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Is there any evidence that deconditioning alone causes pain and fatigue?

Discussion in 'General ME/CFS News' started by oceanblue, Apr 29, 2012.

  1. Firestormm

    Firestormm Guest

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    Good point. Well put. I'll have a read of your link tomorrow if I may. Am retiring for the night.
     
  2. Esther12

    Esther12 Senior Member

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    Sleep well. Probably best not to watch Chalder before bed... I never find her a calming presence!
     
  3. Firestormm

    Firestormm Guest

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    Well. This mornings 'news' has rather dulled my appetite for more today, so it will have to wait a little longer.

    I mentioned above that we were fighting for our local service, well I obviously have a dilemma. Indeed I suspect we all do. And it's the same one. Indeed I don't think we have a choice.

    At the ground level all we have is the NICE Guidelines in relation to state funded resources. And at the ground level all we can do to keep that funding in place for a specific service (though that might prove a contradiction in terms) is to ensure local health authorities provision their services accordingly to ensure each and every person is correctly diagnosed (another contentious contradiction) by specialist medical clinicians, and that they are offered the interventions that this morning were endorsed as being cost effective (another contradiction).

    In addition, that ME doctors are aware of drugs that might be prescribed for specific symptoms, and that they intervene and help support patients through the welfare and social care systems. Also, and importantly, that as local support charities we are kept informed and help shape reporting procedures that attempt to measure the effectiveness of interventions, and how many patients are taking up said therapeutic interventions etc.

    It's an awfully uncomfortable situation to be in. And whilst at the research and national campaigning level I will continue to support change and improvement and publish the failings and flaws inherent in the PACE methodology, and push for more funding for research that leads to a greater acceptance and understanding of the inherent condition itself - until such research reveals specific lines of conventional treatment/new treatment - these therapies which may only have an holistic effect are in essence all that we have from the state.

    Do you think that patients are really afraid of taking up these interventions? That it has been so badly handled and oversold and hyped (form both 'sides') that patients will not take up a referral even if it is offered? In a sense I would want everyone to take a referral and then to report realistically on how it has or hasn't helped. Because if patients don't take up these provisions then I can see the funding disappearing. But it's so damn hard to feel comfortable about any of this.

    If a patient is referred for therapy and they do benefit from it - is that wrong? Should they feel bad? If everyone engaged in CBT and GET and the results didn't support the research - that's more realistic isn't it? Gods it is so hard to know what to do. I've never been referred for GET specifically because it has always been felt that I am doing the best I can. Does that mean I am re-conditioned? And that the therapy I have had with counsellors and with the Mindfullness and CBT course is as much as I can expect? That whilst they were helpful I and my therapists recognised they were 'holistically' of benefit and weren't addressing the underlying condition itself.

    Until such time as the underlying condition is better understood and the diagnostic criteria can be better configured to reflect this (and it still might not prevent it occurring), the questionnaires used at the beginning, during, and end of these sessions of intervention will continue to give the impression that for some they 'work'.

    I wonder though if they are 'working' specifically on patients with ME or is it a case of 'we're all in this together' and that similar/the same interventions would work equally well or better on others with a long term neurological condition? Only I have a suspicion that these interventions and larger central 'treatment' centres will encapsulate not only ME but everyone else too.
     
  4. Esther12

    Esther12 Senior Member

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    I don't know what's best either fire.

    I don't think that I would go to an NHS CFS service until after a number of leading quacks had been fired. I've not really had any medical care (other than a couple of other things) since I attended a CFS centre about seven years ago (I guess that would count as a 'social saving' on health care costs, and indicate how cost effective their services were).

    I don't think that there's anything bad about anyone benefiting from anything: CBT, GET, homoeopathy or anything else. I wish everyone the best. But for me, honesty and a pursuit of truth is important, and a lot of the leading researchers involved with promoting CBT and GET for CFS have shown themselves willing to make deeply misleading claims in order to promote their own interests. They, and their approach to their patients, disgust me and I do not want to place myself under their authority or within a system which believes that they should be paid to provide 'care 'to patients.

