Is the VO2 max on your watch accurate? Slide the error and see what the trend still tells you

Your watch gives you a VO2 max number, but it is a guess from your heart rate and pace, not a lab measurement. Two small studies of the Apple Watch found typical errors of around 13 to 16 percent, and the watch tended to read low.

Slide the controls to see how a wrong number can still show a real trend, and how to use it without being fooled.