By Staci R. Stevens, MA, and Christopher R. Snell, PhD
The Pacific Fatigue Laboratory’s (PFL) two-day testing protocol is designed to objectively measure functional capacity and the symptom of post-exertional malaise in chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME). In the course of our research, we have performed more than 2,000 cardiopulmonary exercise tests (CPETs) for patients diagnosed with CFS/ME[1]. Many of these patients reported prolonged recovery following a single test. Overdoing physical activity by even a small amount invariably resulted in symptom flare up or post-exertional malaise[2].
Our group subsequently developed a testing regimen (Stevens Protocol), requiring patients to perform a second test 24 hours after the first test to assess physical function in the post-exertional state. An inability to reproduce values for oxygen use on the second test at both peak exercise and at the anaerobic threshold provides objective measures of metabolic dysfunction and reduced work efficiency as indicators of post-exertional malaise[3]. CPET performed on consecutive days or weeks is highly reproducible for healthy individuals as well as for those with heart, lung and kidney disease[4]. It is not reproducible for persons with CFS/ME. CPET is invaluable for disability evaluation because it shows high day-to-day variance in the ability to sustain work. The exercise test profiles look like different people on each day and provide the necessary evidence to obtain disability benefits. Armed with this evidence, 90 percent of our clients have received their benefits.
CPET is simply “stress-testing” with some additional complementary measurements. Stress tests use a bicycle or treadmill to look at heart function at rest and during exercise stress. They employ an electrocardiogram (ECG) to monitor heart rhythm with blood pressures taken throughout the test. The CPET simply adds analysis of gases being moved in and out of the mouth throughout the test, achieved using a mask connected to sample tubes that measure every breath during the test. This adds the ability to measure oxygen used by the muscles to produce energy, carbon dioxide exhaled and the amount of air/ventilation moving in and out of the lungs. So, in addition to measuring heart function, cardiopulmonary analysis adds lung and metabolic function, which provide a multisystem view of the body at work.
The two most important measures are peak oxygen use or aerobic capacity (known as VO2peak) and oxygen use at the anaerobic threshold (VO2AT). Work can be sustained below but not above the threshold. CPET is used to measure athletic performance at the high end and for disability assessment at the other end of the functional continuum. In the fields of exercise science and medicine, this approach is considered the gold standard for measuring and evaluating fatigue. Position statements from the American College of Sports Medicine[5], American Heart Association[6], American College of Chest Physicians, American Thoracic Society[7] and the American Medical Association[8], among others, all endorse this method of testing. The PFL has simply adopted this standardized, valid and reliable tool to evaluate post-exertional malaise and disability in CFS/ME. What we find exciting about the two-day Stevens Protocol is that it is being reproduced both nationally and worldwide. Dutch scientist Dr. Ruud Vermeulen[9] has published research replicating our initial findings, and Dr. Betsy Keller at Ithaca College in New York [10] presented similar results at the IACFS/ME conference in September. It is our hope that this protocol will be broadly adopted for CFS/ME to confirm post-exertional malaise, to support disability evaluations and to become the standard for assessing function in research studies and clinical trials.
References
- Vanness, J.M., et al., Subclassifying chronic fatigue syndrome through exercise testing. Med Sci Sports Exerc, 2003. 35(6): p. 908-13.
- VanNess, J.M., et al., Postexertional malaise in women with chronic fatigue syndrome. J Womens Health (Larchmt), 2010. 19(2): p. 239-44.
- VanNess, J.M., Snell, C.R. and Stevens, S.R. , Diminished Cardiopulmonary Capacity During Post-Exertional Malaise in Chronic Fatigue Syndrome. Journal of Chronic Fatigue Syndrome, 2007. 14(2): p. 77-85.
- Hansen, J.E., et al., Reproducibility of cardiopulmonary exercise measurements in patients with pulmonary arterial hypertension. Chest, 2004. 126(3): p. 816-24.
