Evidence browser

Energy MetabolismPost-Exertional Malaise

A map of metabolic phenotypes in patients with myalgic encephalomyelitis/chronic fatigue syndrome.

Hoel, Fredrik, Hoel, August, Pettersen, Ina Kn et al.·JCI insight·2021

This study examined the chemicals in the blood of 83 ME/CFS patients compared to 35 healthy people to understand how their bodies use energy differently. Researchers found that ME/CFS patients had common metabolic changes suggesting their bodies are working harder to produce energy and are using fats and proteins differently as fuel. Interestingly, patients also fell into different subgroups with distinct metabolic patterns, suggesting ME/CFS may involve different energy problems in different people.

E2 ModerateCohortPEM requiredObservational

Markers of Cardiac Autonomic Function During Consecutive Day Peak Exercise Tests in People With Myalgic Encephalomyelitis/Chronic Fatigue Syndrome.

Nelson, Maximillian J, Buckley, Jonathan D, Thomson, Rebecca L et al.·Frontiers in physiology·2021

This study looked at how the hearts of ME/CFS patients respond to exercise on two consecutive days, comparing them to healthy people. Researchers measured heart rate patterns and recovery after exercise, finding that ME/CFS patients had slower heart rate recovery after working out. However, these measurements alone were not reliable enough to diagnose ME/CFS, suggesting that a single heart rate test may not be a useful diagnostic tool on its own.

Homebound versus Bedridden Status among Those with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome.

Conroy, Karl, Bhatia, Shaun, Islam, Mohammed et al.·Healthcare (Basel, Switzerland)·2021

This study looked at over 2,100 people with ME/CFS to understand different levels of severity, focusing on those who are homebound (unable to leave home) and bedridden (unable to leave bed). The researchers found that people who are bedridden experience post-exertional malaise (PEM)—a worsening of symptoms after physical or mental activity—differently or more severely than those who are only homebound. This research helps doctors and patients better understand how severe ME/CFS can become.

E2 ModerateCohortPEM requiredObservational

Predicting post-exertional malaise in Gulf War Illness based on acute exercise responses.

Boruch, Alexander E, Lindheimer, Jacob B, Klein-Adams, Jacquelyn C et al.·Life sciences·2021

This study looked at how Gulf War Veterans' bodies responded during exercise and whether those responses could predict post-exertional malaise (PEM)—the worsening of symptoms after physical activity. Veterans with Gulf War Illness had more severe symptom flare-ups after exercising compared to healthy veterans, but the researchers found that common exercise measurements like breathing patterns and muscle pain didn't reliably predict who would experience worse PEM.

Autoantibodies to Vasoregulative G-Protein-Coupled Receptors Correlate with Symptom Severity, Autonomic Dysfunction and Disability in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome.

Freitag, Helma, Szklarski, Marvin, Lorenz, Sebastian et al.·Journal of clinical medicine·2021

This study examined whether certain antibodies in ME/CFS patients' blood relate to how severe their symptoms are. The researchers tested 116 ME/CFS patients for antibodies that target receptors controlling blood vessel function and other vital processes. They found that patients whose ME/CFS started after an infection had stronger connections between these antibodies and key symptoms like fatigue and muscle pain, suggesting these antibodies might play a role in how the disease develops.

Autonomic Nervous SystemPost-Exertional Malaise

Post-Exertional Malaise May Be Related to Central Blood Pressure, Sympathetic Activity and Mental Fatigue in Chronic Fatigue Syndrome Patients.

Kujawski, Sławomir, Słomko, Joanna, Hodges, Lynette et al.·Journal of clinical medicine·2021

This study looked at 101 ME/CFS patients to understand post-exertional malaise (PEM)—the worsening of symptoms after activity that many patients experience. Researchers measured blood pressure, nervous system function, and fatigue levels in patients with and without PEM. They found that patients with PEM had higher mental fatigue, lower central blood pressure, and greater nervous system imbalance at rest, but the researchers caution that these findings need to be confirmed by larger studies.

E2 ModerateCohortPEM not requiredLongitudinal

Relationship between Cardiopulmonary, Mitochondrial and Autonomic Nervous System Function Improvement after an Individualised Activity Programme upon Chronic Fatigue Syndrome Patients.

