Post-Exertional Malaise

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Definition:

To understand this term, first it's important to understand its component parts:

Malaise is a vague feeling of bodily discomfort or a general feeling of being unwell, much like you feel when you're coming down with a cold or the flu.

Post-exertional means after exercise or other types of exertion.

In chronic fatigue syndrome, post-exertional malaise is a period of intense exhaustion and a spike in other symptoms that lasts for more than 24 hours following physical exertion.

Some people say they experience it after mental exertion as well.

This symptom is a hallmark of the disease. Some research suggests that it may cause detectable differences in the blood, many of which are being studied as a possible diagnostic marker. It's also the basis of a suggested alternative name for chronic fatigue syndrome: systemic exercise intolerance disease, or SEID.

The term "malaise" is a fairly weak one to describe what people with this disease go through. Along with intense exhaustion, they may also have considerable muscle pain, cognitive dysfunction, and flu-like symptoms (sore throat, fever, etc.) In some, it may last for a day or two. In others, it may last for a week or more.

The amount of exertion it takes to trigger this symptom varies greatly. In someone with a mild case, it might take an extra-long workout at the gym or a vacation that includes a lot of walking. In someone with a severe case, it could just take getting out of bed and showering.

Post-exertional malaise is often a source of considerable disability.

Some cases of fibromyalgia may involve a negative reaction to exercise as well. It's not yet clear whether this response is classifiable as post-exertional malaise.

Learn more:

Sources:

Lengert N, Drossel B. Biophysical chemistry. 2015 Jul;202:21-31. In silico analysis of exercise intolerance in myalgic encephalomyelitis/chronic fatigue syndrome.

Miller RR, et al. Journal of translational medicine. 2015 May 20;13:159. Submaximal exercise testing with near-infrared spectroscopy in myalgic encephalomyelitis/chronic fatigue syndrome patients compared to healthy controls: a case-controlled study.

Nijs J, Lundberg M. Clinical rheumatology. 2014 Jan;33(1):151-2. Avoidance behavior toward physical activity in chronic fatigue syndrome and fibromyalgia: the fear for post-exertional malaise.

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