- ACSM’s Guidelines for Exercise Testing and Prescription, 8th ed, ed. N.F.G. Walter R. Thompson, Linda S. Pescatello2009, Philadelphia: Lippincott Williams & Wilkins.
- Balady, G.J., et al., Clinician’s Guide to cardiopulmonary exercise testing in adults: a scientific statement from the American Heart Association. Circulation, 2010. 122(2): p. 191-225.
- ATS/ACCP Statement on cardiopulmonary exercise testing. Am J Respir Crit Care Med, 2003. 167(2): p. 211-77.
- Guides to the Evaluation of Permanent Impairment. 5th ed, ed. A.B. Cocchiarella 2001, Chicago: American Medical Association.
- Vermeulen, R.C., et al., Patients with chronic fatigue syndrome performed worse than controls in a controlled repeated exercise study despite a normal oxidative phosphorylation capacity. J Transl Med, 2010. 8: p. 93.
- Keller, B. Exercise Testing to Quantify Effects of Fatigue on
Functional Capacity in Patients With CFS. in IACFS/ME Biennial Conference; Translating Evidence Into Practice. 2011. Ottawa, Ontario, Canada.
Staci R. Stevens, MA, is the founding executive director of the Pacific Fatigue Laboratory located in the department of sport sciences at the University of the Pacific in Stockton, Calif.
Christopher R. Snell, PhD., is the PFL’s scientific director and professor in the sport sciences department.
For more information on the lab, visit http://www.go.Pacific.edu/PFL.
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This is the kind of objective testing that would help to define/recruit a group of patients to study rather than using questionaire and criteria.
I totally agree. This kind of test objectively measures the body’s ability to produce mechanical work and the repeat test shows PEM or PENE. Applying the Stevens’ protocol before would assure only people that have CFIDS/M.E. are being studied. Applying the Stevens’ protocol again at the conclusion of the study would objectively measure the effectiveness of the treatment being attempted. If the PACE trial had done this it would have instantly lost all credibility.
Thank you for your hard work on trying to give “concrete” evidence to our illness. Social Security does not see us the day after a stress test or “trial” work day to see how horribly incapacitated we are. Most of us want to work, and push ourselves, and then fall flat on our face. Your research gives validity to ourselves as well, as we still struggle to overcome the philosophy of “it’s all in your head.”
Great. I don’t even think I could get through the first test. Even if I drank tons of iced coffee and ate sugar to get through it, I would never be able to get out of bed for several days afterwards to do the second test.
And because I have asthma problems with this disease, I wouldn’t be able to breathe with that mask on.
I don’t know how anyone with this disease can do either or both.
There must be vast differences in stamina with this disease.
Kathy,
I did this test many times during my long years with M.E./CFIDS. At first to be sure it was not heart disease, then as part of my disability application, and still again to test for another possible disease in addition to M.E. A lung disease. I did the test until it was too hard for me to do. Then went home to crash.
The mask does not interfere with breathing, or did not for me. The test does not last very long, just a few minutes.
I never did the test again the next day. Pretty sure I would not replicate my results of day one! There is much useful information in this test. Besides disability confirmation, now it may set the start point to maintain some muscle strength & flexibility and not provoke PENE.
Staci, this research is absolutely invaluable!! So glad that you are testing and demonstrating that the oxygen utilization for CFS patients is greatly diminished.
I’m a former athlete who has a box full of athletic medals but can’t climb stairs without exhaustion. Just can’t tell you how frustrating it’s been to have physicians tell me I just need to “try harder” and to “get out more.”
I’m so grateful for these and other studies you and your colleagues have provided for those of us who struggle with this disease. Thank you!!
Bravo!
Sincere appreciation for you invaluable work. It continues to be so frustrating to confront CFS/ME skeptics without replicated test results demonstrating obvious dysfunction.
I am trying to get approved for Social Security Disability. I have already been denied and am waiting for a hearing.
