Feature The Real Story About Chronic Fatigue Syndrome Research shows that the condition, once ridiculed as imaginary, is a true physiological disease. Here's what to look for, and how PTs are helping those who have it. By Eric Ries | September 2017 Chronic fatigue syndrome (CFS) has come a long way since the 1980s, when it was widely dismissed as "yuppie flu" and was suspected by many health care providers of being a psychological rather than a physiological condition. (A note on terminology: CFS goes by at least 3 names, per the sidebar below this article. As CFS remains the one by which the illness most widely is known, that's the term PT in Motion is using.) Nicole Rabanal, PT, was among the skeptics. Until late 2014 she considered "chronic fatigue syndrome" to be "a catch-all term that meant medical science didn't know what the patient had or didn't have." She changed her mind the morning she woke up "feeling, out of the blue, like I'd been hit by a truck—with severe flu-like symptoms, severe eye pain, headache, 'heavy' head, muscle weakness, random numbness and tingling sporadically throughout my body, and difficulty breathing and swallowing." This sudden and dramatic shift in the then-46-year-old's health led her on a year-long odyssey through the health care system, during which she saw 17 specialists and was at various times told she had depression, Lambert-Eaton myasthenic syndrome, and myasthenia gravis. When her fifth neurologist at last hit the nail on the head—CFS is a diagnosis of exclusion for which there is no test—he told her, "Stop doctor-shopping, get off your own back, and wrap your head around this." "What do you do with that?" she asks. "I decided that I needed to figure out how to manage this on my own." As luck or fate would have it, she soon happened upon—literally dragged herself to—a symposium on CFS at an APTA Combined Sections Meeting. What Rabanal learned that day in Anaheim, California, led her to a treatment relationship with the Salt Lake City-based Bateman Horne Center, which specializes in CFS and fibromyalgia. Today, her life is "all about pacing and management." Rabanal, who owns Kinetic Energy Physical Therapy in Steamboat Springs, Colorado, describes her highly regimented routine. "I work a 2-hour shift in the morning," she says. "I come home and lie down in a quiet room—with oxygen, and with ice on my eyes and head—for 4 hours. I go back to work for another 2-hour shift. I return home to again lie down with ice and oxygen. I get up and have dinner with my family, and am in bed no later than 8 pm." On weekends, she continues, "I stay quiet all day, either lying down or resting. On Sunday, I might get out and do something with my kids for an hour. But that's it. There's no going out to eat, and only minimal socializing with friends because prolonged talking is very draining for me. I have significant sensitivity to light and sound, which greatly limits the surroundings in which I place myself." The upside, if you want to call it that, has been the demonstrated value of Rabanal's professional training. "The knowledge and experience of having been a PT for nearly 25 years has been incredibly helpful to my personal treatment plan," Rabanal says. "Listening for and understanding the signs of when I'm pushing beyond my energy limitations, then implementing appropriate exercise and stretching, is a big part of the management puzzle. This of course is what PTs do every day with patients, in one form or another—we listen closely and apply our knowledge to their presentation and what we learn from them." "I've made significant modifications to my treatment style," Rabanal adds. "I sit a lot, and lean or move to help manage my orthostatic intolerance—which does not allow me to stand still, unsupported, for more than 5 minutes. I co-treat with other therapists in my clinic to perform manual techniques that I no longer can do because of my limited strength. During my work periods, I use a Fitbit to monitor my heartrate and its silent timer to remind me when take my medications." "It's a huge challenge," she says. "But I love what I do, so I'm determined to make it work." Rabanal has a message for her fellow PTs. "We must know the criteria for patients to meet this diagnosis—significant reduction or impairment in ability to engage in pre-illness activity levels, accompanied by fatigue, for more than 6 months; post-exertional malaise; unrefreshing sleep; and either cognitive impairment or orthostatic intolerance. Because if we aren't correctly identifying this patient population, it's easy to push patients into a treatment or exercise program that will make their condition worse. They are likelier to be noncompliant, disinclined to follow up with care, and present as a returning patient whose condition never seems to improve." There is a great deal that PTs can do to help patients with CFS of all severity levels, say those who PT in Motion contacted for this article. It begins with listening and a thorough patient interview and extends through education, individualized