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ME/CFS Atlas is an evidence reference platform, not a medical provider. Content is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional.

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ME/CFS Evidence Browser — Classified Studies on Myalgic Encephalomyelitis

Evidence browser

Search and filter 6,206 studies by evidence level, diagnostic criteria, PEM status, and research domain. Each entry links to the original source.

Studies sorted by evidence level, then year. Browse by topic instead →

Evidence level (E0–E3) reflects study type and replication, not methodological quality. A weak systematic review still sits at E0. How evidence levels work →

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746 studies

E0 — Consensus655E1 — Replicated321E2 — Moderate2,807E3 — Preliminary2,423

ME/CFS4,041Long COVID224Post-infectious190Overlapping1,064

Required for diagnosis417Not specified / unclear2,252Not required3,537

Post-Exertional Malaise1,082Cognitive Dysfunction1,750Pain1,629Unrefreshing Sleep805Orthostatic Intolerance484

Cytokines821Gene Expression573Metabolomics478Neuroimaging472Autoantibodies460

Infection-Triggered1,182Long COVID Overlap604Pediatric496Severe232

Strong Phenotyping445Sex-Stratified330Severe ME Included119

Systematic Review272Meta-Analysis61RCT301

Peer-reviewed6,149Preprint3Unclear54

641–660 of 746 studies

E3 PreliminaryReviewPEM not requiredReview-Narrative

Exercise-induced mitochondrial dysfunction: a myth or reality?

Ostojic, Sergej M·Clinical science (London, England : 1979)·2016

Exercise is usually good for your cells' energy factories (mitochondria), but this review asks whether extremely intense or exhausting exercise might actually damage them instead. The authors explore how very hard exercise could harm mitochondrial function and suggest this might explain some cases of chronic fatigue syndrome and muscle problems.

Post-Exertional Malaise

E3 PreliminaryReviewPEM unclearReview-Narrative

Exercise, not to exercise, or how to exercise in patients with chronic pain? Applying science to practice.

Daenen, Liesbeth, Varkey, Emma, Kellmann, Michael et al.·The Clinical journal of pain·2015

This review examines how exercise affects people with chronic pain, including ME/CFS. While exercise helps many chronic pain conditions, some patients—especially those with ME/CFS, fibromyalgia, and chronic whiplash—experience worsening symptoms or 'crashes' after exercising. The authors emphasize that exercise programs need to be carefully tailored to each person, with proper recovery time built in, rather than using a one-size-fits-all approach.

Post-Exertional Malaise

E3 PreliminaryDiagnosticPEM requiredMethods-Paper

Accurate diagnosis of myalgic encephalomyelitis and chronic fatigue syndrome based upon objective test methods for characteristic symptoms.

Twisk, Frank Nm·World journal of methodology·2015

ME and CFS are often treated as the same condition, but they are actually different illnesses with some overlapping symptoms. ME has specific features like muscle weakness, brain fog, heart and circulation problems, and especially a distinctive symptom called post-exertional malaise—where patients feel much worse after even small amounts of activity. Because many ME/CFS symptoms feel subjective, some doctors have questioned whether they are real physical problems, but this article argues that objective medical tests can measure key symptoms and help doctors diagnose these conditions more accurately.

Cognitive ImpairmentPost-Exertional Malaise

E3 PreliminaryDiagnosticPEM requiredMethods-Paper

Capturing the post-exertional exacerbation of fatigue following physical and cognitive challenge in patients with chronic fatigue syndrome.

Keech, Andrew, Sandler, Carolina X, Vollmer-Conna, Ute et al.·Journal of psychosomatic research·2015

This study developed a new questionnaire called the Fatigue and Energy Scale (FES) to measure the specific type of exhaustion that ME/CFS patients experience after physical or mental activity. Researchers talked with 19 patients to understand what their fatigue feels like, then tested the questionnaire with patients doing exercise, driving simulation, and everyday tasks. The results showed that the FES successfully captured both the physical tiredness and mental fog that worsens after activity in ME/CFS.

Post-Exertional Malaise

E3 PreliminaryCommentaryPEM requiredEditorial

Living with ME/CFS. challenge for scientists?

Weiler, John J A·Neuro endocrinology letters·2015

This case describes a person with ME/CFS for 19 years who experienced an unusual pattern: they could run 10 kilometers without problems, but later that same day, 30 minutes of browsing for books triggered severe exhaustion, muscle pain, and brain fog lasting into the next day. This puzzling difference highlights how ME/CFS symptoms don't always follow expected patterns and suggests that exercise intolerance in ME/CFS may be more complex than previously thought.

Post-Exertional Malaise

E3 PreliminaryCohortPEM unclearCross-Sectional

Consulting patients in setting priorities in Myalgic Encephalomyelitis (M.E.) research: findings from a national on-line survey.

Childs, Nicola, Robinson, Lisa, Chowdhury, Sonya et al.·Research involvement and engagement·2015

Researchers asked over 1,100 people affected by ME/CFS what they thought should be the most important areas for future research. The top priorities were understanding what causes ME/CFS, developing better treatments, and improving how quickly and accurately doctors can diagnose the illness. This study shows that patients have strong, clear opinions about what research funding should focus on.

