Heart Rate Variability measurements recorded by your Apple Watch can give you insight on the stress level your body is under. By using HRV Tracker to track short-term measurements and long-term trends, you can see how your workload during the day, workout sessions or sleeping etc affect your body's readiness, recovery and stress level. Simply put, the higher your HRV is, the better.
*Requires an Apple Watch with watchOS 5.2 or later*
HRV Tracker makes spotting drops in your HRV easy by monitoring your HRV measurements in the background and showing notifications after your HRV drops under your desired level. HRV Tracker will monitor drops in individual measurements and also your 24 hour HRV average. You can change the default notification levels directly in your Apple Watch app. Please note that notifications can get postponed for example because of a low battery level.
***Apple Watch for daily tracking***
Browse through last seven days of HRV measurements by using the digital crown. See how measurements compare to your seven day period and individual days. By tapping the graph you can toggle through the first values of each day. Use complications on your Apple Watch to stay informed on changes in your HRV.
***Compare HRV to other key metrics***
Find possible causes for changes in HRV by using the comparison graphs available on your Apple Watch.
-Estimated sleep hours per night (no additional sleep tracker needed). Either wear your Apple Watch while sleeping or take your Apple Watch of your wrist before going to bed and put it back on after waking up.
-Custom activity score that emphasizes the intensity of daily activity. As an example a day with multiple hours of casual walking could get a lower activity score than a day with just 30 minutes of fast running.
-Daily resting heart rate (RHR).
All data used by comparison graphs is automatically produced and calculated just by wearing your Apple Watch. Toggle between comparison graphs by tapping the upper part of the screen.
***Follow Long-term HRV trend***
Follow your long-term HRV trend on your iPhone and compare your short term measurements to all-time data. Please note that for now the iPhone counterpart app does not contain the sleep, activity and resting heart rate comparison graphs available on the Apple Watch.
Data read from the Apple HealthKit database is only used to show information related to your Heart Rate Variability. Information read by HRV Tracker is only stored and used locally on your iPhone and Apple Watch.
***How is it measured***
Heart rate variability measurements used by HRV Tracker are calculated by measuring the variation between individual heartbeats. Your Apple Watch automatically measures your HRV in the background and stores the outcome into HealthKit. HealthKit uses SDNN heart rate variability, which is calculated using the standard deviation of the inter-beat (RR) intervals between normal heartbeats (measured in milliseconds). Besides background measurements generated automatically by your Apple Watch you can use the Breathe app on your Apple Watch to generate new measurements.