Revisiting VO2max

[YachatsMike]

Fitbit generates a Cardio Fitness Score that maps to a rough value for VO2max.  I also use the formula VO2max = 15.3 * HRmax / RHR.  Is one of these more accurate than the other? 

[LZeeW]

@YachatsMike   I moved your post to the Get Moving forum.  I think it is a better fit and you might get more responses.

You need to do GPS runs to get a single number for your cardio fitness score, instead of a range.  How do your values compare?

Fitbit’s accuracy depends on two things, heart rate accuracy during exercise and GPS distance.  If either or both are off, then Fitbit isn’t very accurate.

The equation you posted depends on the assumption that your RHR isn’t affected by medication.

[YachatsMike]

I have 77 year old knees.  My running days are over.  All I have are the estimates.  I'm just wondering which estimate is better.

[LZeeW]

@YachatsMike   I think Fitbit might be using this formula to generate its range.  Fitbit uses known, accepted formulas when available.  I just did some calculations using my typical RHR range.  My numbers were about equal to their limits.

Fitbit’s algorithm using heart rate and GPS is proprietary.

I want to mention again that many blood pressure and heart medications can lower heart rate, so you can’t rely on either Fitbit or the equation results.