Vernon, Suzanne D, Hartle, Megan, Sullivan, Karen et al. · Work (Reading, Mass.) · 2023 · DOI
This study looked at whether people with Long COVID experience post-exertional malaise (PEM)—a hallmark symptom of ME/CFS where symptoms get worse after physical or mental activity. Researchers surveyed 80 Long COVID patients and compared their experiences to 151 ME/CFS patients. Nearly all Long COVID patients reported having PEM, but the way they experienced it differed significantly from ME/CFS patients in terms of what triggered it, which symptoms appeared, and how to recover.
Understanding whether Long COVID and ME/CFS share the same core pathophysiology has important implications for diagnosis, treatment protocols, and research prioritization. This study provides evidence that PEM is present in Long COVID but manifests differently, which could help clinicians recognize and appropriately manage exertional intolerance in both populations and inform whether shared versus distinct therapeutic approaches are needed.
This study does not establish that Long COVID and ME/CFS are different diseases or that their underlying biological mechanisms differ—only that reported PEM experiences differ. The cross-sectional design cannot determine causation or whether differences reflect true biological distinctions versus differences in patient education, disease duration, or recall accuracy. The findings cannot be generalized beyond patients seeking specialized care at this clinic.
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
The first block is for the primary paper and is the citation you should use in research work. The atlas-snapshot line only applies if you are specifically referring to this atlas’s reading of the paper on the date shown.
Primary citation
Vernon, Suzanne D, Hartle, Megan, Sullivan, Karen, Bell, Jennifer, Abbaszadeh, Saeed, Unutmaz, Derya, et al. (2023). Post-exertional malaise among people with long COVID compared to myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS).. Work (Reading, Mass.). https://doi.org/10.3233/WOR-220581
BibTeX
@article{mecfsatlas-vernon-2023-post-exertional,
author = {Vernon, Suzanne D and Hartle, Megan and Sullivan, Karen and Bell, Jennifer and Abbaszadeh, Saeed and Unutmaz, Derya and Bateman, Lucinda},
title = {Post-exertional malaise among people with long COVID compared to myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS).},
journal = {Work (Reading, Mass.)},
year = {2023},
doi = {10.3233/WOR-220581},
note = {PubMed: 36911963},
url = {https://www.mecfsatlas.com/evidence/vernon-2023-post-exertional},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-25. https://www.mecfsatlas.com/evidence/vernon-2023-post-exertional
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