Repeat Test Reveals Dramatic Drop in ME/CFS Exercise Capacity

View the Post on the Blog


Hooked up for a CPET

Simon McGrath reports on Dr Snell's new study demonstrating that ME/CFS patients have a reduced capacity to exercise when they repeat a maximum exercise test one day on - unlike healthy controls.

One of the biggest problems of getting ME/CFS taken seriously is that often we 'look' normal, even though we feel lousy, and most lab tests produce 'normal' findings. How do we prove to the world that we are sick?

A defining feature of ME/CFS is Post-Exertional Malaise (PEM) and a couple of studies have clearly demonstrated PEM in patients [see box]. However, PEM is a subjective experience and one that can only be measured by patient self-report, which won't satisfy everyone.

Dr Chris Snell, Staci Stevens, Dr Todd Davenport, and Dr Mark VanNess's new study aimed to objectively demonstrate the problem of post-exertional malaise, by using a repeat Cardiopulmonary Exercise Test (CPET). As they formally hypothesized in their paper: "an exacerbation of symptoms following the first test would be reflected in physiological responses to the second".


The study

The 51 CFS patients were all women, met Fukuda criteria and also reported PEM. Controls, also female, were similar in age and BMI, and were fairly sedentary. In fact, the results of the first CPET revealed that the controls were in the bottom 10% of published population norms and would count as deconditioned. CFS patients were barely different from controls so were also deconditioned, but, crucially, they were ill while controls were healthy, casting doubt on the idea that deconditioning is responsible for CFS.


CPET: Cardiopulmonary Exercise Testing explained

CPET is the Gold standard for measuring physical capacity, used by athletes wanting to measure the effectiveness of their training programs. It's also used medically e.g. to diagnose cardiovascular, breathing and muscle disorders.



The principle is to get someone to exercise to exhaustion, using a protocol that starts easy and gets increasingly difficult until the subject can do no more. The key measures for this study are the Volume of Oxygen consumed (VO2) and the amount of work done, measured in Watts on the exercise bike.


Anaerobic/Ventilatory Threshold

A critical factor is the anaerobic threshold, the point at which the body has to supplement normal aerobic (oxygen-burning) metabolism with much less efficient anaerobic metabolism, creating lactic acid. This threshold is measured in CPET by finding the point where carbon dioxide (CO2) starts to be produced faster than Oxygen, and is called the Ventilatory Threshold, or VT (strictly, VO2 VT).




VO2 max versus VO2 peak

One challenge of CPET is detecting if the person is using maximal effort, as opposed to trying pretty hard. Data showed that CFS patients and subjects here all went deep into anaerobic exercise and met at least one other measure of high effort. However, as it's almost impossible to be completely sure, the study reported 'peak' measures instead of maximum, e.g. VO2 peak, not VO2 max.

Note there are equivalent thresholds for work output, in watts: W max, W peak and W VT

More: Lannie's blog on PR about her CPET at Pacific Fatigue Labs.


Day 2 results separated patients from controls



A Day 2 CFS patient...

The big differences between the groups emerged on the second maximal CPET test, 24 hours after the first. On average, controls did slightly better on Day 2 (something that has been observed in other studies too) while patients did substantially worse. Interestingly, VO2 peak did not differ significantly between patients and controls, but peak Watts output was significantly lower, as was VTO2 . The biggest difference of all was for Watts output at VT, down for the patient group by over half.

The study found the repeat test could separate CFS patients from controls in this sample with 95% accuracy (3 errors in total). They also used a statistical technique called 'cross-validation', which indicated the test would achieve a 90% accuracy in an independent sample (though see issue with convenience sample below).

This ability of a 2-day repeat test to discriminate healthy but sedentary controls from CFS patients is critical. In theory, doctors can manage this easily enough without a CPET test. However, where there is doubt about the reality of symptoms, as can happen with disability insurance claims, an objective test can demonstrate that a patient really is sick. As Workwell Foundation notes, it's useful in legal or medical disputes; the reduced performance on VT is "impossible to fake", adds Dr Snell.
The study conclusion said:
the post-exertional state in CFS is characterized by objectively measurable deficits in submaximal metabolism and workload that would be nearly impossible for patients to fabricate
In some ways the findings are unexpected, as it was the same group's earlier finding of a substantial drop in VO2 max on the second test that caused such a buzz amongst patients. And the big drop in output at VT wasn't seen in a study (albeit a small one) by a separate research group, though a smaller drop was seen for VT, and VO2 max in a study presented at an IACFS conference. I asked Chris Snell if he was surprised by the finding. "No", came the reply: the initial study was small making the findings less robust, and he said that a much bigger effect on VT than VO2 max has been seen in the clinic too.


