ME/CFS Evidence Browser — Classified Studies on Myalgic Encephalomyelitis

301–320 of 729 studies

E2 ModerateCohortPEM requiredCross-Sectional

A hierarchical logistic regression predicting rapid respiratory rates from post-exertional malaise.

Cotler, Joseph, Katz, Ben Z, Reurts-Post, Corine et al.·Fatigue : biomedicine, health & behavior·2020

This study looked at whether faster breathing rates could be a sign of post-exertional malaise (PEM)—the worsening of symptoms that many ME/CFS patients experience after activity. Researchers measured breathing rates in 216 ME/CFS patients over two days and compared them to information about PEM and other symptoms. They found that patients with more severe PEM tended to have faster resting breathing rates, while depression, anxiety, and activity level did not explain the faster breathing.

Post-Exertional Malaise

E2 ModerateCohortPEM unclearCross-Sectional

Maximal handgrip strength can predict maximal physical performance in patients with chronic fatigue.

Jammes, Yves, Stavris, Chloé, Charpin, Caroline et al.·Clinical biomechanics (Bristol, Avon)·2020

Researchers tested whether hand grip strength could predict how well patients with ME/CFS could exercise on a stationary bike. They found that patients with stronger hand grip were able to exercise harder and use more oxygen. This suggests that a simple hand grip test might help doctors understand a patient's exercise capacity without needing expensive equipment.

Post-Exertional Malaise

E2 ModerateBehavioralPEM unclearObservational

Guided graded Exercise Self-help for chronic fatigue syndrome: patient experiences and perceptions.

Cheshire, Anna, Ridge, Damien, Clark, Lucy et al.·Disability and rehabilitation·2020

This study looked at what patients experienced when they tried a guided exercise self-help program (GES) for ME/CFS. Some patients improved while others got worse. The researchers found that people who improved tended to be more motivated and faced fewer obstacles, while those who worsened had been sick longer, had other health conditions, and experienced symptom flare-ups from the exercise. The study suggests that the booklet alone isn't enough—patients need support from healthcare professionals who understand ME/CFS, especially during the difficult early weeks when improvements haven't started yet.

Post-Exertional Malaise

E2 ModerateCohortPEM requiredCross-Sectional

Post-exertional Malaise in People With Chronic Cancer-Related Fatigue.

Twomey, Rosie, Yeung, Samuel T, Wrightson, James G et al.·Journal of pain and symptom management·2020

This study looked at whether people with long-lasting cancer-related fatigue experience post-exertional malaise (PEM)—a condition where symptoms get worse after physical or mental activity. Researchers asked 18 people with severe, ongoing fatigue to report their experiences over six months and during exercise testing. They found that up to one-third of participants showed signs of PEM, including fatigue that worsened after minimal effort and recovery taking more than 24 hours.

Post-Exertional Malaise

E2 ModerateCohortPEM requiredObservational

Post-exertional malaise in veterans with gulf war illness.

Lindheimer, Jacob B, Stegner, Aaron J, Wylie, Glenn R et al.·International journal of psychophysiology : official journal of the International Organization of Psychophysiology·2020

This study looked at whether veterans with Gulf War Illness (GWI) experience post-exertional malaise (PEM)—a worsening of symptoms after physical activity. Sixty-seven veterans completed a 30-minute exercise session, and researchers measured their fatigue, pain, and other symptoms before, immediately after, and 24 hours later. Veterans with GWI reported worse overall health and found the exercise more painful and tiring than healthy veterans, but only those who had specifically reported feeling unwell after exertion showed significant symptom worsening 24 hours later.

Post-Exertional Malaise

E2 ModerateCohortPEM requiredCross-Sectional

Numeric Rating Scales Show Prolonged Post-exertional Symptoms After Orthostatic Testing of Adults With Myalgic Encephalomyelitis/Chronic Fatigue Syndrome.

van Campen, C Linda M C, Rowe, Peter C, Verheugt, Freek W A et al.·Frontiers in medicine·2020

This study looked at how a specific test called head-up tilt testing (which checks how your body handles changes in position) affected ME/CFS symptoms. Researchers measured pain, fatigue, and concentration problems before and after the test in 278 ME/CFS patients and 30 healthy people. They found that ME/CFS patients experienced significantly worse symptoms for up to a week after the test, while healthy people's symptoms didn't change—suggesting that even mild physical stress can trigger prolonged symptom flares in ME/CFS.

