Pacing

From MEpedia, a crowd-sourced encyclopedia of ME and CFS science and history
Pacing is • an activity management strategy • to help ME/CFS patients limit relapses/crashes • while remaining as active as possible

Pacing is an activity management strategy to help ME/CFS patients limit the number and severity of relapses while remaining as active as possible. First described by health psychologist Ellen Goudsmit in 1989,[1] it gives patients the advice to: “do as much as you can within your limits”.[2] Pacing recognizes research showing an abnormal metabolic and immunological response to exercise in ME/CFS and offers patients a middle ground between post-exertional malaise and the negative consequences of inactivity. 

Pacing has been used as a management strategy in multi-component treatment trials[3][4][5] and in several large patient surveys the majority of respondents found pacing to be helpful.[6][7][8] Pacing has been suggested by the CDC[9] and 2007 NICE guidelines[10] as an effective component in the treatment of patients with ME/CFS.

History[edit | edit source]

In ME/CFS[edit | edit source]

Pacing was developed as an energy management strategy for ME-patients in the UK in the 1980s.[11] Health psychologist Ellen Goudsmit had suffered from post viral syndrome herself[2] the decade before and noticed how patients had to learn through trial and error how to pace themselves. Patients were forced to discover through their own frustrating experience how to stay as active as possible within the limits the disease had imposed upon them. This resulted in many unnecessary relapses. In order to prevent these, Goudsmit worked out her own approach into an advice that could be used by others. In the 1990s pacing was promoted in factsheets by various ME-groups in the UK.[12] Around the same time, Leonard Jason, a professor of psychology at the University of Chicago who also suffered from a post-viral fatigue syndrome,[13] developed the envelope theory along the same principles of energy conservation.[14] A decade earlier ME-expert Melvin Ramsay had written about the benefits of implementing sufficient rest periods:

"One can hold out no specific cure for the illness but advice should immediately be given that they adapt their lives to a quieter tempo and take adequate periods of complete rest after physical exertion."

In other conditions[edit | edit source]

The term pacing has a longer history in the management of other chronic conditions, though its meaning is ambiguous. Two main traditions exist.[15] In the first, pacing is used in the context of energy conservation, a common element in the treatment of autoimmune and neurological disorders such as rheumatoid arthritis[16] or MS.[17] Energy conservation includes balancing activity and rest, setting priorities, delegating tasks and using assistive devices such a wheelchair. This form of energy management is similar to the principles of pacing used in ME/CFS. 

Pacing is however more frequently used in the context of chronic pain where it has a background in operant conditioning. First described by Wilbert Fordyce in 1976,[18] pacing referred to a time-contingent and gradual increase of activity levels. Fordyce’s main idea was that chronic pain patients shouldn’t be directed by their symptoms but by plans, goals and targets. In this context, pacing referred to the careful planned route, based on positive reinforcements instead of the fear of pain, to reach those goals.[19] Often a task was broken up into manageable parts or quotas so the patient can go forward step by step with breaks in between. Although the principles of operant conditioning are no longer central, in the chronic pain literature pacing still frequently refers to a planned and gradual increase of activity levels. Pacing means doing things “slow but steady”,[20] by splitting up activities in smaller parts, and without discontinuation if the patient is having a bad day. This form of pacing is quite dissimilar and sometimes even contrary to the form of pacing used in ME/CFS.

Definitions of pacing used in the chronic pain literature
Kavanagh (1995)[21] Birkholtz & Aylwin (2000)[22] Strong et al. (2002)[23] Nielson et al. (2013)[24] Jamieson-Lega et al. (2013)[25]
“Pacing involves breaking down activities into smaller steps, resting between steps and doing small amounts regularly rather than a large amount of activity in one go.” “Activity pacing consists of (a) changing position to time, (b) taking frequent short rests, (c) breaking tasks into manageable bits, (d) alternating positions and tasks frequently, (e) slowing down, and (f) increasing activity amounts gradually.”   “introducing tasks in a graded manner, in order for the client to build skills, confidence and tolerance for the activity, so that activity levels can be increased” “Activity pacing is the regulation of activity level and/or rate in the service of an adaptive goal or goals.” “Pacing is an active self-management strategy whereby individuals learn to balance time spent on activity and rest for the purpose of achieving increased function and participation in meaningful activities.”

The principles of pacing[edit | edit source]

Stop before you overdo it[edit | edit source]

The aim of pacing in ME/CFS is to remain as active as possible while avoiding the relapses resulting from overexertion.[26] This requires an understanding of the relationship between symptoms and exertion. Patients have to learn to recognize symptoms of post-exertional malaise and reduce their activities in time, in order to avoid relapses. This can mean that activities have to be limited and structured per day such as washing one day and cooking the next. It also means activities have to be stopped (sometimes abruptly) before they are completed, which can be frustrating and difficult to master.  

No plans or targets but internal cues[edit | edit source]

In contrast to graded exercise therapy, pacing does not rely on plans, targets or goals, but on how patients feel. As one writer poetically described it: “pacing is not a static decision but necessarily fluctuates with the monitoring of the physiological imperative.”[27] Rest is advised at the first signs of muscle weakness. According to Goudsmit & Howes cognitive tasks form the major exception where a time-contingent approach might be more helpful.[26] Because cognitive activities such as reading provide few internal cues to detect overexertion, it might be useful to use a timer to restrict energy expenditure. 

Switching[edit | edit source]

A component that has been added to pacing is called switching. This refers to changing activities in order to avoid tiring specific muscles.[12] As Goudsmit explains:

“For instance, if you've been reading for a while, stop before your eye muscles get tired and do something which involves a different muscle group, e.g. walking, washing clothes, eating, talking. Do that for a while (stop before you reach your limit), and then switch again (you can even go back to reading).”[28]

Rest periods can be inserted between each change of activity. 

Use of a diary or activity tracker[edit | edit source]

Another advice that is often part of pacing is to keep a diary where information about activity levels, stressful events and symptom flare-ups can be recorded. This might help patients to understand the relation between overexertion and symptoms. Abbreviations and scoring systems can be used to limit the energy needed to fill in the diary. Other patients find it helpful to use an activity tracker[29] to obtain more reliable information on the amount of energy they’ve spent each day and how this corresponds with their state of health.