Evidence of Post-Exertional Malaise from subjective studies
As well as the objective evidence from this new paper, PEM has been shown by self-report measures too. A 2010 study from Pacific Fatigue Labs found that only 1 of 25 female CFS patients recovered from a maximal exercise test 48 hours later while all 23 sedentary controls did. Another study using a moderate exercise test found that fatigue and pain increased in the 48 hours after exercise in CFS patients - while it returned to normal in that time for both healthy controls and Multiple Sclerosis patients.

Committed to Maximal CPET

Given that it's hard enough for people with ME/CFS to do one maximal test, let alone two, these results create the temptation to just run the second test as far as the Ventilatory Threshold and forget about VO2 max. But Chris Snell stressed that the Workwell Foundation remains committed to the repeat-maximal approach. First, VT can't be measured on the fly so they wouldn't know when to stop the test. And perhaps more importantly, the post-exertional effect appears to differ by patient, with some showing a greater effect on peak measures and others at VT. Dr Snell suggested that varying post-exertional responses may well reflect different underlying pathologies.


Unique to ME/CFS?

Is this the killer test that uniquely identifies CFS patients? Dr Snell has reported that their clinic has tested patients with numerous illnesses including Multiple Sclerosis and Congestive heart failure, but have only seen the problem in ME/CFS patients. Published studies show normal repeat CPET performance for sarcoidosis, angina, Chronic Airflow Obstruction, Pulmonary Hypertension and heart disease. I’ve seen no studies showing failure to reproduce CPET results in other illnesses, but it’s probably too soon to say if this is unique to ME/CFS, or just very unusual.


What might cause the exercise problems?

The authors suggest that a synergy of small effects across multiple systems could be responsible for the poor exercise performance of the individuals with CFS. Lower oxygen carrying capacity could result from low blood volume, while low oxygen consumption could also result from autonomic dysfunction and reduced ventilation. But research into the causes is needed.


No study is perfect...
  • There were only 10 controls, though as the repeatability of CPET results is firmly established (with 94% reliability between tests), in some ways controls mainly serve to demonstrate that the protocol and equipment is working properly.
  • The CFS patients were a convenience sample, rather than, for example, consecutive referrals to a secondary clinic. This, and the fact that patients had agreed to a repeat maximal exercise test, means the results might not generalize to the patient population as a whole.
  • The earlier study by this group, and the other studes from independent groups, didn't find the dramatic changes with workload at the ventilatory threshold, so further replication would help to confirm the nature of the changes.
These findings, which make visible the hallmark ME/CFS problem of post-exertional malaise, have potentially huge importance. Replication of this study, perhaps with a more representative sample of CFS patients and some sick controls, should in my view be a priority for the research community. Stage two of the huge CDC multi-clinic study could provide the perfect opportunity for this.

Simon McGrath tweets on ME/CFS research





Phoenix Rising is a registered 501 c.(3) non profit. We support ME/CFS and NEID patients through rigorous reporting, reliable information, effective advocacy and the provision of online services which empower patients and help them to cope with their isolation.

There are many ways you can help Phoenix Rising to continue its work. If you feel able to offer your time and talent, we could really use some more authors, proof-readers, fundraisers, technicians etc. and we'd love to expand our Board of Directors. So, if you think you can help then please contact Mark through the Forum.

And don't forget: you can always support our efforts at no cost to yourself as you shop online! To find out more, visit Phoenix Rising’s Donate page by clicking the button below.


View the Post on the Blog
 

Comments

This study do not proof PEM post-exertional malaise but post-exertional fatigue! Read the abstract correctly. Verry important finding.
A valid point, I think. But I usually find that my energy levels appear normal the day after exertion. I become weak and fatigued as part of PEM. I have an initial, short-lived (a few hours at most) spell of fatigue immediately after exertion, which then fades and I feel OK again until PEM (including fatigue) sets in.

How it seems to me is that the exertion causes hyperlactaemia, which then has various downstream effects including overloading the liver.

This paper 'Lactate physiology in health and disease' may be of interest:

http://ceaccp.oxfordjournals.org/content/6/3/128.full
 
This study do not proof PEM post-exertional malaise but post-exertional fatigue! Read the abstract correctly. Verry important finding.
Hi Gus
You're quite right that the abstract only mentions fatigue, but the paper itself mentions both malaise and sympotoms more more generally:

As a corollary to extreme fatigue in CFS, post-exertional malaise (PEM) or exacerbation of symptoms following physical exertion, is considered one of the most common and recognizable aspects of the illness.6, 7 The Canadian Consensus Document on CFS goes so far as to mandate evidence of symptom expression following physical activity.4 The presence of postexertional symptoms in the clinical presentation of CFS suggests that cardiopulmonary exercise testing (CPET) can be reliably employed to elicit symptoms in CFS while also serving as both an indicator of clinical status and a quantifiable model of physical exertion.