Post-Exertional Malaise

E2 ModerateCohortPEM unclearCross-Sectional

Diagnostic sensitivity of 2-day cardiopulmonary exercise testing in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome.

Nelson, Maximillian J, Buckley, Jonathan D, Thomson, Rebecca L et al.·Journal of translational medicine·2019

Researchers tested whether a simple exercise test could help diagnose ME/CFS. They had patients and healthy people exercise on a stationary bike on two consecutive days and measured how their performance changed. ME/CFS patients showed a larger drop in exercise capacity on the second day compared to healthy people, suggesting this difference might be a useful diagnostic tool.

Post-Exertional Malaise

E2 ModerateCohortPEM requiredCross-Sectional

Elevated blood lactate in resting conditions correlate with post-exertional malaise severity in patients with Myalgic encephalomyelitis/Chronic fatigue syndrome.

Ghali, Alaa, Lacout, Carole, Ghali, Maria et al.·Scientific reports·2019

This study looked at lactate levels (a substance produced by muscles) in the blood of ME/CFS patients who were at rest. Researchers found that about 45% of patients had higher-than-normal lactate levels even when not exercising. Importantly, patients with elevated resting lactate tended to experience more severe post-exertional malaise (the symptom flare-ups that follow physical activity).

Energy MetabolismPost-Exertional Malaise

E2 ModerateCohortPEM requiredCross-Sectional

Differentiating Post-Polio Syndrome from Myalgic Encephalomyelitis and Chronic Fatigue Syndrome.

Klebek, Lauren, Sunnquist, Madison, Jason, Leonard A·Fatigue : biomedicine, health & behavior·2019

This study compared three similar long-term illnesses that cause fatigue and muscle problems: Post-polio syndrome (PPS), ME, and CFS. Researchers used questionnaires and computer analysis to identify which symptoms best distinguish these conditions from each other. They found that people with ME/CFS tend to have more severe overall functional impairment than those with PPS, and that three specific areas—brain fog, post-exertional malaise (getting worse after activity), and hormone-related symptoms—are most helpful in telling these illnesses apart.

Post-Exertional Malaise

E2 ModerateCohortPEM requiredObservational

Abnormal blood lactate accumulation during repeated exercise testing in myalgic encephalomyelitis/chronic fatigue syndrome.

Lien, Katarina, Johansen, Bjørn, Veierød, Marit B et al.·Physiological reports·2019

This study looked at how the bodies of ME/CFS patients handle repeated exercise tests done 24 hours apart. Researchers measured how much oxygen patients used and tracked a substance called lactate in their blood during exercise. They found that ME/CFS patients performed worse on the second test and had higher lactate levels, opposite to what happened in healthy people, whose bodies actually recovered better the second time.

Post-Exertional Malaise

E2 ModerateCohortPEM requiredCross-Sectional

Deconstructing post-exertional malaise: An exploratory factor analysis.

McManimen, Stephanie L, Sunnquist, Madison L, Jason, Leonard A·Journal of health psychology·2019

This study looked at post-exertional malaise (PEM)—the worsening of symptoms that happens after physical activity in ME/CFS—to understand whether it is one unified experience or two different types. The researchers found that PEM actually consists of two separate experiences: a whole-body fatigue and a muscle-specific fatigue. This suggests that PEM is more complex than previously thought and may need to be understood as having distinct components.

Post-Exertional Malaise

E2 ModerateCohortPEM requiredObservational

Post-Exertional Malaise Is Associated with Hypermetabolism, Hypoacetylation and Purine Metabolism Deregulation in ME/CFS Cases.

