How to achieve accurate Cardio Recovery readings.

How it works.

Often called heart rate recovery, this is an estimate of how quickly your heart rate can drop after you reach your peak heart rate during exercise. It's estimated by tracking the change in your heart rate one minute after you stop exercising.

The higher your value of Cardio Recovery, the better. It can be an indicator of your cardiovascular health.

So it is important to finish your workout near your high working heart rate, but avoid a sprint finish or the rate may well increase after the workout before it recovers.

I suggest that, apart from races,you keep sprints to the middle of your workout (Fartlek training).

Set a suitable split distance with haptic notifications of say, 250m and make sure that your final 250m split is within your normal working heart rate range by running at an average  pace so that it is not on the rise when you finish.

For run, walk, etc you should Set split notifications according to this user tip         

How to set up workout splits with notific… - Apple Community

You can set audio heart rate notifications according to this user tip 

How to create a heart rate notification w… - Apple Community

It is important that "warming down" happens after a running workout

Finishing on a sprint and then immediately resting or driving back home is not good for physical recovery. 

Certainly Apple Health cardio recovery results can appear terrible after a series of sprint finishes. 

It is important to have the last split near the top of your set HR working range. However a further 200m walk after ending the workout will help warm-down and show true cardio recovery.