Increase activity when you are ready[edit | edit source]

Pacing is about figuring out how much one can do without triggering a relapse. If patients feel their health has stabilized or improved and they no longer experience setbacks, it might be helpful to gradually increase activities to see how it goes. In a consensus document about pacing, Goudsmit & Jason wrote: 

“If increases in activity do not result in symptom flare-ups for three months and patients feel that they are close to about 60 to 70% of their former functioning, they may wish to change to a gentle form of graded exercise therapy (GET), starting at a low level and increasing incrementally in duration and intensity to further increase their fitness and tolerance thresholds.”[11]

One of the other authors of this consensus document, Karen Wallman, tested a symptom-contingent form of graded exercise in a randomized controlled trial in 2004. Patients were allowed to stop or do less if their symptoms became worse while increases in exercise were only advised if patients felt they were coping with the current activity level. After 12 weeks of 'graded exercise with pacing', patients showed improvement on objective outcome measures such as blood lactate production and performance on a Stroop colour word test.[30]

Not a Therapy[edit | edit source]

Pacing often is a helpful coping strategy for patients with ME/CFS, but it is not a therapy.  It does not claim to alleviate the many symptoms of ME/CFS such as sore throat or light sensitivity. Pacing is not so much a treatment as a way of energy management for patients with ME/CFS. It is usually one component of a multidisciplinary program for ME/CFS patients that may also include information about the disease, emotional support or advice on nutrition. Because pacing does not require specialist training, its basic principles can be counseled by a GP or nurse.[11]

Scientific evidence[edit | edit source]

In ME/CFS[edit | edit source]

Pacing has been used in several multi-component treatment trials. In 1996 Goudsmit conducted a controlled trial for patients with post-infectious fatigue syndrome. Pacing was one component of a multidisciplinary treatment protocol prescribed by Darrel O. Ho-Yen[31] which also included medical care, emotional support and advice on avoiding stress. More than 80% of patients reported feeling better. At 6 months there was a significant difference between controls on outcome measures such as fatigue or self-efficacy. Twenty-three percent of the patients had improved to such a degree that they were discharged.[3][4]

In 2004 Renee Taylor offered a similar multidisciplinary program to 47 ME/CFS-patients in a randomized clinical trial.[5] This study was part of the Chronic Fatigue Syndrome Empowerment project, a federally funded research project designed to develop and evaluate the effects of a consumer-driven rehabilitation program for individuals with chronic fatigue syndrome. Participants received four months of illness management groups followed by seven month one-on-one self-advocacy training. Besides pacing the program focused on economic self-sufficiency, coping skills and nutritional advice. Results indicated that overall quality of life had significant improved in the treatment group – a remarkable finding, since trials on cognitive behavioral therapy or graded exercise therapy, often fail to improve quality of life in ME/CFS patients.[32]

Further evidence supporting pacing, comes from research on the envelope theory, an energy management strategy developed by Leonard Jason which is based on similar principles. Patients are advised to stay within the envelope; meaning the limits the disease has imposed upon them. Patients who over-exert themselves are advised to cut back while those who have been inactive for a long time are encouraged to gradually increase their activity. An analysis of the activity pattern of 144 ME/CFS patients showed that those who extend their activities beyond their energy envelope, experience more disability.[33] These results were confirmed in a larger 2017 study involving 429 patients from different locations.[34] Furthermore, a prospective study of 44 patients who were part of a study on nonpharmacological interventions in ME/CFS, showed that “those who were within their energy envelope before treatment showed more improvement in physical functioning and fatigue compared to those outside of their energy envelope."[35]

In several large patient surveys, respondents indicated they’ve found pacing to be helpful in managing ME/CFS. A 1999 survey (n = 820) by the CFIDS Association of America (now Solve ME/CFS initiative) showed that 71% of patients rated pacing as helpful.[6] In a survey conducted by Action for ME (n = 2338) in 2001, 89% of the respondents found pacing to be helpful.[7] These results were confirmed in a follow-up study by Action for ME in 2008.[36]

Action for M.E.’s survey results on treatments in 2001 and 2008[37]
Helpful No change Made Worse
2001 survey 2008 survey 2001 survey 2008 survey 2001 survey 2008 survey
Pacing 89% 82% 9% 15% 2% 3%
CBT 7% 50% 67% 38% 26% 12%
GET 34% 45% 16% 21% 50% 34%

Another large survey set up by the ME Association (n =1428) showed patients preferred pacing over CBT or GET and judged this approach to be more appropriate to their needs. The survey concluded: 

“Pacing was consistently shown to be the most effective, safe, acceptable and preferred form of activity management for people with ME/CFS and should therefore be a key component of any illness management programme […]The benefit of Pacing may relate to helping people cope and adapt to their illness rather than contributing to a significant improvement in functional status.”[8] 

In the treatment of chronic pain[edit | edit source]

While pacing is a highly endorsed clinical strategy in the treatment of chronic pain, empirical evidence to support its effectiveness is currently lacking. Raichel et al. for example found that pacing was correlated with higher levels of pain interference in 157 patients with spinal cord injury.[38] In a study by Ersek et al. pacing was positively associated with physical disability and pain intensity in the elderly.[39]  Kindermans et al. reported a correlation between pacing and higher levels of disability and symptoms of depression. According to the authors, “this seems to suggest that pacing, as it is currently measured, might reflect a (hidden) form of avoidance behavior.”[40]  Using accelerometers to track activity levels, Cuperus et al. were able to demonstrate in a more objective manner that pacing was associated with lower activity. This led the authors to conclude that “activity pacing might not only be ineffective, it might even be potentially harmful, as inactivity-related comorbidities increase the risk for mortality and negatively influence quality of life.”[41] In a 2012 review Andrews et al. concluded that “pacing was generally linked to better psychological functioning but more pain and disability.”[42]

Since then, several explanations have been put forward to explain these bleak results. Susan Murphy argued that there might be a difference between how patients and clinicians view pacing. According to Murphy patients' intrinsic view on pacing is mostly symptom-contingent and directed at reducing pain, while those of clinicians is time-contingent and aimed at increasing activity levels.[43] An appropriate assessment of pacing should thus occur after instructions by a clinician, to account for these differences.[44] Murphy also suggested pacing should be tailored to the individual patient by using physiological measures obtained during an exercise test, as targets.[45] Her ideas were tested in a large trial of 193 patients with osteoarthritis, but once again results were disappointing. Both the general and tailored pacing group, were worse off than the patient group receiving usual care.[46]

