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How to Get a Zone 2 Alert on Apple Watch (So You Stop Drifting Into Zone 3)

Zone 2 is easy to start and hard to stay in. Ten minutes into a run, a hill or a warm day pushes your heart rate up a few beats, it feels fine, and you finish the session in Zone 3. A wrist tap the moment you leave the zone fixes that. Apple Watch can do it in two ways.

Short version: Zone2AI sets your Zone 2 from your own heart and taps your wrist when you drift. Get it on the App Store →

Option 1: Apple's built-in heart rate alert

The Workout app can tap your wrist when your heart rate leaves a zone or a range you choose. Set it once per workout type:

1. Open the Workout app and turn the Digital Crown to the workout you use for Zone 2, for example Outdoor Walk or Indoor Cycle.
2. Tap the More button (the three dots) on that workout, then the Edit button.
3. Scroll to Alerts and tap Heart Rate.
4. Choose Zone and pick Zone 2, or choose Range and type a low and a high number yourself.

From then on, every workout of that type taps your wrist when you go above or below. Repeat the steps for each workout type you train in.

The catch: the alert is only as good as the zone

If you pick Zone, the watch uses Apple's own Zone 2. Apple's support page describes its zones as a percentage of your maximum heart rate, calculated automatically once you have entered your date of birth. That maximum is an estimate from your age. Two people of the same age get the same Zone 2, even if one of them has trained for twenty years and the other is starting this month.

If you pick Range, the numbers are yours to choose, and most people have no good way to choose them. Finding your true maximum takes an all-out effort, which is not a fair ask for most people over 40. We wrote the long version in Why Your Apple Watch Zone 2 Is Wrong.

Your range also moves. Resting heart rate changes with fitness, sleep, stress and season, so a range typed in once in January is out of date by spring.

Option 2: an alert on a range built from your own heart

Zone2AI does the same job with a range that fits you. It anchors your Zone 2 on the highest heart rate seen in your own workouts and your 30-day resting heart rate, grades it by your VO2 max, and starts a workout on your wrist with that range on screen.

During the session the watch taps you when you drift: a blue pulse means speed up, an orange pulse means slow down. After the session you answer one question, how hard it felt, and the range adjusts for next time. Too easy, it nudges up. Could not hold a conversation, it comes down.

Which one should you use?

If you already know your Zone 2 numbers from a lab test, Apple's Range alert is free and works well. Type the numbers in and go.

If you don't, or if the range Apple gives you feels too hard to talk in or too easy to break a sweat, use a range built from your own data and let it adjust with you. The alert matters less than the numbers behind it.

Three habits that keep you in Zone 2

• Start slower than feels necessary. Heart rate lags effort by a minute or two. Most drift happens because the first ten minutes were too fast.
• Slow down on hills, don't push through. Walk the climb if you have to. Zone 2 is about the heart, not the pace.
• Use the talk test as a backup. In Zone 2 you can speak in full sentences. If you can only get out a few words, you are above it, whatever the screen says.