While reading the Ciba Foundation Symposium 173 papers (Wiley, 1993), I came across this quote from Peter White in one of the discussions (after Sharpe's presentation on Non-pharmacological treatments - p310): And thus, CBT/GET was born! However, I looked back at David McCluskey's presentation, and there wasn't any mention of a graded exercise therapy, as he was presenting on pharamacological treatments. So I wondered if he had mentioned something at a previous symposium - and sure enough, he had. This is from the British Medical Bulletin special issue on post-viral fatigue syndrome (McBride & McCluskey, April 1991): But it's clear he was referring to previous work by Wessley. McCluskey's other study (reference 1 in the above quote) looked at exercise capacity in patients with CFS and IBS vs normal controls and found a reduced aerobic work capacity in CFS patients compared with the other two groups. This paper is also cited in the PACE GET manuals. McCluskey comments that patients seem to overestimate their previous exercise capability before becoming ill. I then looked to see what White had done with this info. In 1997, he published his own trial of GET (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2126868/), which seems much more careful than the PACE version. Pts had to monitor their heart rate and make sure that they didn't go above 50% of max, and exercise intensity was modified accordingly. In another paper in Physiotherapy (May 1998), this section caught my eye [my emphasis in itals]: "The key to success is adherence to a structured and monitored programme, whereby they do not overdo or exceed their exercise prescription, even on good days, but where they also continue to exercise, albeit at a reduced level, on the bad days." The 1997 trial doesn't mention reducing the level on bad days (but I suspect that's what happened). This is the relevant section: It seems striking to me that the GET eventually adopted in PACE seems particularly harsh and careless in the light of these earlier studies. To me, it seems that the original intention of any exercise therapy was to manage the ill-effects of deconditioning that could potentially exacerbate symptoms of pain and fatigue, rather than trying to combat the underlying condition itself. Does that seem a fair assessment?