    I also understand that the quality of local services varies greatly, and that I could be in a particularly poor spot. Hopefully your service is better. However, so long as anyone working as a CFS specialist is failing to actively condemn some of the misleading claims being used to promote funding for their centres to provide CBT/GET, then I cannot really respect them. At the moment it seems that there is a very limited amount that can be done for those with CFS, and fighting against quackery should be one of their top priorities.

    edit: Sorry for going OT!
     
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  5. Firestormm

    Firestormm Guest

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    This from the Mail yesterday: http://www.dailymail.co.uk/health/a...-treated-medical-condition.html#ixzz23crAeQsR

    Follows this research I believe: http://jp.physoc.org/content/590/15/3413.full

    Standing up for exercise: should deconditioning be medicalized?

    Apparently, according to the furore raised on MEA Facebook, early editions of the Wail's nonsense referred to CFS/ME as a prime candidate - but such references have now been removed from the article I am told.

    Anyway, this is the kind of thing we were talking about right? Exercise (or lack of it) = deconditioning. I do find this all rather nonsensical. I mean if as seems likely we are a sedentary race how can we be considered deconditioned? Who's the benchmark?

    As it was 'news' I shoved it all on a new thread: http://forums.phoenixrising.me/inde...ioning-be-medicalized-pots.18915/#post-288211
     
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  6. PhoenixDown

    PhoenixDown Senior Member

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    Just stumbled across this: http://www.ncbi.nlm.nih.gov/pubmed/15016575

    It deserves a thread of it's own really. Basically this is one of Wessely's "See, I do physiological research into CFS so why is everyone mad at me?" papers.

    Same old story, according to the authors even though they were doing genuine physiological investigation, there just so happens to be a behavioural cause of their findings. But don't be mad at them, after all they are only trying to help.

    Notice how they claim that no biochemical or immunological abnormalities WITHOUT fully testing for them, thus misleading the medical establishment.
     
  7. Firestormm

    Firestormm Guest

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    Just came across this in my prep. for a meeting next week:


    Will see if they feature any of that research when I get to the end of my reading and will add later as an edit.
     
  8. oceanblue

    oceanblue Senior Member

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    Thanks, Firestormm. I've been off doing other things for a while, but this paper caught my eye, with its longitudinal (rather than usual cross-sectional) method and conclusion that "These data do not support models that posit associations between CF [Chronic Fatigue] and deconditioning." Naturally this is about CF rather than CFS but if the deconditioning model is right, it would surely apply more widely since it is a generic mechanism and should predict chronic fatigue, whatever the definition:

    A longitudinal study of physical activity and body mass index among persons with unexplained chronic fatigue
     
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  9. oceanblue

    oceanblue Senior Member

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    Finally, a summary of the main evidence from this thread:

    Deconditioning and its role in CFS

    The idea that inactivity will lead to a vicious cycle of deconditioning, increased fatigue and further reduced activity is widespread in medicine. In the case of CFS, some have argued that whatever triggers the initial illness, CFS is primarily perpetuated by such a cycle of inactivity and deconditioning. The 2011 PACE trial explicitly used this theory as the rationale for Graded Exercise Therapy, GET.

    Perhaps the sheer plausibility of the Deconditioning hypothesis explains its popularity, but the idea falls when tested against the evidence - such as the effect of deconditioning on healthy people, the actual level of deconditioning among CFS patients and the (in)ability of of exercise programmes to restore fitness and health to patients.

    What is Deconditioning anyway?
    In medical research, deconditioning is usually interpreted as having become so unfit that normal activities of life become fatiguing. Deconditioning in almost always measured in the same way as fitness, by measuring maximal oxygen uptake, VO2 max. This is the volume of oxygen consumed by a person at maximal exertion, and the higher the VO2 max, the fitter person, while very low VO2 max scores indicate deconditioning.