... The purpose of this study was to establish the discriminative validity of objective measurements obtained during CPET to distinguish individuals with CFS from non-disabled sedentary individuals. To control for potential individual differences in preparation for testing and the cyclical nature of CFS symptoms, the present study employed a dual test paradigm comprised of 2 CPETs, each separated by 24 hours. It was hypothesized that an exacerbation of symptoms following the first test would be reflected in physiological responses to the second test.
Fatigue is usually defined subjectively, the objective measures in this test were really markers of the fatigue/malaise, rather than measuring them directly. It could be argued that the earlier onset of the anaerobic threshold at test 2 is an objective marker of fatigue, though the paper doesn't do that (instead it suggests there is a problem with metabolism ie much less output for a similar consumption of oxygen at VT.
 
Any chance we could have access to the full paper?
 
"The authors suggest that a synergy of small effects across multiple systems could be responsible for the poor exercise performance of the individuals with CFS." I think this statement is critical. Its looking increasingly likely that well defined CFS is a heterogenous collection of different problems. Traditional medicine has looked at single-cause disease. For a heart to not supply sufficient blood for everyday use, for example, it must have seriously degraded capacity. I have been asking a question for some years now: what happens if you lose much less capacity, say 10 to 20% in many interacting systems? Rather than failure at one critical point, its the entire system that would be degraded, and testing each individual part would show up as normal.

Consider a chain of things A to D. (This could be mitochondria, muscle function, heart function, circulation function for example.) Now suppose heart function is down 60%, then the circulation output would be down 60% as its on the critical path. Consider however if all of them were down by just 20% each, which might not be considered normal. What is the outcome? (0.8)^4 = approx 41% capacity. This is almost the same as a 60% fall in heart function, if measured over the entire chain of mechanisms.
Interesting. Do you think that this mulitple smaller problems paradigm is underpinned by a common underlying defect?

In a way, deconditioning, or deconditioning plus minor specific health problems could create a such a situation with lots of small problems that individually don't look that out of the ordinary but collectively cause a big problem. So could many other underlying defects ag with the autonomic nervous system. Just thinking out loud here.

Simon. Another cracker and very nicely presented on the full version I must say. Loved the cartoon :D

Having just returned from hospital and spoken with some physiologist science boffin about my 'mass of data' it would appear that initial suggestions are that my poor brain cell is being starved of oxygen during the night. It's too soon to say 'apnea' but we talked a bit around the topic; and I am left wondering to what degree oxygen starvation generally could be responsible for my muscle problems also (and lack of energy too I suppose) during the night and during the day.

It seems that oxygen is tied up with much that might be wrong. If my cells are not getting the oxygen they need then, as you said above, the outcome is more lactic acid and pain and discomfort for me. An inability to operate my muscles or for my muscles to recover from exertion. But above looks at inability to recover from exercise; and not ability to exercise in the first place - I am wondering then if those controls were experiencing the degree of muscle pain and ache etc. that I do constantly. Maybe this is where Prof. Newton's work comes into focus. Are 'we' just not getting enough oxygen, or not processing it, or not being able to process it?
Thanks.

And yes, there is a difference between the problems that many of experience day-to-day, and the objective deficits found in this study after a second maximal exercise test: the Big Bazooka approach. Much as I'm fascinated with this later study, I wish there were a test that could identify objective problems in more real-world conditons.

Hope the sleep tests throw up something useful for you.
 
The results of this study showed that it should detect 90% of CFS cases, or 10% of Fukuda-defined CFS cases would be missed. They didn't assess patients according to other criteria so it doesn't say anything about CCC and ICC - both of these require self-reported symptoms eg post-exertional malaise, rather than objective markers of exercise dysfunction.
Look again at the study's cohort, Simon. The study's subjects both met Fukuda and reported PEM. Fukuda doesn't require PEM. Therefore, the results of this study don't generalize to Fukuda- defined CFS.

You write that both the CCC and ICC “require self-reported symptoms...rather than objective markers of exercise dysfunction.” The ME/CFS Guidelines, however, both require Post-Exertional Malaise and/or Fatigue and include among their list of tests for abnormalities in ME/CFS “Cardiopulmonary Exercise Testing: AMA Guide for Evaluation of Permanent Impairment. Lower cardiovascular and ventilatory values at peak exercise help determine functional capacity, and peak oxygen consumption levels determine disability categories.” Such testing, of course, doesn't involve the Stevens protocol.

