Jammes, Y, Steinberg, J G, Delliaux, S et al. · Journal of internal medicine · 2009 · DOI
This study found that people with ME/CFS experience unusual stress on their cells during exercise, particularly involving harmful molecules called free radicals. Their bodies also fail to mount normal protective responses—both in terms of producing protective proteins (heat shock proteins) and inflammatory markers that healthy people produce during exertion. This combination of excessive cellular damage and insufficient protective response may explain why exercise is so difficult for people with ME/CFS.
This study provides mechanistic evidence for why post-exertional malaise (PEM) occurs in ME/CFS—demonstrating a specific biochemical abnormality in cellular stress response rather than deconditioning. Understanding this protective protein deficiency could lead to targeted therapeutic interventions and validates the biological basis of exercise intolerance in ME/CFS.
This study does not prove that low heat shock protein production is the sole cause of ME/CFS or PEM, only that it is associated with altered exercise response in this cohort. The small sample size (n=9 per group) limits generalizability, and the cross-sectional nature prevents determination of whether the Hsp abnormality is primary or secondary. The study also does not establish whether this pattern is unique to ME/CFS or occurs in other post-exertional conditions.
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
Jammes, Y, Steinberg, J G, Delliaux, S, & Brégeon, F (2009). Chronic fatigue syndrome combines increased exercise-induced oxidative stress and reduced cytokine and Hsp responses.. Journal of internal medicine. https://doi.org/10.1111/j.1365-2796.2009.02079.x
BibTeX
@article{mecfsatlas-jammes-2009-chronic-fatigue,
author = {Jammes, Y and Steinberg, J G and Delliaux, S and Brégeon, F},
title = {Chronic fatigue syndrome combines increased exercise-induced oxidative stress and reduced cytokine and Hsp responses.},
journal = {Journal of internal medicine},
year = {2009},
doi = {10.1111/j.1365-2796.2009.02079.x},
note = {PubMed: 19457057},
url = {https://www.mecfsatlas.com/evidence/jammes-2009-chronic-fatigue},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-30. https://www.mecfsatlas.com/evidence/jammes-2009-chronic-fatigue
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