    Normally VO2 max is given relative to body weight, and a woman of average fitness in her thirties will consume around 35 mls Oxygen per minute, per kilo of body mass, or 35ml O2/min/Kg. The very best elite female endurance athletes can achieve a VO2 max of over 70 ml/min/kg. There are no definitive levels for 'deconditioned', but 15-20 ml/min/kg would probably be seen as deconditioned. At rest, the average person will consume around 5-6 ml/min/kg. [Relevant population norms]


    How could Deconditioning lead to fatigue?
    Deconditioning is widely thought to lead to a vicious cycle of fatigue, inactivity and more deconditioning. James Rimmer recently proposed there may even be a Disability-Associated Deconditioning Syndrome, Rimmer illustrated the presumed vicious cycle in an earlier paper:
    deconcycle.jpg
    However, Rimmer makes clear this is an unproven hypothesis, and, as evidence that disabled patients are deconditioned, he includes a graph of as yet unpublished VO2 max data for disabled patients showing levels around 15ml/O2/kg, which is undoubtedly deconditioned.

    Other researchers make bold claims for the deconditioning without any such evidence to back them up. For instance, a recent review of the link between fatigue and deconditioning in stroke found that there was no association between fatigue and any measure of fitness or activity, yet still managed to conclude that "it still remains highly plausible that exercise can have a positive influence on fatigue". And a review looking at the many possible causes of fatigue concluded that deconditioning leads to fatigue, yet didn't cite a single paper to support this - while running up over 180 references in support of other causes of fatigue.


    Are CFS patients really deconditioned?
    If the deconditioning theory is correct then CFS patients must be deconditioned, otherwise it can't be the cause of their fatigue or other symptoms. There have been at least fourteen studies looking at fitness levels and the largest study, with over 400 patients, did find evidence of deconditioning, but most other studies did not. Authors of the large study suggested their findings were due to assessing more severely affected patients than other studies - though the patients in other studies are probably more typical of the patients targeted in outpatient Graded Exercise programmes.

    Actually, quite a few of these other studies did conclude that CFS patients were deconditioned, but this is because they didn't use properly matched sedentary controls, a point illustrated by Sisto, who noted her patients had lower fitness than controls, but were still within population norms.

    One study that did match controls for activity levels found no difference between these sedentary but healthy controls and CFS patients. But the most impressive study, for me, was by Wallman who very carefully matched controls, and used a sub-maximal rather than maximal test as it was a better test of real-world capability and would be less likely to deter CFS patients from taking part. She found no difference in fitness levels between CFS patients and healthy but sedentary controls. Such is the nature of this field that despite this finding of a lack of deconditioning Wallman nonetheless concluded that GET was the appropriate treatment.

    One important study by Kathy Fulcher (and Peter White, who ran the PACE Trial) found patients had a VO2 max of 31 ml/kg/min, comfortably within population fitness norms and no different from their controls. The authors then suggested that the patients were 'deconditioned' as they had less muscle tone than controls, but firstly the controls were not properly matched sedentary controls, and secondly this seems to be arguing that reduced muscle tone is responsible for CFS - surely not? What makes this study so interesting is that these figures are for patients recruited into a trial of Graded Exercise, which specifically aimed to address deconditioning that appears not to exist in these patients.

    A later study from Peter White concluded that "fatigue was not caused by current levels of inactivity" in the CFS patients studied.

    So it appears that while some patients are deconditioned - and those that are bedbound must surely be - many patients are not deconditioned yet still have CFS. This does rather rule out a primary role for deconditioning in perpetuating the illness.


