Smith, Wayne R, White, Peter D, Buchwald, Dedra · BMC psychiatry · 2006 · DOI
This study compared 33 people with chronic fatigue to 33 healthy people of similar age and sex. Researchers asked both groups about their physical activity before and during the study. People with chronic fatigue reported being much more active before they got sick, but now they spend significantly less time standing and walking (about 4 hours per day versus 9 hours for healthy people) and much more time lying down or reclining.
This study documents the profound reduction in physical function in ME/CFS patients compared to healthy people and highlights an important clinical phenomenon: patients often recall being highly active before illness onset. Understanding this contrast may help clinicians appreciate the severity of functional loss and guide realistic expectations for recovery and activity management.
This study does not prove that high premorbid activity *caused* ME/CFS, nor does it determine whether patients' memories of previous activity levels are accurate or subject to bias. The cross-sectional design cannot establish causation, and the findings describe correlation between reported activity and illness status without explaining the mechanism.
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
Smith, Wayne R, White, Peter D, & Buchwald, Dedra (2006). A case control study of premorbid and currently reported physical activity levels in chronic fatigue syndrome.. BMC psychiatry. https://doi.org/10.1186/1471-244X-6-53
BibTeX
@article{mecfsatlas-smith-2006-case-control,
author = {Smith, Wayne R and White, Peter D and Buchwald, Dedra},
title = {A case control study of premorbid and currently reported physical activity levels in chronic fatigue syndrome.},
journal = {BMC psychiatry},
year = {2006},
doi = {10.1186/1471-244X-6-53},
note = {PubMed: 17101056},
url = {https://www.mecfsatlas.com/evidence/smith-2006-case-control},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-28. https://www.mecfsatlas.com/evidence/smith-2006-case-control
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