Bazelmans, Ellen, Bleijenberg, Gijs, Voeten, Marinus J M et al. · Journal of psychosomatic research · 2005 · DOI
This study tested how a single intense exercise session affected people with ME/CFS compared to healthy controls. People with ME/CFS experienced increased fatigue that lasted up to 2 days after the exercise test, while healthy people felt back to normal within 2 hours. Interestingly, people with ME/CFS didn't actually move around less after the exercise—their fatigue increased even though their measured activity stayed the same.
This study is important because it demonstrates post-exertional malaise (PEM)—a hallmark symptom of ME/CFS—using objective and subjective measurements simultaneously. Understanding that fatigue can increase without corresponding activity decrease challenges assumptions about ME/CFS and provides evidence that abnormal fatigue response to exercise is a measurable biological phenomenon, not simply deconditioning.
This study does not prove what causes the prolonged fatigue response in ME/CFS patients or whether it results from immune dysfunction, metabolic abnormalities, or other mechanisms. It also does not establish whether all ME/CFS patients experience PEM equally, as individual variation was not explored. The small sample size and single exercise bout limit generalizability to real-world activity patterns.
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
Bazelmans, Ellen, Bleijenberg, Gijs, Voeten, Marinus J M, van der Meer, Jos W M, & Folgering, Hans (2005). Impact of a maximal exercise test on symptoms and activity in chronic fatigue syndrome.. Journal of psychosomatic research. https://doi.org/10.1016/j.jpsychores.2005.04.003
BibTeX
@article{mecfsatlas-bazelmans-2005-impact-maximal,
author = {Bazelmans, Ellen and Bleijenberg, Gijs and Voeten, Marinus J M and van der Meer, Jos W M and Folgering, Hans},
title = {Impact of a maximal exercise test on symptoms and activity in chronic fatigue syndrome.},
journal = {Journal of psychosomatic research},
year = {2005},
doi = {10.1016/j.jpsychores.2005.04.003},
note = {PubMed: 16223622},
url = {https://www.mecfsatlas.com/evidence/bazelmans-2005-impact-maximal},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-30. https://www.mecfsatlas.com/evidence/bazelmans-2005-impact-maximal
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