Post-Exertional Malaise

E3 PreliminaryCommentaryPEM requiredEditorial

Reflections on the Institute of Medicine's systemic exertion intolerance disease.

Jason, Leonard A, Sunnquist, Madison, Brown, Abigail et al.·Polskie Archiwum Medycyny Wewnetrznej·2015

The Institute of Medicine proposed renaming chronic fatigue syndrome to 'systemic exertion intolerance disease' (SEID) and created new diagnostic criteria. This editorial critiques that change, noting that most patients rejected the new name and the new criteria were not tested on actual patient populations before being recommended. The new criteria may incorrectly identify more people as having the disease while missing key features that define it.

Post-Exertional Malaise

E3 PreliminaryMechanismPEM not requiredCross-Sectional

The relationship between interleukin-6 in saliva, venous and capillary plasma, at rest and in response to exercise.

Cullen, T, Thomas, A W, Webb, R et al.·Cytokine·2015

Researchers measured a protein called IL-6 that the body produces during exercise and inflammation. They took samples from blood and saliva before and after exercise to see if IL-6 levels changed and whether different measurement methods gave similar results. They found that IL-6 increased in blood after exercise, but saliva samples did not show this increase, suggesting saliva may not be a reliable way to track this immune marker.

Immune SystemPost-Exertional Malaise

E3 PreliminaryDiagnosticPEM requiredMethods-Paper

Problems in defining post-exertional malaise.

Jason, Leonard A, Evans, Meredyth, So, Suzanna et al.·Journal of prevention & intervention in the community·2015

This study looked at how post-exertional malaise (PEM)—the characteristic worsening of symptoms after physical or mental effort—is measured in ME/CFS patients. Researchers asked 32 people with CFS to answer survey questions about PEM and found that small changes in how questions are worded can change whether someone is diagnosed with PEM. This suggests that the current ways of diagnosing this condition may not be reliable or consistent.

Post-Exertional Malaise

E3 PreliminaryReviewPEM requiredReview-Narrative

Review of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: an evidence-based approach to diagnosis and management by clinicians.

Bested, Alison C, Marshall, Lynn M·Reviews on environmental health·2015

This review helps doctors understand ME/CFS better by explaining what it is, how to diagnose it, and how to treat it. ME/CFS is a serious illness that causes extreme tiredness, brain fog, pain, and sleep problems that get worse after physical activity. The review emphasizes that pacing activities—carefully balancing rest with gentle exercise—is one of the most important strategies patients can use to manage their symptoms and avoid crashes.

Post-Exertional Malaise

E3 PreliminaryMechanismPEM requiredMechanistic

In silico analysis of exercise intolerance in myalgic encephalomyelitis/chronic fatigue syndrome.

Lengert, Nicor, Drossel, Barbara·Biophysical chemistry·2015

This study used computer models to understand why people with ME/CFS struggle with exercise. The researchers simulated what happens in muscle cells during and after physical activity, focusing on mitochondria—the parts of cells that produce energy. Their model showed that when mitochondrial function is reduced, muscles can't make enough energy (ATP), which causes them to accumulate toxic substances like lactate and acid, and can lead to cell death. Importantly, repeated exercise made this problem much worse in their simulations.

Energy MetabolismPost-Exertional Malaise

E3 PreliminaryMechanismPEM not requiredMechanistic

Evidence for sensitized fatigue pathways in patients with chronic fatigue syndrome.

Staud, Roland, Mokthech, Meriem, Price, Donald D et al.·Pain·2015

This study tested whether ME/CFS patients have unusually sensitive "fatigue pathways" in their muscles and nerves that overreact to exercise. Researchers had patients and healthy controls do hand exercises, then briefly cut off blood flow to the forearm to trap muscle chemicals in the tissues. ME/CFS patients reported increased fatigue during the blood flow cutoff, while healthy people's fatigue actually decreased—suggesting their muscles and nerves are sending stronger fatigue signals.

Post-Exertional Malaise

E3 PreliminaryCohortPEM not requiredCase-Control

Are stamina and fatigue polar opposites? A case study.

So, Suzanna, Evans, Meredyth, Jason, Leonard A et al.·Journal of prevention & intervention in the community·2015

This study looked at whether fatigue and stamina are opposite sides of the same coin in ME/CFS. The researchers found that some people with ME/CFS have low fatigue but still cannot do much physically, while others have high fatigue that stops them from being active. This suggests that fatigue and stamina may be separate issues, and current diagnostic criteria that focus mainly on fatigue might miss people who have low energy and endurance but don't report severe fatigue.

Post-Exertional Malaise

E3 PreliminaryDiagnosticPEM unclearMethods-Paper

Variability in Symptoms Complicates Utility of Case Definitions.

