The VO₂ Accuracy of Wearables | Peter Attia
Peter Attia examines the reliability of VO₂ max estimates on wearables, revealing significant accuracy limitations that make them unreliable for serious fitness tracking. He explains that wearables cannot directly measure gas exchange and instead rely on imprecise algorithms combining heart rate, pace, and demographic data—often producing estimates with swings of up to 20 points (e.g., reading 52 when actual VO₂ max could be 42 or 62). Attia argues that wrist-based optical heart rate sensors introduce compounding errors that make wearable VO₂ max metrics too inaccurate to rely on as a primary performance indicator.
Key takeaways
- • Wearables estimate VO₂ max rather than measure it directly, since they cannot access actual gas exchange data and instead infer values from heart rate, pace, and power metrics combined with age and weight.
- • Wrist-based optical heart rate sensors are significantly less accurate than many assume, with errors large enough to meaningfully distort downstream VO₂ max calculations by 5-10% or more.
- • Wearables often generate automatic VO₂ max estimates from general workout data without user control, causing false depression of estimates when performing high-volume zone 2 training.
- • A wearable displaying a VO₂ max of 52 could realistically represent an actual value anywhere from 42 to 62, making the data unreliable for precision-dependent fitness planning.
- • Rather than relying solely on wearable VO₂ max readings, individuals should seek more controlled and direct measurement methods for accurate aerobic capacity assessment.
More from these creators
How Women Can Start Alzheimer’s Prevention | Lisa Mosconi, Ph.D.
381‒Alzheimer’s disease in women: how hormonal transitions impact the brain, new therapies, & more
Cooking with Lard vs Seed Oils | Layne Norton, Ph.D.
380 ‒ The seed oil debate: are they uniquely harmful relative to other dietary fats?
A guide to cardiorespiratory training at any fitness level to improve longevity (AMA 79 sneak peek)
378 ‒ Women’s health & performance: how training, nutrition, & hormones interact across life stages