Because some studies[47][48] did find positive results for pacing in the treatment of chronic pain conditions, Deborah Antcliff argued that the term pacing, denotes several different aspects. In the Activity Pacing Questionnaire (APQ), the questionnaire she helped develop, 5 factors were differentiated: activity adjustment, activity consistency, activity progression, activity planning, and activity acceptance.[49] Research by Antcliff suggested that adjustment, acceptance and progression were associated with worsened symptoms, while consistency was correlated with improved symptoms.[50] This has pushed Antcliff to promote the use of a time-contingent graded increase in activity levels, as an essential element in the definition of pacing.[51]

Other forms of pacing used in ME/CFS[edit | edit source]

Energy Envelope Theory[edit | edit source]

Main article: Energy Envelope Theory
Main article: Energy Envelope Theory

Leonard Jason's energy envelope theory is very similar to pacing. Patients are advised to stay within their envelope; meaning the limits the disease has imposed upon them. According to Jason: "the phrase, 'staying within the envelope' is used to designate a comfortable range of energy expenditure, in which an individual avoids both over-exertion and under-exertion, maintaining an optimal level of activity over time.”[52] Research has shown that ME/CFS patients who go beyond their envelope and spent more energy than they estimate to have, experience more symptoms over time.[34][35]

Adaptive pacing therapy (APT)[edit | edit source]

A modified form of pacing is called adapative pacing therapy (APT). This version was promoted by Action for ME[37] and was used in the PACE trial[53] as an alternative to cognitive behavioral therapy, graded exercise therapy and specialist medical care. There are some major differences between APT and the original form of pacing advocated by Goudsmit. The former for example stresses splitting up activities, while this is not necessarily an advice used in the latter. APT seems more influenced by chronic pain literature as it gives more weight to planning and building up activities. A booklet on pacing, produced by Action for ME explains to patients: “you are likely to notice a temporary increase in stiffness or fatigue when increasing your activity levels. This is normal and your body will need a few days to adjust and adapt.”[37] No such advice is given in the pacing, developed by Goudsmit or Jason as this may not be adequate in the treatment of patients with ME/CFS. One of the (anonymous) participants in the 2015 ME association survey,  for example, complained that pacing put too much emphasis on increasing activity:

"It taught me to listen to my body and not ignore symptoms and I gradually began to see the link between exercise/activity and delayed fatigue, which I hadn't done beforehand. That was crucial in slowing down my deterioration. But I wish someone had said 'if you are experiencing symptoms you should rest' – the message was, 'you can get worse briefly but symptoms should then go again'. I kept waiting for them to go and they never did. Then I had a massive relapse which I have not recovered from. Pacing is not very satisfactory – it is full of confusing contradictory messages […]  I felt the emphasis was too heavily on increasing activity – I should have been told to rest.”[8]

These criticisms seem to apply to APT, and not to pacing. 

Another major difference is that APT promotes the use of preemptive rest. In the PACE trial for example patients were advised to follow the 70%-rule, meaning they shouldn’t go beyond 70% of their perceived energy. This is also not an element in the writings of Goudsmit or Jason, where patients are advised to correctly balance perceived energy and energy expenditure. Telling ME/CFS patients to do even less than their perceived energy limit might have negative consequences, as was noticed by Leonard Jason: “By doing less than what patients have the energy to do, and the resulting preemptive rest, this intervention could even have the unwitting effects of increasing social isolation.”[54] This was what Goudsmit found in the clinical trial where the protocol of Ho Yen was tested. The treatment arm also included preemptive rest and some patients said they felt isolated as a result of the prescribed reduction in activity.[3]

Finally, APT proposes pacing as a therapy, while Goudsmit has emphasized the opposite. She explicitly warned that: “both the rationale behind pacing and the findings from controlled trials do not support the promotion by some patient groups of pacing as a “therapy” for CFS. […] given the lack of evidence that this strategy can alleviate a range of symptoms and promote healing,  descriptions of pacing as a form of therapy may be construed as misleading.”[26]

The findings of the PACE-trial, analyzed according to the original protocol, did not find a significant difference between APT, specialist medical care, graded exercise therapy or cognitive behavioral therapy. Jason remarked that the label APT, included much more than pacing: “It is important to note that APT (Cox et al., 2004) also included advice on stress management, sleep, and so on, and this makes it difficult to determine what was effective or ineffective if one cannot separate the effects […] the authors evaluated APT, not solely pacing.”[54]  According to Goudsmit and Howes, “the differences between APT and pacing almost certainly explain the discrepancy between the results relating to the former, and the research as well as positive experiences of pacing reported by patients in surveys conducted by support groups.”[55]

Activity pacing-self management[edit | edit source]

Another form of pacing, Activity Pacing Self-Management (APSM) is promoted by the Belgian research group of Jo Nijs, one of the authors of the 2012 consensus document on pacing. His version of pacing is more in line with the tradition of operant conditioning in the chronic pain literature, and less with the principles of energy conservation. According to Nijs, the PACE authors made a mistake by placing pacing and GET in opposition to each other, as it is more effective to use both strategies in the treatment of ME/CFS.[56] Nuñes (2011) also used a pacing approach to physical activity and exercise, with positive results.[57] In APSM patients first learn to pace themselves to find a baseline of activity that doesn’t result in relapses. Only if they’ve managed to stabilize their condition - and this might take several weeks - can they proceed to the next phase which aims to gradually increase activities according to time-contingent scheme. In APSM pacing is thus used a stepping stone to graded exercise therapy.  

Nijs' research group tested the APSM approach in a 2015 randomized control trial in which the control group received relaxation therapy.[56] The results were favorable for APSM, though no objective performance measures were used. The study was also rather small as only 16 ME/CFS patients were involved in the experimental group, of which 4 (25%) stopped the treatment prematurely.

See also
Graded exercise therapy.

Pacing for chronic pain patients:[edit | edit source]

In 2018, Thomson et al., a research team at the University of Manchester, studied pacing in 114 ME/CFS patients using the Chronic Pain Coping Inventory (CPCI).[58]  In 2001, Nielson et al. had added six questions to this questionnaire to assess the use of pacing.[59] As the CPCI was designed for patients with chronic pain, the added pacing section focuses on doing things “slow and steady” and breaking up tasks into manageable pieces, instead on listening to symptom-flare ups and balancing energy expenditure. This form of pacing thus differs significantly form the version promoted by Goudsmit and Jason.

Thomson et al. searched for cross-sectional associations between pacing and levels of pain, disability and fatigue, but made a remarkable choice in outcome measures. For fatigue they used the Chalder Fatigue Scale with Likert score, despite detailed criticism of this method.[60] Disability was assessed using the Fibromyalgia Impact Questionnaire (FIQ) physical impairment subscale, on the basis that ME/CFS- and fibromyalgia patients share many symptoms.

