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“Our studies clearly show that dynamic exercise like walking or jogging exacerbates symptoms associated with ME/CFS.” ~J. Mark VanNess, Ph.D.

One of the ongoing debates among ME/CFS clinicians, as well as their patients, is whether exercise is good or bad for patients with ME/CFS. The Centers for Disease Control and Prevention (CDC) maintains that patients with ME/CFS need to maintain a steady, low-impact exercise regimen to avoid becoming deconditioned. But while some physicians recommend exercise as one of their chief ME/CFS therapies, other clinicians disagree. They point out that post-exertional malaise (PEM) is a hallmark symptom of ME/CFS and that symptoms invariably worsen after any form of exercise.

Single-photon emission computed tomographic (SPECT) scans have shown that in ME/CFS patients who exercise, brain blood volume is reduced one to three days after exercising. In patients who are acutely or seriously ill, this could have profoundly negative effects on immune and endocrine system regulation. In patients with ME/CFS, exercise also lowers cortisol levels, which makes it more difficult for the body to control inflammation.

GET and Daily Exercise Programs

GET (graded exercise therapy) is a training program that increases exercise in small increments on a day-to-day basis. Typically GET begins with active stretching, followed by range-of-motion contractions and extensions, done for only a few minutes a day for a completely inactive individual. Exercise is increased daily following a schedule until normal activity is resumed. GET is usually accompanied by CBT (cognitive behavioral therapy), a psychotherapeutic program designed to correct “illness beliefs.” The underlying concept of GET is that maintaining the habit of avoiding exercise perpetuates Chronic Fatigue Syndrome & Myalgic Encephalomyelitis symptoms.

The GET program has been met with a great deal of criticism. Both patient groups and researchers have pointed out that exercise intolerance is the hallmark symptom of ME/CFS and that a program of systematic exercise will inevitably cause relapse. Researchers who have investigated the mitochondrial defects and resultant cardiac insufficiencies that are common in ME/CFS patients have added that it may, in fact, be dangerous to force severely ill ME/CFS patients into any kind of exercise regime.

The supporters of GET answered this flood of criticism with an extensive randomized trial comparing GET, CBT, Pacing and specialist medical care in 641 ME/CFS patients. Predictably, the PACE trial, as it was called, concluded that GET and CBT could be added to specialized medical care to improve outcomes, but that Pacing (which limits physical activity and requires resting) is not effective.

Almost immediately after the PACE trial publication, the CFIDS Association of America responded with a five-page analysis, in which they pointed out that the cohort selected for the study was skewed. The PACE Group selected their subjects on the basis of the Oxford Criteria for ME/CFS, which only requires six months of fatigue for a diagnosis. This allows for the inclusion of patients with depression and other disorders.

In addition, the CFIDS Association pointed out that the conclusions drawn by the PACE study were biased, not just in the diagnostic criteria used, but on the basis of patients selected. The PACE study excluded severely ill or homebound patients. Nor did it include patients who had been ill longer than six years. In addition, the cohort was relatively young, with a mean age of 38. After a careful analysis, the CFIDS Association concluded that the only concrete result of the study was that a program of graded exercise might be somewhat beneficial to young, moderately or mildly ill patients with non-specific “fatigue” of short duration.

According to a 2008 survey conducted by the M.E. Association, GET is one of the least successful, if not directly harmful, ME/CFS treatments. While ME/CFS doctors in the U.S. encourage gentle exercise in patients who are well on the road to recovery, they do not endorse graded exercise programs. In addition, most studies have concluded that GET has a negative impact on ME/CFS patients. Numerous ME/CFS patients have reported relapses, flares, and a general worsening of symptoms after starting the GET program.

Starting in 2015, David Tuller, academic coordinator of University of California, Berkeley’s joint masters program in public health and journalism, published a series of critical articles about the PACE trial which drew international attention to the flaws of the trial. His critiques sparked scientific scrutiny of the trial by statisticians, researchers, and psychologists. Subsequently, a number of articles were published, culminating in a special edition of the Journal of Health Psychology devoted to the topic of the PACE trial.


While a number of physicians promote the idea that prolonged lack of exercise will worsen ME/CFS by leading to “deconditioning,” there is little evidence to support this. In fact, research suggests the opposite.

In one of the few longitudinal studies of ME/CFS patients, Matthews and Komaroff found that physical capacity was not only undiminished, but had improved in 99 ME/CFS patients over a 10-year period – even though they had not engaged in exercise. There is plenty of anecdotal evidence from ME/CFS patients that even long periods of inactivity do not worsen the illness. There are also reports of patients who, after being treated successfully with Ampligen, Rituxan, or antivirals, have simply gotten up – sometimes after years in bed – and resumed normal activities. Once recovery is underway the body regains its strength fairly quickly.

Dr. Christopher Snell, in a presentation given to the Pathways to Prevention Workshop, stated that in cardio-pulmonary exercise tests (CPET), patients with ME/CFS have a VAT (oxygen consumption during submaximal exercise) was 56% and 55%. In people with deconditioning, this value is around 30%, which means the patients with ME/CFS are rarely deconditioned.

What kind of exercise can you do?

While patients who are severely ill will immediately worsen with exercise, patients who are mildly ill, or who are well on the way to recovery, can consider exercise. Most ME/CFS clinicians advise a very gradual reintroduction of exercise. Initially, simple stretching exercises are recommended.  Once stretching is tolerated, and recovery is well underway, patients can begin subaerobic exercise, that is, exercise that does not increase heart rate. (On a scale of 1-10, recovery begins at 5 – 7.) The advantage of subaerobic exercise is that it helps with blood circulation. It also puts little strain on ATP production, making it appropriate for people with ME/CFS-induced metabolic disturbances. Walking and swimming are probably the best forms of exercise for this purpose. Patients can use a heart rate monitor to see if they have surpassed their heart rate limit.

When you are able to walk for six or seven minutes without feeling short of breath, you can consider yoga or “weightless” weight training to strengthen specific sets of muscles. (Some ME/CFS patients have had success using weight-lifting equipment set at zero to help tone muscles.)

Once you begin to exercise, it is important to remember that you are not in a contest. How fast you go, how many laps you swim, how many blocks you walk, or how much weight you lift is not only irrelevant, it can be counterproductive. Symptoms in most patients fluctuate from day to day, which means if you force yourself to stick to a daily exercise regime – even if it’s only walking around the block – you may very well cause a relapse. Your body will tell you when you can exercise, and when you shouldn’t.

*Adapted from Chronic Fatigue Syndrome: A Treatment Guide, 2nd Edition by Erica Verrillo.