Wearables often estimate VO2 max automatically from general workout data rather than allowing users to initiate a true test, which can lead to inaccurate readings, especially if a user primarily does Zone 2 training.

“The final point that I struggle with a lot of these risk based things is you don't really control when and how the estimate is taken. So a lot of these wearables, although not true for all of them, don't let you initiate a true V2 max test. So they're kind of estimating or generating an estimate auto automatically from the data you collect during your outdoor workouts. If you're doing a lot of zone 2, then they're falsely going to depress your estimate.”