McManimen, Stephanie L, Jason, Leonard A, Williams, Yolonda J·Fatigue : biomedicine, health & behavior·2015

This study looked at how ME/CFS is defined and diagnosed across different research centers. Researchers found that when different studies measure key symptoms like post-exertional malaise (feeling worse after activity), unrefreshing sleep, and brain fog, they get very different numbers—suggesting that either different patients are being studied, or researchers are asking questions in different ways. The study concluded that ME/CFS research needs more standardized, consistent methods for measuring symptoms so findings can be compared fairly.

Post-Exertional Malaise

E3 PreliminaryDiagnosticPEM not requiredMethods-Paper

Effects of Time Frame on the Recall Reliability of CFS Symptoms.

Evans, Meredyth, Jason, Leonard A·Evaluation & the health professions·2015

This study looked at how accurately people with ME/CFS can remember and report their symptoms depending on how far back they think about (one week, one month, or six months). Researchers found that asking patients to recall symptoms from the past six months was most reliable for most symptoms, though joint pain was best recalled over one month. This matters because doctors need to know the best time frame to ask about when diagnosing ME/CFS.

Post-Exertional Malaise

E3 PreliminaryCohortPEM not requiredCross-Sectional

The Nature of Fatigue in Chronic Fatigue Syndrome.

Olson, Karin, Zimka, Oksana, Stein, Eleanor·Qualitative health research·2015

This study asked 14 people with ME/CFS to describe their experience of fatigue in their own words. Participants identified three different types of tiredness: regular tiredness (before diagnosis), fatigue (during daily activities), and exhaustion (after overexertion). The most helpful strategies people used were pacing activities and taking extended rest periods to manage their symptoms and prevent crashes.

Post-Exertional Malaise

E3 PreliminaryMechanismPEM not requiredMechanistic

Abnormalities of AMPK activation and glucose uptake in cultured skeletal muscle cells from individuals with chronic fatigue syndrome.

Brown, Audrey E, Jones, David E, Walker, Mark et al.·PloS one·2015

Researchers grew muscle cells from ME/CFS patients and healthy people in the lab and stimulated them electrically to mimic exercise. They found that muscle cells from ME/CFS patients didn't respond normally to this simulated exercise: they failed to activate a key energy-sensing protein (AMPK) and didn't increase glucose uptake like healthy cells did. This suggests the problem may be rooted in how the muscle cells themselves are built or programmed, not just from being inactive.

Energy MetabolismPost-Exertional Malaise

E3 PreliminaryReviewPEM not requiredReview-Narrative

[Biopersistence and systemic distribution of intramuscularly injected particles: what impact on long-term tolerability of alum adjuvants?].

Gherardi, Romain K, Cadusseau, Josette, Authier, François-jérôme·Bulletin de l'Academie nationale de medecine·2014

This review examines how aluminum-based vaccine adjuvants (immune-boosting ingredients) may rarely cause long-term health problems in susceptible people, including muscle pain, exhaustion, and brain fog that can last years. The researchers found that aluminum particles can travel from the injection site through the body to distant organs and the brain, and that a specific immune protein called MCP-1 may control how much this happens. For most people, aluminum adjuvants are safe, but genetic and environmental differences may make some individuals more vulnerable to prolonged effects.

Immune SystemPost-Exertional Malaise

E3 PreliminaryMechanismPEM requiredObservational

Inability of myalgic encephalomyelitis/chronic fatigue syndrome patients to reproduce VO₂peak indicates functional impairment.

Keller, Betsy A, Pryor, John Luke, Giloteaux, Ludovic·Journal of translational medicine·2014

This study tested whether people with ME/CFS can perform the same on an exercise test when it's repeated the next day, similar to how healthy people typically do. The researchers found that ME/CFS patients performed significantly worse on the second test—using about 14% less oxygen and doing about 12% less work—even though they were trying their hardest both times. This suggests that doing one exercise test may give doctors an unrealistic picture of what ME/CFS patients can actually do.

Post-Exertional Malaise

E3 PreliminaryDiagnosticPEM requiredMethods-Paper

Comparing and Contrasting Consensus versus Empirical Domains.

Jason, Leonard A, Kot, Bobby, Sunnquist, Madison et al.·Fatigue : biomedicine, health & behavior·2014

Researchers compared different sets of diagnostic criteria used to identify ME/CFS patients. They looked at criteria developed by expert groups (like the Canadian Consensus Criteria) and compared them to criteria identified through statistical analysis of actual patient data. The study found that the fatigue and post-exertional malaise domain (worsening symptoms after activity) was the best feature for distinguishing ME/CFS patients from healthy people, and that older diagnostic criteria were less accurate.

Post-Exertional Malaise

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Or browse by topic

PEM Immune Neuro Metabolic Biomarkers Severe ME Long COVID Cognitive

Curated Collections

Thematic groupings by clinical question or research area.

Neuroinflammation Evidence

PET imaging and other studies providing evidence for brain inflammation in ME/CFS.

Metabolism & Mitochondria

Metabolomics and mitochondrial function studies revealing energy metabolism disruption.

Biomarkers

Studies identifying potential biological markers for ME/CFS diagnosis and stratification.

PEM-Specific Research

Studies specifically examining post-exertional malaise, the hallmark symptom of ME/CFS.