Using these outcome measures, Thompson et al. found no significant associations between pacing and levels of pain, fatigue or disability. In the second part of the study, a smaller sample of 35 ME/CFS patients followed a graded exercise program. Although participants reported significant reductions in fatigue, these improvements were not explained by pacing as measured with the CPCI. According to the authors “It would therefore seem that factors other than pacing were more important determinants of improvements following treatment.”[58]

Criticism[edit | edit source]

Focus on symptoms? [edit | edit source]

Some have argued that close monitoring of symptoms might aggravate distress and disability.[61][62] According to Goudsmit & Howes, however “it is important to differentiate between responding to symptoms as one becomes aware of them, an inherent part of pacing, and constant monitoring, which is unnecessary and should be discouraged.”[26]

Trapped in the envelope?[edit | edit source]

Others have argued that pacing might hamper recovery as it lets symptoms of pain and fatigue determine the amount of activity patients do. According to Peter White: the theoretical risk of pacing is that the patient remains trapped by their symptoms in the envelope of ill health".[63] Pacing however does not limit the activity of patients, as long as they feel they are up to it. Goudsmit wrote: “my concept of pacing means responding to your symptoms so if you feel OK, there's no reason to stop. If you want to increase your activity levels, you are free to do so as long as you don't over-exert yourself in the process.”[28]

Reliance on subjective symptoms instead of objective limits[edit | edit source]

Researchers from the Workwell Foundation have argued that self-managed pacing puts too much emphasis on the subjective experience of symptoms and that objective limits to avoid relapse are preferable. In 2010 Davenport et al. wrote: 

“To date, recommendations for pacing self-management in people with CFS/ME have been made on the basis of symptom acuity and irritability. Although these criteria seem to be intuitive, they may fail to account for the rapid changes in function that are characteristic of CFS/ ME. An impaired perception of effort in people with CFS/ME may interfere with the optimal maintenance of symptom-free activity levels if pacing self-management criteria that are based solely on symptomatology are used.”[64]  

As an alternative the authors propose to use a cardiopulmonary exercise test (CPET) to gather information about the patient’s physiology. The anaerobic threshold (AT) in particular can be seen as the boundary where exercise becomes harmful for ME/CFS patients. Davenport et al. suggest that a 10% margin below the estimated heart rate at the AT should be used as an exercise limit. Patients can set a heart rate monitor to make an alarm noise, each time the heart rate exceeds this limit. This might provide more reliable feedback to avoid relapses than the mere perception of muscle weakness originally used in pacing. 

A case study by Stevens and Davenport (2010) describes the use of pacing in a patient with CFS using a heart rate set to below the patient's anaerobic threshold; this resulted in significant improvements and reduced periods of over-exertion.[65]

Too much activity?[edit | edit source]

Instead of advising too little activity, some have argued that pacing actually instructs patients to do too much. ME advocate Gabby Klein, for example wrote:  “My treating physician -  Dr. Enlander - always told me to do 50% of what I think I can do. It was the best advice I got. There is much more potential harm from activity/exercise than from rest.”[66] ME blogger Sally Burch argued that ME/CFS patients will usually do too much activity, so that the best advice a physician can give, is preemptive rest.[67] According to Goudsmit and Jason however, advising patients to do less than they could without exacerbating symptoms, might impede them from engaging in meaningful activities such as contact with friends and family. As such, preemptive rest might increase distress and disability.[54]

Learn more and Pacing Guides[edit | edit source]

Factsheets and information[edit | edit source]

Worksheets[edit | edit source]

Blogs and articles:[edit | edit source]

Books[edit | edit source]

Translations into Norweigan and Islandic also available

Notable studies:[edit | edit source]

  • Jason et al. (2008). The Energy Envelope Theory and myalgic encephalomyelitis/chronic fatigue syndrome - (Full text)
  • Stevens et al. (2010). Functional outcomes of anaerobic rehabilitation in an individual with chronic fatigue syndrome: case report with 1-year follow-up.[65] - (Full text)
Pacing using a HR monitor to avoid most over-exertion.
  • Nuñez et al (2011). Health-related quality of life in patients with chronic fatigue syndrome: group cognitive behavioural therapy and graded exercise versus usual treatment. A randomised controlled trial with 1 year of follow-up[57] - (Full Text)
  • Goudsmit et al. (2012). Pacing as a strategy to improve energy management in myalgic encephalomyelitis/chronic fatigue syndrome: a consensus document[11] - (Full text)
Describing graded exercise in comparison with symptom-contingent graded exercise therapy or pacing
  • O'Connor et al. (2017). Energy envelope maintenance among patients with myalgic encephalomyelitis and chronic fatigue syndrome: Implications of limited energy reserves - (Full text).

See also[edit | edit source]

References[edit | edit source]

