Zx: Heart Rate Zones Training
Interval Timer & HIIT Trainer
Free · In‑App Purchases
Zx is your personal heart rate coach designed to guide you through your interval training. Create your own interval workouts or download workouts created by the community. Official Zx workouts are updated regularly. Zx supports Apple Watch or any compatible stand alone bluetooth heart rate monitor.
◎ Benefits of HIIT:
- Weight loss
- Improve your body’s ability to burn fat
- Increase your anaerobic threshold
- Improve your vo2Max
- Improve performance in sports
- Feel better by releasing beta-endorphins
- More fun then steady state training!
◎ Integrates with the Health app to gain deep insight into your training:
- View relevant Heart Rate and Workout stats for Day, Week, and Month on the home screen
- See which zone your workout heart rate has spent the most time in to help you plan your next workout.
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App Features
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◎Open Mode (Apple Watch only):
- Not up for a guided session? Open session lets you see what Zone you’re in and how long you’ve been in it.
◎ Guided Interval Training
- Zx will help you stay in a specific zone for the right amount of time.
◎ Create custom workouts
- Studio lets you create custom guided training suited to your personal goals
◎ Download workouts created by other users
- See what other users have created, download and remix.
Health Disclaimer: Zx cannot treat or diagnose any medical condition. Zx is designed to push you to your maximum heart rate; while there shouldn’t be cause for concern with healthy individuals, always consult with your physician prior to starting any training regimen.
Subscription Terms: Your subscription automatically renews every month or year unless auto-renewal is turned off at least 24 hours before the end of the current subscription. 3 day free trial is provided for monthly subscriptions. You will be charged starting at $2.99 per month, depending on the subscription pack. Your account will be charged for a renewed subscription within 24 hours prior to the end of current subscription. You can manage your subscription and switch off the auto-renewal by accessing your iTunes account settings after purchase. You cannot cancel the current subscription during the active subscription period. Any unused part or time-span of a free trial period will be forfeited, as soon as you purchase a subscription. Buy subscribing, you affirm your agreement to our Terms of Use and Privacy Policy.
Terms of Use:
https://www.oversphere.net/terms-of-use/
Privacy Policy:
https://www.oversphere.net/privacy-policy/
- Fixed a Studio issue preventing small intervals from being added to custom workouts.
The developer, OverSphere 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 Linked to You
The following data may be collected and linked to your identity:
- User Content
Data Not Linked to You
The following data may be collected but it is not linked to your identity:
- Identifiers
- Usage Data
- Diagnostics
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- OverSphere LLC
- Size
- 53.8 MB
- Category
- Health & Fitness
- Compatibility
Requires iOS 18.0 or later.
- iPhone
Requires iOS 18.0 or later. - Apple Vision
Requires visionOS 2.0 or later. - Apple Watch
Requires watchOS 9.0 or later.
- iPhone
- Location
- This app may use your location even when it isn’t open, which can decrease device battery life.
- Languages
English and 9 more
- English, Dutch, French, German, Italian, Japanese, Korean, Portuguese, Simplified Chinese, Spanish
- Age Rating
9+
- 9+
- Contains
User-Generated Content
Health or Wellness Topics
- In-App Purchases
Yes
- Premium Monthly $0.99
- Premium Lifetime Access $14.99
- Premium Monthly $2.99
- Premium 6 months $7.99
- Premium 6 months $9.99
- Premium Yearly $24.99
- Copyright
- © 2026 OverSphere LLC