    Space Age studies: the effect of deconditioning on healthy people
    The ideal way to measure the negative effects of deconditioning is to take a bunch of healthy people and get them to become almost completely inactive, then see what deconditioning does to their health. Fortunately a number of such studies have been done thanks to NASA and the Soviet Space Agency (and their volunteers), who wanted to see what the long-term effects of weightlessness (or microgravity) would be on their astronauts. It turns out that the best proxy for weightlessness on Earth is long-term Bed Rest, a rather low-tech solution, but a very informative one for understanding the effects of inactivity separate from any possible illness.

    Unsurprisingly, long-term bed rest is not good for the human body. Amongst other problems, blood volume reduces rapidly, calcium is lost from the bones and the immune system suffers. Deconditioning takes place too, but at a relatively slow rate. A 2006 study found that while VO2 max (fitness) reduced by 13% in 14 days (1% a day), it only declines by twice that over 3 months, an average 0.3% loss a day. Contrast this with the statement in the PACE GET Manual given as a reason not to rest after a setback: "we can lose 10 % of our muscle strength in just one week of bed-rest, or even 1% per day". The implication is that after 30 days you would lose 30%, maybe even 365% in a full year...

    The only studies I could find* that noted fatigue as a problem were very long-term: a 6-month study noted: "Mild fatigue was noted for several months and then disappeared". Another, even longer term study, (n=3, 7-8.5 months) commented: "During reambulation [recovery after bed rest] ... easy fatigability was subjectively noted for 4-6 months."

    Which suggests that deconditioning might at best cause mild fatigue (presumably at rest), and that when highly deconditioned activity can cause easy fatigability similar to the situation with CFS. But the people in these studies had just spent around 8 months confined to bed and would have been way, way more deconditioned that CFS patients in outpatient clinics.

    So deconditioning, even from months of enforced bed rest, only seems to cause minor problems with fatigue at rest or fatigability, and this was at levels of deconditioning far greater than apply to CFS patients attending GET clinics.
    Does Graded Exercise work for CFS?
    The ultimate test of the theory that deconditioning plays the primary role in perpetuating CFS is to use exercise to reverse the deconditioning and so produce recovery. This is exactly the approach tested in the PACE trial, as the therapists manual explains:
    The Lancet trial paper itself merely talks of 'improvements' fatigue and function, but if deconditioning is the primary cause then dramatic results should follow from reversing it.

    The effects of exercise on CFS
    Compared with the control group, Graded Exercise (GET) led to rather modest improvements in fatigue and physical function. Fatigue improved by an average of 2 points on what is effectively a 22 point scale, while function improved by 9.4 points (0-100 scale). However, both of these measures rely on patient reports and so are liable to self-report bias, especially in an unblinded trial. The one more objective measure included in the Trial was the 6-Minute Walking Test. GET patients improved their walking distance by an average of just 35 metres (compared with controls) after a year of exercise training. This left them completing an average distance of 379 metres, spectacularly short of the expected 575m for healthy adults - even though the most common choice of exercise for GET patients was walking. There is a wonderful animation that shows the walking distance progress made in PACE compared with healthy controls:



    To really put these results into context, the GET Therapists manual expects most CFS participants will be able to start aerobic exercise by week 4 [page 46], and riding an exercise bike for 20 minutes every day is given as an example of a long term goal by the end of the programme [page 41] It also states that,
    The Trial also found that there was no improvement in working hours lost in the GET group relative to controls.

    Big trials, small results
    PACE was the largest clinical trial of CFS treatment ever carried out, with 160 patients in the GET group. FINE, the second largest CFS clinical trial (n=95) tested 'Pragmatic Rehabilitation', a therapy that also aims to reverse the presumed deconditioning responsible for perpetuating CFS. This study found no improvement, relative to controls, in either fatigue or function one year after treatment. The authors went on to re-analyse their data using a different scoring method and found a small improvement in fatigue, similar to PACE, but still no improvement in function. These results are not consistent with the idea that deconditioning is the primary force perpetuating CFS.

