Lindheimer, Jacob B, Stegner, Aaron J, Wylie, Glenn R et al. · International journal of psychophysiology : official journal of the International Organization of Psychophysiology · 2020 · DOI
This study looked at whether veterans with Gulf War Illness (GWI) experience post-exertional malaise (PEM)—a worsening of symptoms after physical activity. Sixty-seven veterans completed a 30-minute exercise session, and researchers measured their fatigue, pain, and other symptoms before, immediately after, and 24 hours later. Veterans with GWI reported worse overall health and found the exercise more painful and tiring than healthy veterans, but only those who had specifically reported feeling unwell after exertion showed significant symptom worsening 24 hours later.
Post-exertional malaise is a hallmark feature of ME/CFS and similarly affects some Gulf War veterans. This study provides evidence that PEM may occur selectively in a subgroup rather than universally, which could help identify which patients are vulnerable and guide more targeted treatment approaches. Understanding PEM mechanisms in GWI also informs broader ME/CFS research given the diagnostic and symptomatic overlaps between these conditions.
This study cannot establish causation or the biological mechanisms underlying PEM—only that symptom worsening correlates with exercise in certain subgroups. The lack of significant findings in the full GWI sample does not prove PEM doesn't exist in GWI; rather, it suggests heterogeneity in symptom responses that may relate to self-reported history of post-exertional unwellness. Results may not generalize to civilians with ME/CFS or female populations, as the sample consisted of veterans.
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
Lindheimer, Jacob B, Stegner, Aaron J, Wylie, Glenn R, Klein-Adams, Jacquelyn C, Almassi, Neda E, Ninneman, Jacob V, et al. (2020). Post-exertional malaise in veterans with gulf war illness.. International journal of psychophysiology : official journal of the International Organization of Psychophysiology. https://doi.org/10.1016/j.ijpsycho.2019.11.008
BibTeX
@article{mecfsatlas-lindheimer-2020-post-exertional,
author = {Lindheimer, Jacob B and Stegner, Aaron J and Wylie, Glenn R and Klein-Adams, Jacquelyn C and Almassi, Neda E and Ninneman, Jacob V and Van Riper, Stephanie M and Dougherty, Ryan J and Falvo, Michael J and Cook, Dane B},
title = {Post-exertional malaise in veterans with gulf war illness.},
journal = {International journal of psychophysiology : official journal of the International Organization of Psychophysiology},
year = {2020},
doi = {10.1016/j.ijpsycho.2019.11.008},
note = {PubMed: 31786249},
url = {https://www.mecfsatlas.com/evidence/lindheimer-2020-post-exertional},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-30. https://www.mecfsatlas.com/evidence/lindheimer-2020-post-exertional
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