  1. ↑ Goudsmit, Ellen M.; Howes, Sandra. "Pacing: An additional strategy to manage fatigue in chronic fatigue syndrome". axfordsabode.org. Retrieved November 15, 2019.
  2. ↑ 2.0 2.1 Ellen Goudsmit, Ellen (May 2005). "Pacing for ME and CFS: a guide for patients" (PDF). WAMES. Retrieved November 15, 2019.
  3. ↑ 3.0 3.1 3.2 Goudsmit, E.M.  (1996). The psychological aspects and management of chronic fatigue syndrome. PhD thesis. Department of Psychology. Brunel University, Uxbridge, UK.
  4. ↑ 4.0 4.1 Goudsmit, Ellen M.; Ho-Yen, Darrel O.; Dancey, Christine P. (November 2009). "Learning to cope with chronic illness. Efficacy of a multi-component treatment for people with chronic fatigue syndrome". Patient Education and Counseling. 77 (2): 231–236. doi:10.1016/j.pec.2009.05.015. ISSN 1873-5134. PMID 19576714.
  5. ↑ 5.0 5.1 Taylor, Renée R. (January 2004). "Quality of life and symptom severity for individuals with chronic fatigue syndrome: findings from a randomized clinical trial". The American Journal of Occupational Therapy: Official Publication of the American Occupational Therapy Association. 58 (1): 35–43. ISSN 0272-9490. PMID 14763634.
  6. ↑ 6.0 6.1 1999 Chronicle Reader Survey. Charlotte, NC: CFIDS Association of America. CFIDS Chronicle. 1999;12(4):9.
  7. ↑ 7.0 7.1 Action for M.E. Severely Neglected: M.E. in the UK—Membership Survey. London: Action for M.E.; 2001.
  8. ↑ 8.0 8.1 8.2 ME Association. “No decisions about me without me”. ME/CFS illness management survey results, part 1. Gawcott, Bucks (England), (2015).
  9. ↑ "Treatment | Myalgic Encephalomyelitis/Chronic Fatigue Syndrome". Centers for Disease Control and Prevention. May 18, 2018. Retrieved August 19, 2018.
  10. ↑ National Institute for Health and Care Excellence. Chronic fatigue syndrome/myalgic encephalomyelitis (or encephalopathy): diagnosis and management Clinical guideline (CG53). August 2007.
  11. ↑ 11.0 11.1 11.2 11.3 Goudsmit, Ellen M.; Nijs, Jo; Jason, Leonard A.; Wallman, Karen E. (2012). "Pacing as a strategy to improve energy management in myalgic encephalomyelitis/chronic fatigue syndrome: a consensus document". Disability and Rehabilitation. 34 (13): 1140–1147. doi:10.3109/09638288.2011.635746. ISSN 1464-5165. PMID 22181560.
  12. ↑ 12.0 12.1 "Pacing for ME/CFS: The Facts - Prohealth". Prohealth. January 17, 2007. Retrieved August 19, 2018.
  13. ↑ "Feeling fatigued: studying CFS at Northwestern". northbynorthwestern.com. Retrieved August 19, 2018.
  14. ↑ Jason, L. A.; Melrose, H.; Lerman, A.; Burroughs, V.; Lewis, K.; King, C.P.; Frankenberry, E.L. (January 1999). "Managing chronic fatigue syndrome: overview and case study". AAOHN journal: official journal of the American Association of Occupational Health Nurses. 47 (1): 17–21. ISSN 0891-0162. PMID 10205371.
  15. ↑ Nielson, Warren R.; Jensen, Mark P.; Karsdorp, Petra A.; Vlaeyen, Johannes W.S. (May 2013). "Activity pacing in chronic pain: concepts, evidence, and future directions". The Clinical Journal of Pain. 29 (5): 461–468. doi:10.1097/AJP.0b013e3182608561. ISSN 1536-5409. PMID 23247005.
  16. ↑ Furst, G. P.; Gerber, L.H.; Smith, C.C.; Fisher, S.; Shulman, B. (February 1987). "A program for improving energy conservation behaviors in adults with rheumatoid arthritis". The American Journal of Occupational Therapy: Official Publication of the American Occupational Therapy Association. 41 (2): 102–111. ISSN 0272-9490. PMID 3565525.
  17. ↑ Mathiowetz, Virgil G.; Finlayson, Marcia L.; Matuska, Kathleen M.; Chen, Hua Yun; Luo, Ping (October 2005). "Randomized controlled trial of an energy conservation course for persons with multiple sclerosis". Multiple Sclerosis (Houndmills, Basingstoke, England). 11 (5): 592–601. doi:10.1191/1352458505ms1198oa. ISSN 1352-4585. PMID 16193899.
  18. ↑ Fordyce WE. Behavioural methods for chronic pain and illness. Mosby: St. Louis; 1976
  19. ↑ Gill, Joanna R.; Brown, Cary A. (February 2009). "A structured review of the evidence for pacing as a chronic pain intervention". European Journal of Pain (London, England). 13 (2): 214–216. doi:10.1016/j.ejpain.2008.03.011. ISSN 1532-2149. PMID 18448368.
  20. ↑ Nielson, W.R.; Jensen, M.P.; Hill, M.L. (January 2001). "An activity pacing scale for the chronic pain coping inventory: development in a sample of patients with fibromyalgia syndrome". Pain. 89 (2–3): 111–115. ISSN 0304-3959. PMID 11166466.
  21. ↑ Kavanagh J (1995) Management of chronic pain using the cognitive-behavioural approach. British Journal of Therapy and Rehabilitation, 2(8), 413-18
  22. ↑ Birkholtz M, Aylwin L (2000) OT in chronic pain management: a specialist area. Occupational Therapy News, 8(11), 26-27.
  23. ↑ Strong J, Unruh AM, Baxter GD. Pain: a textbook for therapists. Toronto: Churchill Livingstone; 2002.
  24. ↑ Nielson, Warren R.; Jensen, Mark P.; Karsdorp, Petra A.; Vlaeyen, Johannes W.S. (May 2013). "Activity pacing in chronic pain: concepts, evidence, and future directions". The Clinical Journal of Pain. 29 (5): 461–468. doi:10.1097/AJP.0b013e3182608561. ISSN 1536-5409. PMID 23247005.
  25. ↑ Jamieson-Lega, Kathryn; Berry, Robyn; Brown, Cary A (2013). "Pacing: A concept analysis of a chronic pain intervention". Pain Research & Management : The Journal of the Canadian Pain Society. 18 (4): 207–213. ISSN 1203-6765. PMC 3812193. PMID 23717825.
  26. ↑ 26.0 26.1 26.2 26.3 Goudsmit, EM; Howes, S (2008). "Pacing: a strategy to improve energy management in chronic fatigue syndrome". Health Psychol Update. 17: 46–52.