goal-setting, pacing, movement and strengthening exercises, manual therapy, and appropriate referral. What PTs can offer, too, is what people with CFS arguably need the most, says Jessie Podolak, PT, DPT, owner of Phileo Health in Altoona, Wisconsin, and a certified therapeutic pain specialist. "We can bring them hope." Putting 2 and 2 Together A turning point for those facing CFS came in 2015, when the Institute of Medicine issued an extensively researched report on the disease subtitled "Redefining an Illness."1 It firmly established that CFS has a physiological basis—albeit an ill-defined one—and that it is a "serious, chronic, complex, systemic disease that often can profoundly affect the lives of patients" and "requires timely and appropriate care." CFS affects between 836,000 and 2.5 million Americans, according to the Centers for Disease Control and Prevention (CDC). But that's really only a guess, the agency concedes, as "an estimated 84% to 91% of people with CFS have not been diagnosed.2 What causes it? This also is hazy. As APTA summarizes in its consumer-oriented "Physical Therapist's Guide to Chronic Fatigue Syndrome,3 "Many researchers suspect impairment of the aerobic energy, immune, and gastrointestinal systems may be responsible for the functional impairment experienced in individuals with this condition." The Mayo Clinic advises that CFS may be caused by "a combination of factors that affect people who were born with a predisposition to the disorder."4 Factors that have been studied, Mayo notes, include viral infections, immune system disorders, and hormonal imbalances. Todd Davenport, PT, DPT, MPH, edited the APTA consumer guide to CFS and has conducted research on the disease. He also long has been active with the Workwell Foundation—a Ripon, California, based nonprofit that researches functional aspects of the disease and conducts cardiovascular and pulmonary exercise testing to determine and document postexertional malaise and symptom exacerbation after physical activity. Per the CDC's figures on diagnosis, it is atypical, Davenport notes, for PTs to get patients who've been referred by physicians with a diagnosis of CFS. "Typically you're seeing patients based on their referral label being only part of the condition," says Davenport, an associate professor and program director of the Department of Physical Therapy at the University of the Pacific in Stockton, California, and a board-certified clinical specialist in orthopaedic physical therapy. "So, the referral may be for 'widespread bodily pain.' Or, perhaps the patient has noticed a functional decline and has been talking to his or her primary care physician about a fatigue issue. That individual, then, may be referred with a diagnosis of deconditioning." It's imperative on the PT, therefore, "to put 2 and 2 together—to determine whether the patient may have CFS and might, therefore, require appropriate management strategies," Davenport says. One of the stated aims of an analysis that Davenport and his Workwell colleagues published in Physical Therapy in 20105 was to discuss aerobic system deficits that may lead to the clinical presentation of CFS. "Where the literature seems to be relatively strong," Davenport says, "is in the etiology that there are aerobic system impairments in people with CFS/ME." ("ME" stands for myalgic encephalomyelitis; see the sidebar on the facing page). "We're not sure why this is. We just know that the aerobic system is not as effective in these individuals." This information is instructive for PTs, Davenport says. "If you start with the assumption that the aerobic system is impaired, that guides what PTs should do. The first step is to teach patients about activity pacing that will keep them within the limits of their symptoms. We don't want people going to Costco and then being zonked out for the rest of the week. So, we advocate for people to look at the peaks and valleys of their daily activities and saw off the peaks—using that energy to help fill in the valleys." "The second step," he continues, "is to train people in lower-level anaerobic activities that register under the ventilatory threshold for aerobic activation and take less than 2 minutes. Focus on stretching and gentle exercise, with the aid of a heartrate monitor that's set below the ventilatory threshold and can alert the patient when that threshold has been exceeded and rest is needed." Finally, Davenport says, "the last piece is to get patients into longer-duration activities by way of gradually building on anaerobic training—while recognizing that the prognosis for full functional recovery is very guarded and limited." Anaerobic threshold training and pacing "aren't going to 'fix' impaired aerobic metabolism," he advises. "You're going to be seeing these patients for months and years—albeit less frequently, for the most part, as time goes on." Davenport concedes that this "go-slow" approach can seem counterintuitive when "exercise is our wheelhouse as PTs" and "a lot of forms of fatigue are seen as variations on