Active minutes aren’t based only on relative heart rate and continuous duration?

[techprof]

I’m “new again” to Fitbit after five years without one and am trying to figure out how heart rate figures in now. I thought I understood from reading other posts that active minutes are based on intensity as assessed by heart rate changes during an activity along with a minimum duration, and that a brisk walk that shows exertion can give you active minutes. I’ve been taking a 10 to 15 minute work break during which I jog until I feel like I’m risking sweating too much for work, then I switch to a walk. I’m not sure whether to log this as a walk or a run. (I like the stats I get from logging vs GPS tracking.) Today I experimented. I first logged the 18 minutes of my walk/jog as walking. Fitbit told me this was 12 minutes cardio and six minutes fat burn and did not give me credit for any active minutes. Then I logged a second activity for exactly the same time span (so same total length, same heart rate, same 12 min cardio and 6 min fat burn) and called it a run. Fitbit gave me credit for 18 active minutes after I changed the label. (It also changed the recorded distance, understandably making different stride length assumptions.) I think this hybrid activity should be counted as active minutes so I deleted the walk entry, but this leaves me wondering about Fitbit’s apparent assignment of intensity based on my having changed the label rather than based on the measured heart rate and cardio percentage. I thought Fitbit would estimate a personal MET knowing my resting rate and heart rate during exertion rather than going by the label I put on the activity. What am I not understanding about how Fitbit uses my resting vs exertion heart rate measures and how it assigns active minutes?

I’m using an Inspire HR.

Thanks!

[Rich_Laue]

Simply recording a period as an exercise does not affect recorded active minutes. 

Let's go to Fitbit help. 

What are active minutes?

[techprof]

Can you explain further please? I had read that article and many posts about this prior to posting my question. My experience was different than I expected based on what I had read, with active minutes posted when an exercise was labeled as running but not when the same exercise was labeled as walking.

[techprof]

Rich, here’s another detail. I saw that you said logging wouldn’t change active minutes, and since that wasn’t my experience, I tried another experiment. I added two minutes to the end of the logged exercise described previously, knowing that my heart rate would still be in the fat burning zone during a recovery period. Extending the length of time of that activity by two minutes did give me two more active minutes.