Summary
| Direction in PACVS | ↓ Reduced — lower than in the comparison group |
|---|---|
| Category | Functional |
| Also described as | Pulse oximetry |
| Compared against | HC (healthy controls) |
| Associated symptoms | Exercise-induced hypoxemia |
| Test type | Clinical or physiological test |
| Source | Halma 2024 — doi:10.2196/preprints.70342 |
| Condition atlas | PACVS Biomarker Atlas |
Trials, interventions and tests
In clinical-trial registrations this marker maps to the outcome term Change in Pulse Oximetry at Rest and During the 6MWT (7 registered trials use a matching outcome measure).
Clinical trials using Exertional SpO₂ nadir as an outcome
- NCT06231238: Balance Acceptance and Commitment Therapy for Long COVID (Active Not Recruiting)
Outcome measure: Lung function (spirometry, Resting pulse oximetry; SpO2) - NCT07492953: Using Enhanced External Counterpulsation to Recover Cardiovascular Function for Patient of Chronic Diseases (Completed)
Outcome measure: Peak oxygen uptake (Peak VO₂) - NCT05094622: Physical Training in Patients With POTS After Covid-19 (Active Not Recruiting)
Outcome measure: Change in oxygen saturation during 6 minute walk test - NCT05877534: Effects of Individual Tailored Physical Exercise in Patients With POTS After COVID-19 - a Randomized Controlled Study (Enrolling By Invitation)
Outcome measure: Change in oxygen saturation during 6 minute walk test - NCT04482595: BIO 300 Oral Suspension in Previously Hospitalized Long COVID Patients (Unknown)
Outcome measure: Change in Pulse Oximetry at Rest and During the 6MWT - NCT04905888: Hyperbaric Oxygen for Long COVID-19 Pulmonary Sequela (Withdrawn)
Outcome measure: Exercise tolerance - NCT07579026: Effects of Breathing Retraining Exercises in Pregnant Females With Postural Orthostatic Tachycardia Syndrome. (Recruiting)
Outcome measure: Pulse oximetry
Interventions studied alongside this marker
Hypothesis-generating links from trial outcome usage and literature co-occurrence. Not treatment recommendations.
- Exercise therapy — 2 trials, 1 PubMed co-citations
e.g. Acute effects of manual breathing assist technique on lung volume and dyspnea in individuals with severe… - Diaphragmatic breathing exercise — 1 trial, 1 PubMed co-citations
e.g. Safety and efficacy of motor imagery-based physical activity in high-risk pregnancy: A randomized controlled…
Related Functional markers in PACVS
- 6-minute walk distance ↓
- Chester Step Test (VO₂ proxy) ↓
- Orthostatic heart rate increment ↑
- PAC-19QoL score ↓
- Salivary nitric oxide ↓
- Neurofilament light chain (NfL) ↑
- Heart rate variability (HRV) ↓
Full list: PACVS Biomarker Atlas.
Frequently asked questions
Is Exertional SpO₂ nadir high or low in PACVS?
Reduced. Studies summarised in the OSMF atlas report lower Exertional SpO₂ nadir in PACVS than in healthy controls. Source: Halma 2024.
What symptoms is Exertional SpO₂ nadir associated with in PACVS?
The cited literature associates this marker with Exercise-induced hypoxemia. These are population-level associations and do not mean the marker causes the symptoms.
Which test measures Exertional SpO₂ nadir?
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 Exertional SpO₂ nadir result diagnostic of PACVS?
No. No single biomarker is diagnostic of PACVS. Exertional SpO₂ nadir 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.
Cite this page
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Last reviewed: 2026-06-30 · Page generated from pacvs.json · Browse: PACVS 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.