The ME Primer, on the other hand, requires Post-Exertional Neuoroimmune Exhaustion (PENE), which is confirmed under its Laboratory/Investigative Protocol using the Stevens protocol. “In a 2 consecutive day comprehensive 8-12 minute cardiopulmonary exercise stress test (measuring heart, lung, and metabolic function), only ME patients have significantly worse scores the second day & abnormal recovery from exertion:”
* Exercise tolerance test with expired gas exchange - (2 consecutive days) – measure cardiovascular, pulmonary & metabolic responses at rest & during exercise: peak oxygen consumption VO2 or VO2 at anaerobic threshold (AT) - decline of 8% or greater on test 2 indicates metabolic dysfunction, post-exercise blood analysis - increase in sensory, adrenergic and immune genes - increase in metabolite receptors unique to ME
Staci Stevens is a member of the International Consensus Panel, and the ME Primer uses the Stevens protocol to operationalize PENE. Those studies published as of last October are included in the Primer's description of the pathophysiology of PENE (pp. 2-4). This study (received October 27, 2011) builds on that research.

Given that the International Consensus Panel uses the Stevens protocol to operationalize PENE, a cardinal feature of ME, and calls for the removal of ME patients from the more encompassing CFS classification, Dr. Unger should indeed be using this protocol, as you suggest, in her multi-site study.
 
Thanks Simon, for a great article. It's very helpful.

This really is an interesting study, and if the findings can be reliably replicated, then the results will be exceptionally useful for so many reasons.

I like the way they used healthy but deconditioned individuals as a control group, and then objectively demonstrated that CFS patients (biologically) react differently to exertion when compared to deconditioned healthy individuals. This, in itself, is essential evidence to demonstrate that CFS is not a simple state of deconditioning, due to a fear and avoidance of activity etc. An objective biomarker would transform the field of ME/CFS.

Like others have mentioned, this research ties in with Julia Newton's objective findings that muscles from CFS patients produce a lot more acid than healthy controls.

Both these research studies lead to so many vital questions about ME/CFS, such as the one that Firestormm asked earlier in the thread: is oxygen not getting into our cells? And if it isn't, what is the reason?
Another question is: do we have dysfunctional mitochondria and, if so, what viruses potentially affect the function of mitochondria?

Repeating other people's comments again, I think much more biomedical research should be focused on the post exertional reaction in ME/CFS patients, as it is at the heart of the illness.
 
Thanks SImon - great reading
yes low blood volume mwy be one cause and that is easily tested for

Likewise POTS/OI - common symptoms of ME and could contribute to this in a major way - not enough blood to your heart and other muscles when exercising? not going to help anything.

POTS/OI are easily tested for but strangely very few PWME are ever tested for them - correctly that is - one BP reading sitting or lying then again standing is NOWHERE close to accurate - yet this is how I was measured and fobbed off for years - now I Know I DO have OI/POTS and managing them helps the ME a LOT.

cheers

ALly
 
I wonder if you could use this test on patients and controls before, during, and after something like GET with the aim of seeing if the loss of exercise ability can indeed be recovered by gradually increasing the exercise to the initial test level. I don't mean necessarily to prove if GET is useful or not; but really to see when and if a person's exercise ability returns to initial levels i.e. to see how long on average this 'PEM' lasts.

I also think it is important as a next step to try and better understand the knock-on effects of this inability to exercise as well on day 2 with the appearance of other symptoms generally subscribed to 'malaise'. It could be that the exhaustion on day 2 (or 3 whatever) leads to a person feeling sicker; there may be nothing demonstrable e.g. sore throat, swollen glands though perhaps sore muscles, pain and headaches might be more relevant - though subjective - or cognitive performance; but it would be very useful to study the after-effects of this 'over-exertion' in some way.

'Malaise' has been a useful term as is does describe the feeling rather well but I think we can now seek to better understand what this might encompass and explain why: the 'starvation' of oxygen could be responsible for so much more; and if it is then in what way.

And as part of para 1 above we could also look at establishing how long this post-exertion state lasts. Get a better understanding of how long recovery takes, comparing resting for example, with gradual increases in exercise. It might help to determine - as I said - how long our cells/whatever are taking to recover. Not recover to a healthy state; but recover to a state that allows us to 'over-exert' in this way again. Then run the same study. Then run the after-study. See if this inability persists and try and gauge for how long - as well as in other studies better determining why.

Just random morning thoughts :)

Health Rising also have an article about this study published yesterday:

Busted! Exercise Study Finds Energy Production System is Broken in CFS
 
Thanks for the article and link to the abstract -- I passed it on to my dr.
They did this type of testing back in the early Ampligen studies. It is sad that it has taken this long to get a study like this completed and published.
Glad to see it though.
 
Hi Simon , with regard to reduced level of function in a system of problems, while its possible there is a common underlying dysfunction, its more likely to define a family of dysfunctions. In other words, CFS with PEM/PENE is a family of disease with similar final symptoms. However that does not mean that most of us do not have the same thing.

If a large number of system failures are involved, over many organs and tissues, then the impact of individual variations including comorbid diseases and genetics will be large. At the very least I expect to see variations based on individual genetics for a range of issues, including methylation and other aspects of metabolism.

