OK, so I'm doing the thing that you really shouldn't on the internet, asking a bunch of strangers for medical advice, but I'm feeling that all the feedback from the 'experts' (GP and cardiologist) that I'm getting is being totally dismissive of what the data seems to be telling me. Here is an example of the data that my Fitbit gives me on my heart rate, it is pretty typical data for me; Each data point is the averaged rate for 5 mins, heart rate zones are determined using the standard 220-age calculation. My activity shown above was to get up, eat breakfast, remain seated until lunch, go to my appointment after lunch, then visit two shops while we were out, then once we were back home I was either led on my bed recovering, sat at my desk or sat on the sofa until I went to bed. While I understand the heart is going to react to changes in activity, I feel that the reaction is extreme whereas the experts I've seen so far don't - problem is I have no faith in them. BIt of background on me. Male, 44, live in the UK, officially diagnosed CFS 10 years ago but I suspect I've had this from childhood, was still able to just about work full time up to 8 years ago, went part time to try to cope better but had to give that up 4 years ago and haven't worked since. Was doing daily exercise for 13 months up until December last year, with hindsight this wasn't sensible of me but it was my last attempt at getting better that way, although, in my opinion, it limits the effect deconditioning should have on my HR results. So I guess I'm looking for opinions on whether I'm being reasonable in being concerned with what is shown or not. I appreciate that there won't be a lot that can be done anyway but it's nice to get confirmation of anything with this disease. I also understand that the Fitbit won't be 100% accurate but it lines up pretty closely with a Polar HR monitor with chest strap that I have. I just don't think that what is being shown is normal, which is what I'm being told.