Nixon, P G · Journal of the Royal College of Physicians of London · 1993
This article reviews the historical concept of 'effort syndrome'—a condition where the body loses its ability to handle physical exertion due to chemical imbalances, particularly in how the body buffers acids produced during exercise. The author argues that this old diagnosis remains relevant today and should be considered when evaluating chronic fatigue and other unexplained illnesses, especially when emotional stress and overbreathing (hyperventilation) are present.
This perspective highlights that ME/CFS may represent a metabolic and homeostatic disorder rather than a psychiatric condition, validating the physiological basis of patients' symptoms. Including effort syndrome in diagnostic frameworks could shift clinical approaches toward rehabilitation-based treatment rather than purely symptomatic management or psychological dismissal.
This editorial does not present new empirical data or clinical trial evidence proving that effort syndrome causes ME/CFS or demonstrating that rehabilitation is effective. It is a historical and conceptual review, not experimental research, so it cannot establish causation or quantify treatment outcomes. The normal resting bicarbonate levels in some patients remain unexplained under this model.
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
Nixon, P G (1993). The grey area of effort syndrome and hyperventilation: from Thomas Lewis to today.. Journal of the Royal College of Physicians of London. https://pubmed.ncbi.nlm.nih.gov/8289156/
BibTeX
@article{mecfsatlas-nixon-1993-grey-area,
author = {Nixon, P G},
title = {The grey area of effort syndrome and hyperventilation: from Thomas Lewis to today.},
journal = {Journal of the Royal College of Physicians of London},
year = {1993},
note = {PubMed: 8289156},
url = {https://www.mecfsatlas.com/evidence/nixon-1993-grey-area},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-29. https://www.mecfsatlas.com/evidence/nixon-1993-grey-area
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