How to Handle HRV Outliers

If you notice HRV outliers in your data—such as very large spikes—Athlytic provides an option to filter out these anomalies using the rMSSD method for HRV calculation.

What Causes HRV Outliers?

HRV (Heart Rate Variability) is calculated using beat-to-beat heart rate data recorded by your Apple Watch. Occasionally, Apple Health may record unusually high or low HRV values due to:

✔️ Inconsistent heart rate readings

✔️ Movement artifacts (e.g., wrist movement affecting readings)

✔️ HR measurement errors from Apple Watch sensors

By default, Apple calculates HRV using the SDNN method, which may include unfiltered HRV spikes and outliers.

How to Filter Out HRV Outliers in Athlytic

To reduce the impact of HRV spikes and artifacts, you can enable rMSSD for HRV in Athlytic’s settings.

How to Enable RMSSD

Open Athlytic on your iPhone.
Go to More tab → Recovery Preferences.
Toggle ON “Use RMSSD for HRV.”

✔️ When ON → Athlytic calculates HRV using the rMSSD method, filtering out artifacts from your beat-to-beat measurements prior to calculating your HRV

❌ When OFF → Athlytic uses Apple’s default HRV samples (SDNN method), which are unfiltered and may contain outliers.

Important Notes About Syncing RMSSD Data

Turning on RMSSD requires syncing across all Athlytic apps (iPhone, iPhone Widget, Watch, Watch Widget).
It may take a few hours for everything to fully sync after enabling RMSSD.
If you frequently toggle RMSSD on and off, data may get out of sync temporarily.
This setting may also increase your load time since it requires additional data.

If none of these troubleshooting steps resolve the issue, consider reaching out to Athlytic support for further assistance.