  27. ↑ Wiener CL. The burden of rheumatoid arthritis. In: Straus AL, Corbin J, Fagerhaugh S, Glaser BG, Maines D, Suczek B, Wiener CL, editors. Chronic illness and the quality of life. 2nd ed. St. Louis: The CV Mosby Company; 1984. p 94.
  28. ↑ 28.0 28.1 Pacing for ME and CFS: a guide for patients by Dr Ellen Goudsmit. Wames. May 2005. 
  29. ↑ Beauts (January 5, 2013). "Come with M.E. on a journey: ME CFS CFIDS and activity monitoring". Come with M.E. on a journey. Retrieved August 19, 2018.
  30. ↑ Wallman, Karen E.; Morton, Alan R.; Goodman, Carmel; Grove, Robert; Guilfoyle, Andrew M. (May 3, 2004). "Randomised controlled trial of graded exercise in chronic fatigue syndrome". The Medical Journal of Australia. 180 (9): 444–448. ISSN 0025-729X. PMID 15115421.
  31. ↑ Ho-Yen DO. Better recovery from viral illnesses. 3rd ed. Inverness: Dodona Books, 1993.
  32. ↑ Smith, M. E. Beth; Nelson, Heidi D.; Haney, Elizabeth; Pappas, Miranda; Daeges, Monica; Wasson, Ngoc; McDonagh, Marian (December 2014). July 2016 Addendum. Agency for Healthcare Research and Quality (US).
  33. ↑ Jason, Leonard; Muldowney, Kathleen; Torres-Harding, Susan (May 2008). "The Energy Envelope Theory and myalgic encephalomyelitis/chronic fatigue syndrome". AAOHN journal: official journal of the American Association of Occupational Health Nurses. 56 (5): 189–195. ISSN 0891-0162. PMID 18578185.
  34. ↑ 34.0 34.1 O'Connor, Kelly; Sunnquist, Madison; Nicholson, Laura; Jason, Leonard A.; Newton, Julia L.; Strand, Elin B. (January 1, 2017). "Energy envelope maintenance among patients with myalgic encephalomyelitis and chronic fatigue syndrome: Implications of limited energy reserves". Chronic Illness: 1742395317746470. doi:10.1177/1742395317746470. ISSN 1745-9206. PMC 5750135. PMID 29231037.
  35. ↑ 35.0 35.1 Brown, Molly; Khorana, Neha; Jason, Leonard A. (March 2011). "The Role of Changes in Activity as a Function of Perceived Available and Expended Energy in Non-Pharmacological Treatment Outcomes for ME/CFS". Journal of clinical psychology. 67 (3): 253–260. doi:10.1002/jclp.20744. ISSN 0021-9762. PMC 3164291. PMID 21254053.
  36. ↑ "Survey 2008 « Action for M.E." afme.wordpress.com. Retrieved August 19, 2018.
  37. ↑ 37.0 37.1 37.2 Pacing for people with ME. Action for ME. December 2013.
  38. ↑ Raichle, Katherine A.; Hanley, Marisol; Jensen, Mark P.; Cardenas, Diana D. (September 2007). "Cognitions, Coping and Social Environment Predict Adjustment to Pain in Spinal Cord Injury". The journal of pain : official journal of the American Pain Society. 8 (9): 718–729. doi:10.1016/j.jpain.2007.05.006. ISSN 1526-5900. PMC 2045649. PMID 17611163.
  39. ↑ Ersek, Mary; Turner, Judith A.; Kemp, Carol A. (November 2006). "Use of the chronic pain coping inventory to assess older adults' pain coping strategies". The Journal of Pain: Official Journal of the American Pain Society. 7 (11): 833–842. doi:10.1016/j.jpain.2006.04.002. ISSN 1526-5900. PMID 17074625.
  40. ↑ Kindermans, Hanne P. J.; Roelofs, Jeffrey; Goossens, Marielle E. J.B.; Huijnen, Ivan P.J.; Verbunt, Jeanine A.; Vlaeyen, Johan W.S. (October 2011). "Activity patterns in chronic pain: underlying dimensions and associations with disability and depressed mood". The Journal of Pain: Official Journal of the American Pain Society. 12 (10): 1049–1058. doi:10.1016/j.jpain.2011.04.009. ISSN 1528-8447. PMID 21704568.
  41. ↑ Cuperus, Nienke; Hoogeboom, Thomas J.; Neijland, Yvette; van den Ende, Cornelia Hm; Keijsers, Noël Lw (November 2012). "Are people with rheumatoid arthritis who undertake activity pacing at risk of being too physically inactive?". Clinical Rehabilitation. 26 (11): 1048–1052. doi:10.1177/0269215512437417. ISSN 1477-0873. PMID 22327885.
  42. ↑ Andrews, Nicole E.; Strong, Jenny; Meredith, Pamela J. (November 2012). "Activity pacing, avoidance, endurance, and associations with patient functioning in chronic pain: a systematic review and meta-analysis". Archives of Physical Medicine and Rehabilitation. 93 (11): 2109–2121.e7. doi:10.1016/j.apmr.2012.05.029. ISSN 1532-821X. PMID 22728699.
  43. ↑ Murphy, Susan Lynn; Kratz, Anna Louise (December 2014). "Activity pacing in daily life: A within-day analysis". Pain. 155 (12): 2630–2637. doi:10.1016/j.pain.2014.09.028. ISSN 1872-6623. PMC 4353388. PMID 25267209.
  44. ↑ Murphy, Susan L.; Clauw, Daniel J. (June 2010). "Activity pacing: what are we measuring and how does that relate to intervention?". Pain. 149 (3): 582–583. doi:10.1016/j.pain.2010.03.031. ISSN 1872-6623. PMID 20381246.
  45. ↑ Murphy, Susan L.; Lyden, Angela K.; Smith, Dylan M.; Dong, Qian; Koliba, Jessica F. (November 2010). "Effects of a tailored activity pacing intervention on pain and fatigue for adults with osteoarthritis". The American Journal of Occupational Therapy: Official Publication of the American Occupational Therapy Association. 64 (6): 869–876. ISSN 0272-9490. PMC 3655423. PMID 21218677.
  46. ↑ Murphy, Susan L.; Kratz, Anna L.; Kidwell, Kelley; Lyden, Angela K.; Geisser, Michael E.; Williams, David A. (July 2016). "Brief time-based activity pacing instruction as a singular behavioral intervention was not effective in participants with symptomatic osteoarthritis". Pain. 157 (7): 1563–1573. doi:10.1097/j.pain.0000000000000549. ISSN 1872-6623. PMC 4912409. PMID 26963847.
