Thanks for the replies, the reason I'd asked is this: I hadn't had fatigue for a long time, since suppressing candida. But at the peak of this virus cold on Saturday afternoon, I seemed to be undergoing an intensification of CFS symptoms - including the return of fatigue. The most curious was that my leg muscles were not recovering from exercise. Having been reading others' stories of severe post exercise problems, I'd begun thinking that I had maybe entered a downward spiral that I might not get out of.
But on Sunday morning, I was okay again - cold symptoms were mostly gone and leg muscles were good. It seemed as if inflammation from the cold virus had affected muscle state. But no one else seems to have experienced the same.