    One final point on effectiveness, from that Fulcher & White study again. This found that fitness (VO2 max) improved by 13% in the GET group compared with baseline indicating a modest gain from exercise. It also found a modest improvement in this group relative to controls. However, the two were unrelated:
    So they took patients who, on average, were not deconditioned and found that they could improve their fitness by a modest amount, but that fitness improvement did not correlate at all with overall improvement.

    Conclusion
    To sum up, the bulk of the evidence weighs strongly against deconditioning playing a primary role in perpetuating CFS. Firstly, most CFS patients - at least those well enough to get to secondary clinics for measurement and treatment - are not deconditioned compared with sedentary but healthy controls. Secondly, studies of long-term bed rest in healthy adults indicates that deconditioning can, at best, play only a minor role in fatigue amongst outpatients, either at rest or in response to exercise. And finally, the largest studies carried out to date on CFS patients show that exercise or rehabilitation programmes do not lead to substantial gains of the kind that would be expected from reversing the underlying cause of the illness.

    Each of these individually is a serious obstacle to the deconditioning theory of CFS. Taken together, it's hard to see how anyone can still argue that deconditioning plays a primary role in perpetuating CFS.

    Feedback welcome
    Please let me know if you see any errors or think I've missed out any important evidence.
     
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  10. user9876

    user9876 Senior Member

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    I think this is an excellent write up, perhaps you could try to submit it somewhere as a short review paper.

    The area where there may be more evidence is in the rehabilitation of people who have had long stays in hospital. Nice have guidelines for rehabilitation from critical illness http://www.nice.org.uk/CG83 . Physios routinely help people who have been in hospital strengthen their muscles etc I'm sure they would have more success of 35m extra walk because they are dealing with people who have been treated.
     
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  11. Firestormm

    Firestormm Guest

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    Blimey Ocean. You come straight back with a welcomed BANG!! Nice job dude. I shall take a while and give your summation the attention it deserves old chap. Well Done. There's been some excellent efforts of late with regard to matters pertaining to the perceived 'understanding' of people with our condition - 'us' - and I shall add yours to my 'file' for use in the real world. Thanks :)
     
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  12. oceanblue

    oceanblue Senior Member

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    Thanks. Cort has said he's willingto use this as a front page piece and I'd like to see it written up for a journal since there is so little challenge to the prevailing 'wisdom' in CFS, but not sure who'd take it.

    Really good point about rehab for those recovering from longs stays in hospital as a comparison. I'll take a look at the NICE stuff, but let me know if you are aware of any good references in this area.
    Thanks. Look forward to your comments (and maybe even a 'like' to take me to 300, at which point I can retire happy).
     
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  13. oceanblue

    oceanblue Senior Member

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    Woohoo! Thanks, user9876, I have now achieved my life's goal. I'm outta here...
     
  14. Esther12

    Esther12 Senior Member

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    Possible typos:

    [this doesn't sound right to me. being unfit? someone being unfit?]


    [remove 'of' and ','?]


    I thought that this section seemed a bit less good, but you may well disagree with me here... lets see! CFS patients may be no more deconditioned than sedentary controls who do not suffer from disabling fatigue, but rather choose a sedentry lifestyle... but that's still a type of deconditioning. Just because studies did not use sedentary controls does not mean that they are not showing genuine deconditioning amongst CFS patients. That many CFS patients suffer from far more severe and disabling fatigue than those sedentary controls with an equivalent level of deconditioning would seem to show that the deconditioning is not the cause of fatigue in CFS, but it does not show that CFS patients are not deconditioned.

    Also, post PACE, I have problems with population norms that doesn't provide a lot of raw data... eg:

    Regardless of what the population norms for deconditioning are, I think that it's possible to have a reasonable definition of 'CFS patient' which would require a reasonable definition of 'deconditioning'. It could well be that as a society we're so unfit and deconditioned that CFS patients aren't that unusual in this regard, but much seems to be depend upon the criteria being used.