CFS could be the touchstone that creates a paradigm shift in medicine. That alone will create huge resistance in medicine in my view. If CFS represents the final common symptoms of a variety of disorders, then a single fully reliable test based on causation is unlikely. However I think repeat exercise testing might represent a reliable test on consequences, measuring the final outcome.

I am not convinced even ME is a single disease entity. I suspect it might be at least two different but similar diseases. Only in an ME outbreak are you fairly sure that patients will have the same disease, and then only for that one outbreak.

I really hope there is one single common mechanism though ... but its hope, not science at this point. If there is one cause, there can be one really reliable treatment. If its many causes, treating or curing it is going to be a long tough road, even after effective treatments for subgroups become widespread.

However if there is are common outcomes, then symptomatic treatment can vastly improve, even if the underlying cause is not cured.
 
The study's subjects both met Fukuda and reported PEM. Fukuda doesn't require PEM. Therefore, the results of this study don't generalize to Fukuda- defined CFS.
Yes, Fukuda + PEM, though as I said in the blog the results don't generalise to Fukuda+PEM either since it was a convenience sample, and subjects had to sign up to a double maximial exercise test, which not everyone will want to do.

You write that both the CCC and ICC “require self-reported symptoms...rather than objective markers of exercise dysfunction.” The ME/CFS Guidelines, however, both require Post-Exertional Malaise and/or Fatigue and include among their list of tests for abnormalities in ME/CFS “Cardiopulmonary Exercise Testing: AMA Guide for Evaluation of Permanent Impairment. Lower cardiovascular and ventilatory values at peak exercise help determine functional capacity, and peak oxygen consumption levels determine disability categories.” Such testing, of course, doesn't involve the Stevens protocol.
But this is not a mandatory test? Also, that test is to test functional capacity, separate from symptoms or fatigue (and is used widely to do the same in many illnesses).

The ME Primer, on the other hand, requires Post-Exertional Neuoroimmune Exhaustion (PENE), which is confirmed under its Laboratory/Investigative Protocol using the Stevens protocol. “In a 2 consecutive day comprehensive 8-12 minute cardiopulmonary exercise stress test (measuring heart, lung, and metabolic function), only ME patients have significantly worse scores the second day & abnormal recovery from exertion:”
* Exercise tolerance test with expired gas exchange - (2 consecutive days) – measure cardiovascular, pulmonary & metabolic responses at rest & during exercise: peak oxygen consumption VO2 or VO2 at anaerobic threshold (AT) - decline of 8% or greater on test 2 indicates metabolic dysfunction, post-exercise blood analysis - increase in sensory, adrenergic and immune genes - increase in metabolite receptors unique to ME
Staci Stevens is a member of the International Consensus Panel, and the ME Primer uses the Stevens protocol to operationalize PENE. Those studies published as of last October are included in the Primer's description of the pathophysiology of PENE (pp. 2-4). This study (received October 27, 2011) builds on that research.
Does this mean the Stevens protocol is mandatory to diagnose ICC ME, or is that an optional test? Mandatory would be worrying as a lot of people have relapses way below maximal exertion (also, VO2 max was not significantly different on test 2 for CFS patients for this new study).They are also quoting the unreplicated Lights study on increased mRNA expression; again surely not mandatory? I'm pretty sure that neither study - certainly not this one - used ICC criteria, so I'm not sure how anyone can be certain these are definitive tests and that falling below a particular threshold is exclusionary.

Given that the International Consensus Panel uses the Stevens protocol to operationalize PENE, a cardinal feature of ME, and calls for the removal of ME patients from the more encompassing CFS classification, Dr. Unger should indeed be using this protocol, as you suggest, in her multi-site study.
I do think this new test could be very important but needs replicating, especially as the dramatic fall in VTO2 is a new finding: the CDC study, with a larger and more representative sample would be the ideal place to do this.
 
And as part of para 1 above we could also look at establishing how long this post-exertion state lasts. Get a better understanding of how long recovery takes, comparing resting for example, with gradual increases in exercise. It might help to determine - as I said - how long our cells/whatever are taking to recover. Not recover to a healthy state; but recover to a state that allows us to 'over-exert' in this way again. Then run the same study. Then run the after-study. See if this inability persists and try and gauge for how long - as well as in other studies better determining why.
Just been searching my files to see if I had anything on 'recovery' time, and this video apparently cites an average of 4 days:


(I haven't watched it but found the link in a WordPress article)

I haven't had time to search for links for the following but they should be easy enough to find. Sorry about poor formatting but the info is copied from pdfs.

from 'A review on cognitive behavorial therapy (CBT) and graded exercise therapy (GET) in myalgic encephalomyelitis (ME) / chronic fatigue syndrome (CFS): CBT/GET is not only ineffective and not evidence-based, but also potentially harmful for many patients with ME/CFS' by Twisk and Maes:

