Clinical exercise testing in CFS/ME research and treatment

This is a summary of the (rather long) lecture from the CFIDS conference in Sweden this week; “Clinical exercise testing in CFS/ME research and treatment“. I have omitted a lot of the discussion on the advantages/disadvantages of various scientific methods etc. and stuck mainly to the items that I would assume a non-scientific interested person would wish to know. If you’re of a scientific bent, you would probably get more benefit from watching the actual lecture. All credit to Professor Christopher R Snell of the Pacific Fatigue Laboratory, California (USA).

If you’re a sufferer, I recommend watching from 54:00 through to 59:20 – they go through a brief summary of energy conserving techniques, which could be very useful! Following this there is a case study of how they applied some of these techniques to a 17 year old sufferer to allow her to manage the condition better.

Clinical exercise testing in CFS/ME research and treatment: A summary

On an exercise test where a person has to exercise until they are exhausted, a healthy person will recover usually within a day, definitely within 48 hours (on the outside). When they did this with CFS patients, they had only one person recover within 48 hours – the average recovery was 4 days.

CFS patients also had symptom flares as a result of this test.

There are problems with the PACE trial:
– they very selectively reported results
– they only took high-functioning CFS patients
– they used the 6-minute walking test (see below)
– patients at the end of the trial, were still walking at a severely disabled speed, even when they had improved the distance they could walk. If a patient who needed a heart transplant could only walk this speed due to a lung problem, they would not be allowed onto the transplant list because they would not be deemed well enough to actually survive.
– there is no mention of any improved functioning in any other area for any of the trial participants

There are problems with the 6-minute walking test (as used in the PACE trial as a measure of functioning) and other similar tests
– they assume that the patient does not exercise to exhaustion, or anywhere near exhaustion. All the understanding of the results are based on the assumption that it was just a casual exercise experience that they could easily repeat.
– it does not work for specific groups of unhealthy people, it is designed only for a healthy population, so results from an unhealthy group can’t be interpreted validly. This is because they rely on the heart rate as a measure of energy production, but the way the heart rate and energy production are linked in a healthy person is not necessarily the same in a sick person. Many studies in fact show that the link between them in certain diseases is very different – meaning you cannot rely on these tests in sick individuals, without first carrying out studies to determine what the connection is.
– the american heart association says not to use tests with heart-rate measures, as many people use heart-rate controlling medication (eg: for POTS, migraines)

The best way to assess physical function is to use “cardio-pulmonary exercise testing”, which is to measure:
– oxygen consumption (as oxygen is used directly to produce energy, this will always be a correct measure). This is effected by lungs, heart and muscles.
– the “anaerobic threshold” – which is the point at which the carbon dioxide you breathe out is greater than the oxygen you take in. In a healthy person this is 50-60% of max. oxygen consumption; in an athlete it may be as high as 90%. In CFS patients it is very very low, and going above it makes you worse – and is very easy to do
– you can prove beyond doubt that someone is not faking these results because you are measuring the amounts of oxygen and carbon dioxide in the air they breathe in and out.
– you can establish beyond doubt that the persons capabilities in the test have nothing to do with motivation/effort because the “effort” of the person is shown in the oxygen intake/carbon dioxide given out
– these are a good measure of function, they are very reliable and accurate
– there are alreasy established measures of this for many other healthy people and disease states, meaning you can compare ME patients to others easily

Exercise will not cure ME/CFS. But – people who do not exercise will suffer the effects of a sedentary lifestyle, so if you can do some exercise without making symptoms worse, it is probably beneficial to do so

Post exertional malaise occurs across all the spectrum of ME/CFS patients – regardless of how severe they are
It does not show up in an single exercise test – you need to test again (they do it 24 hours later). This allows them to measure the post-exertional effect. (Many ME/CFS patients could be assessed as normal on a single test, due to eg: having rested beforehand, it is the second test which shows they are ill)
It is hard to separate the effects of deconditioning from the effects of CFS with a single test – but with multiple tests you can see what CFS has done.
At 37 minutes there is a table of results for ME patients