    It seemed like the evidence being presented wasn't really answering the question 'Are CFS patients really deconditioned?', but instead, 'Are CFS patients more deconditioned than sedentary controls who do not suffer from disabling fatigue?' It felt a bit like you were conflating these matters in an inappropriate way.

    This seemed too strong to me, following on from the evidence you'd presented. But I know that you had focused upon the evidence for bed rest leading to fatigue. How about something like:

    re PACE: could be worth mentioning new data on hours worked too?

    I thought that did a really great job of condensing a lot of info into a very short and easy to understand summary. As someone who has followed this thread, I know how much information went in to that. I think it will make a grand article.
     
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  15. oceanblue

    oceanblue Senior Member

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    Thanks all for the likes - I'm not sure if this is a compliment or a determined effort (e12 tried very hard here) to make sure I will keep my promise of leaving the forum having reached my life's goal... Will in fact be moving on once Deconditioning is done and dusted, but i'm not quite done yet.
    done, thanks.

    Interesting point, I probably need to tighten up the language. The problem is that there isn't an absolute definition of deconditioning, but in medical terms e.g. the Rimmer papers it's generally used to mean 'so unfit as to cause problems with functioning'. So maybe I should have start with that as my definition of deconditioning, and leave eg healthy sedentary controls are merely 'unfit', as I don't think that kind of unfitness is usually covered by what researchers refer to as deconditioning. Let me know what you think.
    Entirely understandable, and I'm working on this. Getting population norms isn't easy, at least not well-referenced ones (there are plenty online, and that's what I've relied on here) so I've had to order some books from university library.
    Used that, thanks. Might look at putting more emphasis on all the studies that don't mention fatigue as an issue.
    Good point, done.

    Ta very much.
     
  16. user9876

    user9876 Senior Member

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    I had a quick look around rehabilitaion, deconditioning and cancer as I thought this would be an interesting comparison.
    http://www.oncologypractice.com/jso/journal/articles/0502094.pdf talks about some of the issues although only points to two pieces of evidence. I thought this was an interesting comment since it relates fitness with fatigue


    That seemed to make some kind of sense to me.


    http://www.minnisjournals.com.au/_images/articles/pdf/article-pdf-0191.pdf
    Reviews the use of exersice routines for reducing cancer fatigue. They seem to conclude that it is useful but the evidence is of poor quality. It may be that patients exercise more as fatigue is reduced!

    Another paper around exersice studies is http://deepblue.lib.umich.edu/bitstream/2027.42/55869/1/22267_ftp.pdf which may be of interest since they record VO2max levels(blood results are also in the paper)
    These are sedentary subjects who are undergoing radiotherapy so it may be interesting to see how they compare with people with ME.

    I also found a NASA study paper but I assume this is the one you are referring to:
    http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20030052739_2003041669.pdf
     
  17. Esther12

    Esther12 Senior Member

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    You can't leave us! I've unliked your posts.
     
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  18. oceanblue

    oceanblue Senior Member

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    Thanks for digging this out: problem is, cancer is another area where deconditioning is argued without too much evidence to back it up. That oncology practice article is based on an interivew; I'd seen the claims before that activities of daily living could make cancer patients go anaerobic, though it would be a reasonable definition of deconditioning.
    16 ml/min/kg is deconditioned by any definition, 25ml is marginal and would depend on age and sex of the patient for comparison, but I would like to see the source for that 16-25ml figure, and this piece was only an interview. On these figures, only the most unfit of the patients would have problems with daily activities, and there was no evidence cited for the daily living data either.

    Thanks - that was the NASA study I'd used, a perky little read.
    Good point, also a Cochrane review of exercise for cancer fatigue found an effect size of only 0.23, which is small.