Blacket al. (2005b) concluded that ME/CFS patients may develop exercise intolerance as demonstrated by reduced total activity after 4–10 days.
from 'Chronic fatigue syndrome and mitochondrial dysfunction' by Myhill, Booth and McLaren-Howard:

when the concentration of ADP in the cytosol increases and the ADP cannot be recycled quickly enough to ATP, another chemical reaction takes place. This becomes important if there is any mitochondrial dysfunction. Two molecules of ADP interact to produce one of ATP and one of AMP (adenosine monophosphate). The AMP cannot be recycled [6] and thus half of the potential ATP is lost. This takes some days to replenish and may account for the post-exertional malaise symptom experienced by patients.
from 'Differential heat shock protein responses to strenuous standardized exercise in chronic fatigue syndrome patients and matched healthy controls' by Thambirajah AA, Sleigh K, Stiver HG, Chow AW:
Basal hsp27 was significantly higher among CFS patients compared to controls, and decreased immediately post-exercise, remaining below basal levels even at 7 days. A similar pattern was observed for HSP60, which gradually decreased in CFS patients but increased in controls post-exercise.
from 'A real-time assessment of the effect of exercise in chronic fatigue syndrome' by Yoshiuchi K, Cook DB, Ohashi K, Kumano H, Kuboki T, Yamamoto Y, Natelson BH:
Following exercise, physical symptoms did get worse but not until a five-day delay in CFS patients.
from 'Time course of exercise induced alterations in daily activity in chronic fatigue syndrome' by Black and McCully:
Over the first 4-10 days of walking the subjects with CFS were able to reach the prescribed activity goals each day. After this time, walking and total activity counts decreased. Sedentary controls subjects were able to maintain their daily walking and total activity goals throughout the 4 weeks. Unlike our previous interpretation of the data, we feel this new analysis suggests that CFS patients may develop exercise intolerance as demonstrated by reduced total activity after 4-10 days. The inability to sustain target activity levels, associated with pronounced worsening of symptomology, suggests the subjects with CFS had reached their activity limit.
This study: 'Immunological Changes After Both Exercise and Activity in Chronic Fatigue Syndrome:
A Pilot Study' by White PD, Nye KE, Pinching AJ, Yap TM, Power N, Vleck V, Bentley DJ, Thomas JM, Buckland M, Parkin JM (interesting combination!) found that the journey to hospital for testing changed some immunological markers, a potential confounding factor when baseline values are taken on arrival at hospital instead of before leaving home.

from 'Physical activity before and after exercise in women with chronic fatigue syndrome' by Sisto SA, Tapp WN, LaManca JJ, Ling W, Korn LR, Nelson AJ, Natelson BH:
There was a significant reduction in overall average activity after the treadmill test, with the greatest decrease on days 12 through 14.
from 'International Consensus Primer for Medical Practitioners':
Activation and worsening of symptoms can be immediate or delayed by several days. When exercise is repeated the next day, abnormalities are more severe...prolonged recovery period: usually 24 hours,often 48 but can last days, weeks or cause a relapse....Post-exertional exhaustion may occur immediately after activity or be delayed by hours or days.
from 'Mitochondrial dysfunction and the pathophysiology of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS)' by Norman E Booth, Sarah Myhill, John McLaren-Howard:
The most characteristic and disabling symptom of M.E. is the postexertional malaise following activity or exercise, either physical or mental, often one to three days later...The replacement of the lost adenine nucleotides can take several days. This may explain one clinical feature of ME/CFS, namely delayed fatigue.
from 'DIAGNOSING AND TREATING CHRONIC FATIGUE SYNDROME (CFS)' by Dr Sarah Myhill:
delayed fatigue (mental and physical) – i.e. symptoms persist for 24 - 96 hours if you over-do things.
This is because when mitochondria are stressed, all the energy molecules (ATP, ADP and AMP) are drained out and cells have to wait 1-4 days for new energy molecules to be made via the pentose phosphate shunt.
(There is more detailed info about (possible) reasons for slow recovery in this document.)

Also from the above document, I am including this about 'boom and bust' for anyone who needs more understanding of the necessity of pacing:
all CFSs tend to push themselves to their particular limit every day and therefore do not give themselves a chance to get better. This means they have one day doing as much as possible, then three days to recover. Whilst you are on this roller coaster ride of activity and dives, you cannot hope to improve overall.
Fatigue and pain are the symptoms that prevent the body from damaging itself. Ignore these at your peril!
There is other excellent advice in the above document but IMO an over-emphasis on D-ribose, which many people cannot tolerate, and it can be risky, e.g. causing hypoglycaemia.
 
