In ME/CFS they use up energy (ATP) faster than they can make it

ProHealth.com
by Dr. Sarah Myhill, MD, March 2, 2011:

We now know why CFSs get delayed fatigue – it is because when they use up energy (ATP) faster than they can make it, there is a build up of ADP. Some is shunted into AMP, which is only recycled very slowly, if at all. [Note: Dr. Myhill’s 2009 research paper - "Chronic fatigue syndrome and mitochondrial dysfunction" - suggests that in CFS the mitochondria's normal ability to produce adenosine triphosphate (ATP) and recycle adenosine diphosphate (ADP) or adenosine monophosphate (AMP) to replenish the supply is compromised.]

Cells have to make brand new de novo ATP from D-ribose, but this only happens very slowly, 1 to 4 days. In the meantime, cells can get a small amount of ATP directly from glucose via anaerobic metabolism, but this produces lactic acid, which causes many of the muscle symptoms. Read more>>