E0 ConsensusPreliminaryPEM ?Review-NarrativePeer-reviewedMachine draft
Physical Activity and Fatigue Symptoms: Neurotypical Adults and People with Chronic Multisymptom Illnesses.
Boruch, Alex, Branchaw, Grace, O'Connor, Patrick J et al. · Current topics in behavioral neurosciences · 2024 · DOI
Quick Summary
This review examined how physical activity affects fatigue in people with ME/CFS and similar long-term illnesses, compared to healthy people. In healthy adults, exercise usually makes people feel more energized, but in people with ME/CFS and related conditions, exercise often makes fatigue worse. Short-term exercise programs show small improvements in fatigue for healthy people, but little to no improvement for those with these chronic illnesses.
Why It Matters
This study highlights a critical distinction: exercise recommendations that benefit healthy people may worsen outcomes for ME/CFS patients. Understanding why ME/CFS responds differently to exercise is essential for developing safe, personalized treatment approaches and avoiding potentially harmful activity prescriptions based on general population guidelines.
Observed Findings
- Single bouts of low-to-moderate intensity exercise increase fatigue feelings in ME/CFS and similar chronic multisymptom illnesses, opposite to effects in healthy adults.
- Chronic moderate-intensity exercise programs (1-6 months) produce small-to-moderate fatigue improvements in neurotypical populations but minimal or no improvement in CMI populations.
- The mechanisms underlying acute exercise-induced fatigue worsening in CMIs remain unknown.
- Multiple neural circuits and neurotransmitters are implicated in fatigue responses to exercise, but disease-specific mechanisms in CMIs are poorly understood.
- Limited data on longer-term exercise interventions in CMI populations precludes strong conclusions about sustained activity effects.
Inferred Conclusions
- Exercise produces paradoxically opposite acute and chronic fatigue effects between healthy populations and people with chronic multisymptom illnesses, suggesting fundamentally different physiological responses.
- The pathophysiology of CMIs—potentially involving brain, immune, and autonomic system dysfunction—likely drives the divergent exercise response compared to typical patterns.
- Current exercise recommendations developed for healthy populations may be inappropriate for ME/CFS patients and may cause harm rather than benefit.
- Mechanisms of exercise effects on fatigue remain poorly understood and require disease-specific investigation to develop safe interventions for CMI populations.
What This Study Does Not Prove
This review does not establish the specific biological mechanisms causing exercise intolerance in ME/CFS or whether any form of physical activity could eventually be beneficial. It also does not prove that exercise is harmful long-term for all CMI patients, as data on longer-term interventions and individual variability remain limited. Correlation between activity and fatigue worsening does not establish causation at the mechanistic level.
Tags
Symptom:Post-Exertional MalaiseFatigue
Phenotype:Long COVID Overlap
Method Flag:PEM Not DefinedMixed Cohort
Metadata
- DOI
- 10.1007/7854_2024_502
- PMID
- 39037494
- Review status
- Machine draft
- Evidence level
- Established evidence from major reviews, guidelines, or evidence maps
- Last updated
- 8 April 2026