Watch VO₂max estimates are right on average, but any one reading can be off by about ±10 mL/kg/min
How accurate is VO₂max from a smartwatch?
The finding
Algorithms using exercise data had a mean bias of −0.09 mL/kg/min, with limits of agreement from −9.92 to 9.74. Algorithms using resting data significantly overestimated VO₂max.
- Authors
- Molina-Garcia P, Notbohm HL, Schumann M, et al.
- Published
- Sports Medicine 52(7):1577–1597 · 2022
- Evidence
- Read in the primary source; numbers checked.
- Source
- doi.org/10.1007/s40279-021-01639-y
How it was studied
Systematic review and meta-analysis of 14 validation studies of wearable VO₂max estimates.
What it does not show
Few, small and heterogeneous studies. The authors call the estimates good for populations and poor for individuals.
What Longstanding does with it
The app can read VO₂max from Apple Health or Health Connect, and says which source each value came from. An error of this size is larger than the gap between neighbouring percentile bands, so a watch-based percentile is a rough placement. A field test or a lab result, repeated the same way each quarter, is the better input.
Tests this bears on
Related
- Apple’s own validation reports a mean VO₂max error of +1.4 ± 4.7 mL/kg/min, against a projected referenceApple Inc. · 2021
- Independent lab tests find Apple Watch underestimates VO₂max by about 6 mL/kg/minLambe R · 2025; 2026; 2024
- Garmin VO₂max has done better in small studies, but the evidence is thinCarrier B · 2025