Systemic Exertion Intolerance Disease (SEID).

Optional

 * In the Fukuda criteria, the symptom of post-exertional malaise can be used to help form a diagnosis. Unusually, it is not a required symptom for diagnosis.
 * In the Canadian Consensus Criteria (CCC) PEM is an option with an and/or with fatigue although most researchers require PEM.
 * In the Holmes criteria, prolonged (24 hours or greater) generalized fatigue after levels of exercise that would have been easily tolerated in the patient's premorbid state is an optional criteria for diagnosis, under the section Minor Symptom Criteria.

Notable studies

 * 1999, Demonstration of delayed recovery from fatiguing exercise in chronic fatigue syndrome (Abstract)
 * 2013, Post-exertion malaise in chronic fatigue syndrome: symptoms and gene expression [(Abstract)
 * 2015, Myalgic Encephalomyelitis: Symptoms and Biomarkers (Full Text)
 * 2015, Changes in Gut and Plasma Microbiome following Exercise Challenge in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) (Full Text)
 * 2016, Deconstructing post-exertional malaise: An exploratory factor analysis (Full Text)


 * 2018, Comparing Post-Exertional Symptoms Following Serial Exercise Tests (Abstract)



Notable articles

 * Dec 30, 2015 Suggestion to replace PEM (Post Exertional Malaise) with PAR (Post Activity Relapse)


 * Nov 4, 2016 Postexertion 'Crash,' not Fatigue per se, Marks Syndrome

Talks & interviews

 * 2012, Top 10 Things You Should Know About Post-Exertional Relapse
 * 2013, CFS gene expression after exercise (part 1)
 * 2015, 72. Gene-expression and exercise / Gen-expressie en inspanning – dr. Lucinda Bateman
 * 2015, Post-Exertion Malaise: The Intersection of Biology and Behavior


 * 2016, Inducing Post-Exertional Malaise in ME/CFS: A Look at the Research Evidence

Possible causes
Dysfunction of the Adenosine triphosphate (ATP) adenosine diphosphate (ADT) cycle. Dr. Sarah Myhill has developed a test to assess ATP profiles.

Learn more

 * International CFS/ME Awareness Day - What Health (PEM Definition Included)
 * Post-Exertional Malaise in Chronic Fatigue Syndrome
 * Post-Exertional Malaise: Cause and Effect
 * What is Post-Exertional Malaise
 * Post-Exertional Malaise - The ME/CFS Ghost
 * The Exercise Intolerance in POTS, ME/CFS and Fibromyalgia Explained?