deconditioning." Presented with a patient who is tired, "we PTs want our exercise tool to work well." He cautions, however, that, "We're employing the wrong tool for the job if we're pushing graded exercise and telling patients that they just need to get up and get moving." He cites as a cautionary tale the infamous-in-CFS-circles PACE study of 2011,6 which essentially suggested that a combination of psychotherapy and exercise might be the CFS patient's best friends. It caused an uproar in the scientific community over its methodology and conclusions, and was famously eviscerated on the Virology Blog,7 a popular online resource for dissemination of knowledge about viruses and viral disease. "To me," Davenport says, "best practice with this patient population, as with all patients we see as PTs, comes back to good, old-fashioned listening—taking on good faith what the patient what the patient has to say, and going on from there." The Power of Listening Ben Keeton, PT, DPT, director of clinical operations at The Jackson Clinics in northern Virginia, lauds the 2010 Physical Therapy piece that Davenport lead-authored as "capturing quite well the complexity of CFS" and the importance of building patient strength and endurance from an anaerobic foundation. "When an individual gets that super-malaise from exertion, that can foster kinesiophobia, or fear of movement," Keeton notes. "If you can empower the patient to find movements that don't trigger that, while correlating to patient-identified problems and impairments that you've noted, your therapeutic alliance with that patient improves, along with the prognosis. That's very powerful." Keeton, a board-certified clinical specialist in orthopaedic physical therapy, adds that the value of the "physical" part of what physical therapists do can't be understated with this patient population. "One of our great advantages is the physical connection we have with our patients," he says. "We're in a unique position as PTs to add a positive connotation to movement in the case of people with CFS. Passive or assisted active range of motion, where there's good quality of contact and the practitioner has strong manual therapy skills, builds that trust that moving won't hurt—or at least that it won't hurt as much." The first step in all this, according to Adriaan Louw, PT, PhD, goes back to Davenport's comments about "old-fashioned listening." "I have treated these patients and conducted research on them, and there are so many things that therapists can offer them. But it all starts with the patient interview," Louw says. "Ninety percent of our patients with chronic fatigue syndrome start crying during this process, simply because we're spending time with them, taking them seriously, and demonstrating that we care about them as human beings." Louw, who is based in Iowa, has worked clinically with people with chronic pain for 25 years and is president of the International Spine and Pain Institute, which offers continuing education courses and certifications. "If they don't cry during the subjective exam, they often do during the physical one," he says. "They'll say, 'That's the most thorough medical exam I've had in 10 years.'" "People who are in chronic pain tend to look 'normal' to others, and often feel disbelieved and very isolated," notes Jessie Podolak. "It's huge when we encourage them to tell their whole story and say, 'I hear and understand you.' It's important that we explain what's happened to them in a way that makes sense—that we say, 'There's been a tipping point, a shift in your homeostasis, but things will get better, and I'll support you throughout the process." "You have to be present with patients with CFS," is how Andrew Zang, PT, DPT, puts it. "You need to learn as much as you can about what they can and can't do, what their goals are, and what their perception is of why they can't do things. You almost need to be part psychologist, to ensure that they get the most out of their treatment sessions. You need to help them understand the 'what' and 'why' of their chronic fatigue, so that you then can guide them toward greater function and more energy." The owner of Zang Physical Therapy in Lemoyne, Pennsylvania, he's a board-certified clinical specialist in orthopaedic physical therapy and a fellow of the American Academy of Orthopedic Manual Physical Therapists. "Active listening by the physical therapist is key," echoes Becky Vogsland, PT, DPT, who coordinates the Comprehensive Pain Center of the Minneapolis VA Health Care System and is a board-certified clinical specialist in orthopaedic physical therapy. "To borrow a term from our psychology colleagues, follow the 'VEMA' model: validate, educate, motivate, activate." Achieving Goals PTs who treat patients with CFS must leaven their messages of hope with acknowledgement that improvement likely will be incremental and recovery far from complete. They therefore are reluctant to recount memorable "success stories" without asterisks—even while acknowledging the significance of relative improvements. Keeton