How are daily readiness and cardio load calculated?

[LeslieFok]

I understand Dail Readiness and cardio Loads are related.  But how are they calculated?  Since Sleep score is a component of Daily Readiness, how the sleep score is calculated should be re-explored.  Some days I have very little deep sleep, even though I had a load of zone minutes.  The sleep score indicates fair.  But yet the Readiness score is "high".  Further to cardio load, it indicates 2-25, which is the lowest setting, I think.  It matches the deep sleep I had, but how does it make readiness "high"? 

Also, the cardio load does not match zone minutes.  Yesterday, I had 75 zone minutes, but a cardio load of 91?

I know I shouldn't ask more than one question, but all these are getting very confusing.

[robworkingout]

. I think heart rate max-min contributes alot towards the cardio load stats. Also remember the cardio load uses the Average over the last 7 days. So when looking at your sleep patterns take into account the past 7 days. This also applies to heart rate. So a single day of low activity or high intensity may not change much with your cardio load. I think the cardio load feature takes most notice of the highs/lows heart rate Obviously many other stats can’t make a difference. 

[RiekoC · Accepted solution]

Hello @LeslieFok 

This help page describes how Cardio Load and Cardio Target Load are calculated (<-- click link) and this one describes how the Daily Readiness score is calculated (<-- click link).

The Daily Readiness score and Cardio Target Load ranges are not directly related. The Daily Readiness score identifies how well your body has recovered from your previous activities based on your sleep data. The Cardio Target Load range is based on your fitness goal - Maintain/Improve - and your activities from the past 7 days. You can have a High readiness score, meaning your body has recovered, and low Cardio Target Load. I have gotten this, like you have.

Also, there isn't a 1-to-1 correlation between the Cardio Load "points" and Active Zone Minutes. If there was, they would be redundant & we wouldn't need to have both of them.

[LeslieFok]

Thank you.

[RiekoC]

You're very welcome, @LeslieFok  😁

[LZeeW]

@LeslieFok   I just want to add a few things.  First, you mentioned your previous night's sleep.  Your Daily Readiness Score used to look at last night's sleep.  It was updated to look at your last week of sleep.  Second, Fitbit looks at your last four weeks of cardio load in addition to your last seven days.  It is looking for acute and chronic changes.  Finally, like @RiekoC wrote, there is no correlation between active zone minutes and cardio load.  AZMs are calculated using simple arithmetic.  Cardio load calculation is much more complicated.  AZMs measure activity.  The best real wold description for cardio load that I found is training stress.