Physical activity before and after exercise in women with chronic fatigue syndrome, 1998, Sisto et al.

Abstract
We measured physical activity after strenuous exercise in 20 women with chronic fatigue syndrome (CFS), compared to 20 sedentary healthy volunteers who exercised no more than once per week.

Activity was measured for 2 weeks using a portable waist-worn vertical accelerometer. After the first week of activity monitoring, all participants returned for a maximal treadmill test, followed by continued activity monitoring for the second week. Five activity measures were derived from the data: (i) average activity; (ii) total activity; (iii) duration of waking day; (iv) duration; and (v) number of daily rests.

A repeated measures ANCOVA was used to determine post-treadmill group differences accounting for pre-treadmill differences. There was a significant reduction in overall average activity after the treadmill test, with the greatest decrease on days 12 through 14. This reduction was accompanied by a significant increase in the duration of the waking day and number of daily rests.

Thus, marked exertion does produce changes in activity, but later than self-report would suggest, and are apparently not so severe that CFS patients cannot compensate.

Link: https://pubmed.ncbi.nlm.nih.gov/9797929/

 

An old study from 1998 by the research team of Benjamin Natelson. They measured activity levels before and after an exercise test.

The exercise test had remarkably little effect on activity levels. There appears to be no anticipation or reduction of activity before the test and activity levels remained relatively constant afterwards. Interestingly there was a reduction in activity and more rest but only 5 days after the exercise test.

 

Cannot see how you are going to recruit people with significant PEM from an advertisement for people with fatigue. When I had Long Covid mildly there is no way I would have volunteered for a study like this. Anyone I can think of with significant ME/CFS I would expect to keep well clear of this sort of study.

And performance will have been modified by all sorts of expectations on the subjects' parts.

It is interesting that researchers actually tried this sort of documentation of PEM thirty years ago but I don't see any interpretable data coming out of one off maximal exertion tests.

 

Something similar was found in this study that used graded activity with activity meters. Patients were able to increase their activity levels but only for a couple of days. After 4–10 day, their activity level dropped indicating they were unable to keep up this level.
Time course of exercise induced alterations in daily activity in chronic fatigue syndrome - PMC (nih.gov)

 

What does a vertical accelerometer measure? Would it record the difference between, say, resting in a chair with your feet up while reading/working/doing something manual (eg knitting) and resting in bed with the curtains closed doing absolutely nothing?

 

A Dutch study did the same thing but only up to 5 days after the exercise test. Here the actometer results showed no notable decrease before or after the exercise test.

Impact of a maximal exercise test on symptoms and activity in chronic fatigue syndrome - PubMed (nih.gov)

 

This is interesting but it just leaves me with a lot of questions, some of which might be answered if I could see more of the article.

I get the impression the actometer axis isn't 'number of steps in a day' [on basis of it being eg 40], so would like to know what is actually in it. I'm guessing the test itself isn't included here, but the steps to get there would be. And whilst maybe some HCs and maybe some CFS might have had to do other things on the same day it might have taken up most of the day and it is one where both might have similar 'committments'.

So it is perhaps interesting to use this as an anchor and note that is a 'low activity' day for those who are HCs vs CFS it is consistent with their max days. All I can tell from sure really from this is that the CFS group might equal but don't really do 'more' than the level on that test day, where the control is the same amount as the test day leading up then it varies above as well as below this level.

As well of course I have questions about knowing more about the CFS participants - looking at the dip at day 2, vs the little dip straight after for the HCs I suspect maybe some did have PEM but who knows if they all did. And how severe were they? what other committments did they have?

And of course the slight issue is rolling 20 people's data together when onset of PEM could be 12-48hrs mightn't be such an issue if you were looking at people with more severe ME/CFS who all had PEM that lasted quite a long time, but if you've a mixed bag of more mild, maybe some 'chronic fatigue' instead of ME/CFS and add in differing commitments..

Anyway I suspect people don't realise that they really need to be profiling and getting a lot more information about their ME/CFS participants with these things, whether they are controlling them or not. Because of floor and ceiling effects.

In effect we are 'tethered' around what we have to do to manage. Not our 'baseline' but the compromise we have with a world that often doesn't allow us what we need.

Someone who is more ill might not even do much on a well day and then their PEM might involve needing to wee a lot. Someone who isn't severe might have committments they can't avoid even when they are in PEM like caring responsibilities, having a medical appointment, work, so the most they can dip has to be 'planned'.

 

I agree with @Hutan noting their son returning to school eventually and slowly collapsing, having tried to do so over a space of time. And note that it is interesting the top article talks about 12-14 days being the actual point they noted a reduction.

I think this serves more as a warning for methodology focused only on actimeter, rather than all the blurb put around these 'findings'. Because like other ill people we can only reduce our activity to the minimum we have to do. Until it catches up with us and permanently reduces our threshold or enforces a 'world on hold' crash. And I guess even child-caring has to drop, it becomes an utter can't and a whole new struggle of life. But these measures call themselves longitudinal and have no idea. The harms claims is ridiculous

 

Does the day of the exercise test actually include the test?

I assumed it included walking to and from, and agree that you've probably taken the day off work or it is a weekend where they might have been doing something similar going by the graph.

I agree on the moving other tasks, and we've an issue - which might now be better accomodated for with the latest tech - of all the other tasks like showering that wouldn't show on an actimeter that I consider probably are in many pwme more the hallmarks of how someone is feeling than just pure footsteps. How much you have to recline/many hours you are having to lie down is another one - if you are well enough you can make food in PEM then the walk to the kitchen is the same (or maybe more if you are coming from the bedroom).

This doesn't really show for example if any of them (back in those days) might have in a normal week been going to the gym or had a few days a week at work that had to be reined back on to keep things only to essential. Because it isn't comparing it with any other weeks. And even those who might know they would be affected could have taken the week off work to do this and fill in all the forms.

As there is a floor effect (everyone will go to the loo and that will involve steps, they might have to answer the door or get food etc), we've no sense at all of what I assume is the real issue of interest which is whether CFS 'dipped more' in what they did vs HCs. Because we don't have the standard week comparator.

To me this doesn't feel like it was really an open-minded test, but maybe I'm being harsh given how knowledge has moved on with time, but one that was only really open to 'ruling out' unless there was some way a dramatic difference could be shown