This testing would be very helpful for my case. How would I get it? I do have Medicaid.
I wish articles like this would not only sell the provider but also tell us where else we might get this test and what it costs and whether it has to be ordered by a doctor.
Two days is insufficient to accurately assess the realities of post exertional malaise from ME/CFS. It requires at least a two week window of multiple tests.
Both my GP and Consultant refuse to let me try a stress test at all, though I’ve been pushing for it. As walking has its problems and breathing becomes impaired very quickly I’d love to have more of an idea about what is going on. I’m sure there are many others like me. Could a less vigorous test be designed, or a test that has a ‘safe’ stopping point before collapse? Any ideas would be very welcome so that I can put them to my Consultant.
Hi C,
There is a debate occurring now with respect to the types of laboratory testing that will “best” provoke the post-exertional relapse experienced in “real life” by people with CFS. Some researchers believe it should be a maximal exercise challenge, where a person exercises on a treadmill or bike for a short period at high intensity, while others feel that it should be conducted at less intensity for a longer period of time. Both kinds of tests are being used in various studies now, and that may account for some of the conflicting reports that appear in the literature.
For monitoring the activities that can provoke a relapse, many physicians and physical therapists familiar with CFS suggest using a heart rate monitor, like the kind runners use. From an article on “The ‘E’ Word” (http://www.cfids.org/cfidslink/2010/100604.asp ):
“Patients can begin with detailed observation of heart rate and activity. Stevens recommends wearing a heart rate monitor and noting one’s heart rate frequently throughout the day. Every activity can affect the heart rate, including lying down, sitting up, watching television, cooking a meal, climbing stairs, showering, etc. Patients should also pay attention to how different activities feel. Stevens suggests using the Borg scale to measure an individual’s Rating of Perceived Exertion (RPE). Using this scale, an individual assigns a number between 6 and 20 to the overall level of perceived exertion during an activity. By observing heart rate and RPE, patients can begin to establish correlations and identify AT limits. For example, cooking a meal could raise a patient’s heart rate to 110 beats per minute and feel very hard (17 on the scale). For such a patient, that heart rate (110 bpm) might be over his/her AT.
“The Pacific Fatigue Lab model uses heart rate biofeedback to help CFS patients stay within a safe zone: activity must be under the AT and must be followed by sufficient rest. The patient’s heart rate monitor is set with an alarm for 10 percent below the AT. When a patient’s heart rate reaches that number, the monitor alarm sounds and the patient should immediately sit down and rest. The alarm is an objective measure of how hard the CFS body is working, and helps patients recognize when they are exceeding their limitations.”
This response was for me very interesting and has given me insentive to try the daily.hourly testing with several events. I am not such my way will match your specifics I will try to check back here if possible for further reference. thanks
I have been searching locally for someone who can do this kind of exercise testing to support my disability claim (I have now been turned down twice and have one more chance, in front of a judge).
How can I find a facility/doctor locally who can do the Stevens Protocol? I live in Delaware, about midway between Baltimore and Philly.
Thanks –
Sue Jackson
jacksonde@comcast.net
Dear Sue,
Thank you for your interest in our testing. Cardiopulmonary exercise testing (CPET) is a well-established testing protocol; however it requires a high level of expertise to perform the testing well and someone familiar with the special needs of CFS/ME. We recommend an exercise physiologist with experience performing CPET, ideally a Ph.D. It is also helpful to have a physician knowledgeable in the both the interpretation of CPET results and also familiar with CFS/ME. It has taken us 10 years to refine our interpretation of these reports for CFS/ME due to the unique responses. Our 10-12 page written report takes considerable time to prepare. Most physicians simply do not have this luxury. It may be easier to just come and see us. In addition, we provide resting pulmonary function tests to measure lung function before exercise on both days as well as reaction time testing to determine cognitive function after the exercise test. This is something other entities do not offer. If you are looking to use the report for a disability determination having someone familiar with writing disability reports is crucial.