https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1371214/ Abstract A case definition for post-viral fatigue syndrome is proposed within which various subgroups of patients exist. Any one treatment may not apply to all the subgroups. In particular, patients' experiences do not show that avoidance of exercise is maladaptive. It is proposed that the recently ill often try to exercise to fitness whereas the chronically ill have learnt to avoid exercise. Recovery is more likely to be achieved if patients learn about their illness and do not exhaust their available energy.
I don't agree with everything in this paper, but it's a lot closer to being accurate than many more recent papers.
I consider this paper the origin of the BPS's "boom-bust" claim. It was written in response to Wessely and Chalder's first published paper about CBT for ME ("Management of chronic (post viral) fatigue syndrome", 1989) Wessely and Chalder (together with David and Butler) had set out their CBM around activity avoidance. They had derived that from a certain Philips' CBM for pain, saying "this model has been succesfully applied to chronic pain". Not only was Philips' piece just as hypothetical als Wessely and Chalder's, making that statement untrue, but it also doesn't make practical sense. Ho-Yen point this out. I think he's being generous (as, given their writings and attitudes, I think Wessely and Chalder cared more for old harmful prejudices and their own theories than actual patient observation), but he says that their model is flawed because they have looked at patients that have been ill for more than five years, meaning that from experience they have learned to avoid certain activities because of the effects on their illness level, in contrast to patients who have gotten ill more recently who still have to learn what does and doesn't work for them, and take their illness seriously. "Those who are chronically ill have recognized the folly of the approach which is taken by the recently ill and, far from being maladaptive, their behaviour shows that they have insight into their illness." (See also Hutan's posted table above) This reality of course poses a problem. Their whole premise is that after the acute phase patients start to unnecessarily limit activity in reaction to "fatigue" or other normal, mild complaints because they fear it's bad for them. Without that the whole CBM, the reason for CBT (which is about graded exposure to the avoided thing) falls apart. In a reaction to this paper, Wessely et al try to make it seem like Ho-Yen and they themselves are saying the same thing really (they're not), and that this has been their observation all along too. They then twist Ho-Yens piece, and say that that gives an "even more convincing explanation" for activity avoidance, because due to operant conditioning patients "powerful experience of failure" will lead to "persistent avoidance". Boom-bust was an adaptation of the CBM narrative in reaction to its utter failure to fit actual reality.
Another important thing about Ho-Yens paper is that he rightly points out that nothing about Wessely et al's proposed approach was "new" but it was "no more than the conventional view". Ho-Yen seems to be explicitly talking about the treatment of patients with PVFS: "patients have been told for decades to 'get out and exercise' or 'go back to work'. Indeed, the truly new approach is that of moderating activity." But he is also right in general, which isn't a surprise, as Wessely thought he was treating "abnormal illness behaviour", a fusion of hypochondria and hysteria.
