Where do I check the alert threshold?
On your iPhone, open the Watch app, then My Watch, then Heart. High Heart Rate and Low Heart Rate show the beats-per-minute limits you selected. These limits are notification settings, not a diagnosis.
Apple Watch heart-rate notifications
Apple Watch Heart Rate Alerts: High, Low and What to Do
A high or low heart-rate alert means Apple Watch detected a heart rate that stayed beyond your selected notification limit. It does not explain the cause or diagnose a heart condition. Check how you feel first, then review the reading, your settings, and what was happening at the time.
Educational only, not medical advice. LongevityMate is not affiliated with Apple. Last reviewed: September 6, 2026.
Quick rule
Context before panic
Check whether the alert was high or low, the BPM threshold, and what you were doing around it.
Compare the alert with resting heart rate, walking average, workout heart rate, HRV, sleep, stress, and symptoms.
Check Low Power Mode, Heart Rate, Wrist Detection, watch fit, tattoos, cold exposure, and sensor reliability before reacting to one reading.
Do not use a high or low heart-rate notification as a diagnosis, all-clear, medication-change reason, or training clearance.
If you have chest pain, pressure, tightness, severe shortness of breath, fainting, or symptoms that feel urgent, call emergency services immediately.
It still needs context
Recent activity, stress, sleep, illness, heat, alcohol, caffeine, medication, sensor fit, and your usual baseline can all change how a heart-rate alert should be read.
Why might I get no notification?
Low Power Mode disables high and low heart-rate notifications. The watch also cannot detect a heart attack. Get medical help for concerning symptoms even if it shows no alert.
Do not treat an alert as a diagnosis or all-clear
Apple says Apple Watch cannot detect heart attacks, may not get a reliable heart-rate reading every time for everybody, and should not be used to change medication without talking to your doctor. If you feel unwell, get medical help even without a notification.
Put the alert beside the rest of the pattern
LongevityMate is built around joining heart-rate alerts, resting heart rate, HRV, sleep, stress, training load, ECG context, AFib context, blood work, goals, and Mate follow-up questions.
Is it different from irregular rhythm alerts?
Yes. High and low heart-rate notifications are based on a BPM threshold. Irregular rhythm notifications occasionally look for a rhythm that may be suggestive of AFib. Treat those as different signals.
Source context used for this guide
Apple support, Apple Watch User Guide, MedlinePlus, and CDC guidance describe heart-rate notifications, sensor limits, arrhythmia symptoms, heart-attack emergency guidance, and when to involve a clinician. Use those details as prompts for better questions, not as care instructions.
Follow for calmer Apple Watch heart context
We post plain-English high and low heart-rate alerts, resting heart rate, HRV, ECG, Apple Watch, wearable, blood-work, and Mate updates without turning one alert into the whole plan.