Readiness Score and Zone Minutes

[Bill_209]

The Readiness Score used to be calculated based on activity level, sleep quality and HRV and there appeared to be a correlation between zone minutes and readiness score before Cardio Load was introduced as a performance metric.  On days that I exceeded the zone minute target, I got a lower readiness score the next day, which seemed to make sense.

After Cardio Load was introduced, the Readiness score was changed to be based upon RHR, sleep quality and HRV, so I assumed that activity level (zone minutes) was no longer used to calculate the readiness score.

However, now my zone minute target remains fixed at 22 and when I work hard to 'meet' my Cardio Load target and that results in me exceeding my zone minute target, my readiness score goes way down the next day.

Are zone minute targets still being used to determine daily readiness now?  If not, what are zone minutes being used for since Cardio Load was introduced?

[RiekoC · Accepted solution]

Hello @Bill_209 

I'll explain as best as I understand Daily Readiness score & Active Zone Minutes.

As you said, the Daily Readiness score was updated to indicate how well your body recovered from recent activity based on sleep, RHR, & HRV. Active Zone Minutes are not included in the algorithm calculation.

When your Readiness score goes way down, do you look at the page to see which factors impacted your score? I've noticed that my Daily Readiness score will be on the lower side if my RHR is higher than usual and/or my HRV is lower than usual. My sleep score tends to be in the 80's, so it's rarely a factor.

Fitbit's Active Zone Minutes are in line with the current CDC & WHO activity recommendations for a minimum of 150 min/wk of moderate activity or 75 min/wk of vigorous activity or a combination of the two (CDC Source) . The daily AZM of 22 is the target to reach the weekly goal of 150 minutes of moderate activity.

Please let us know if you have more questions.

[Bill_209]

Thanks for the explanation, @RiekoC.

I don't dispute Fitbit's Active Zone Minute recommendations, but it would be almost impossible for most people not to get at least 150 Zone Minutes in a week, so I can see where the Cardio Load metric might be more useful, based upon what I've read about it.

As an example, I had 110 Zone minutes and a Cardio Load score of 51 yesterday, with a target of 52 - 76.  Today, I had a low readiness score of 25 and I am 'maintaining' my cardio load.  The low readiness score was reportedly due to my HRV being 29% lower than usual and my RHR being 4% higher than usual.

Since Cardio Load is a function of both heart rate zones and the duration within those zones, I guess that I can see were getting a specific cardio load number doing yard work or any kind of resistance training is going to be much harder on your body than getting the same cardio load number taking a brisk walk.

[RiekoC]

You're welcome, @Bill_209 .

When I was working, my job was very sedentary as I spent most of my time at my desk on the computer or in meetings. I don't doubt that there would have been weeks where getting 150 AZM would have been a challenge for me. It's not an issue for me, now that I'm retired.

One of my friends had a very good description for Cardio Load: training stress. I think that goes perfectly with your example of yard work/resistance training versus taking a brisk walk. 😁

[Bill_209]

It appears that the trick to improving one's fitness without burning out is to choose activities and exercises on a daily basis that always help to keep the Cardio Load number within or somewhat above rhe cardio load target range, without significantly exceeding the Zone Minute target.

[RiekoC]

That's a great way to look at it, @Bill_209 

I believe there's soon going to be a Fitbit blog post about Cardio Load & Cardio Target Load. Hopefully, that will help users understand the feature & how to use it.