Montague, T J, Marrie, T J, Klassen, G A et al. · Chest · 1989 · DOI
This study looked at heart function in 41 ME/CFS patients compared to healthy volunteers. While the hearts looked normal at rest, patients became exhausted during exercise much sooner than healthy people—their heart rates climbed more slowly and didn't reach the expected levels, even though their resting heart rhythms and structure were completely normal.
This study provides early objective evidence that ME/CFS involves a real physiological abnormality affecting exercise capacity, not a psychological condition. Understanding the cardiac contribution to exercise intolerance helps validate the disease and may guide treatment strategies.
This study does not establish the underlying mechanism of reduced exercise capacity—it could reflect cardiac, pulmonary, muscular, metabolic, or neurological dysfunction. The cross-sectional design cannot determine causation or whether cardiac abnormalities precede or result from illness. It also does not address post-exertional malaise or long-term cardiac consequences.
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
Montague, T J, Marrie, T J, Klassen, G A, Bewick, D J, & Horacek, B M (1989). Cardiac function at rest and with exercise in the chronic fatigue syndrome.. Chest. https://doi.org/10.1378/chest.95.4.779
BibTeX
@article{mecfsatlas-montague-1989-cardiac-function,
author = {Montague, T J and Marrie, T J and Klassen, G A and Bewick, D J and Horacek, B M},
title = {Cardiac function at rest and with exercise in the chronic fatigue syndrome.},
journal = {Chest},
year = {1989},
doi = {10.1378/chest.95.4.779},
note = {PubMed: 2924607},
url = {https://www.mecfsatlas.com/evidence/montague-1989-cardiac-function},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-30. https://www.mecfsatlas.com/evidence/montague-1989-cardiac-function
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