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How to increase the Apple Watch HRV sampling rate

There is a simple trick you can use to increase the frequency of heart variability (HRV) measurements on the Apple Watch.

HRV readings are useful. This data feeds into algorithms which estimate your level of fatigue. And recovery metrics have become all the rage in the last year or two. Previously these types of stats were limited to Whoop, Oura and a few other devices. Now you have a plethora of watches from Garmin, Polar and others spitting out all sorts of recovery metrics.

The Apple Watch is a bit behind the game on this count. While the latest version of the operating system does bring a bunch of useful performance metrics, particularly for runners, recovery stats based on HRV are not present.

Essential readingTop fitness trackers and health gadgets

Of course, you can tap into third party options such as Athlytic, connect it to your Apple Watch and get the recovery stats. The problem is the sampling rate. By default, the Apple Watch only takes an HRV measurement every 2-5 hours which is not nearly frequent enough.


The simple hack

But there’s a simple hack that will increase this sampling rate. What you need to do is set-up the Apple Watch so that it looks out for Afib. This is a chronic condition that is a specific type of irregular heart rhythm where the upper chambers of the heart beat out of sync with the lower chambers. 

Switching Afib History on will automatically switch off irregular heart rhythm notifications. So you will lose access to that feature.

“Since the irregular rhythm notification is not intended for people with Afib, it is turned off automatically when you set up Afib History.” Apple writes on its support pages.

To enable Afib History, open the Health app and go to the Heart page. Choose AFib History > Set Up. Then answer the questions to complete the process.

It turns out, when looking out for AFIb, the Apple Watch takes HRV measurements more frequently, about every hour or so depending on the type of activity you are engaged in.

It is not ideal to have to do this to get more frequent measurements of HRV, but it does the job. Presumably, Apple has done this in order to preserve battery life, which is pretty miserable as it is. But this simple tweak means you can now use third party software to calculate your readiness to train with more precision.

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