    What I'd be really interested to see is how fast people recover fitness after long-stays in hospital/intensive care where once the trauma was over they were in reasonable shape. I'm pretty such patients they go through fairly aggressive, and reasonably successful rehab regimes which would make a neat counterpoint to The CFS Experience. Must look at the NICE review you mentioned. edit: just had a peek: looks like the NICE team couldn't find much evidence since very little research has been done in this area, and what had been done was not of the highest quality.

    Damn, hadn't thought of that.
     
  19. oceanblue

    oceanblue Senior Member

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    New population 'norms' could classify CFS patients as deconditioned
    but the new 'norms' may be unrepresentative

    Slight complication: I've argued in this thread that most of the studies purporting to show that CFS patients are deconditioned fail to use properly matched healthy controls. But that the same patients don't qualify as deconditioned by comparison with previous population norms.

    New data
    A more recent, larger and widely quoted set of VO2 max norms probably would classify patients as deconditioned. So I've spent some time trying to understand why the new set of norms are so much higher (fitter) than the previous ones. This is mainly as deconditioning proponents might argue the new norms back up their case. The notes are really for my benefit so no need to read unless you are really interested.

    Original population norms: Shvartz, 1990
    These are based on reviews of earlier VO2max studies:
    Unfortunately I can't find the full text for this and the abstract doesn't say how many people were involved.

    New population norms: American College Sports & Medicine, 2009
    These are based on an enormous dataset (n>10,000) collected under the same conditions over several decades. However, there study is not directly representative of the wider population - the key issue is how much it would diverge from 'true' population norms.

    The data comes from The Cooper Institute, set up by Kenneth Cooper, the man who invented aerobics. . So, The Cooper Clinic is a private organisation in Texas that assesses fitness and gives preventative health advice to thousands of people. Most of those it assesses are sent by their employers. They are overwhelmingly white, around 80% are college-educated and probably the majority are from Texas too.

    However, 40% are overweight and another 20% are obese so they are not wildy fit, presumably. Some undoubtedly have health issues: the person I conacted there thought it was about 10%, but there are no hard figures for this.

    Also, this study did not measure VO2max directly, instead using a simple treadmill test. They cite studies showing an very high correlation between the treadmill test time and VO2max (r=0.92 to 0.94) but the total number of patients involved is only 100, so it's possibly a big step to project that to such a large sample across so many age groups.

    Comparing old 'norms' vs new 'norms'
    For the original norms (Shvartz 1990) they key category is "fair", defined as from the bottom 12th percentile to the bottome 34th percentile (below this are 'poor' and 'very poor', which might well be described as deconditioned).

    The typical profile for CFS patients in deconditioning studies is 75% female aged 30-39.
    Shvartz VO2 max population norms matched to this are:
    Fair (low, 12th percentile) = 27 ml O2/min/kg
    Fair (high, 34th percentile) = 31

    Most studies find CFS patients are within this range ie no more deconditioned than healthy people in 'fair' condition.

    However, you have to go much further down the New ACSM norms to get the same VO2 max:

    5th percentile = 27.6 (=12th percentile for Schvarz)
    15th percentile = 31.7 (=34th percentile for Schvarz)

    i.e. most CFS patients fall between 5th - 15th percentile of the ACSM scores. It's just not clear whether or not that means deconditioned.

    Because of the uncertainty around population norms, perhaps the best answer is to use well-matched sedentary but healthy controls in these studies, and leave population norms out of it.
     
  20. oceanblue

    oceanblue Senior Member

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    One final comparison. James Rimmer, who proposes there is a disability-related 'Deconditioning Syndrome' included some unpublished data in his paper (ie this data was not peer-reviewed) for VO2max for patients with disabilities:
    I don't think I can reproduce the graph, but for 30-39 year olds, the disabled patients have VO2max score around 15 ml O2/min/kg, i.e. unambiguously deconditioned and well below CFS patients.

    This indicates that CFS patients are in much better shape than disabled patients, many of whom will have far less fatigue than CFS patients (even though fatigue is a common problem in such illnesses).
     
    ukxmrv and Purple like this.

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