McGregor, Neil R, Armstrong, Christopher W, Lewis, Donald P et al.·Diagnostics (Basel, Switzerland)·2019

This study looked at what happens in the body during post-exertional malaise (PEM)—the exhaustion and worsening of symptoms that ME/CFS patients experience after physical or mental activity. Researchers measured chemical changes in blood and urine over 7 days in 35 ME/CFS patients who reported PEM and compared them to healthy controls. They found that during PEM, the body shows signs of increased metabolism (burning energy faster), low levels of a molecule called hypoxanthine, and problems with how cells use and process energy, along with evidence that the body is breaking down muscle protein.

Post-Exertional Malaise

E2 ModerateBehavioralPEM unclearCross-Sectional

Myalgic encephalomyelitis/chronic fatigue syndrome patients' reports of symptom changes following cognitive behavioural therapy, graded exercise therapy and pacing treatments: Analysis of a primary survey compared with secondary surveys.

Geraghty, Keith, Hann, Mark, Kurtev, Stoyan·Journal of health psychology·2019

This study asked ME/CFS patients about their experiences with three different treatment approaches: cognitive behavioural therapy (CBT), graded exercise therapy (GET), and pacing. The researchers found that pacing—where patients carefully manage their activity levels without pushing beyond their limits—was reported as most helpful and caused the fewest problems. In contrast, GET led to significant symptom worsening in over half of patients, while CBT helped only a small percentage of people.

Post-Exertional Malaise

E2 ModerateCohortPEM requiredCross-Sectional

Systemic exertion intolerance disease/chronic fatigue syndrome is common in sleep centre patients with hypersomnolence: A retrospective pilot study.

Maness, Caroline, Saini, Prabhjyot, Bliwise, Donald L et al.·Journal of sleep research·2019

This study looked at people visiting sleep clinics who reported excessive daytime sleepiness and found that 21% of them also met criteria for ME/CFS (systemic exertion intolerance disease). People with both conditions reported more severe fatigue and were less likely to benefit from standard wake-promoting medications compared to those with only sleep disorders. The findings suggest that ME/CFS frequently occurs alongside sleep disorders and may make treatment more difficult.

Post-Exertional Malaise

E2 ModerateCohortPEM not requiredCross-Sectional

Onset Patterns and Course of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome.

Chu, Lily, Valencia, Ian J, Garvert, Donn W et al.·Frontiers in pediatrics·2019

This study surveyed 150 people with ME/CFS about how their illness started and changed over time. Most people reported their ME/CFS began after an infection, stress, or chemical exposure. While some symptoms like fatigue and flu-like feelings improved slightly over time, others like brain fog stayed about the same or got worse, and nearly half of participants couldn't work by the time of the study.

Post-Exertional Malaise

E2 ModerateCohortPEM unclearObservational

Unexplained exertional intolerance associated with impaired systemic oxygen extraction.

Melamed, Kathryn H, Santos, Mário, Oliveira, Rudolf K F et al.·European journal of applied physiology·2019

This study examined 313 patients with unexplained exercise intolerance using specialized heart and lung testing. Researchers found that about 12.5% of these patients have trouble exercising because their muscles cannot extract and use oxygen properly from the bloodstream, rather than having heart or lung problems. In these patients, the blood remained less acidic during exercise and had higher oxygen levels than expected, suggesting the muscles simply weren't using the available oxygen efficiently.

Post-Exertional Malaise

E2 ModerateCohortPEM requiredCross-Sectional

Chronic fatigue syndrome in the emergency department.

Timbol, Christian R, Baraniuk, James N·Open access emergency medicine : OAEM·2019

This study surveyed 282 people with ME/CFS to understand their experiences in emergency departments (EDs). About 59% had visited an ED, often due to symptoms like dizziness or severe fatigue. Many patients reported that ED staff didn't understand their illness and sometimes dismissed their symptoms as psychological rather than physical, leading to poor experiences and feelings that they weren't taken seriously.

Post-Exertional Malaise

E2 ModerateCohortPEM unclearObservational

Energy envelope maintenance among patients with myalgic encephalomyelitis and chronic fatigue syndrome: Implications of limited energy reserves.

