VO2 max can be estimated by drawing a line through the heart rate values measured during a submaximal graded exercise test and extrapolating to the age-adjusted maximal heart rate. This VO2 max could be incorrect if

This VO2 max could be incorrect if

- the measurement of treadmill speed and grade were inaccurate

- the subjects true maximal heart rate was incorrectly estimated

- the subject held onto the treadmill railing during the test

The number is also found by dividing beats by minute or number of beats in 20 seconds multiplied by three. For a more in-depth look at the formulas and calculations, read here. In short, your Vo2 max is the number that expresses just how much oxygen you consume when exercising your hardest.