May, Marcella, Milrad, Sara F, Perdomo, Dolores M et al. · Journal of psychosomatic research · 2020 · DOI
This study compared people with ME/CFS who experience severe post-exertional malaise (PEM—getting much worse after activity) with those who experience mild PEM. People with severe PEM reported more intense symptoms, greater disruption to their daily lives and social activities, and higher levels of depression and mood problems. Importantly, people in both groups had similarly stressful life experiences, suggesting that PEM severity itself—not just general stress—drives these differences.
This research demonstrates that PEM severity is associated not only with worse physical symptoms but also with significant psychological distress, suggesting that patients with prominent PEM may benefit from targeted psychological interventions. The findings underscore the heterogeneity of ME/CFS and support consideration of PEM as a key stratification variable in future research and clinical management.
This study cannot establish whether psychological distress causes worse PEM, results from worse symptom burden, or represents a separate phenomenon. The cross-sectional design means we observe associations at a single time point and cannot determine causality. Additionally, this study uses the Fukuda criteria, which does not require PEM, so findings may not fully characterize PEM-defined ME/CFS populations.
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
May, Marcella, Milrad, Sara F, Perdomo, Dolores M, Czaja, Sara J, Fletcher, Mary Ann, Jutagir, Devika R, et al. (2020). Post-exertional malaise is associated with greater symptom burden and psychological distress in patients diagnosed with Chronic Fatigue Syndrome.. Journal of psychosomatic research. https://doi.org/10.1016/j.jpsychores.2019.109893
BibTeX
@article{mecfsatlas-may-2020-post-exertional,
author = {May, Marcella and Milrad, Sara F and Perdomo, Dolores M and Czaja, Sara J and Fletcher, Mary Ann and Jutagir, Devika R and Hall, Daniel L and Klimas, Nancy and Antoni, Michael H},
title = {Post-exertional malaise is associated with greater symptom burden and psychological distress in patients diagnosed with Chronic Fatigue Syndrome.},
journal = {Journal of psychosomatic research},
year = {2020},
doi = {10.1016/j.jpsychores.2019.109893},
note = {PubMed: 31884303},
url = {https://www.mecfsatlas.com/evidence/may-2020-post-exertional},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-27. https://www.mecfsatlas.com/evidence/may-2020-post-exertional
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