Measurement · not graded
Portable Metabolic Analysis (VO2 and resting metabolism)
What the evidence looks at: agreement with laboratory metabolic carts.
At a glance
A portable metabolic analyzer is a mask you breathe into during exercise or rest. It measures the oxygen you use and estimates fitness and how many calories you burn at rest. This page asks how close it comes to a full lab machine. In small studies one device agreed well during cycling and less well during walking. It measures, and it does not treat.
What the studies looked at: Agreement with laboratory metabolic carts
Why this letter
Ungraded: a metabolic analyzer is a measurement instrument, not an intervention. The A-D scale grades treatment efficacy; no trial randomizes people to being measured.
It is a measurement instrument, not an intervention. Measured VO2max The most oxygen the body can use during all-out exercise, a standard measure of aerobic fitness. is itself one of the objective functional endpoints The outcome a trial measures to decide whether the treatment worked, such as heart attacks, blood pressure or a symptom score. that can carry the top letter on another record, so an accurate measurement matters. Against a stationary metabolic cart on a cycle ergometer, PNOE showed strong agreement for VO2 (r=0.98) and high test-retest reliability in 22 adults (Tsekouras 2019, PMID PubMed ID: the permanent number the US National Library of Medicine gives a published paper. Each one links to that paper's record on PubMed. 33344948). Against a COSMED K5 during treadmill walking in 21 adults, agreement was moderate (r=0.60 to 0.79) (Kwok 2025, PMID 40407443). A bench test of 15 systems found accuracy differed substantially between systems (Van Hooren 2024, PMID 37697640).
Evidence notes: not independently replicated The same finding reproduced by a separate research group. A result seen once can be chance or bias; a replicated one is harder to explain away.
Last reviewed: September 2026
Dose, form and timing
A change in VO2max between two tests is interpretable only when the device, the protocol and the effort were the same both times.
Products carry no letter. The letter belongs to the therapy as the trials studied it, and no trial tested these products unless the entry says so. Listed alphabetically; payment does not affect order.
Portable breath-by-breath metabolic analyzer for VO2max, resting metabolic rate The energy the body burns at rest, measured under looser conditions than the basal rate, such as a shorter fast. It usually runs slightly higher than the basal metabolic rate. and fuel use. Validated against laboratory metabolic carts, with strong agreement on a cycle ergometer and moderate agreement during walking.
Usually run by a clinic or trainer; the test result depends on the protocol and on maximal effort.
Grade history
How this letter has changedLatest: No. 39 · September 2026 · Added.
New measurement entry, ungraded by design. PNOE agreed strongly with a laboratory metabolic cart on a cycle ergometer (Tsekouras et al., Front Sports Act Living 2019; PMID 33344948) and moderately with another portable system during walking (Kwok et al., J Funct Morphol Kinesiol 2025; PMID 40407443). Accuracy varies widely between metabolic systems (Van Hooren et al., Scand J Med Sci Sports 2024; PMID 37697640).PMID 33344948 PMID 40407443 PMID 37697640
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Sources
Primary evidenceThree papers, each linked to its PubMed record.
Tsekouras et al. (Front Sports Act Living, 2019; PMID 33344948): PNOE against COSMED Quark CPET, 22 adults, cycle ergometer. Kwok et al. (J Funct Morphol Kinesiol, 2025; PMID 40407443): PNOE against COSMED K5, 21 adults, treadmill walking. Van Hooren et al. (Scand J Med Sci Sports, 2024; PMID 37697640): accuracy of 15 CPET systems against a metabolic simulator. Ungraded: measurement validity, not a treatment claim.
Disclosure
Educational use only · Not medical advice · EBL grades published human evidence and does not recommend treatment.
Evidence Based Longevity, Inc. is owner-operated and edited by Arnold Sandlow, D.C., a California-licensed chiropractor. Evidence Based Longevity publishes in English only · Machine translations are not produced or reviewed by EBL for accuracy
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