O'connor, Kelly, Sunnquist, Madison, Nicholson, Laura et al.·Chronic illness·2019

This study tested whether staying within your personal energy limits helps people with ME/CFS feel better. Researchers compared six groups of patients based on how much energy they had available and whether they stayed within those limits. The results showed that people with more available energy generally functioned better, but pushing beyond their limits was particularly harmful for those with higher energy reserves.

Post-Exertional Malaise

E2 ModerateCohortPEM requiredCross-Sectional

Impaired Health-Related Quality of Life in Adolescent Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: The Impact of Core Symptoms.

Roma, Maria, Marden, Colleen L, Flaherty, Marissa A K et al.·Frontiers in pediatrics·2019

This study looked at how ME/CFS affects the daily lives and well-being of teenagers and young adults compared to healthy peers. Young people with ME/CFS reported much worse quality of life across all areas tested, and the study found that post-exertional malaise (feeling much worse after activity) was the strongest predictor of this reduced quality of life. The findings confirm that ME/CFS in young people is as serious as or more serious than other chronic childhood illnesses like asthma, diabetes, and cystic fibrosis.

Post-Exertional Malaise

E2 ModerateCohortPEM requiredLongitudinal

Whole blood human transcriptome and virome analysis of ME/CFS patients experiencing post-exertional malaise following cardiopulmonary exercise testing.

Bouquet, Jerome, Li, Tony, Gardy, Jennifer L et al.·PloS one·2019

Researchers gave ME/CFS patients and healthy controls exercise tests on two consecutive days, then tracked their blood samples for up to a week to look for signs of immune activation or virus reactivation during post-exertional malaise (PEM). Although ME/CFS patients felt significantly worse after exercise and some showed reduced oxygen use on day 2, blood tests revealed almost no differences in gene expression between patients and controls, and no evidence of viruses reactivating during PEM symptoms.

Immune SystemPost-Exertional Malaise

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A hierarchical logistic regression predicting rapid respiratory rates from post-exertional malaise.

Maximal handgrip strength can predict maximal physical performance in patients with chronic fatigue.

Guided graded Exercise Self-help for chronic fatigue syndrome: patient experiences and perceptions.

Post-exertional Malaise in People With Chronic Cancer-Related Fatigue.

Post-exertional malaise in veterans with gulf war illness.

Numeric Rating Scales Show Prolonged Post-exertional Symptoms After Orthostatic Testing of Adults With Myalgic Encephalomyelitis/Chronic Fatigue Syndrome.

Diagnostic sensitivity of 2-day cardiopulmonary exercise testing in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome.

Elevated blood lactate in resting conditions correlate with post-exertional malaise severity in patients with Myalgic encephalomyelitis/Chronic fatigue syndrome.

Differentiating Post-Polio Syndrome from Myalgic Encephalomyelitis and Chronic Fatigue Syndrome.

Abnormal blood lactate accumulation during repeated exercise testing in myalgic encephalomyelitis/chronic fatigue syndrome.

Deconstructing post-exertional malaise: An exploratory factor analysis.

Post-Exertional Malaise Is Associated with Hypermetabolism, Hypoacetylation and Purine Metabolism Deregulation in ME/CFS Cases.

Myalgic encephalomyelitis/chronic fatigue syndrome patients' reports of symptom changes following cognitive behavioural therapy, graded exercise therapy and pacing treatments: Analysis of a primary survey compared with secondary surveys.

Systemic exertion intolerance disease/chronic fatigue syndrome is common in sleep centre patients with hypersomnolence: A retrospective pilot study.

Onset Patterns and Course of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome.

Unexplained exertional intolerance associated with impaired systemic oxygen extraction.

Chronic fatigue syndrome in the emergency department.

Energy envelope maintenance among patients with myalgic encephalomyelitis and chronic fatigue syndrome: Implications of limited energy reserves.

Impaired Health-Related Quality of Life in Adolescent Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: The Impact of Core Symptoms.

Whole blood human transcriptome and virome analysis of ME/CFS patients experiencing post-exertional malaise following cardiopulmonary exercise testing.

Curated Collections

Neuroinflammation Evidence

Metabolism & Mitochondria

Biomarkers

PEM-Specific Research