  47. ↑ Nielson, Warren R.; Jensen, Mark P. (June 2004). "Relationship between changes in coping and treatment outcome in patients with Fibromyalgia Syndrome". Pain. 109 (3): 233–241. doi:10.1016/j.pain.2004.01.002. ISSN 0304-3959. PMID 15157683.
  48. ↑ Cane, Douglas; Nielson, Warren R.; McCarthy, Mary; Mazmanian, Dwight (May 2013). "Pain-related activity patterns: measurement, interrelationships, and associations with psychosocial functioning". The Clinical Journal of Pain. 29 (5): 435–442. doi:10.1097/AJP.0b013e31825e452f. ISSN 1536-5409. PMID 23247000.
  49. ↑ Antcliff, Deborah; Campbell, Malcolm; Woby, Steve; Keeley, Philip (September 2015). "Assessing the Psychometric Properties of an Activity Pacing Questionnaire for Chronic Pain and Fatigue". Physical Therapy. 95 (9): 1274–1286. doi:10.2522/ptj.20140405. ISSN 1538-6724. PMC 4556956. PMID 25908522.
  50. ↑ Antcliff DC. (2014). The development of an activity pacing questionnaire for chronic pain and fatigue. Phd thesis. Faculty of Medical and Human Sciences, University of Manchester.
  51. ↑ Antcliff, Deborah; Keeley, Philip; Campbell, Malcolm; Woby, Steve; Keenan, Anne-Maree; McGowan, Linda (July 2018). "Activity pacing: moving beyond taking breaks and slowing down". Quality of Life Research: An International Journal of Quality of Life Aspects of Treatment, Care and Rehabilitation. 27 (7): 1933–1935. doi:10.1007/s11136-018-1794-7. ISSN 1573-2649. PMC 5997723. PMID 29396652.
  52. ↑ Jason, Leonard; Benton, Mary (November 2009). "The Impact of Energy Modulation on Physical Functioning and Fatigue Severity among Patients with ME/CFS". Patient education and counseling. 77 (2): 237–241. doi:10.1016/j.pec.2009.02.015. ISSN 0738-3991. PMC 2767446. PMID 19356884.
  53. ↑ Cox et al. (2004) Manual for participants Adaptive Pacing Therapy for CFS/ME. 
  54. ↑ 54.0 54.1 54.2 Jason, Leonard A (August 1, 2017). "The PACE trial missteps on pacing and patient selection". Journal of Health Psychology. 22 (9): 1141–1145. doi:10.1177/1359105317695801. ISSN 1359-1053.
  55. ↑ Goudsmit, Ellen; Howes, Sandra (August 1, 2017). "Bias, misleading information and lack of respect for alternative views have distorted perceptions of myalgic encephalomyelitis/chronic fatigue syndrome and its treatment". Journal of Health Psychology. 22 (9): 1159–1167. doi:10.1177/1359105317707216. ISSN 1359-1053.
  56. ↑ 56.0 56.1 Kos, Daphne; van Eupen, Inge; Meirte, Jill; Van Cauwenbergh, Deborah; Moorkens, Greta; Meeus, Mira; Nijs, Jo (September 2015). "Activity Pacing Self-Management in Chronic Fatigue Syndrome: A Randomized Controlled Trial". The American Journal of Occupational Therapy: Official Publication of the American Occupational Therapy Association. 69 (5): 6905290020. doi:10.5014/ajot.2015.016287. ISSN 1943-7676. PMC 4564796. PMID 26356665.
  57. ↑ 57.0 57.1 Núñez, Montserrat; Fernández-Solà, Joaquim; Nuñez, Esther; Fernández-Huerta, José-Manuel; Godás-Sieso, Teresa; Gomez-Gil, Esther (March 2011). "Health-related quality of life in patients with chronic fatigue syndrome: group cognitive behavioural therapy and graded exercise versus usual treatment. A randomised controlled trial with 1 year of follow-up". Clinical Rheumatology. 30 (3): 381–389. doi:10.1007/s10067-010-1677-y. ISSN 1434-9949. PMID 21234629.
  58. ↑ 58.0 58.1 Thompson, D. P.; Antcliff, D.; Woby, S.R. (March 2018). "Symptoms of chronic fatigue syndrome/myalgic encephalopathy are not determined by activity pacing when measured by the chronic pain coping inventory". Physiotherapy. 104 (1): 129–135. doi:10.1016/j.physio.2017.07.005. ISSN 1873-1465. PMID 28843450.
  59. ↑ Nielson, W.R.; Jensen, M.P.; Hill, M.L. (January 2001). "An activity pacing scale for the chronic pain coping inventory: development in a sample of patients with fibromyalgia syndrome". Pain. 89 (2–3): 111–115. ISSN 0304-3959. PMID 11166466.
  60. ↑ "S4ME: Submission to the public review on common data elements for ME/CFS: Problems with the Chalder Fatigue Questionnaire". Science for ME. Retrieved August 20, 2018.
  61. ↑ Heins, Marianne; Knoop, Hans; Nijs, Jo; Feskens, Remco; Meeus, Mira; Moorkens, Greta; Bleijenberg, Gijs (June 2013). "Influence of symptom expectancies on stair-climbing performance in chronic fatigue syndrome: effect of study context". International Journal of Behavioral Medicine. 20 (2): 213–218. doi:10.1007/s12529-012-9253-2. ISSN 1532-7558. PMID 22865100.
  62. ↑ Dittner, A., & Chalder, T. (2003). Measuring symptoms and fatigue severity. In L.A. Jason., P.A. Fennell., & R.R. Taylor (Eds.), Handbook of chronic fatigue syndrome   (pp. 363-383). New Jersey: John Wiley & Sons.
  63. ↑ White, P. D. (August 2002). "Chronic unexplained fatigue". Postgraduate Medical Journal. 78 (922): 445–446. ISSN 0032-5473. PMC 1742445. PMID 12185213.
  64. ↑ Davenport, Todd E.; Stevens, Staci R.; VanNess, Mark J.; Snell, Christopher R.; Little, Tamara (April 2010). "Conceptual model for physical therapist management of chronic fatigue syndrome/myalgic encephalomyelitis". Physical Therapy. 90 (4): 602–614. doi:10.2522/ptj.20090047. ISSN 1538-6724. PMID 20185614.
  65. ↑ 65.0 65.1 Stevens, Todd E; Davenport (2010). "Functional outcomes of anaerobic rehabilitation in an individual with chronic fatigue syndrome: case report with 1-year follow-up" (PDF). Bulletin of the IACFS/ME. 18 (3): 93–98.
  66. ↑ "Gabby Klein on Twitter". Twitter. Retrieved August 20, 2018.
  67. ↑ "Sally Burch on Twitter". Twitter. Retrieved August 20, 2018.
  68. ↑ http://www.recoveryfromcfs.org/chapter7.htm
  69. ↑ "Play-Up & Lay-Up not Boom & Bust