cites a patient who'd experienced chronic back pain for 20 years and had been diagnosed with CFS as a comorbid condition. "This may sound underwhelming," he says, "but at the end of 12 weeks in physical therapy her baseline pain level was down from 6 or 7 all day on a 10 scale to 3 or 4. That made a big difference in her life. We created a plan of care to conserve energy and restore mobility. We incorporated all of the manual therapy and exercise components necessary to manage the low back pain, but we did it within the context of chronic fatigue—with an eye to functional activity." The patient had been an avid kayaker earlier in her life. "After 10 years of no kayaking, it was a pretty big celebration when she paddled her first tenth of a mile," Keeton says. "It was very rewarding for me as a PT. She's empowered now to make her own decisions about how to manage her exertion and budget her energy. What she said to me was, 'I either could maintain a pain level of 3 or 4 and just do my daily life stuff, or I could maintain that pain level, do my daily life stuff a little bit less, and use that energy to hit the water. I choose water.'" Louw recalls a frank exchange he had with a stay-at-home mom with CFS who struggled daily with fatigue and pain in order to meet her family's needs. "While her husband and kids were eating dinner, she was crying in bed by herself," he says. "I explained that she must space out her activities, take breaks, and make other adjustments. She told me her life was too busy to do that. I responded, 'You don't have a life,'" Louw recounts. "I wasn't trying to be rude," he emphasizes. "I just meant that the way she was living was not the way anyone should have to live. She looked at me and said, 'Wow, it isn't [a life]." After making the necessary adjustments, that patient ultimately was able to enjoy dinner with her family, while "in very little if any pain," says Louw. Podolak has been seeing a patient with CFS for the past 2 years who, at the outset, could walk only 50 feet—"if that." He loves nature and had sorely missed walking outside, so she's helped get him to the point that he now can walk around a local park for 10 minutes. "That was a very meaningful goal for him to meet," she says. The next goal will be enabling him to make short drives downtown and decrease his isolation, Podolak says. Socialization should help combat his depression issues, she notes, adding, "Depression is a common comorbidity in this patient population of which PTs should be aware. If it's present, is the patient being treated for it? Ask questions." The Future Exactly how bright the future looks for people with CFS in terms of finding answers through research depends on who you talk to. Louw is particularly encouraged by the body of work of Belgian researchers Mira Meeus and Jo Nijs, with whom he's collaborated, calling them "world-leading authorities in the field of neuroscience and people with chronic fatigue syndrome." Their work, he says, suggests that a "mid-range" of exercise is best, with no exercise or too much exercise both making the patient's condition worse. Their research, Louw says, "is very therapy-specific. I encourage PTs to look up their papers." Davenport, however, argues that a "pain science approach" sometimes can underplay the value of patients "listening to their body" in favor of the message that "pain perception does not equal tissue damage." It's an area in which, he says, "pain science proponents and I have some robust debate." He adds that while "some interesting papers have come out in recent years that seem to support the etiology of possible aerobic-system dysfunction" in people with CFS, a "causal link" to why CFS happens—and thus how it might best be addressed—remains elusive. Nicole Rabanal, meanwhile, follows developments in CFS research with all the intensity that her disease will allow. She is encouraged by what she sees. "Tremendous research is being conducted around the world," she says. "In Norway they're looking at rituximab"—a medication used to treat certain autoimmune diseases and types of cancer—"as a treatment. Biomarkers are being identified in Australia. And, in fact, I'm 1 of 20 patients scheduled to take part in the first of 3 phases of a CFS study at the National Institutes of Health in Maryland, as long as funding continues to be provided." She concedes, however, that the effort it will take her to get to the airport and fly to the East Coast for the study "is going to crush me. The last time I was a passenger in a car, for 3 hours, I couldn't walk more than 50 feet for 2 days afterward." Eric Ries is the associate editor of PT in Motion. The BasicsDescriptionChronic fatigue syndrome (CFS) is a devastating and complex disorder. People with CFS have overwhelming fatigue and a host of other symptoms that are not improved by bed rest and that can worsen after physical activity or mental exertion. They often function at a substantially lower level of activity than they were capable of before they became ill.Besides severe fatigue, other