Summary
| Direction in ME/CFS | ↓ Reduced — lower than in the comparison group |
|---|---|
| Category | Functional |
| Also described as | Cardiopulmonary exercise test |
| Compared against | Day 1 vs Day 2 |
| Associated symptoms | PEM, exercise intolerance |
| Test type | Clinical or physiological test |
| Source | Holden et al. 2020 — doi:10.1186/s12967-020-02477-4 |
| Condition atlas | ME/CFS Biomarker Atlas |
Trials, interventions and tests
In clinical-trial registrations this marker maps to the outcome term Cardiopulmonary exercise testing (CPET) (25 registered trials use a matching outcome measure).
Clinical trials using 2-day CPET VO₂ peak (day 2) as an outcome
- NCT05699538: Fatigability in Long COVID-19 (Completed)
Outcome measure: peak VO2 - NCT06631287: Randomized Double-Blind Placebo-Controlled Trial EValuating Baricitinib on PERSistent NEurologic and Cardiopulmonary Symptoms of Long COVID (Recruiting)
Outcome measure: Cardiopulmonary exercise testing (CPET) - NCT07553897: Tele-exercise Training Program for Long COVID (Completed)
Outcome measure: Cardiorespiratory Fitness - Peak Oxygen Uptake (VO₂peak) - NCT06161688: Ensitrelvir for Viral Persistence and Inflammation in People Experiencing Long COVID (Active Not Recruiting)
Outcome measure: Duke Activity Status Index (DASI) - NCT07492953: Using Enhanced External Counterpulsation to Recover Cardiovascular Function for Patient of Chronic Diseases (Completed)
Outcome measure: Peak oxygen uptake (Peak VO₂) - NCT05619653: Myocardial Protection in Patients With Post-acute Inflammatory Cardiac Involvement Due to COVID-19 (Active Not Recruiting)
Outcome measure: Cardiopulmonary exercise testing (CPET) - NCT05877508: Anti-SARS-CoV-2 Monoclonal Antibodies for Long COVID (COVID-19) (Active Not Recruiting)
Outcome measure: Duke Activity Status Index (DASI) - NCT06366724: LIFT: Life Improvement Trial (Recruiting)
Outcome measure: Physiologic Response - Oxygen Uptake Efficiency Slope (OUES)
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 — 8 trials, 6 PubMed co-citations
e.g. Predictive Equation for Peak Heart Rate and First Ventilatory Threshold Heart Rate in Patients With Coronary… - Losartan — 1 trial, 3 PubMed co-citations
e.g. Comparative effects of losartan and nifedipine therapy on exercise capacity, Doppler echocardiographic… - Pyridostigmine — 1 trial, 3 PubMed co-citations
e.g. Neurovascular Dysregulation and Acute Exercise Intolerance in Myalgic Encephalomyelitis/Chronic Fatigue… - Cardiopulmonary Rehabilitation — 1 trial, 6 PubMed co-citations
e.g. Effects of Cardiopulmonary Rehabilitation on Cardiorespiratory Fitness and Clinical Symptom Burden in Long… - Coenzyme Q10 — 1 trial, 2 PubMed co-citations
e.g. Coenzyme Q10 terclatrate and creatine in chronic heart failure: a randomized, placebo-controlled… - Endurance Training — 1 trial, 6 PubMed co-citations
e.g. VO(2) on-kinetics and aerobic exercise training in females with systemic lupus erythematosus. - Concurrent Training — 1 trial, 2 PubMed co-citations
e.g. Physiological Profiles of Male and Female CrossFit Athletes. - Inspiratory muscle training — 1 trial, 6 PubMed co-citations
e.g. Effects of physical rehabilitation interventions on pulmonary hypertension: an overview of systematic…
Related Functional markers in ME/CFS
Full list: ME/CFS Biomarker Atlas.
Frequently asked questions
Is 2-day CPET VO₂ peak (day 2) high or low in ME/CFS?
Reduced. Studies summarised in the OSMF atlas report lower 2-day CPET VO₂ peak (day 2) in ME/CFS than in the reference group of the cited comparison (Day 1 vs Day 2). Source: Holden et al. 2020.
What symptoms is 2-day CPET VO₂ peak (day 2) associated with in ME/CFS?
The cited literature associates this marker with PEM, exercise intolerance. These are population-level associations and do not mean the marker causes the symptoms.
Which test measures 2-day CPET VO₂ peak (day 2)?
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 2-day CPET VO₂ peak (day 2) result diagnostic of ME/CFS?
No. No single biomarker is diagnostic of ME/CFS. 2-day CPET VO₂ peak (day 2) 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.
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Last reviewed: 2026-06-29 · Page generated from me-cfs.json · Browse: ME/CFS 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.