Heart rate doesn't record accurately on some activities - fēnix 5 series - Wearables - Garmin Forums
Garmin Fenix 5 Review: The Best Outdoor GPS Watch | Tom's Guide
Heart rate chart (widget) | Garmin Connect IQ
PSA: Look at the heart rate sensor of your fenix 5. Has it cracks like mine? If yes, it's a common problem. Send it to Garmin and get a free replacement. Do
Garmin Fenix 5x Plus Sapphire Sports Watch | R&A Cycles