Yes, Fukuda + PEM, though as I said in the blog the results don't generalise to Fukuda+PEM either since it was a convenience sample, and subjects had to sign up to a double maximial exercise test, which not everyone will want to do.
So then it can't be claimed that “the results of this study showed that it should detect 90% of CFS cases, or 10% of Fukuda-defined CFS cases would be missed.”
But this is not a mandatory test?
The ME/CFS test is not: “While there is not one definitive test for ME/CFS, many tests may indicate abnormalities.”
Does this mean the Stevens protocol is mandatory to diagnose ICC ME, or is that an optional test? ... I'm not sure how anyone can be certain these are definitive tests and that falling below a particular threshold is exclusionary.
PENE, among other symptom patterns and abnormalities, is confirmed by testing according to the ME Primer's Laboratory/Investigative Protocol (p. 11):
Laboratory/Investigative Protocol: Diagnose by criteria. Confirm by laboratory and other investigations. A broad panel of tests provides a more robust basis to identify symptom patterns, abnormalities and orient treatment.
[...]
PENE: In a 2 consecutive day comprehensive 8-12 minute cardiopulmonary exercise stress test (measuring heart, lung, and metabolic function) - only ME patients have significantly worse scores the second day & abnormal recovery from exertion.
* Exercise tolerance test with expired gas exchange - (2 consecutive days) – measure cardiovascular, pulmonary & metabolic responses at rest & during exercise: peak oxygen consumption VO2 or VO2 at anaerobic threshold (AT) - decline of 8% or greater on test 2 indicates metabolic dysfunction, post-exercise blood analysis - increase in sensory, adrenergic and immune genes - increase in metabolite receptors unique to ME
I do think this new test could be very important but needs replicating, especially as the dramatic fall in VTO2 is a new finding: the CDC study, with a larger and more representative sample would be the ideal place to do this.
Pressure should be brought to bear.
 
MeSci thank you for that lot! :) Blimey. Lot of effort there. Appreciate it. I shall come back later and read more deservedly. That Pinching/White study is in full here. Interesting as you say. Shame it doesn't appear to have been replicated or even taken on board elsewhere.
 
Thanks, MeSci, you have been busy

That immune one in particular, featuring Peter White and Anthony Pinching looks so interesting (esp the effect of travel on immune markers), but is yet another case on a tantalising pilot (n=9) that never got replicated (maybe some of the authors didn't want to pursue that line of inquiry). Similarly, the Black study and heatshock study both only have 6 CFS patients :(.

There is a good deal of debate about mitochondrial function. This new Snell paper quotes an earlier study that found reduced performance at day 2 but normal oxidative phosphorylation. The new MRC study at Liverpool will be using new and more sensitive techniques to focus in on mitochondrial functioning.

On a more positive note, the Klimas/Fletcher labs are working on a good day/bad day study of immune markers, as well as looking at them post-exercise, and I'm hoping the study will be of a decent size. The Horning/Lipkin study (n=loads) is also measuring some immune markers - not post-exercise or post-travel but generally - and the study size as well as rigorously matched controls should produce robust data on immune markers.
 
Blog updated: more information on 'uniqueness' of findings, plus another supporting study

After getting more information from Chris Snell, I added this, with more published studies:
Unique to ME/CFS?

Is this the killer test that uniquely identifies CFS patients? Dr Snell has reported that their clinic has tested patients with numerous illnesses including Multiple Sclerosis and Congestive heart failure, but have only seen the problem in ME/CFS patients. Published studies show normal repeat CPET performance for sarcoidosis [n=20, new], angina [n=14, 3 tests in 3 days], Chronic Airflow Obstruction [n=11, 2 tests in 3 days], Pulmonary Hypertension [n=42, >200 tests total as most patients did multiiple repeat tests over extended period] and heart disease[n=17]. I’ve seen no studies showing failure to reproduce CPET results in other illnesses, but it’s probably too soon to say if this is unique to ME/CFS, or just very unusual.
Nb a lot of repeat test studies have at least 7 days between first ad second tests, so don't provide a useful comparison.

I've also mentioned a study by Betsy Keller, presented at the IACFS 2011 conference, and about to be submitted for publication. Like the new study it finds declines in both VT VO2 and workload, though the workload findings are nowhere near as dramtic as this new study. n=12, results highlights:

Significant decreases from test 1 to test 2 were:
13.5% for VO2ma; 9.4% for Wmax
18.8% for AT [VT] and 17.3% for ATwork [work output at VT]

However, there was no change in maximum RER indicating that subject effort was maximum and also comparable during both tests
 
Simon I have something I would like your opinion and that of others on in relation to this kind of testing; and that relates to safety.

Let me take this from Jennie's wonderful blog, it doesn't cover all my point, but does exemplify it to some extent:

3 June 2013

Oh CDC, You So Crazy

...Dr. Unger said that the clinicians in the multi-site study felt a two-day exercise test was “not advisable.” She elaborated that patients travel some distance to get to the physicians involved in the study and that a two-day test was not feasible. It was not clear to me whether the concern was the time required or the physical impact on the patients. I was very surprised that the clinicians (Natelson, Klimas, Peterson, Kogelnik, Bateman, Lapp, Podell) were the ones who advised against using the test because most (if not all of them) have used two day testing for some of their patients....
When we talk about 'exercise' and most especially GET we express concern and alarm that some practitioners, clinicians, might lack the necessary understanding of ME and push people to exercise above their safe ability etc.

