Loy, Bryan D, O'Connor, Patrick J, Dishman, Rodney K · Medicine and science in sports and exercise · 2016 · DOI
This review of seven studies looked at how a single exercise session affects fatigue in people with ME/CFS. The combined results showed that exercise increased fatigue more in people with ME/CFS compared to healthy controls. Importantly, fatigue got worse over time—it was most noticeable 4 or more hours after exercise ended, rather than immediately during or right after the activity stopped.
This is one of the few systematic syntheses of exercise effects specifically in ME/CFS, providing quantitative evidence that post-exertional malaise (fatigue worsening after activity) is a measurable phenomenon. Understanding the timing and magnitude of fatigue response helps validate patient experiences and may inform safer activity management strategies.
This meta-analysis does not establish mechanisms of exercise-induced fatigue in ME/CFS, nor does it determine optimal exercise intensity thresholds for individual patients. The heterogeneity between studies suggests different patient populations, diagnostic criteria, and exercise protocols may produce different outcomes—findings may not apply universally to all ME/CFS subtypes.
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
Loy, Bryan D, O'Connor, Patrick J, & Dishman, Rodney K (2016). Effect of Acute Exercise on Fatigue in People with ME/CFS/SEID: A Meta-analysis.. Medicine and science in sports and exercise. https://doi.org/10.1249/MSS.0000000000000990
BibTeX
@article{mecfsatlas-loy-2016-effect-acute,
author = {Loy, Bryan D and O'Connor, Patrick J and Dishman, Rodney K},
title = {Effect of Acute Exercise on Fatigue in People with ME/CFS/SEID: A Meta-analysis.},
journal = {Medicine and science in sports and exercise},
year = {2016},
doi = {10.1249/MSS.0000000000000990},
note = {PubMed: 27187093},
url = {https://www.mecfsatlas.com/evidence/loy-2016-effect-acute},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-25. https://www.mecfsatlas.com/evidence/loy-2016-effect-acute
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