Staci R. Stevens, Christopher R. Snell, Jared N. Stevens et al. · Journal of Translational Medicine · 2018 · DOI
ME/CFS patients underwent two consecutive days of cardiopulmonary exercise testing (CPET). On the second day, patients showed significantly reduced VO2 max and anaerobic threshold compared to the first day — and compared to healthy and disease controls who recovered normally. This objective impairment matches the subjective PEM experience.
Two-day CPET is the only validated physiological test that objectively demonstrates PEM. This study provides objective evidence that ME/CFS patients cannot recover from exertion the way healthy people or those with other chronic illnesses do. It has important implications for disability assessments.
The two-day CPET does not prove the mechanism of PEM. It cannot tell us why ME/CFS patients fail to recover, only that they demonstrably do not.
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
Staci R. Stevens, Christopher R. Snell, Jared N. Stevens, Brayden Keller, & J. Mark Van Ness (2018). Cardiopulmonary exercise testing and post-exertional malaise in ME/CFS: A retrospective analysis. Journal of Translational Medicine. https://doi.org/10.1186/s12967-018-1397-7
BibTeX
@article{mecfsatlas-stevens-2018-two-day-cpet,
author = {Staci R. Stevens and Christopher R. Snell and Jared N. Stevens and Brayden Keller and J. Mark Van Ness},
title = {Cardiopulmonary exercise testing and post-exertional malaise in ME/CFS: A retrospective analysis},
journal = {Journal of Translational Medicine},
year = {2018},
doi = {10.1186/s12967-018-1397-7},
url = {https://www.mecfsatlas.com/evidence/stevens-2018-two-day-cpet},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-25. https://www.mecfsatlas.com/evidence/stevens-2018-two-day-cpet
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