With the Snell test, as I understand it, patients are told to push it as much as they can for the duration of the test, and it could be said that, in order to prove you have ME you must crash on the next day.

Is this safe? Is it safe for everyone or for only some? Is it safe for the undiagnosed? How might it be viewed in light of widespread concerns over the misuse of GET?

We are essentially saying 'Prove you have ME by crashing' and that this is the best (one of the best) objective measures. Is it not rather extreme? Could it be achieved any other - less intrusive - means?

Any thoughts? I refer of course to the scenario of having this test in it's current state used outside of research in a clinical setting as part of a process for diagnosing ME; and to calls for it being incorporated in the existing CDC data collection project.

I believe that you said yourself, Snell's work needs replication. So maybe we are not there yet with something that could or even should be considered for mass-use?

There is also the cost of course but I would like to talk a bit about concerns over safety and whether or not such a test could possibly be considered suitable for all with ME or who need a diagnosis.

Thanks :)
 
Simon I have something I would like your opinion and that of others on in relation to this kind of testing; and that relates to safety.

Let me take this from Jennie's wonderful blog, it doesn't cover all my point, but does exemplify it to some extent:
...Dr. Unger said that the clinicians in the multi-site study felt a two-day exercise test was “not advisable.” She elaborated that patients travel some distance to get to the physicians involved in the study and that a two-day test was not feasible. It was not clear to me whether the concern was the time required or the physical impact on the patients. I was very surprised that the clinicians (Natelson, Klimas, Peterson, Kogelnik, Bateman, Lapp, Podell) were the ones who advised against using the test because most (if not all of them) have used two day testing for some of their patients....
When we talk about 'exercise' and most especially GET we express concern and alarm that some practitioners, clinicians, might lack the necessary understanding of ME and push people to exercise above their safe ability etc.

With the Snell test, as I understand it, patients are told to push it as much as they can for the duration of the test, and it could be said that, in order to prove you have ME you must crash on the next day.

Is this safe? Is it safe for everyone or for only some? Is it safe for the undiagnosed? How might it be viewed in light of widespread concerns over the misuse of GET?

We are essentially saying 'Prove you have ME by crashing' and that this is the best (one of the best) objective measures. Is it not rather extreme? Could it be achieved any other - less intrusive - means?

Any thoughts? I refer of course to the scenario of having this test in it's current state used outside of research in a clinical setting as part of a process for diagnosing ME; and to calls for it being incorporated in the existing CDC data collection project.

I believe that you said yourself, Snell's work needs replication. So maybe we are not there yet with something that could or even should be considered for mass-use?
I think the Snell work is fascinating and potentially a very imprtant way to reveal what goes wrong in our illness.

However, until there is hard safety data I don't think it's appropriate to use as a standard diagnostic tool. I do think the CDC study would be a great place to look for validation/replication, and measure sustained response to exercise eg for a couple of weeks afterwards. Would also be good to know what proportion of clinic patiens would refuse the test (we don't know if self-selection is a big factor).

And I agree about your point re GET: many patients object to it because it pushes them too hard, and that can causes relapses. No GET currently recommended includes anything like maximal exertion (though obviously is over a much longer period).

Disclosure: I have relapses at way less than maximal exertion, so would refuse even a single maximal CPET, let alone 2 in 24 hours.
 
I think the Snell work is fascinating and potentially a very imprtant way to reveal what goes wrong in our illness.

However, until there is hard safety data I don't think it's appropriate to use as a standard diagnostic tool. I do think the CDC study would be a great place to look for validation/replication, and measure sustained response to exercise eg for a couple of weeks afterwards. Would also be good to know what proportion of clinic patiens would refuse the test (we don't know if self-selection is a big factor).

And I agree about your point re GET: many patients object to it because it pushes them too hard, and that can causes relapses. No GET currently recommended includes anything like maximal exertion (though obviously is over a much longer period).

Disclosure: I have relapses at way less than maximal exertion, so would refuse even a single maximal CPET, let alone 2 in 24 hours.
Thank you and for the italicised final sentence. I think I would agree with you there as well. And it would be useful to know how many patients if offered the choice would decline such a test in the field as it were as this would impact on any clinical outrolling of it as a diagnostic test.

Not sure how reasonable it would be to ask the CDC to introduce such an unreplicated test but I don't remember off hand how far committed to their protocols and study they are to be honest. Might be too late and anyway, Unger seems to have been advised not to do it. Certainly would support another independent study of this and other studies that try and pin down PEM. No argument there :)