Vøllestad, Nina K, Mengshoel, Anne Marit · Frontiers in physiology · 2023 · DOI
This paper reviews how post-exertional malaise (PEM)—the worsening of symptoms after physical or mental activity—is experienced and studied in ME/CFS patients. Patients describe PEM in many different ways and report that it can start immediately or be delayed by days, lasting anywhere from a few days to months. When researchers use standardized exercise tests in laboratories, they see more immediate symptom worsening, but the duration still varies widely between patients.
Understanding how PEM actually manifests in patients' daily lives versus controlled research settings helps clinicians better recognize and validate patient experiences. This review identifies critical gaps in how PEM is studied and measured, which could lead to better diagnostic tools and more effective treatments tailored to the actual recovery processes that go wrong in ME/CFS.
This perspective paper does not provide new experimental data proving the mechanisms causing PEM—it is a literature review and conceptual analysis. It does not establish which specific biological pathways (metabolic, autonomic, or other) are definitively responsible for PEM, only that altered responses occur during repeated exercise.
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
Vøllestad, Nina K & Mengshoel, Anne Marit (2023). Post-exertional malaise in daily life and experimental exercise models in patients with myalgic encephalomyelitis/chronic fatigue syndrome.. Frontiers in physiology. https://doi.org/10.3389/fphys.2023.1257557
BibTeX
@article{mecfsatlas-vllestad-2023-post-exertional,
author = {Vøllestad, Nina K and Mengshoel, Anne Marit},
title = {Post-exertional malaise in daily life and experimental exercise models in patients with myalgic encephalomyelitis/chronic fatigue syndrome.},
journal = {Frontiers in physiology},
year = {2023},
doi = {10.3389/fphys.2023.1257557},
note = {PubMed: 38111900},
url = {https://www.mecfsatlas.com/evidence/vllestad-2023-post-exertional},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-29. https://www.mecfsatlas.com/evidence/vllestad-2023-post-exertional
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