Kujawski, Sławomir, Cossington, Jo, Słomko, Joanna et al.·Journal of clinical medicine·2021

This study tested whether a personalized activity program could help ME/CFS patients feel less tired and function better. Thirty-four patients followed a 16-week program tailored to their individual abilities. After the program, patients reported significant improvements in fatigue, and blood tests showed improvements in mitochondrial markers (Mfn1 and Mfn2)—the energy-producing components of cells. However, about half of the patients found exercise difficult to tolerate.

Autonomic Nervous SystemPost-Exertional Malaise

E2 ModerateCohortPEM requiredLongitudinal

COVID-19 Symptoms Over Time: Comparing Long-Haulers to ME/CFS.

Jason, Leonard A, Islam, Mohammed, Conroy, Karl et al.·Fatigue : biomedicine, health & behavior·2021

This study compared how symptoms change over time in people with long COVID versus people with ME/CFS. Researchers asked 278 long-haulers to describe their current symptoms and symptoms from about 5 months earlier, and compared them to 502 ME/CFS patients. They found that long-haulers generally improved over time, with better sleep and less post-exertional malaise, but their brain fog and memory problems actually got worse. Long-haulers started off more symptomatic than ME/CFS patients but became less symptomatic over time, though orthostatic symptoms (dizziness when standing) remained similar in both groups.

Long COVID OverlapPost-Exertional Malaise

Chronic fatigue syndrome: an emerging sequela in COVID-19 survivors?

Mantovani, Elisa, Mariotto, Sara, Gabbiani, Daniele et al.·Journal of neurovirology·2021

Some people who recover from COVID-19 continue to experience symptoms that look very similar to ME/CFS, including severe tiredness, pain, and difficulty thinking clearly. This study found that about 27% of COVID-19 survivors had these ME/CFS-like symptoms, and they reported worse sleep, more fatigue, and more difficulty with basic activities compared to those who recovered normally. The researchers measured markers of nerve damage and inflammation to understand what might be causing these symptoms.

E2 ModerateCohortPEM unclearCase-Control

Reduced Parasympathetic Reactivation during Recovery from Exercise in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome.

Van Oosterwijck, Jessica, Marusic, Uros, De Wandele, Inge et al.·Journal of clinical medicine·2021

This study examined how the nervous system controls heart rate and other body functions in ME/CFS patients compared to healthy people, both at rest and after exercise. Researchers found that while ME/CFS patients had normal nerve function at rest, their bodies had difficulty recovering after exercise—specifically, their parasympathetic nervous system (the 'rest and digest' system) didn't reactivate properly. This delayed recovery is concerning because similar patterns in other diseases are linked to worse health outcomes.

Patients with Persistent Polyclonal B-Cell Lymphocytosis Share the Symptomatic Criteria of Systemic Exertion Intolerance Disease.

Morizot, Romain, de Korwin, Jean-Dominique, Feugier, Pierre et al.·Journal of clinical medicine·2021

Researchers studied a rare blood condition called persistent polyclonal B-cell lymphocytosis (PPBL) and found that most patients with PPBL experience symptoms very similar to ME/CFS, including severe fatigue that doesn't improve with rest, worsening after physical activity, sleep problems, and difficulty thinking clearly. Out of 39 patients surveyed, 72% met the official criteria for ME/CFS, and nearly all reported chronic fatigue lasting more than 6 months. This finding suggests these two conditions may share common underlying features, though more research is needed to understand why.

E2 ModerateCohortPEM not requiredObservational

Breathing pattern disorders (dysfunctional breathing) characteristics and outcomes of children and young people attending a secondary care respiratory clinic.

Newson, Timothy P, Elias, Annie·Pediatric pulmonology·2020

This study looked at 18 young people (ages 11-16) who had breathing pattern disorders—abnormal ways of breathing that caused problems like chest tightness, difficulty breathing during exercise, or feeling like their throat was closing. Most of these young people also had asthma, anxiety, or other conditions. When properly diagnosed and treated by a speech therapist, most improved significantly and felt more confident managing their symptoms, though it often took months to get the right diagnosis.

