Thanks for digging that one out. I had seen it and of course it commits the schoolboy error of confusing correlation with causation (what the ???? are reviewers doing?). Compare this with the pregnancy and pain/deconditioning study DQ posted which looked at a time sequence and found that in fact pain came before deconditiong.Haven't time to read all of this one Blue but it seems to have tried and defined the extent of 'deconditioning' in relation to the condition although it does conclude with a GET recommendation
I'll keep looking but I have a feeling it's one of those things that is just accepted. Long term illness especially one that leaves you hospital-bound and in bed leads to deconditioning. I think it's perhaps easier to think about what 'conditioning' is i.e. a healthy body able to and actively exercising. So 'exercise' would seem to be the common denominator - or lack of it.
If one is unable to move then things like e.g. atrophy can and do occur which will lead of course to the symptoms you describe.
Anyway, have to leave it there for now. Back to bed for me :headache:
Chronic fatigue syndrome: physical and cardiovascular deconditioning.
1998: http://qjmed.oxfordjournals.org/content/91/7/475.short
very belated edit: For completeness, it's worth pointing out that the 1998 Lorenzo failed to used properly sedentary healthy controls so the differences between controls and patients tell us nothing.
Like you I have found surprisingly little evidence linking decon to symptoms - and actually haven't seen any evidence that atrophy causes pain and fatigue either, so rest easy in your bed... Think the NASA review of decon of healthy volunteers will be key but it's a bit of a monster and I don't have the energy right now.