symptoms include muscle pain, impaired memory or mental concentration, insomnia, and postexertion malaise lasting more than 24 hours. In some cases, CFS can persist for years.Researchers have not yet identified what causes CFS, and there are no tests to diagnose CFS. Moreover, because many illnesses have fatigue as a symptom, doctors need to take care to rule out other conditions, which may be treatable.www.cdc.gov/cfs/general/index.htmlPrevalenceCFS affects 836,000 to 2.5 million Americans. An estimated 84%–91% of people with CFS have not been diagnosed, meaning the true prevalence is unknown. CFS affects women more often than men. The average age at onset is 33, but it has been reported in patients younger than 10 and older than 70.www.nap.edu/read/19012/chapter/1Diagnostic Criteria Diagnosis requires that the patient have 1 of the following 3 symptoms:A substantial reduction or impairment in the ability to engage in pre-illness levels of occupational, educational, social, or personal activities that persists for more than 6 months and is accompanied by fatigue, which is often profound, is of new or definite onset (not lifelong), is not the result of ongoing excessive exertion, and is not substantially alleviated by rest,Postexertional malaise,* andUnrefreshing sleep.At least 1 of the 2 following manifestations also is required:Cognitive impairment* orOrthostatic intolerance.*Frequency and severity of symptoms should be assessed. The diagnosis of ME/CFS should be questioned if patients do not have these symptoms at least half of the time with moderate, substantial, or severe intensity.www.nap.edu/read/19012/chapter/1Seeking and receiving a diagnosis can be a frustrating process for several reasons, including skepticism of health care providers about the serious nature of CFS and the misconception that it is a psychogenic illness or even a figment of the patient's imagination. Less than one-third of medical schools include CFS-specific information in the curriculum, and only 40% of medical textbooks include information on the disorder. It often is seen as a diagnosis of exclusion, which also can lead to delays in diagnosis, or to misdiagnosis of a psychological problem. Once diagnosed, patients frequently complain that their health care providers do not know how to deliver appropriate care for their condition and often subject them to treatment strategies that exacerbate their symptoms.www.nap.edu/read/19012/chapter/2That's What She SEID (About the Name)"Trivializing." "Stigmatizing." "A disservice to many patients." "Does not accurately describe the major features of the disease."Those are some of the ways the Health and Medicine Division of the National Academies of Science, Engineering, and Medicine (formerly the Institute of Medicine), in a highly publicized 2015 report, characterized the name of the medical condition commonly known as chronic fatigue syndrome (CFS).Ronald Davis, PhD, a biochemist who heads the Genome Technology Center at Stanford University, hit on the crux of the problem in an interview with Science magazine after the report's release. "My son is sick with [CFS], and when I tell people, they say, 'I had that once' because they were tired once," a frustrated Davis remarked.1The disease also sometimes is called myalgic encephalomyelitis (ME), CFS/ME, or ME/CFS. "ME is a better name," Davis told the magazine—but, he observed, "there are no real data to fit [it]."Davis was on the committee that compiled the 2015 report, titled "Beyond Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Redefining an Illness."2 After reviewing more than 9,000 scientific studies, weighing expert testimony, and soliciting public input, the panel concluded not only that "ME/CFS is a serious, chronic, complex, and systemic disease that frequently and dramatically limits the activities of affected patients" and that merits new diagnostic criteria, but also that the words commonly used to describe the illness are offensive in the case of chronic fatigue syndrome and inaccurate in the case of myalgic encephalomyelitis.Regarding ME, the report read, "The committee concludes that the term 'myalgic encephalomyelitis' is inappropriate because there is a lack of evidence for encephalomyelitis (brain inflammation) in ME/CFS patients, and myalgia (muscle pain) is not a core symptom of the disease."The new term the panel chose to describe the illness was "systemic exertion intolerance disease," or SEID. "This name," the panelists wrote, "captures a central characteristic of the disease: the fact that exertion of any sort—physical, cognitive, or emotional—can adversely affect patients in many organ systems and in many aspects of their lives."While SEID—a term that has yet to capture the public's imagination—has accuracy on its side, even Davis concedes its descriptive flatness. "It's hard to come up with a good name, and I don't think this is a perfect name," he told Science 2 years ago.The words "systemic exertion intolerance disease" do not exactly roll off the tongue, agrees Nicole Rabanal, PT. Nevertheless, she