@LeeWest I wouldn't be worried about the cardio score. Fitbit says the cardio score is the same as VO2Max, however, the company doesn't really reveal how it's being tested so it is really hard to use it as a reference for anything. Usually, VO2Max is tested using the Cooper Test. The test can be done, for example, using the Endomondo app. To find out your real VO2Max you should perform the test properly:
- ...Run for 12 minutes
- ...As fast as you can (if your body will need to slow down, do so, just get the 12 minutes done)
- ...On the flat surface
Then you can compute your VO2Max using the Cooper Test formula:
VO2Max = (35.97 x 12_minutes_distance_in_miles)
You can see whether it's any close to what Fitbit shows. Mind that VO2Max may not improve even if you perform better with each run. Genetics, age, and gender are responsible for a very significant part of that metric. Not sure whether it helps but your cardio score may change if you go for runs which are based on the Cooper test rather than doing many runs with a similar pace etc.
