Mitochondrial Dysfunction and Post-Exertional Malaise

Though this article refers to Chronic Fatigue Syndrome, these symptoms often overlap with other chronic conditions, like Fibromyalgia.  Also, people with EDS are often suspected of having mitochondrial issues.

A patient who lacks post-exertional malaise as described below does not have mitochondrial dysfunction. This type of exhaustion is unique to mitochondrial problems.

It has been well documented that there is an abnormal increase in cytokines (chemicals released by the immune system) in CFS/ME patients following mild exercise. This causes another type of fatigue on top of the mitochondrial dysfunction fatigue discussed below. Cytokines in general, without the exercise trigger, can cause fatigue.  There are probably additional causes of fatigue (such as orthostatic intolerance) as well.

Role of mitochondria in cellular function