personally has experienced the new name's ability to positively alter perceptions. Rabanal, who owns Kinetic Energy Physical Therapy in Steamboat Springs, Colorado, was diagnosed in late 2014 with CFS, an illness that has greatly circumscribed her personal and professional life. Nevertheless, she says, "When people ask me, 'What's wrong with you? Did they ever figure it out?' and I say, 'I have chronic fatigue,' they pat me on the shoulder and say, 'Oh, you'll be okay. Just lie down and rest.'"Such reactions, she says, are "devastating—the stigma is horrible." But when Rabanal instead replies that her diagnosis is an illness called systemic exertional intolerance disease, the response is, "My gosh, that's awful! What can I do for you? How can I help you?"—even though it's clear that the questioner hasn't a clue what the term means. Sometimes a simple lack of pejorative association makes all the difference.The trick going forward, Rabanal says, will be to teach both the public and still-skeptical members of the medical community that a condition they may underappreciate or even dismiss under the CFS/ME moniker is one and the same with the scientifically validated disease that more accurately has been rechristened SEID."If you can't make that connection, there's no validation for the thousands upon thousands of people who are afflicted with this disease," Rabanal argues. "This patient population has to be validated in its suffering, which can be extensive. Education is the only way to do that." "Names change all the time," observes Adriaan Louw, PT, PhD. He has worked clinically with people with chronic pain for 25 years and is president of the International Spine and Pain Institute. What's most important for PTs to do, Louw says, is encapsulated in the title of a presentation he gave in February at APTA's Combined Sections meeting in San Antonio, Texas.In that talk, which focused on how PTs best can understand CFS and other persistent pain disorders, Louw emphasized the need to base clinical decision-making not on generalized protocols and preconceived notions, but on the individual's specific presentation and information the clinician has culled from extensive patient interviewing. He titled it "Treat the Patient, Not the Label."ReferencesCohen J. Goodbye chronic fatigue syndrome, hello SEID. Science. February 10, 2015. www.sciencemag.org/news/2015/02/goodbye-chronic-fatigue-syndrome-hello-seid. Accessed June 19, 2017.Beyond Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Redefining and Illness. Committee on the Diagnostic Criteria for Myalgic Encephalomyelitis/Chronic Fatigue Syndrome, Board on the Health of Select Populations, Institute of Medicine. Washington, DC: National Academies Press; 2015.ResourcesGeneralPhysical Therapist's Guide to Chronic Fatigue Syndromewww.moveforwardpt.com/SymptomsConditionsDetail.aspx?cid=13f232c1-2d06-4063-8a3b-5ae844fdd075Centers for Disease Control Toolkit for Providerswww.cdc.gov/cfs/pdf/cfs-toolkit.pdf Mayo Clinicwww.mayoclinic.org/diseases-conditions/chronic-fatigue-syndrome/basics/definition/con-20022009 Workwell Foundation: Research on Chronic Fatigue Syndromewww.workwellfoundation.org/ Bateman Horne Center for ME/CFS and Fibromyalgiahttps://batemanhornecenter.org/ Articles"The Tragic Neglect of Chronic Fatigue Syndrome"www.theatlantic.com/health/archive/2015/10/chronic-fatigue-patients-push-for-an-elusive-cure/409534/ "Goodbye Chronic Fatigue Syndrome, Hello SEID"www.sciencemag.org/news/2015/02/goodbye-chronic-fatigue-syndrome-hello-seid "A New Name, and Wider Recognition, for Chronic Fatigue Syndrome"www.newyorker.com/tech/elements/chronic-fatigue-syndrome-iom-report Reports and Reviews"Beyond Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Redefining an Illness"www.nap.edu/read/19012/chapter/1 "Exercise As Treatment for Patients with Chronic Fatigue Syndrome"www.cochrane.org/CD003200/DEPRESSN_exercise-treatment-patients-chronic-fatigue-syndrome Selected ResearchDavenport TE, Stevens SR, Van Ness JM, et al. Conceptual model for physical therapist management of chronic fatigue syndrome/myalgic encephalomyelitis. Phys Ther. 2010;90(4):602-614.Hornig M, Montoya JG, Klimas NG, et al. Distinct plasma immune signatures in ME/CFS are present early in the course of the disease. Sci Adv. 2015;1(1).Nagy-Szakal D, Williams BL, Mishra N, et al. Fecal metagenomic profiles in subgroups pf patients with myalgic encephalomyelitis/chronic fatigue syndrome. Microbiome. 2017;5:44. Snell CR, Stevens SR, Davenport TE, Van Ness JM. Discriminative validity of metabolic and workload measurements for identifying people with chronic fatigue syndrome. Phys Ther. 2013;93(11):1484-1492.Stevens SR, Davenport TE. Functional outcomes of anaerobic rehabilitation in a patient with chronic fatigue syndrome: case report with 1-year follow-up. Bulletin of the IACFS/ME. 2010;18(3):93-98.Van Cauwenbergh D, De Koonung M, Ickmans K, Nijs J. How to exercise people with chronic fatigue syndrome: evidence-based practice guidelines. Eur J Clin Invest. 2012.42(10):1136-1144.