Intracortical inhibition refers to the 'voluntary preparation of movement" in the brain. I believe it has to do with movement planning and preparation. This article suggests to me that the brain is just not ready for movement . The authors suggest the problem is different in FM than muscular dystrophy. InMD - the reduced intra inhibition simply occurs because the muscles are so weak there is little need to rev the brain up (my interpretation). In FM the problem seems to be a 'central disinhibition'; central refers to the brain - this suggests to me that a global disinhibition - or inability to ully enter into the planning necessarly for movement. This would play out I would think - in a kind of stuckness - a frozen state - which makes sense given the 'frozen muscles' and myofascial problems etc.....the muscles seem to be stuck in a contracted state. I would expect this would play out in CFS as well.