What is Post-Exertional Malaise?
New to ME/Chronic Fatigue Syndrome? MEAction's* wiki page on PEM gives a good run-down of the basics (with citations!) and then goes in-depth to cover everything you probably ever wanted to know on the topic. Here's a sample to kick things off...
"In ME/CFS, Post-exertional malaise (PEM) refers to a worsening of the illness after physical or cognitive exertion which was previously tolerated. This can include a worsening of ME/CFS symptoms, the appearance of new symptoms, and a worsening of “baseline” (capacity for exertion). These characteristics are often delayed 24-72 hours or more after the triggering event.
...While in most fatiguing diseases patients experience symptom relief after exercise, the opposite is true for ME/CFS patients...
In ME/CFS recovery time from exertion is prolonged, lasting days, weeks, months, or longer. PEM can lead to a permanent worsening of the condition and increased disability."
* "MEAction (The Myalgic Encephalomyelitis Action Network) is a worldwide ME/CFS patient advocacy group co-founded May 12, 2015 by Jennifer Brea and Beth Mazur. Its focus is on empowering patients to take action to improve the status of research and clinical care through nationally organized efforts with the support of local affiliate groups in countries around the world."