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.

E2 ModerateCohortPEM unclearObservational

Cognitive Function Declines Following Orthostatic Stress in Adults With Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS).

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

This study found that people with ME/CFS experience significant problems with memory and thinking speed after their body has been stressed by a tilt test (a medical test that checks how the body handles position changes). Specifically, when tested right after the tilt procedure, patients made more mistakes on memory tasks and responded much more slowly compared to before the test. This suggests that the physical stress of orthostatic intolerance directly worsens cognitive problems in ME/CFS.

Two-Day Cardiopulmonary Exercise Testing in Females with a Severe Grade of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Comparison with Patients with Mild and Moderate Disease.

van Campen, C Linda Mc, Rowe, Peter C, Visser, Frans C·Healthcare (Basel, Switzerland)·2020

This study tested how exercise affects female ME/CFS patients with different disease severity levels. Researchers had 82 women complete exercise tests on two consecutive days and measured how much oxygen their bodies could use and how much work they could do. Patients with severe ME/CFS showed the biggest drop in exercise capacity between day one and day two, suggesting their bodies recover more poorly from physical activity.

E2 ModerateCohortPEM unclearObservational

Preliminary ICF core set for patients with myalgic encephalomyelitis/chronic fatigue syndrome in rehabilitation medicine.

Bileviciute-Ljungar, Indre, Schult, Marie-Louise, Borg, Kristian et al.·Journal of rehabilitation medicine·2020

Researchers studied 100 ME/CFS patients to identify which body functions, activities, and life areas are most affected by the illness. They found that nearly all patients experience severe fatigue, poor sleep, and pain, while most struggle with work, household tasks, and socializing. This study created a standardized checklist that doctors can use to understand and measure how ME/CFS impacts different aspects of patients' lives.

BiomarkersPost-Exertional Malaise

Machine Learning Detects Pattern of Differences in Functional Magnetic Resonance Imaging (fMRI) Data between Chronic Fatigue Syndrome (CFS) and Gulf War Illness (GWI).

Provenzano, Destie, Washington, Stuart D, Rao, Yuan J et al.·Brain sciences·2020

This study used brain imaging (fMRI) and computer learning programs to see if people with ME/CFS and Gulf War Illness have different patterns of brain activity during memory tasks, both before and after exercise. Researchers found that computer programs could correctly distinguish between the two conditions about 75-82% of the time, and identified about 30-33 brain regions that showed different activation patterns between the two groups. This suggests that ME/CFS and Gulf War Illness may have measurable biological differences in how the brain works during cognitive tasks and recovery from exertion.

BiomarkersImmune SystemCognitive ImpairmentPost-Exertional Malaise

The role of low-grade inflammation in ME/CFS (Myalgic Encephalomyelitis/Chronic Fatigue Syndrome) - associations with symptoms.

Jonsjö, Martin A, Olsson, Gunnar L, Wicksell, Rikard K et al.·Psychoneuroendocrinology·2020

This study looked at whether low-level inflammation in the blood is connected to ME/CFS symptoms like exhaustion after activity, brain fog, muscle pain, and flu-like illness. Researchers tested 53 ME/CFS patients for various inflammatory markers and found that several of these markers were associated with cognitive problems and pain, though they were surprisingly less connected to post-exertional fatigue. Interestingly, the connection between inflammation and symptoms was different for men and women in some cases.

Validation of the Severity of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome by Other Measures than History: Activity Bracelet, Cardiopulmonary Exercise Testing and a Validated Activity Questionnaire: SF-36.

van Campen, C Linda M C, Rowe, Peter C, Visser, Frans C·Healthcare (Basel, Switzerland)·2020

This study tested whether doctors can accurately grade how severe a patient's ME/CFS is based on what patients tell them. Researchers compared clinical severity grades (mild, moderate, or severe) with three objective measures: a questionnaire about physical function, a wristband that counts daily steps, and a heart/lung exercise test. The results confirmed that the clinical grades matched up well with these objective measurements, suggesting that doctors' assessments based on patient reports are reasonably accurate.