The second test shows:
– ME/CFS patients do worse on the second test; they are significantly worse (in terms both of workload they accomplish, and the oxygen/anaerobic measures)
– non-ME/CFS patient will improve on the second test (graph at 42mins).
– ME/CFS patients have a drop in the oxygen consumption, but a much much worse drop in the amount of work actually achieved. This shows that the exercise on the second test is less effcient
– the drop in peak-oxygen consumption is actually less for severe patients than for milder patients; but severe patients start out with a much lower oxygen consumption than a milder patient.
– the drop in workload done is more in severe patients than milder patients
– The theory is that there is a basic level of oxygen consumption that you need to survive, and the more severe you are the closer you are to this base level. So severe patients cannot drop any lower or they would die, so they reduce workload instead.
This is a reproducable, reliable test which shows the extent of the post-exertional malaise; other research groups have replicated these results

Their tests show objectively for CFS patients:
– an atypical recovery
– an abnormal stress-test
– post exertional malaise

There are many theories as to why post-exertional malaise occurs

Their research shows ME/CFS patients
– have a reduced physical working capability
– the aerobic energy generation (the production of energy in the presence of oxygen) is impaired
– activity exacerbates symptoms ( every ME/CFS patient has post exertional malaise)

Their research can be used as an objective proof of disability (for example, for disability assessments and clinical trials)
It is quantifiable – ie: it can measure accurately to a degree how ill the patient is
It reveals abnormality across many systems

Cognitive behavioural therapy is not a cure for ME/CFS – but it can be useful to help patients manage/adjust to their illness

ME patients can go a very long way into the anaerobic threshold (longer than most people manage) because they have adjusted to being ill; but this results in huge PEM. So short-term, patients can often manage a lot more than they can manage long-term.

Avoiding activities above the anaerobic threshold will help patients avoid PEM
– heart rate monitors can help; they are set to go off just before you hit the anaerobic threshold, to get you to rest instead of using too much energy
– activity logs can help; you can identify activities which make you worse (what activities make you ill? How do you feel the next day? Do you get PEM? Can you carry out other normal activities and these activities?)
– “rates of perceived exertion” can help; this is a fancy way of saying, if it feels like a lot of effort, it is a lot of effort – stop!
Resting will help recovery from going into the anaerobic threshold
If you go above the anaerobic threshold, you will have to pay back far more energy

Physiotherapy can help – but physios often need to be re-trained to understand ME/CFS
– reconditioning will not work with ME/CFS patients

They have a therapy called “energy conservation therapy” – I think this is basically working out how to manage your life now with less energy. It involves
– pacing
– body positioning (ie: sit instead of stand to use less energy)
– protecting joints
– using assistive devices
– planning activities (to make sure you don’t over-exert)
– using any energy saving thing you can do etc.

They also have a “theraputic exercise program” – (nothing like GET!) – this can be aided by trained physios
– learning to breathe properly
– training the anaerobic system, not the aerobic system
– exercise must be recovered from within 24 hours – if you take longer than that to recover, it is harming you, not helping
– stretching
– only doing a little bit at a time
– only ever increase amounts if you aren’t experiencing symptom increase – decrease amounts if you experience symptoms

He closed with the comment: “It doesn’t really matter what you call it, there are hundreds and thousands of people who are really really sick; if the medical profession is not helping them, their government representatives are not helping them; they need help urgently.”


2 responses to “Clinical exercise testing in CFS/ME research and treatment

  1. I am wondering if a person with ME/CFS will get short of breath when hitting the anaerobic threshold the same way as a healthy person. In other words is shortness of breath a good indicator of doing too much?

    • Hi Lorraine,

      I’m not an expert in this I’m afraid, this is just notes from the presentation. So I will do my best, but it isn’t medical advice!

      The anaerobic threshold is the point at which the carbon dioxide given out is more than the oxygen taken in, meaning that you are short of oxygen at that point, so yes, you should be feeling shortness of breath if you’ve reached it.
      But – I don’t know whether shortness of breath starts to occur significantly before the anaerobic threshold or not, especially with ME patients who have other issues with breathing (such as fatigued chest muscles) and often report issues like air hunger, even when no activity has taken place.
      So basically I don’t know if shortness of breath necessarily means you’ve reached the anaerobic threshold if you have ME – it may well be different than to healthy people!

      However, it seems in general from this research and others I have read, that if you are having a physical reaction to what you are doing (which would include shortness of breath, and other things like high heart rate) you probably are doing too much. It probably does serve as an indicator of over-exertion, although how reliable it is I couldn’t say for sure.