You are exactly correct, @PattyP. VO2max is not a power number!
@PattyP consider this…when you want to estimate whether or not you are in that 90% VO2max zone, DO NOT use your observed heart rate divided by your max heart rate as an indicator. That tends to OVERestimate the 90% VO2max point. This is the main answer to your question.
Instead, use 1 - (max HR - observed HR)/(max HR - resting HR).
Let’s say your resting HR is 60 bpm & max HR is 198 bpm. Using straight % Max HR predicts 90% VO2max if your heart rate is at or above about 178 bpm. Using the formula I mentioned above your actual HR target should be more like 185 bpm.
So depending on what your resting HR is, 186bpm to 188bp is probably just right at that 90% VO2max level. If you ramped it up a little bit to 188-190 you would for sure be there (if if if your resting HR is 60).
