Frequency of measurement from wearables:HR and HRV

We frequently get asked if we have any info on how often wearable devices measure data. Since we could not find a compiled list of how often heart rate (HR) and heart rate variability (HRV) readings are taken for different wearables, we decided to make one.

Knowing the measurement frequencies for different health metrics, especially for HR and HRV, is an important consideration when choosing which wearable is right for you or when comparing health trends between two or more wearables.

The recording frequency of a wearable, for this discussion, refers to how often a wearable device stores a measurement that you can then view using a fitness app or obtain using our API. We are not referring here to the actual sample rate of the wearable's sensor, but instead to how often HR and HRV readings are stored for use. For instance, your heart rate throughout the day is recorded every 5 minutes on an Apple Watch, but it may sample many times a second when actually measuring your HR to obtain an accurate reading.

For this article, the measurement frequencies of heart rate and heart rate variability are compared for a variety of wearables. For heart rate, the frequencies for HR readings taken throughout the day as well as the frequencies for continuous heart rate tracking are noted.

Let's take a look at the table below. We have noted which wearables support HR and HRV, and the corresponding measurement frequencies for both.

Some things to note. Continuous tracking for most wearables is a feature that is only activated during workouts and certain activities. For example for certain wearables, when you initially sit down after spending time standing up, an accurate resting heart rate reading is taken using continuous heart rate tracking.

Most wearables' standard measurement frequency is 5 minutes for HR readings when not continuous. Continuous measurement frequencies are typically 5 seconds. Garmin, Samsung, Suunto, and Coros tout 1 second measurement frequency for their wearables that offer continuous heart rate tracking. Polar wearables feature continuous heart rate tracking, but they only store readings every 5 minutes.

HRV has greater variation in terms of its measurement frequency for different wearables, the lowest current measurement frequency is 5 minutes for some of the wearables listed above. Most wearables still only measure HRV periodically due to the high sensitivity of HRV readings (see this article for more on HRV and wearables). However, Garmin do state that they track HRV continuously and provide an average HRV value every 5 minutes.