Wow, excellent thread, Moxie. I get all of these effects, but only in episodes that might last a few days or weeks. Then I'm normal again. Just this morning, I was reading through the Newton paper, "Abnormalities in pH handling by peripheral muscle and potential regulation by the autonomic nervous system in chronic fatigue syndrome". But right away, I had to wonder why they're not mentioning the motor end plates, aka neuromuscular junction. That's where the signal from the motor neuron enters the myocyte. As an off-the-cuff theory, this can all fit together, maybe like this. at least in my case: The muscle fibers get into some pathological condition (inflammation is involved, big surprise) where they are very susceptible to injury. Yes, I get that phone thing, too, just a few weeks ago. The phone is so light but I got some tearing right in the middle of the bicep from holding the phone (on speakerphone, arm bent at 90 degrees) for many minutes. During this period, I also experienced a surprising loss of strength (as in lifting a heavy object one time). That almost never happens to me. So maybe the motor end plates are operating in their defensive fashion, keeping the muscle from exerting too much force so as to prevent injury - like keeping strands in a violin bow from popping. So some plates won't conduct the signal. Holding a phone circumvents that tactic, which is meant for heavy weight, because ony a few fibers contract and so the injury occurs anyway - but just in a few fibers. Tendons are also involved. I've had this new, weird condition where my fingers won't work right. Some having swelling. There is pain in some of them when I try to bend them fully. Immune chemicals at work, this came out of the blue ceating some pathological condition. So my tendons also need to be protected by keeping muscles from exerting full force. But then conversely, I do have good stamina now. Two days ago, I went on an hour bike ride, including 20 minutes straight up a grade, with surprisingly no problem. So there's appparently no fuel problem involved. I also always have poor lung power, since getting sick - but I was never great at that, even pre-CFS. (I haven't had full-fledged PEM in years.) Excellent thread. Moxie, and I'm thankful to everyone who posted their own experience.