Zone 2 AI: Vo2 Max & Endurance
Heart Rate Zones & Training
Free · In-App Purchases
Zone2AI turns your Apple Watch or Garmin into a personal endurance coach.
Train in your personal Zone 2 heart rate range — calculated from your real data and refined after every workout. Build your aerobic base, burn fat efficiently, and raise your VO2 max with the Norwegian 4x4 sprint protocol.
- Personalised heart rate zones that adapt with your RPE feedback
- AI coaching with real-time insights after every session
- Sprint credits + guided 4x4 intervals for your VO2 max
- Power Score: watts per kg in Zone 2 — watch your efficiency grow
- Works with Apple Watch and Garmin
Build your engine. Start today.
Zone2AI Pro (in-app purchase) is required to use the app beyond setup: a weekly or annual auto-renewing subscription, or a one-time lifetime purchase. Prices are shown in the app before you buy, and every feature described here is included in Pro.
Ratings & Reviews
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Your fitness age, and where it is going.
Open the Age tab and your number is right there, poster size, with the sentence that explains it and the line from where you are to where six months of your plan takes you. Below it, new: the trend. Where your fitness age was when you started, where it is today, and your VO2 max beside it, each on its own line. One tap shares the card.
Put it on your Home Screen. Two new widgets: Fitness Age, with your last seven days of Zone 2 and your VO2 max, and VO2 Max on its own, which lights up the day a new reading lands. Both work on the Lock Screen too.
One range scores everything. The Zone 2 range you see on Home is the range behind every session, on the celebration, on Today and on your week, this week and every week before it.
The Zone 2 habit is how the number gets younger. Easy, conversational-pace minutes are the fastest lever on it, and this is the app built around them: a range from your own resting heart rate, VO2 max and age, five levels from Restoration to Apex, and a coach who reads the week around the workout. Four straight weeks on plan now count for more.
Outdoor sprints save as runs. A 4x4 on the road lands in Apple Health as an Outdoor Run with its route and distance; indoors it stays an interval session.
Settings, What You Told Us: every input behind your numbers, now editable, including your resting heart rate.
Built for Apple Watch and Garmin.
The developer, Unbounded Technologies LLC, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Used to Track You
The following data may be used to track you across apps and websites owned by other companies:
- Purchases
- Identifiers
Data Linked to You
The following data may be collected and linked to your identity:
- Purchases
Data Not Linked to You
The following data may be collected but it is not linked to your identity:
- Health & Fitness
- Identifiers
- Usage Data
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Provider
- Unbounded Technologies LLC
- Size
- 89.9 MB
- Category
- Health & Fitness
- Compatibility
Requires iOS 17.6 or later.
- iPhone
Requires iOS 17.6 or later. - Apple Watch
Requires watchOS 11.2 or later.
- iPhone
- Languages
- English
- Age Rating
9+
- 9+
- Contains
Health or Wellness Topics
- In-App Purchases
Yes
- Unlimited Access USD 29.99
- Premium Lifetime USD 39.99
- Lifetime Unlimited Premium USD 29.99
- Unlimited Premium Annual Access USD 29.99
- Weekly Premium Access USD 3.99
- Lifetime USD 29.99
- Zone2AI Pro Six Months USD 19.99
- Unlimited Access USD 3.99
- Lifetime USD 39.99
- Unlimited Access USD 29.99
- Copyright
- © 2026 Unbounded Technologies LLC

