Sisto, S A, Tapp, W N, LaManca, J J et al. · QJM : monthly journal of the Association of Physicians · 1998 · DOI
This study tracked the physical activity of 20 women with ME/CFS and 20 healthy volunteers for two weeks using a movement monitor worn at the waist. After all participants did a strenuous treadmill exercise test, researchers measured how their activity changed. Women with ME/CFS showed a noticeable drop in activity levels after the exercise, with the biggest decrease happening around days 12-14, and they took more rest breaks during the day.
This study provides objective evidence that ME/CFS patients experience measurable changes in activity patterns after strenuous exercise, supporting the clinical reality of post-exertional malaise. The delayed onset of activity reduction (peaking around day 12-14) suggests symptom flares may occur later than patients initially report, which could improve how healthcare providers counsel patients on pacing and activity management.
This study does not establish the mechanisms underlying post-exertional malaise or explain why the response is delayed. It does not prove that all ME/CFS patients respond identically to exercise, nor does it clarify whether the adaptive compensations observed represent true recovery or simply unsustainable coping mechanisms. The small sample size and single maximal exercise test limit conclusions about typical daily exertion.
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
Sisto, S A, Tapp, W N, LaManca, J J, Ling, W, Korn, L R, Nelson, A J, et al. (1998). Physical activity before and after exercise in women with chronic fatigue syndrome.. QJM : monthly journal of the Association of Physicians. https://doi.org/10.1093/qjmed/91.7.465
BibTeX
@article{mecfsatlas-sisto-1998-physical-activity,
author = {Sisto, S A and Tapp, W N and LaManca, J J and Ling, W and Korn, L R and Nelson, A J and Natelson, B H},
title = {Physical activity before and after exercise in women with chronic fatigue syndrome.},
journal = {QJM : monthly journal of the Association of Physicians},
year = {1998},
doi = {10.1093/qjmed/91.7.465},
note = {PubMed: 9797929},
url = {https://www.mecfsatlas.com/evidence/sisto-1998-physical-activity},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-27. https://www.mecfsatlas.com/evidence/sisto-1998-physical-activity
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