pacing The practice of staying within one's "energy envelope" or personal limit by combining periods of activity with periods of rest or avoiding exerting beyond a certain level. ME/CFS patients use pacing to avoid or reduce post-exertional malaise (PEM). Some patients use a heart rate monitor to help with pacing.

Centers for Disease Control and Prevention (CDC) - The Centers for Disease Control and Prevention is a U.S. government agency dedicated to epidemiology and public health. It operates under the auspices of the Department of Health and Human Services.

See Centers for Disease Control and Prevention.

NICE guidelines Clinical guidelines used in the UK.

Concerning living organisms, such as cells or the human body.[1]  Physio logical (as in physio) is not to be confused with psych ological (emotional stress).

physiological Concerning living organisms, such as cells or the human body.  Physio logical (as in physio) is not to be confused with psych ological (emotional stress).

cognition Thought processes, including attention, reasoning, and memory.

flare-up A symptoms flare in ME/CFS is a temporary increase in symptoms, alternatively known as experiencing post-exertional malaise. May be referred to as a "crash" or "collapse".

graded exercise therapy (GET) - A gradual increase in exercise or activity, according to a pre-defined plan. Focuses on overcoming the patient's alleged unhelpful illness beliefs that exertion can exacerbate symptoms, rather than on reversing physical deconditioning. Considered controversial, and possibly harmful, in the treatment or management of ME. One of the treatment arms of the controversial PACE trial.

See Graded exercise therapy.

An outcome of a clinical trial that is independent of the judgement of opinion of the assessor/clinician, e.g. distance walked in 6 minutes. Patient-reported outcomes like questionnaires are not objectives.[2]

objective outcome An outcome of a clinical trial that is independent of the judgement of opinion of the assessor/clinician, e.g. distance walked in 6 minutes. Patient-reported outcomes like questionnaires are not objectives.

cognitive behavioral therapy (CBT) - A type of psychotherapy geared toward modifying alleged unhealthy thinking, behaviors or illness beliefs. One of the treatment arms used in the controversial PACE trial.

Energy Envelope Theory A self-management tool developed and tested by Dr. Leonard Jason to reduce symptom severity and the frequency of post-exertional malaise or relapses for people with ME/CFS. According to this theory, ME/CFS patients should not expend more energy than they perceive they have, as this results in post-exertional malaise and higher disability. Instead patients are advised to stay within their energy envelope, meaning the physical limits the disease has imposed upon them. As the energy envelope theory also cautions about the dangers of under-exertion, its principles are almost identical to ‘pacing’, an activity management strategy for ME patients devised by Ellen Goudsmit in the UK.

Chronic Fatigue and Immune Dysfunction Syndrome (CFIDS) - Chronic Fatigue and Immune Dysfunction Syndrome is another term for Chronic Fatigue Syndrome, but one which emphasizes the immunological aspects of the disease. Popular in the 1990s, this term has apparently fallen into disuse.

See Chronic Fatigue and Immune Dysfunction Syndrome.

Action for ME (AfME) - Action for ME is a British non-profit organization that was set up in 1987 as The M.E. Action Campaign. Its founders were Martin Lev, Sue Findlay and Clare Francis. In September 1993 it changed its name and logo to Action for ME and Chronic Fatigue. It then changed its name in 1993 to Action for ME.

cognitive behavioral therapy (CBT) - A type of psychotherapy geared toward modifying alleged unhealthy thinking, behaviors or illness beliefs. One of the treatment arms used in the controversial PACE trial.

See cognitive behavioral therapy.

Energy Envelope Theory A self-management tool developed and tested by Dr. Leonard Jason to reduce symptom severity and the frequency of post-exertional malaise or relapses for people with ME/CFS. According to this theory, ME/CFS patients should not expend more energy than they perceive they have, as this results in post-exertional malaise and higher disability. Instead patients are advised to stay within their energy envelope, meaning the physical limits the disease has imposed upon them. As the energy envelope theory also cautions about the dangers of under-exertion, its principles are almost identical to ‘pacing’, an activity management strategy for ME patients devised by Ellen Goudsmit in the UK.

PACE trial A controversial study which claimed that CBT and GET were effective in treating "CFS/ME", despite the fact that its own data did not support this conclusion. Its results and methodology were widely disputed by patients, scientists, and the peer-reviewed scientific literature.

flare-up A symptoms flare in ME/CFS is a temporary increase in symptoms, alternatively known as experiencing post-exertional malaise. May be referred to as a "crash" or "collapse".

See ME/CFS.

(HR) - the number of times the heart beats within a certain time period, usually a minute[3]

heart rate (HR) - the number of times the heart beats within a certain time period, usually a minute

(HRM) - A device that measures your heart rate (pulse rate). Heart rate monitors may come as a chest strap, wrist strap, smartwatch, or even as a mobile phone app. Heart rate monitors are often used by ME/CFS patients to pace their exertion, in order to avoid post-exertional malaise (PEM). For more information, see pacing with a heart rate monitor.

heart rate monitor (HRM) - A device that measures your heart rate (pulse rate). Heart rate monitors may come as a chest strap, wrist strap, smartwatch, or even as a mobile phone app. Heart rate monitors are often used by ME/CFS patients to pace their exertion, in order to avoid post-exertional malaise (PEM). For more information, see pacing with a heart rate monitor.

heart rate (HR) - the number of times the heart beats within a certain time period, usually a minute

randomized controlled trial (RCT) - A trial in which participants are randomly assigned to two groups, with one group receiving the treatment being studied and a control or comparison group receiving a sham treatment, placebo, or comparison treatment.

myalgic encephalomyelitis (M.E.) - A disease often marked by neurological symptoms, but fatigue is sometimes a symptom as well. Some diagnostic criteria distinguish it from chronic fatigue syndrome, while other diagnostic criteria consider it to be a synonym for chronic fatigue syndrome. A defining characteristic of ME is post-exertional malaise (PEM), or post-exertional neuroimmune exhaustion (PENE), which is a notable exacerbation of symptoms brought on by small exertions. PEM can last for days or weeks. Symptoms can include cognitive impairments, muscle pain (myalgia), trouble remaining upright (orthostatic intolerance), sleep abnormalities, and gastro-intestinal impairments, among others. An estimated 25% of those suffering from ME are housebound or bedbound. The World Health Organization (WHO) classifies ME as a neurological disease.

myalgic encephalomyelitis (M.E.) - A disease often marked by neurological symptoms, but fatigue is sometimes a symptom as well. Some diagnostic criteria distinguish it from chronic fatigue syndrome, while other diagnostic criteria consider it to be a synonym for chronic fatigue syndrome. A defining characteristic of ME is post-exertional malaise (PEM), or post-exertional neuroimmune exhaustion (PENE), which is a notable exacerbation of symptoms brought on by small exertions. PEM can last for days or weeks. Symptoms can include cognitive impairments, muscle pain (myalgia), trouble remaining upright (orthostatic intolerance), sleep abnormalities, and gastro-intestinal impairments, among others. An estimated 25% of those suffering from ME are housebound or bedbound. The World Health Organization (WHO) classifies ME as a neurological disease.

chronic illness any long-term illness, regardless of the severity. Chronic illnesses are typically incurable, requiring long-term management.

chronic illness any long-term illness, regardless of the severity. Chronic illnesses are typically incurable, requiring long-term management.

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