Fitness Score Sudden Decline

[Azode7]

I don’t check my fitness score often but it’s usually on the higher side of average. I do a variety of workouts including orange theory and Pilates regularly. I also lift weight and ran a sub 9 min mile this week (which is decent for someone over 50). I’ve had some slightly shorter nights sleep and a slight increase in my RHR from 54 to 59 over the past two weeks but now my cardio fitness score is down from a 27 where it’s been for years to a poor 20.  
It’s making me want to just ignore this metric all together now. And since there is no trend data I don’t really know when this changed. I look at it about once a month and it’s not really changed. 

[LZeeW]

Hello @Azode7 and welcome to the Community.  Your Cardio Fitness Score is an estimate of your VO2max, the maximum amount of oxygen your body can use during exercise.  Orangetheory workouts can improve and maintain VO2max.  Pilates and weight training do not.  Fitbit uses your resting heart rates as one factor to estimate your VO2max.  Your increased RHR is playing a role in your change.  It probably increased your average heart rate during your run.  Fitbit used to include the following explanation in its Help article.  If you have two otherwise identical people running side by side, the person with the lower average heart rate has the higher VO2max.  This Cardio Fitness Score  Help article has more information.

[Azode7]

The articles don’t really address the issue. And I found the old data and it was 45 one for weeks and then night it dropped to 20 and remained there ever since. I continue to do a lot of running and the number remains at 20 for over a month now. One thing I’ve noticed is that the auto workout keeps coming on when I’m just walking around my house trying to get steps.