Summary
| Direction in Gulf War Illness | ↓ Reduced — lower than in the comparison group |
|---|---|
| Category | Functional |
| Also described as | Functional capacity |
| Compared against | HGV (healthy Gulf War veteran controls) |
| Associated symptoms | Physical limitation |
| Test type | Clinical or physiological test |
| Source | Gean et al. 2021 — doi:10.1016/j.lfs.2021.119456 |
| Condition atlas | Gulf War Illness Biomarker Atlas |
Other conditions where 6-minute walk distance is reported
- 6-minute walk distance in ME/CFS — ↓ reduced vs HC
- 6-minute walk distance in PACVS — ↓ reduced vs HC
See the cross-condition hub: 6-minute walk distance across conditions.
Trials, interventions and tests
In clinical-trial registrations this marker maps to the outcome term Functional Capacity (25 registered trials use a matching outcome measure).
Clinical trials using 6-minute walk distance as an outcome
- NCT07317401: Investigating the Effects of Intermittent Hypoxia-Hyperoxia Treatment (IHHT) in People With Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) to Improve Fatigue, Pain, and Quality of Life by Targeting Mitochondrial Dysfunction and Autonomic Nervous System Impairment (Not Yet Recruiting)
Outcome measure: Change in functional capacity (FUNCAP-27) - NCT06871293: Evaluating the Impact of a Functional and Cognitive Strategy in Patients With Long Covid-19 (Recruiting)
Outcome measure: Composite Change in Functional Capacity, Cognitive Function, Health-Related Quality of Life, and Strength - NCT06928272: Long Covid (LC)-REVITALIZE - A Long Covid Repurposed Drug Study (Recruiting)
Outcome measure: General participant reported severity of post-exertional malaise (PEM) using the FUNCAP27 questionnaire - NCT06766825: Study to Evaluate the Efficacy and Safety of Plitidepsin in Adults With Post-COVID-19 Condition (PCC) (Recruiting)
Outcome measure: To compare functional capacity changes in patients from each group using the post-COVID-19 Functional State (PCFS) scale. - NCT06161688: Ensitrelvir for Viral Persistence and Inflammation in People Experiencing Long COVID (Active Not Recruiting)
Outcome measure: Duke Activity Status Index (DASI) - NCT07454395: Is Swimming a More Tolerable Form of Movement for Individuals With Myalgic Encephalomyelitis/ Chronic Fatigue Syndrome? (Suspended)
Outcome measure: Severity of ME/CFS - NCT06330376: Diaphragmatic Breathing Exercises for Post-COVID-19 Diaphragmatic Dysfunction (DD) (Completed)
Outcome measure: 6-minute walk test (6MWT) - NCT07190105: Vagal Approaches on Long COVID-19 (Completed)
Outcome measure: Steps
17 more trials reference this marker.
Interventions studied alongside this marker
Hypothesis-generating links from trial outcome usage and literature co-occurrence. Not treatment recommendations.
- Exercise therapy — 4 trials, 6 PubMed co-citations
e.g. Effects of Telerehabilitation Based on Motion Recognition Technology on Exercise Endurance of Patients With… - Cognitive rehabilitation — 2 trials, 6 PubMed co-citations
e.g. Randomised active controlled trial examining effects of aerobic exercise, cognitive and music interventions… - Pyridostigmine — 1 trial, 1 PubMed co-citations
e.g. Elevated Heart Rate is Associated with Cardiac Denervation in Patients with Heart Failure: A 123-Iodine-MIBG… - Low-dose naltrexone — 1 trial, 1 PubMed co-citations
e.g. Effect of Naltrexone on Spinal and Supraspinal Pain Mechanisms and Functional Capacity in Women with… - Cardiopulmonary Rehabilitation — 1 trial, 6 PubMed co-citations
e.g. Effectiveness of Early Cardiorespiratory Rehabilitation Combined With Melatonin Supplementation During the… - Acceptance and commitment therapy — 1 trial, 1 PubMed co-citations
e.g. Acceptability and feasibility of acceptance and commitment therapy for improving outcomes in hematopoietic… - Transcranial direct current stimulation — 1 trial, 6 PubMed co-citations
e.g. Home-Based Transcranial Direct Current Stimulation for Menstrual Pain and Premenstrual Symptoms: A… - Motor Training — 1 trial, 4 PubMed co-citations
e.g. Lower limb sensory training improves functional capacity in hemiparesis: a single-blinded randomized…
Related Functional markers in Gulf War Illness
Full list: Gulf War Illness Biomarker Atlas.
Frequently asked questions
Is 6-minute walk distance high or low in Gulf War Illness?
Reduced. Studies summarised in the OSMF atlas report lower 6-minute walk distance in Gulf War Illness than in healthy Gulf War veteran controls. Source: Gean et al. 2021.
What symptoms is 6-minute walk distance associated with in Gulf War Illness?
The cited literature associates this marker with Physical limitation. These are population-level associations and do not mean the marker causes the symptoms.
Which test measures 6-minute walk distance?
It is measured as a clinical or physiological test. Many of the cited studies used research-grade assays, so clinical availability may vary.
Is one abnormal 6-minute walk distance result diagnostic of Gulf War Illness?
No. No single biomarker is diagnostic of Gulf War Illness. 6-minute walk distance findings come from group comparisons, overlap considerably between patients and controls, and vary with study design, timing and comparison group. A result should be interpreted by a clinician alongside symptoms, history and other tests.
Is 6-minute walk distance specific to Gulf War Illness?
No. The same marker is also reported in ME/CFS, PACVS in this atlas, so it reflects shared biology (for example inflammation or vascular stress) rather than a condition-specific signature.
Cite this page
Subscribe on Substack
Last reviewed: 2026-06-29 · Page generated from gulf-war-illness.json · Browse: Gulf War Illness atlas · Biomarker Index · All marker pages
Disclaimer: This page is an educational synthesis of published, peer-reviewed research and is not medical advice. Biomarker findings vary across studies with case definitions, comparison groups, timing and assay methods. Direction of change reflects the predominant finding in the cited source and does not establish a diagnostic threshold. Discuss any test result with a qualified clinician.