Topic Guide
What Is Zone 2 cardio?
Zone 2 cardio is a subject covered in depth across 1 podcast episode in our database. Below you'll find key concepts, expert insights, and the top episodes to listen to — all distilled from hours of conversation by leading experts.
Key Concepts in Zone 2 cardio
Vo₂ max
VO₂ max refers to the maximum rate of oxygen consumption measurable during incremental exercise. This episode highlights that while it's a critical fitness metric, wearables only estimate it, rather than directly measuring the gas exchange required for true accuracy.
Optical sensors (wrist-based)
These sensors on wearables use light to detect changes in blood volume under the skin, estimating heart rate. Peter Attia points out their significant inaccuracy and drift as a major flaw, undermining the reliability of other metrics like estimated VO₂ max.
What Experts Say About Zone 2 cardio
- 1.Wearables do not directly measure VO₂ max; they estimate it using algorithms based on inferred gas exchange.
- 2.The algorithms used by wearables infer gas exchange from data points like heart rate, pace, power, and demographic variables such as age, sex, and weight.
- 3.Wrist-based optical heart rate sensors, a critical data source for wearables, are often inaccurate and can drift significantly, compromising VO₂ max estimates.
- 4.Many wearables do not allow users to initiate a true VO₂ max test, instead generating automatic estimates from daily workouts.
- 5.Automatic VO₂ max estimates can be artificially lowered if a user primarily focuses on Zone 2 cardio, leading to an inaccurate representation.
- 6.Peter Attia notes that a wearable's reported VO₂ max of 52 could actually be anywhere from 42 to 62, indicating a substantial margin of error.