I was recently informed that there is new research suggesting that high impact exercise supports repair to mitochondria. This was from a doctor who, though not a CFS specialist, definitely thinks PWCs are sick, and is especially interested in mitochondrial damage as an underlying factor. This is not my area of expertise at all. I tried to have a look around here and online, but was very overwhelmed, and in well over my head. Does anyone know what studies he might have been referring to, and whether they have anything to do with ME/CFS or are about mitochondrial function more generally? His advice to me: start high impact exercise (a little at a time). Specifically, run as hard as possible until you can't continue and/or weight bearing exercise (not at the same time ), giving yourself plenty of time to recover. So, needless to say, I am more than a bit hesitant to just jump in with both feet, especially given the extreme caution towards this type of exercise displayed by every knowledgable ME/CFS doc I know of. [Note: I have been mostly bed/housebound for the last year or so.] Interestingly, this MD noted he thought the light/slow graded exercise approach was all wrong. Thanks in advance! Saw this on Dr. Myhill's website, and thought it might be related?