van Campen, C Linda M C, Visser, Frans C · Healthcare (Basel, Switzerland) · 2021 · DOI
This study tested whether people with ME/CFS and people with chronic fatigue (but not ME/CFS) respond differently to exercise on two consecutive days. Researchers had 50 women with ME/CFS and 51 women with chronic fatigue perform exercise tests while measuring oxygen use and heart rate. Women with ME/CFS performed worse on day 2, while women with chronic fatigue actually performed slightly better, suggesting ME/CFS creates a unique pattern of exercise intolerance.
This study provides objective evidence that ME/CFS produces a distinctive physiological signature—post-exertional deterioration on repeated exercise testing—that differs from other chronic fatigue conditions. This distinction is crucial for accurate diagnosis and could help validate ME/CFS as a separate medical condition with its own pathophysiology.
This study does not prove what causes the post-exertional deterioration in ME/CFS, only that it occurs. The cross-sectional design cannot establish causality or longitudinal changes over time. Results apply only to female patients; findings may not generalize to male ME/CFS populations.
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
van Campen, C Linda M C & Visser, Frans C (2021). Female Patients with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome or Idiopathic Chronic Fatigue: Comparison of Responses to a Two-Day Cardiopulmonary Exercise Testing Protocol.. Healthcare (Basel, Switzerland). https://doi.org/10.3390/healthcare9060682
BibTeX
@article{mecfsatlas-van-campen-2021-female-patients,
author = {van Campen, C Linda M C and Visser, Frans C},
title = {Female Patients with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome or Idiopathic Chronic Fatigue: Comparison of Responses to a Two-Day Cardiopulmonary Exercise Testing Protocol.},
journal = {Healthcare (Basel, Switzerland)},
year = {2021},
doi = {10.3390/healthcare9060682},
note = {PubMed: 34198913},
url = {https://www.mecfsatlas.com/evidence/van-campen-2021-female-patients},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-29. https://www.mecfsatlas.com/evidence/van-campen-2021-female-patients
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