How to improve my cardio score?

[Shelvis]

Can I really only improve my cardio score by going for a run?

I have been working out loads over the last 6 weeks and am a lot fitter. My RHR has dropped from 69 to 57 but my cardio fitness score is unchanged. It tells me to go for a run to improve accuracy is that really the only measure? I had to stop running due to an injury.

Moderator Edit: Clarified subject

[LZeeW]

Hello @Shelvis and welcome to the Help forums.  Congratulations on your fitness accomplishment!

I think a little explanation might help.  Your cardio fitness score is an estimate of your VO2 max, the maximum amount of oxygen you can use during exercise.  Your Fitbit makes an estimate and gives you a range based on your daily activity.  But there are equations that can give a better estimate by measuring distance and heart rate.  Doing that GPS run improves the accuracy of the estimate.  When you do a run, you will get a single number, not a range.  

There are other ways to estimate VO2 max that don't involve running.  If you put "VO2 max calculator" in a search engine, you will find other options.  I am confident that you will be able to find a way to follow your cardio fitness that doesn't involve running, but might take a little more effort on your part.