Physical activity measures in patients with myalgic encephalomyelitis/chronic fatigue syndrome [...], 2020, Rowe et al

Pre-print, not peer-reviewed.

Physical activity measures in patients with myalgic encephalomyelitis/chronic fatigue syndrome: correlations between peak oxygen consumption, the physical functioning scale of the SF-36 questionnaire, and the number of steps from an activity meter

Rowe PC, Campen C(Mv, Verheugt FW, Visser FC

Preprint from Research Square, 08 Apr 2020
DOI: 10.21203/rs.3.rs-21479/v1 PPR: PPR148584

Link: https://europepmc.org/article/ppr/ppr148584
Article: https://assets.researchsquare.com/files/rs-21479/v1/manuscript.pdf

 

This could be useful. A step towards something like the ACR score in rheumatology?

If developed, you could then use it to develop minimum clinically important differences which aren't just 'whatever we say they are'.

 

I'm not sure I do like that. They have three different measures that correlate, though not fully, and it's unclear why or whether they should be given various weights or in what context one should be more important than another.

Not quite sure how to think about this.

What do you think, @Jonathan Edwards?

 

I don't see much logic in the abstract. I have no idea what the correlations tell us - partly because there are no actual data, just p values. If the correlations were very close then there would been need for combining measures. They tell us there was a lot of variation so presumably they were not that close.

The talk about integrating measures but do not indicate why they think that helps. It sounds as if they think it will reduce the variability - but why would one want to do that if things really are variable?

I don't get the impression they have any insight into what it is they are wanting to achieve and how they might do it.

 

In my view the approach is leading to nowhere anyway. I think that they don´t have the right idea of the illness (I think also that some patients might not have the right idea, although it might be more than one disease, of course).

As far as I understood other patients from forums, the symptoms are ranging in a huge variability, and this already indicates that at least here no strict linear relationship takes place.

Well, they looked at physical symptoms, maybe here is one?? But whatfor then? One should better look at the junction where all symptoms could be generated. I think the ICC may give a good idea (even if they might be too restrictive).

One of their three measurements is VO2. Speaking for myself, having been especially mentally affected (still I am), I can say:I had some difficulties to go for a walk lasting longer than an hour, but I could ride a sporty bike all the day (though only two times a week if I din´t want to get worse). I do not see how the approach they take would measure this. I had no "energy" to do my beloved push ups or yoga, but I could work halftime effortless (if I only reach my bed timely).

I would recommend to think and ask more adroitly, albeit maybe the result will tell something interesting, someday.

 

The key point is that VO2Peak is not equal to VO2Max unless those central hemodynamic limits have been reached (lung capacity limits are far from being reached in CFS or ME patients, unless they also suffer from COPD or other lung condition).

It is indeed difficult for some patients to exercise to a true VO2Max, and I agree this should not be an exclusion criterion, but you have to ask the question as to why are these patients even doing a single maximal CPET in the first place?

 

On the topic of push ups and skeletal muscles.

A while ago I changed my physical activity from walking to push ups and pull ups. About 15 and 5 on most days, sometimes repeated later in the day. I clearly gained muscle strength and mass but my endurance has changed very little. My feeling is that the limitation in this kind of exercise is indeed the muscles, but if the muscles are being exhausted on a daily basis, even if just briefly, shouldn't endurance increase? Is it unusual that it's not increasing or does it take more for endurance to improve?

 

No.

 

I have a strange experience. In 2010 I heavily got worse after having changed my diet. For one week I could not lift up things (I had to occasionally lift up at work) of some weight. It felt as if the muscle would not be able to exert its strength.

After a week or so I still felt worse, but the muscles were fine again.

Yes.

 

Part of the picture of ME is that there is a certain level of overall function which can give a number on something like the SF 36 but it is far too blunt a tool to pick up anything much about the processes going wrong.

The original criteria included variability over minutes, hours, days and so on which CPET testing can pick up if done twice but results for any random day don't tell us anything.

Questionnaires only give the least interesting results for ME, like continually doing research which shows that blind people can't see. A waste of money and of little use to patients.

I wish papers like this were part of a move to ditch the questionnaire for proper tools of inquiry.

 

Now published, open access, here, https://translational-medicine.biomedcentral.com/articles/10.1186/s12967-020-02397-7