Can Overtraining Syndrome cause ME/CFS?
Answer:
No, but it may trigger it, depending on what you class 'it' as, as ME/CFS doesn't exist any more legitimately than MS/CFS. So to answer accurately you'd have to decide yourself what your ME or your CFS is, to be able to develop it!
Honestly, the simplistic question is as answerable as asking: can eating more than the average person make you fat? It all depends on your initial BMI, type of food ingested, calories, genetic profile, hormone levels etc.
So with ME or CFS it also depends as both have no diagnostic test.
Taking hypothetically:
*Exercise when run down can cause immunity to weaken
*Infection and subsequent autoimmunity are linked.
Now add the components, including genetics, required to develop ME
Then yes, if your own ME or CFS is caused by persistent infection triggering autoimmunity, then theoretically yes.
If not, then no!
The same would apply for MS. If you were hammering yourself into the floor with exercise, and had an infection such as chronic EBV, that for reasons not known to science may be involved with CNS infiltration, HERV activation and so forth. Then theoretically with the right bad set of circumstances, infection mediated MS, may be triggered by overtraining syndrome in which a certain causative pathogen is able to take hold.
On a relevant topic many with severe ME were sporty first, and developed ME, or over-trained their sick bodies with GET (via CBT) and became permanently worse. If you have a mitochondrial infection and try and carry on with your life, even this becomes a state of over training, in the chronic metabolically injured.